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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 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.

  4. 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.

  5. Optical Computing: Childhood's End

    NASA Astrophysics Data System (ADS)

    Caulfield, H. John; Goodman, Joseph W.; Guenther, Bob D.; Hendrickson, Brian M.; Neff, John A.; Rhodes, William T.; Turpin, Terry M.

    1990-02-01

    For the quarter of a century I have been involved in optical computing we have put forward a rather consistent set of arguments and beliefs which have led to a great increase in our numbers, knowledge, funding, and capabilities. I believe we must now challenge these basic tenants of our faith in the name of honesty and in the hope of a brighter future.

  6. 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.

  7. 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.

  8. Optical design using computer graphics.

    PubMed

    Howard, J M

    2001-07-01

    For decades the computer has been the primary tool used for optical design. Typical tasks include performing numerical calculations for ray tracing and analysis and rendering graphics for system drawings. As machines become faster with each new generation, the time needed for a particular design task has greatly reduced, allowing multiple assignments to be performed with little noticeable delay. This lets the designer modify a system and then immediately see the results rendered in graphics with a single motion. Such visual design methods are discussed here, where graphics of systems and plots relating to their performance are produced in real time, permitting the optical designer to design by pictures. Three examples are given: an educational tutorial for designing a simple microscope objective, an unobstructed reflective telescope composed of three spherical mirrors, and a modified Offner relay with an accessible pupil. PMID:11958264

  9. Hybrid (optical/electronic) computing and digital computing

    NASA Astrophysics Data System (ADS)

    Lee, Sing H.

    1988-06-01

    The program consists of two areas of optical information processing: (1) optical-analog/electronic hybrid computing for optical image processing, optical pattern recognition and solution of partial differential equations, and (2) nonlinear optical devices and digital optical computing. The optical-analog/electronic digital hybrid system consist of an analog optical processor with input/output interfaces to a microcomputer. The analog optical processor is employed to perform time consuming computations, while the logical decisions and controls are provided by an electronic microcomputer. For image processing we have implemented, with hybrid systems, numerous space-variant transformations (e.g., Hough transform for detection of high-order parametric curves, coordinate transform for rotation and scale invariant feature extraction, etc.).

  10. Recent advances in optical computing in Japan

    NASA Astrophysics Data System (ADS)

    Ishihara, Satoshi

    The results of recent Japanese research in optical and hybrid computer systems and components are summarized and illustrated with drawings and diagrams, and the organizational structure of the research efforts is outlined. Topics addressed include optical logic devices, spatial light modulators, two-dimensional lasers, optical bistable devices, device theory, optically controlled array processing, an optical bus for a multiprocessor system, real-time multiple-matrix-product processing, optical numerical processing, optical parallel-array logic systems, optical associative memory, and neural-network computation. Consideration is given to the roles of the Optical Computer Group of the Japan Society of Applied Physics, industry, and government (through the universities and Ministry of Education and through the Ministry of International Trade and Industry).

  11. Optical Interconnection Via Computer-Generated Holograms

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang; Zhou, Shaomin

    1995-01-01

    Method of free-space optical interconnection developed for data-processing applications like parallel optical computing, neural-network computing, and switching in optical communication networks. In method, multiple optical connections between multiple sources of light in one array and multiple photodetectors in another array made via computer-generated holograms in electrically addressed spatial light modulators (ESLMs). Offers potential advantages of massive parallelism, high space-bandwidth product, high time-bandwidth product, low power consumption, low cross talk, and low time skew. Also offers advantage of programmability with flexibility of reconfiguration, including variation of strengths of optical connections in real time.

  12. 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.

  13. Lower bounds on the computational efficiency of optical computing systems

    NASA Astrophysics Data System (ADS)

    Barakat, Richard; Reif, John

    1987-03-01

    A general model for determining the computational efficiency of optical computing systems, termed the VLSIO model, is described. It is a 3-dimensional generalization of the wire model of a 2-dimensional VLSI with optical beams (via Gabor's theorem) replacing the wires as communication channels. Lower bounds (in terms of simultaneous volume and time) on the computational resources of the VLSIO are obtained for computing various problems such as matrix multiplication.

  14. Optical computing at NASA Ames Research Center

    NASA Technical Reports Server (NTRS)

    Reid, Max B.; Bualat, Maria G.; Downie, John D.; Galant, David; Gary, Charles K.; Hine, Butler P.; Ma, Paul W.; Pryor, Anna H.; Spirkovska, Lilly

    1991-01-01

    Optical computing research at NASA Ames Research Center seeks to utilize the capability of analog optical processing, involving free-space propagation between components, to produce natural implementations of algorithms requiring large degrees of parallel computation. Potential applications being investigated include robotic vision, planetary lander guidance, aircraft engine exhaust analysis, analysis of remote sensing satellite multispectral images, control of space structures, and autonomous aircraft inspection.

  15. 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.}

  16. The Particle Beam Optics Interactive Computer Laboratory

    NASA Astrophysics Data System (ADS)

    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.

  17. Exploiting data redundancy in computational optical imaging.

    PubMed

    Munro, Peter R T

    2015-11-30

    We present an algorithm which exploits data redundancy to make computational, coherent, optical imaging more computationally efficient. This algorithm specifically addresses the computation of how light scattered by a sample is collected and coherently detected. It is of greatest benefit in the simulation of broadband optical systems employing coherent detection, such as optical coherence tomography. Although also amenable to time-harmonic data, the algorithm is designed to be embedded within time-domain electromagnetic scattering simulators such as the psuedo-spectral and finite-difference time domain methods. We derive the algorithm in detail as well as criteria which ensure accurate execution of the algorithm. We present simulations that verify the developed algorithm and demonstrate its utility. We expect this algorithm to be important to future developments in computational imaging. PMID:26698693

  18. 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.

  19. Silicon Photonic Devices for Optical Computing

    NASA Astrophysics Data System (ADS)

    Qiu, Ciyuan

    The requirement for high performance computer will be significantly increased by the fast development of the internet. However, traditional CMOS computer will meet its bottleneck due to the miniaturization problem. Optical computer comes to be the leading candidate to solve this issue. Silicon photonic technology has tremendous developments and thus it becomes an ideal platform to implement optical computing system. In Chapter 1, I will first show the development of the optical computing and silicon photonic technology. I will also discuss some key nonlinear optical effects of silicon photonic devices. Based on the current silicon photonic technology, I will then make a brief introduction on the optical direct logic for the 2D optical computing and spatial light modulator for the 3D optical computing, both of which will be discussed in detail in the followed chapters. In Chapter 2, I will discuss micro-ring resonator which is the key element of optical directed logic circuit discussed in Chapter 3. I will give the analytical model based on photonic circuit to explain the performance of the micro-ring resonator. The group delay and the loss of the micro-ring resonator will be analyzed. And I will also show the active tuning of the transmission spectrum by using the nonlinear effect of silicon. In Chapter 3, I will show a revised optical direct-logic (DL) circuit for 2D optical computer that is well suited for complementary metal-oxide-semiconductor (CMOS)-compatible silicon photonics. It can significantly reduce the latency compared with traditional CMOS computers. For proof of concept, I demonstrated a scalable and reconfigurable optical directed-logic architecture consisting of a regular array of micro-ring resonator based optical on-off switches. The switches are controlled by electrical input logic signals through embedded p-i-n junctions. The circuit can be reconfigured to perform any 2x2 combinational logic operations by thermally tuning the operation modes of

  20. Fast blur removal via optical computing

    NASA Astrophysics Data System (ADS)

    Suo, Jinli; Yue, Tao; Dai, Qionghai

    2014-11-01

    Non-uniform image blur caused by camera shake or lens aberration is a common degradation in practical capture. Different from the uniform blur, non-uniform one is hard to deal with for its extremely high computation complexity as the blur model computation cannot be accelerated by Fast Fourier Transform (FFT). We propose to compute the most computational consuming operation, i.e. blur model calculation, by an optical computing system to realize fast and accurate non-uniform image deblur. A prototype system composed by a projector-camera system as well as a high dimensional motion platform (for motion blur) or original camera lens (for optics aberrations) is implemented. Our method is applied on a series of experiments, either on synthetic or real captured images, to verify its effectiveness and efficient.

  1. Role of optical computers in aeronautical control applications

    NASA Technical Reports Server (NTRS)

    Baumbick, R. J.

    1981-01-01

    The role that optical computers play in aircraft control is determined. The optical computer has the potential high speed capability required, especially for matrix/matrix operations. The optical computer also has the potential for handling nonlinear simulations in real time. They are also more compatible with fiber optic signal transmission. Optics also permit the use of passive sensors to measure process variables. No electrical energy need be supplied to the sensor. Complex interfacing between optical sensors and the optical computer is avoided if the optical sensor outputs can be directly processed by the optical computer.

  2. Role of optical disk at computing centers

    SciTech Connect

    Peskin, A.M.

    1984-01-01

    Mass storage plays an increasingly important part in the changing role of the traditional open-shop computing center precipitation by the trend toward decentralization. A large number of mass storage applications are of the write-once type, for which the emerging optical disk technology is well suited. Some of the broad application areas are experiment data capture, shared reference data bases, program and documentation libraries, and medical studies requiring individual patient data. The utility of currently available optical disk products is being investigated for these applications for a variety of computing environments including those of IBM/sup tm/, DEC-VAX/sup tm/, and UNIX/sup tm/ products.

  3. Computational adaptive optics of the human retina

    NASA Astrophysics Data System (ADS)

    South, Fredrick A.; Liu, Yuan-Zhi; Carney, P. Scott; Boppart, Stephen A.

    2016-03-01

    It is well known that patient-specific ocular aberrations limit imaging resolution in the human retina. Previously, hardware adaptive optics (HAO) has been employed to measure and correct these aberrations to acquire high-resolution images of various retinal structures. While the resulting aberration-corrected images are of great clinical importance, clinical use of HAO has not been widespread due to the cost and complexity of these systems. We present a technique termed computational adaptive optics (CAO) for aberration correction in the living human retina without the use of hardware adaptive optics components. In CAO, complex interferometric data acquired using optical coherence tomography (OCT) is manipulated in post-processing to adjust the phase of the optical wavefront. In this way, the aberrated wavefront can be corrected. We summarize recent results in this technology for retinal imaging, including aberration-corrected imaging in multiple retinal layers and practical considerations such as phase stability and image optimization.

  4. Real-time computed optical interferometric tomography

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    High-resolution tomography is of great importance to many areas of biomedical imaging, but with it comes several apparent tradeoffs such as a narrowing depth-of-field and increasing optical aberrations. Overcoming these challenges has attracted many hardware and computational solutions. Hardware solutions, though, can become bulky or expensive and computational approaches can require high computing power or large processing times. This study demonstrates memory efficient implementations of interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO) - two computational approaches for overcoming the depthof- field limitation and the effect of optical aberrations in optical coherence tomography (OCT). Traditionally requiring lengthy post processing, here we report implementations of ISAM and CAO on a single GPU for real-time in vivo imaging. Real-time, camera-limited ISAM processing enabled reliable acquisition of stable data for in vivo imaging, and CAO processing on the same GPU is shown to quickly correct static aberrations. These algorithmic advances hold the promise for high-resolution volumetric imaging in time-sensitive situations as well as enabling aberrationfree cellular-level volumetric tomography.

  5. Analog optical computing primitives in silicon photonics

    NASA Astrophysics Data System (ADS)

    Jiang, Yunshan; DeVore, Peter T. S.; Jalali, Bahram

    2016-03-01

    Optical computing accelerators may help alleviate bandwidth and power consumption bottlenecks in electronics. We show an approach to implementing logarithmic-type analog co-processors in silicon photonics and use it to perform the exponentiation operation. The function is realized by exploiting nonlinear-absorption-enhanced Raman amplification saturation in a silicon waveguide.

  6. Analog optical computing primitives in silicon photonics.

    PubMed

    Jiang, Yunshan; DeVore, Peter T S; Jalali, Bahram

    2016-03-15

    Optical computing accelerators help alleviate bandwidth and power consumption bottlenecks in electronics. We show an approach to implementing logarithmic-type analog co-processors in silicon photonics and use it to perform the exponentiation operation and the recovery of a signal in the presence of multiplicative distortion. The function is realized by exploiting nonlinear-absorption-enhanced Raman amplification saturation in a silicon waveguide. PMID:26977687

  7. Optics Program Modified for Multithreaded Parallel Computing

    NASA Technical Reports Server (NTRS)

    Lou, John; Bedding, Dave; Basinger, Scott

    2006-01-01

    A powerful high-performance computer program for simulating and analyzing adaptive and controlled optical systems has been developed by modifying the serial version of the Modeling and Analysis for Controlled Optical Systems (MACOS) program to impart capabilities for multithreaded parallel processing on computing systems ranging from supercomputers down to Symmetric Multiprocessing (SMP) personal computers. The modifications included the incorporation of OpenMP, a portable and widely supported application interface software, that can be used to explicitly add multithreaded parallelism to an application program under a shared-memory programming model. OpenMP was applied to parallelize ray-tracing calculations, one of the major computing components in MACOS. Multithreading is also used in the diffraction propagation of light in MACOS based on pthreads [POSIX Thread, (where "POSIX" signifies a portable operating system for UNIX)]. In tests of the parallelized version of MACOS, the speedup in ray-tracing calculations was found to be linear, or proportional to the number of processors, while the speedup in diffraction calculations ranged from 50 to 60 percent, depending on the type and number of processors. The parallelized version of MACOS is portable, and, to the user, its interface is basically the same as that of the original serial version of MACOS.

  8. Parallel Algormiivls For Optical Digital Computers

    NASA Astrophysics Data System (ADS)

    Huang, Alan

    1983-04-01

    Conventional computers suffer from several communication bottlenecks which fundamentally limit their performance. These bottlenecks are characterized by an address-dependent sequential transfer of information which arises from the need to time-multiplex information over a limited number of interconnections. An optical digital computer based on a classical finite state machine can be shown to be free of these bottlenecks. Such a processor would be unique since it would be capable of modifying its entire state space each cycle while conventional computers can only alter a few bits. New algorithms are needed to manage and use this capability. A technique based on recognizing a particular symbol in parallel and replacing it in parallel with another symbol is suggested. Examples using this parallel symbolic substitution to perform binary addition and binary incrementation are presented. Applications involving Boolean logic, functional programming languages, production rule driven artificial intelligence, and molecular chemistry are also discussed.

  9. 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. PMID:27140113

  10. Parallel algorithms for optical digital computers

    SciTech Connect

    Huang, A.

    1983-01-01

    Conventional computers suffer from several communication bottlenecks which fundamentally limit their performance. These bottlenecks are characterised by an address-dependent sequential transfer of information which arises from the need to time-multiplex information over a limited number of interconnections. An optical digital computer based on a classical finite state machine can be shown to be free of these bottlenecks. Such a processor would be unique since it would be capable of modifying its entire state space each cycle while conventional computers can only alter a few bits. New algorithms are needed to manage and use this capability. A technique based on recognising a particular symbol in parallel and replacing it in parallel with another symbol is suggested. Examples using this parallel symbolic substitution to perform binary addition and binary incrementation are presented. Applications involving Boolean logic, functional programming languages, production rule driven artificial intelligence, and molecular chemistry are also discussed. 12 references.

  11. Integrated optical circuits for numerical computation

    NASA Technical Reports Server (NTRS)

    Verber, C. M.; Kenan, R. P.

    1983-01-01

    The development of integrated optical circuits (IOC) for numerical-computation applications is reviewed, with a focus on the use of systolic architectures. The basic architecture criteria for optical processors are shown to be the same as those proposed by Kung (1982) for VLSI design, and the advantages of IOCs over bulk techniques are indicated. The operation and fabrication of electrooptic grating structures are outlined, and the application of IOCs of this type to an existing 32-bit, 32-Mbit/sec digital correlator, a proposed matrix multiplier, and a proposed pipeline processor for polynomial evaluation is discussed. The problems arising from the inherent nonlinearity of electrooptic gratings are considered. Diagrams and drawings of the application concepts are provided.

  12. Sensitivity of volume holographic optical computing

    NASA Astrophysics Data System (ADS)

    Yi, Yao; Cao, Liang-cai; Zheng, Tian-xiang; Guo, Wei; He, Qing-sheng; Jin, Guo-fan

    2013-08-01

    Volume holographic correlator (VHC) calculates the inner product between two data pages through parallel optical correlation. It has great potential in the field of information processing and real-time identification because of its high storage density, integration of storing and computing, and multi-channel parallel processing ability. Current studies on the improvements of VHC mainly focus on the processing speed and channel uniformity. However, the accuracy of the VHC is mainly related to the minimum output intensity varying with the spatial light modulator (SLM) pixel intensity, which is the sensitivity of the VHC. In this work, the Minimum Pixel Block Size (MPBS) is proposed to characterize the sensitivity of the VHC. The Effective Number of Pixels (ENP) is employed to evaluate the optical computing ability, which is more accurate compared with traditional calculating method based on the pixel number of the SLM. The theoretical and experimental results are instructive in the system design. Desired system performance can be achieved by optimizing the system parameters.

  13. 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.

  14. 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

  15. A short history of optical computing: rise, decline, and evolution

    NASA Astrophysics Data System (ADS)

    Ambs, Pierre

    2009-10-01

    This paper gives a brief historical review of the development of optical computing from the early years, 60 years ago, until today. All the major inventions in the field were made in the sixties, generating a lot of enthusiasm. However it is between 1980 and 2000, that optical computing had its golden age with numerous new technologies and innovating optical processors been designed and constructed for real applications. Today the field of optical computing has evolved and its results benefit to new research topics such as nanooptics, biophotonics, or communication systems.

  16. Computer-controlled optical scanning tile microscope.

    PubMed

    Wang, C; Shumyatsky, P; Zeng, F; Zevallos, M; Alfano, R R

    2006-02-20

    A new type of computer-controlled optical scanning, high-magnification imaging system with a large field of view is described that overcomes the commonly believed incompatibility of achieving both high magnification and a large field of view. The new system incorporates galvanometer scanners, a CCD camera, and a high-brightness LED source for the fast acquisition of a large number of a high-resolution segmented tile images with a magnification of 800x for each tile. The captured segmented tile images are combined to create an effective enlarged view of a target totaling 1.6 mm x 1.2 mm in area. The speed and sensitivity of the system make it suitable for high-resolution imaging and monitoring of a small segmented area of 320 microm x 240 microm with 4 microm resolution. Each tile segment of the target can be zoomed up without loss of the high resolution. This new microscope imaging system gives both high magnification and a large field of view. This microscope can be utilized in medicine, biology, semiconductor inspection, device analysis, and quality control. PMID:16523776

  17. Computational design of an optic fiber temperature sensor

    NASA Astrophysics Data System (ADS)

    Campo Caicedo, Damián Andrés

    2012-06-01

    I will present a computational method for the analysis and design of a temperature sensor based on optical fiber. I will combine symbolic and numerical computations using the following software: Maple, for symbolic computation; Ansys: and Quick-Field for the numerical-graph computation of temperature profiles; Opticfiber for the numerical-graph computation of the electromagnetic modes in the fiber optics. The design strategy is to convert the patterns of temperature in changes of the refractive index of the fiber and the detection of changes in the electro-optical normal modes in the fiber. The proposed method has many advantages for the design of optical fiber sensors nowadays, for temperature measurements as well for other physical variables. We will use many special functions of Mathematical Physics such as the error function, Bessel functions, Kummer functions, Heun functiions, Whittaker functions and Laguerre functions. We will use Maple to make very complex computations with such functions.

  18. Hybrid (optical/electronic) computing and digital optical computing. Final report, 1 September 1985-31 August 1988

    SciTech Connect

    Lee, S.H.

    1988-08-31

    Hybrid optical-analog/electronic computing is performed for optical image processing, optical pattern recognition, and optical solution of partial differential equations. For example, image processing designed and fabricated space-variant filters to optically implement numerous space-variant transformation (e.g., Hough transform for detection of high-order parametric curves, coordinate transforms to detect rotation and scale-invariant features of images, etc.). For spike removal from noisy images, one can develop a new parallel algorithm suitable for optical/analog/electronic hybrid implementation. This parallel algorithm is space-variant and performs better than the space-invariant low-pass filter and the time-consuming median filter. Digital optical computing research develops nonlinear optical devices and studies their uses in parallel architectures for implementation of parallel algorithms. The nonlinear optical devices are based on integrating silicon with PLZT. LPCVD techniques to deposit polycrystalline Si onto the electro-optic PLZT substrate and then recrystallizing the polysilicon using an Ar+ laser are used to produce single crystal silicon grains, to fabricate and test a 12 x 12 electrically addressed spatial light modulator (SLM) array and a 16 x 16 optically addressed SLM array. Optical parallel computing architectures are investigated by different interconnection topologies and holographic optical elements are generated to implement fully interconnected and hypercube interconnected topologies.

  19. Spin-wave based realization of optical computing primitives

    SciTech Connect

    Csaba, G. Papp, A.; Porod, W.

    2014-05-07

    We use micromagnetic simulations to demonstrate that spin waves can perform optically inspired, non-Boolean computing algorithms. We propose and design coherent spin-wave sources and phase shifters, which act akin to the key components of an optical signal processing system. We show that the functionality of the proposed on-chip spin-wave based signal processing system is similar to known optical computing devices. We argue that such computing system can serve as a practical, energy efficient, and integrated component of nanoscale image processing systems.

  20. A virtual network computer's optical storage virtualization scheme

    NASA Astrophysics Data System (ADS)

    Wang, Jianzong; Hu, Huaixiang; Wan, Jiguang; Wang, Peng

    2008-12-01

    In this paper, we present the architecture and implementation of a virtual network computers' (VNC) optical storage virtualization scheme called VOSV. Its task is to manage the mapping of virtual optical storage to physical optical storage, a technique known as optical storage virtualization. The design of VOSV aims at the optical storage resources of different clients and servers that have high read-sharing patterns. VOSV uses several schemes such as a two-level Cache mechanism, a VNC server embedded module and the iSCSI protocols to improve the performance. The results measured on the prototype are encouraging, and indicating that VOSV provides the high I/O performance.

  1. Photonic temporal integrator for all-optical computing.

    PubMed

    Slavík, Radan; Park, Yongwoo; Ayotte, Nicolas; Doucet, Serge; Ahn, Tae-Jung; LaRochelle, Sophie; Azaña, José

    2008-10-27

    We report the first experimental realization of an all-optical temporal integrator. The integrator is implemented using an all-fiber active (gain-assisted) filter based on superimposed fiber Bragg gratings made in an Er-Yb co-doped optical fiber that behaves like an 'optical capacitor'. Functionality of this device was tested by integrating different optical pulses, with time duration down to 60 ps, and by integration of two consecutive pulses that had different relative phases, separated by up to 1 ns. The potential of the developed device for implementing all-optical computing systems for solving ordinary differential equations was also experimentally tested. PMID:18958098

  2. Electron Optics Cannot Be Taught through Computation?

    ERIC Educational Resources Information Center

    van der Merwe, J. P.

    1980-01-01

    Describes how certain concepts basic to electron optics may be introduced to undergraduate physics students by calculating trajectories of charged particles through electrostatic fields which can be evaluated on minicomputers with a minimum of programing effort. (Author/SA)

  3. Optical computing based on neuronal models

    NASA Astrophysics Data System (ADS)

    Farhat, Nabil H.

    1987-10-01

    Ever since the fit between what neural net models can offer (collective, iterative, nonlinear, robust, and fault-tolerant approach to information processing) and the inherent capabilities of optics (parallelism and massive interconnectivity) was first pointed out and the first optical associative memory demonstrated in 1985, work and interest in neuromorphic optical signal processing has been growing steadily. For example, work in optical associative memories is currently being conducted at several academic institutions (e.g., California Institute of Technology, University of Colorado, University of California-San Diego, Stanford University, University of Rochester, and the author's own institution the University of Pennsylvania) and at several industrial and governmental laboratories (e.g., Hughes Research Laboratories - Malibu, the Naval Research Laboratory, and the Jet Propulsion Laboratory). In these efforts, in addition to the vector matrix multiplication with thresholding and feedback scheme utilized in early implementations, an arsenal of sophisticated optical tools such as holographic storage, phase conjugate optics, and wavefront modulation and mixing are being drawn on to realize associative memory functions.

  4. 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.

  5. Optical computed tomography liquid calibration phantom

    NASA Astrophysics Data System (ADS)

    Jordan, K.

    2013-06-01

    Fluorinated ethylene propylene tubing is investigated as a method of preparing a contrast-resolution phantom for quantitative characterization of optical CT scanners and hydrogel dosimeters. Two sizes of tubing were examined: 6 and 13 mm inner diameter with 0.75 and 0.5 mm wall thicknesses, respectively. Water solutions of carbon black, nanoparticles in micelles provided continuously adjustable absorption contrast. Cross-sectional slices from two phantoms scanned with two different optical CT scanners are presented. Reconstructions from these simple phantoms can be used to identify scanner artefacts and improve instrument design. These phantoms represent a more reproducible approach than casting "gel fingers" into gel phantoms for system characterization. The thinner walled tubes have fewer optical artefacts.

  6. 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.

  7. 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

    2014-05-01

    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. PMID:24921786

  8. The Particle Beam Optics Interactive Computer Laboratory for Personal Computers and Workstations

    NASA Astrophysics Data System (ADS)

    Gillespie, G. H.; Hill, B.; Brown, N.; Martono, H.; Moore, J.; Babcock, C.

    1997-05-01

    The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) is a new software concept to aid both students and professionals in modeling charged particle beams and particle beam optical systems. The PBO Lab has been designed to run on several computer platforms and includes four key elements: a graphic user interface shell; (2) a knowledge database on electric and magnetic optics elements, including interactive tutorials on the physics of charged particle optics and on the technology used in particle optics hardware; (3) a graphic construction kit for users to interactively and visually construct optical beam lines; and (4) a set of charged particle optics computational engines that compute transport matrices, beam envelopes and trajectories, fit parameters to optical constraints, and carry out similar calculations for the graphically-defined beam lines. The primary computational engines in the first generation PBO Lab are the third-order TRANSPORT code, the multiple ray tracing program TURTLE, and a new first-order matrix code that includes an envelope space charge model with support for calculating single trajectories in the presence of the beam space charge. Progress on the PBO Lab development is described and a demonstration will be given.

  9. Computing Temperatures In Optically Pumped Laser Rods

    NASA Technical Reports Server (NTRS)

    Farrukh, Usamah O.

    1991-01-01

    Computer program presents new model solving temperature-distribution problem for laser rods of finite length and calculates both radial and axial components of temperature distributions in these rods. Contains several self-checking schemes to prevent over-writing of memory blocks and to provide simple tracing of information in case of trouble. Written in Microsoft FORTRAN 77.

  10. 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.

  11. REVIEW: Optical neural computers based on photorefractive crystals

    NASA Astrophysics Data System (ADS)

    Bel'dyugin, Igor'M.; Zolotarev, M. V.; Sviridov, K. A.

    1992-05-01

    The results are given of recent investigations of the feasibility of using photorefractive crystals in the construction of optical neural computers and of associative memories. The physical basis of the interaction of laser radiation with photorefractive crystals is given and the principles governing the formation of an all-optical neuron and of links (synapses) between neurons in such crystals are discussed. An analysis is made of the learning capabilities of various models of neural networks (Boltzmann machine, perceptron, associatron, neural networks with competition, etc.) and optical systems implementing these models with the aid of photorefractive crystals are described. Extensive experimental data are reported and the results are given of modeling of various tasks (multidimensional optimization, image recognition, etc.) by optical neural computers.

  12. CALL FOR PAPERS: Optical implementation of quantum computers

    NASA Astrophysics Data System (ADS)

    Rarity, John; Weinfurter, Harald

    2004-09-01

    A topical issue of Journal of Optics B: Quantum and Semiclassical Optics will be devoted to recent advances in optical implementation of quantum computers. The topics to be covered will include, but are not limited to: bullet Linear optics quantum gates bullet Progress towards nonlinear optics quantum gates bullet Interface between optical qubits and atomic/solid state qubits bullet Novel architectures bullet Single-photon sources and detectors bullet Photonic quantum networks bullet Few-qubit applications The DEADLINE for submission of contributions is 15 January 2005 to allow the topical issue to be published in about October 2005. All contributions will be peer-reviewed in accordance with the normal refereeing procedures and standards of Journal of Optics B: Quantum and Semiclassical Optics. Submissions should preferably be in either standard LaTeX form or Microsoft Word. Advice on publishing your work in the journal may be found at www.iop.org/journals/authors/jopb. There are no page charges for publication. The corresponding author of each paper published will receive a complimentary copy of the topical issue. Contributions to the topical issue should preferably be submitted electronically at www.iop.org/journals/authors/jopb or by e-mail to jopb@iop.org. Authors unable to submit online or by e-mail may send hard copy contributions (enclosing the electronic code) to: Dr Claire Bedrock (Publisher), Journal of Optics B: Quantum and Semiclassical Optics, Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK. All contributions should be accompanied by a readme file or covering letter, quoting `JOPB Topical Issue - Optical implementation of quantum computers', giving the postal and e-mail addresses for correspondence. Any subsequent change of address should be notified to the publishing office. We look forward to receiving your contribution to this topical issue.

  13. 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.

  14. An optical pattern classification using computer-generated holograms

    NASA Astrophysics Data System (ADS)

    Kajiki, Yoshinori; Matsushita, Kenji; Shimizu, Eiji

    1990-07-01

    An optical pattern classification system is proposed which performs weighting and summation by the optical system using computer-generated holograms (CGHs). The system makes it possible to simplify the structure and to improve the processing speed. A trainable pattern classification system which performs weight modification by using a CGH matrix and a dot matrix liquid crystal display (LCD) as a shutter array is proposed. The trainable pattern classifier using a CGH matrix and LCD is described, and the experimental results are presented.

  15. Optical signal processing using photonic reservoir computing

    NASA Astrophysics Data System (ADS)

    Salehi, Mohammad Reza; Dehyadegari, Louiza

    2014-10-01

    As a new approach to recognition and classification problems, photonic reservoir computing has such advantages as parallel information processing, power efficient and high speed. In this paper, a photonic structure has been proposed for reservoir computing which is investigated using a simple, yet, non-partial noisy time series prediction task. This study includes the application of a suitable topology with self-feedbacks in a network of SOA's - which lends the system a strong memory - and leads to adjusting adequate parameters resulting in perfect recognition accuracy (100%) for noise-free time series, which shows a 3% improvement over previous results. For the classification of noisy time series, the rate of accuracy showed a 4% increase and amounted to 96%. Furthermore, an analytical approach was suggested to solve rate equations which led to a substantial decrease in the simulation time, which is an important parameter in classification of large signals such as speech recognition, and better results came up compared with previous works.

  16. A scheme for efficient quantum computation with linear optics

    NASA Astrophysics Data System (ADS)

    Knill, E.; Laflamme, R.; Milburn, G. J.

    2001-01-01

    Quantum computers promise to increase greatly the efficiency of solving problems such as factoring large integers, combinatorial optimization and quantum physics simulation. One of the greatest challenges now is to implement the basic quantum-computational elements in a physical system and to demonstrate that they can be reliably and scalably controlled. One of the earliest proposals for quantum computation is based on implementing a quantum bit with two optical modes containing one photon. The proposal is appealing because of the ease with which photon interference can be observed. Until now, it suffered from the requirement for non-linear couplings between optical modes containing few photons. Here we show that efficient quantum computation is possible using only beam splitters, phase shifters, single photon sources and photo-detectors. Our methods exploit feedback from photo-detectors and are robust against errors from photon loss and detector inefficiency. The basic elements are accessible to experimental investigation with current technology.

  17. Morphing for faster computations in transformation optics.

    PubMed

    Aznavourian, Ronald; Guenneau, Sébastien

    2014-11-17

    We propose to use morphing algorithms to deduce some approximate wave pictures of scattering by cylindrical invisibility cloaks of various shapes deduced from the exact computation (e.g. using a finite element method) of scattering by cloaks of two given shapes, say circular and elliptic ones, thereafter called the source and destination images. The error in L(2) norm between the exact and approximate solutions deduced via morphing from the source and destination images is typically less than 2 percent if control points are judiciously chosen. Our approach works equally well for rotators and concentrators, and also unveils some device which we call rotacon since it both rotates and concentrates electromagnetic fields. However, it breaks down for superscatterers (deduced from non-monotonic transforms): the error in L(2) norm is about 25 percent. We stress that our approach might greatly accelerate numerical studies of 2D and 3D cloaks. PMID:25402072

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Boppart, Stephen A.

    2015-03-01

    High-resolution real-time tomography of biological tissues is important for many areas of biological investigations and medical applications. Cellular level optical tomography, however, has been challenging because of the compromise between transverse imaging resolution and depth-of-field, the system and sample aberrations that may be present, and the low imaging sensitivity deep in scattering tissues. The use of computed optical imaging techniques has the potential to address several of these long-standing limitations and challenges. Two related techniques are interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO). Through three-dimensional Fourierdomain resampling, in combination with high-speed OCT, ISAM can be used to achieve high-resolution in vivo tomography with enhanced depth sensitivity over a depth-of-field extended by more than an order-of-magnitude, in realtime. Subsequently, aberration correction with CAO can be performed in a tomogram, rather than to the optical beam of a broadband optical interferometry system. Based on principles of Fourier optics, aberration correction with CAO is performed on a virtual pupil using Zernike polynomials, offering the potential to augment or even replace the more complicated and expensive adaptive optics hardware with algorithms implemented on a standard desktop computer. Interferometric tomographic reconstructions are characterized with tissue phantoms containing sub-resolution scattering particles, and in both ex vivo and in vivo biological tissue. This review will collectively establish the foundation for high-speed volumetric cellular-level optical interferometric tomography in living tissues.

  20. 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...

  1. QNIX: A Linear Optical Architecture for Quantum Computing

    NASA Astrophysics Data System (ADS)

    Gimeno-Segovia, Mercedes; Shadbolt, Peter J.; Rudolph, Terry G.; Browne, Dan E.; Mendoza, Gabriel; Russell, Nicholas J.; Silverstone, Joshua W.; Santamato, Alberto; Carolan, Jacques; O'Brien, Jeremy

    2015-03-01

    There is currently a great deal of effort to develop a large-scale quantum computer, and one of the most promising platforms to do so is integrated linear optics. We present a proposal for a dynamical scheme for an integrated linear optics implementation of a one-way quantum computer. We go beyond the purely theoretical work and address practical issues in order to create a physically realistic design. We describe every step of cluster state construction and processing, showing the outstanding issues left to be addressed and our contributions to the different stages of the dynamical process. These include optimised interferometers for the generation of GHZ states, a universal and scalable architecture which requires entangled sources of no more than 3 photons with no active feed-forward, and loss-tolerant and fault-tolerant strategies specifically tailored to our proposed architecture. Our work demonstrates that building a linear optical quantum computer need be less challenging than previously thought, and brings large-scale switch-free linear optical architectures for quantum computing much closer to experimental realisation.

  2. Beam steering by computer generated hologram for optical switches

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Keita; Suzuki, Kenya; Yamaguchi, Joji

    2016-02-01

    We describe a computer generated hologram (CGH) method for application to a multiple input and multiple output (MxN) optical switch based on a liquid crystal on silicon (LCOS). The conventional MxN optical switch needs multiple spatial light modulations. However, the CGH method realizes an MxN optical switch simply with a one-time spatial light modulation, resulting in fewer optical elements and better cost efficiency. Moreover, the intrinsic loss of the proposed MxN switch resulting from beam splitting can be reduced by routing multiple signals with a single knob control, which is called a multi-pole multi-throw switch. In this paper, we demonstrate a 5x5 wavelength selective switch (WSS) and a 2-degree ROADM that we realized using the above CGH method. The experimental results indicate that these switches work well with a crosstalk of < -14.9 dB.

  3. 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. PMID:18648434

  4. Fiber Optics For High Speed Computer Input/Output Channels

    NASA Astrophysics Data System (ADS)

    Crow, J. D.; Comerford, L. D.; Johnson, M.; Lynch, R. T.; Rogers, D. L.; Widmer, A. X.

    1982-10-01

    In a mainframe computing system, the transfer of data between the processor/memory and the input/output/storage subsystems is done on the I/O channel links. With the demands for computing power increasing at above 40% per year, there is an ever increasing demand for more channel links and more performance on the link. Recent enhancements of the channel protocols make it possible to push the data transfer rate to the hardware limit due to the skew of bits on the parallel lines of the current link. The serialization of the interface with a fiber optic implementation would offer the potential of even more performance from the I/O Channel. For fiber optics to be attractive, the components must offer performance in the hundreds of Mbits/sec, with high reliability (less than 10-12 BER), low power consumption, small packaging profile, and low cost. To date, such components are not commercially available. At IBM Research, a 200 Mbit/sec, 1 km prototype serial subsystem has been built with emphasis on the development of attractive electro-optic components. Laser packaging was done using a Si chip as the substrate for both laser and fiber. A single chip, high sensitivity receiver was built with a digital IBM logic gate array chip. A monolithic dual laser chip and package were developed to enhance the availability of the transmitter. This talk will discuss the features of these developments and the possibilities for fiber optics in a large computer system.

  5. Computational Modeling of Ultrafast Pulse Propagation in Nonlinear Optical Materials

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Agrawal, Govind P.; Kwak, Dochan (Technical Monitor)

    1996-01-01

    There is an emerging technology of photonic (or optoelectronic) integrated circuits (PICs or OEICs). In PICs, optical and electronic components are grown together on the same chip. rib build such devices and subsystems, one needs to model the entire chip. Accurate computer modeling of electromagnetic wave propagation in semiconductors is necessary for the successful development of PICs. More specifically, these computer codes would enable the modeling of such devices, including their subsystems, such as semiconductor lasers and semiconductor amplifiers in which there is femtosecond pulse propagation. Here, the computer simulations are made by solving the full vector, nonlinear, Maxwell's equations, coupled with the semiconductor Bloch equations, without any approximations. The carrier is retained in the description of the optical pulse, (i.e. the envelope approximation is not made in the Maxwell's equations), and the rotating wave approximation is not made in the Bloch equations. These coupled equations are solved to simulate the propagation of femtosecond optical pulses in semiconductor materials. The simulations describe the dynamics of the optical pulses, as well as the interband and intraband.

  6. 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

  7. Computational analysis of endometrial photocoagulation with diffusing optical device

    PubMed Central

    Kwon, Jinhee; Lee, Chang-Yong; Oh, Junghwan; Kang, Hyun Wook

    2013-01-01

    A balloon-catheter optical diffuser for endometrial treatment was evaluated with computational thermal analysis. Various catheter materials and dimensions were implemented to identify the optimal design for the device. Spatial and temporal development of temperature during 30-sec irradiation of 532-nm light demonstrated thermal insulation effects of polyurethane on temperature increase up to 384 K, facilitating the irreversible denaturation. The current model revealed the degree of thermal coagulation 13% thicker than experimental results possibly due to lack of tissue dynamics and light intensity distribution. In combination with photon distribution, the analytical simulation can be a feasible tool to optimize the new optical diffuser for efficient and safe endometrial treatment. PMID:24298406

  8. 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.

  9. Cooperative integration of stereopsis and optic flow computation

    NASA Astrophysics Data System (ADS)

    Sudhir, G.; Banerjee, Subhashis; Biswas, K. K.; Bahl, R.

    1995-12-01

    A cooperative integration of stereopsis and optic flow computation is presented. Central to our approach is the modeling of the visual processes as a sequence of coupled Markov random fields by definition of suitable interprocess interactions based on some natural constraints. The integration makes each of the individual processes better constrained and more reliable. Further, as a result of the integration, it becomes possible to obtain accurately the discontinuities in both the flow and the disparity fields along with the regions of stereo occlusion. Results on both noisy synthetic image data and real images are presented. Copyright (c) 1995 Optical Society of America

  10. Validation of a Prototype Optical Computed Tomography System

    PubMed Central

    Zakariaee, Seyed Salman; Molazadeh, Mikaeil; Takavar, Abbas; Shirazi, Alireza; Mesbahi, Asghar; Zeinali, Ahad

    2015-01-01

    In radiation cancer treatments, the most of the side effects could be minimized using a proper dosimeter. Gel dosimeter is the only three-dimensional dosimeter and magnetic resonance imaging (MRI) is the gold standard method for gel dosimeter readout. Because of hard accessibility and high cost of sample reading by MRI systems, some other alternative methods were developed. The optical computed tomography (OCT) method could be considered as the most promising alternative method that has been studied widely. In the current study, gel dosimeter scanning using a prototype optical scanner and validation of this optical scanner was performed. Optical absorbance of the irradiated gel samples was determined by both of conventional spectrophotometer and the fabricated OCT system at 632 nm. Furthermore, these irradiated vials were scanned by a 1.5 T MRI. The slope of the curves was extracted as the dose-response sensitivity. The R2-dose sensitivity measured by MRI method was 0.1904 and 0.113 for NIPAM and PAGAT gels, respectively. The optical dose sensitivity obtained by conventional spectrophotometer and the fabricated optical scanner was 0.0453 and 0.0442 for NIPAM gels and 0.0244 and 0.0242 for PAGAT gels, respectively. The scanning results of the absorbed dose values showed that the new OCT and conventional spectrophotometer were in fair agreement. From the results, it could be concluded that the fabricated system is able to quantize the absorbed dose values in polymer gel samples with acceptable accuracy. PMID:26120572

  11. Parallel multithread computing for spectroscopic analysis in optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Trojanowski, Michal; Kraszewski, Maciej; Strakowski, Marcin; Pluciński, Jerzy

    2014-05-01

    Spectroscopic Optical Coherence Tomography (SOCT) is an extension of Optical Coherence Tomography (OCT). It allows gathering spectroscopic information from individual scattering points inside the sample. It is based on time-frequency analysis of interferometric signals. Such analysis requires calculating hundreds of Fourier transforms while performing a single A-scan. Additionally, further processing of acquired spectroscopic information is needed. This significantly increases the time of required computations. During last years, application of graphical processing units (GPU's) was proposed to reduce computation time in OCT by using parallel computing algorithms. GPU technology can be also used to speed-up signal processing in SOCT. However, parallel algorithms used in classical OCT need to be revised because of different character of analyzed data. The classical OCT requires processing of long, independent interferometric signals for obtaining subsequent A-scans. The difference with SOCT is that it requires processing of multiple, shorter signals, which differ only in a small part of samples. We have developed new algorithms for parallel signal processing for usage in SOCT, implemented with NVIDIA CUDA (Compute Unified Device Architecture). We present details of the algorithms and performance tests for analyzing data from in-house SD-OCT system. We also give a brief discussion about usefulness of developed algorithm. Presented algorithms might be useful for researchers working on OCT, as they allow to reduce computation time and are step toward real-time signal processing of SOCT data.

  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. A Degenerate Optical Parametric Oscillator Network for Coherent Computation

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Marandi, Alireza; Takata, Kenta; Byer, Robert L.; Yamamoto, Yoshihisa

    Laws of physics have proved useful for solving combinatorial optimization problems. This chapter introduces a network of degenerate optical parametric oscillators which takes advantage of principles of quantum optics to tackle NP-hard problems. The underlying mechanism originates from the bistability of the output phase of each oscillator, coherent interactions between coupled oscillators, and the inherent preference of the network for oscillating in a mode with the minimum photon loss. Computational experiments have been extensively performed using instances of an NP-hard problem in graph theory with the number of vertices ranging from 4 to 20000. The numerical results clearly demonstrate the effectiveness of the network. In addition, the network can be physically implemented on a single ring cavity with multiple trains of femtosecond pulses and configurable mutual couplings. The implementation has been realized for the instance on the cubic graph with 4 vertices, and no computational error is detected in 1000 runs.

  14. Digital optical computing II; Proceedings of the Meeting, Los Angeles, CA, Jan. 17-19, 1990

    SciTech Connect

    Arrathoon, R.

    1990-01-01

    Various papers on digital optical computing are presented. Individual topics addressed include: complexity of networks realized by fiber optic logic elements, optoelectric arrays for hybrid optical/electronic computing, monolithic model-locked laser arrays in optical computing, three-dimensional multistage interconnection networks, optical fiber crossbar switch, multidimensional optical interconnection networks, high-speed photodetectors, disorder-delineated semiconductor waveguides, quantum well structures for integrated optoelectronics, electrooptic polymers for optical interconnects, hybrid content-addressable memory MSD arithmetic, new concept for a photonic switch, digital fiber optic-delay-line memory, optical neural networks using smectic liquid crystals, speech recognition using optical neural networks, solid optical correlators, hybrid optical/digital neural network, unified optical symbolic substitution processor, hybrid higher-order optical symbolic recognition, optoelectronic multilayer network.

  15. 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.

  16. Optical design and characterization of an advanced computational imaging system

    NASA Astrophysics Data System (ADS)

    Shepard, R. Hamilton; Fernandez-Cull, Christy; Raskar, Ramesh; Shi, Boxin; Barsi, Christopher; Zhao, Hang

    2014-09-01

    We describe an advanced computational imaging system with an optical architecture that enables simultaneous and dynamic pupil-plane and image-plane coding accommodating several task-specific applications. We assess the optical requirement trades associated with custom and commercial-off-the-shelf (COTS) optics and converge on the development of two low-cost and robust COTS testbeds. The first is a coded-aperture programmable pixel imager employing a digital micromirror device (DMD) for image plane per-pixel oversampling and spatial super-resolution experiments. The second is a simultaneous pupil-encoded and time-encoded imager employing a DMD for pupil apodization or a deformable mirror for wavefront coding experiments. These two testbeds are built to leverage two MIT Lincoln Laboratory focal plane arrays - an orthogonal transfer CCD with non-uniform pixel sampling and on-chip dithering and a digital readout integrated circuit (DROIC) with advanced on-chip per-pixel processing capabilities. This paper discusses the derivation of optical component requirements, optical design metrics, and performance analyses for the two testbeds built.

  17. 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.

  18. 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.

  19. Non-diffusing photochromic gel for optical computed tomography phantoms

    NASA Astrophysics Data System (ADS)

    Jordan, K.

    2013-06-01

    This study examines photochromic response in radiation sensitive hydrogels. Genipin, crosslinked, gelatin gel can support high resolution images because the chromophores do not diffuse. A low power, 633 nm He-Ne laser was used to write lines into the gels by a photobleaching reaction. Optical cone-beam computed tomography (CBCT) scans mapped the high resolution images in 3D with 0.25 mm voxel resolution. A straight line was written into a deformed gel and then readout in its relaxed, initial shape. The curved, photo-bleached line demonstrated deformable 3D dosimetry is possible with this system to the balloon edge. High resolution, photochromic images provide key information for characterizing optical CT scanners and 3D dosimeters. Many, ionizing radiation, dosimeter materials demonstrate either a photochromic or photothermal response, allowing this approach to be widely used in quantitative 3D scanning.

  20. Performance of latex balloons for optical computed tomography

    NASA Astrophysics Data System (ADS)

    Jordan, K.; Walsh, A.; Peng, M.; Battista, J.

    2013-06-01

    Latex balloons filled with radiation sensitive hydrogels were evaluated as 3D dosimeters with optical computed tomography (CT) readout. Custom balloons, with less than 10 cm diameters, were made from latex sheets. Commercial, 13 cm diameter, clear balloons were investigated for larger volumes. Ferrous-xylenol orange and genipin gelatin gels selected for 1 and 30 Gy experiments, respectively. The thin stretched latex membrane allowed optical imaging to within 1 mm of the interior balloon edge. Reconstructed dose distributions demonstrated valid measurements to within 2 mm of the balloon surface. The rubber membrane provides a hybrid approach to deforming hydrogels. Uniform irradiation of a deformed gel resulted in a uniform dose being measured when scanned in the relaxed, initial balloon shape. The 13 cm diameter balloons were also effective and inexpensive vessels for hydrogels due to their high clarity, thinness and mechanical strength. Latex balloons represent an inexpensive method to obtain useful information from nearly the entire dosimeter volume.

  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. 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.

  3. Multi-aperture optics as a universal platform for computational imaging

    NASA Astrophysics Data System (ADS)

    Tanida, Jun

    2016-08-01

    Computational imaging is a novel imaging framework based on optical encoding and computational decoding. To avoid a heuristic design that depends on the particular problem to be solved, multi-aperture optics is useful as a universal platform for optical encoding. In this paper, the fundamental properties of multi-aperture optics are summarized. Then some examples of interesting functions implemented by multi-aperture optics are explained, together with some effective applications.

  4. 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.

  5. 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.

  6. Multiscale modeling and computation of optically manipulated nano devices

    NASA Astrophysics Data System (ADS)

    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.

  7. Computer-assisted optics teaching at the Moscow Institute of Physics and Technology

    NASA Astrophysics Data System (ADS)

    Soboleva, Natalia N.; Kozel, Stanislav M.; Lockshin, Gennady R.; Entin, M. A.; Galichsky, K. V.; Lebedinsky, P. L.; Zhdanovich, P. M.

    1995-10-01

    Traditional methods used in optics teaching lack clarity and vividness when illustrating abstract notions such as polarization or interference. Here's where computer models may help, but they usually show only a single phenomenon or process and don't let the student see the entire picture. For this reason at Moscow Institute of Physics and Technology was developed the courseware 'Wave Optics on the Computer' consisting of a number of related simulations. It is intended for students studying optics at the Universities. Recently we have developed different simulations in optics for secondary school level. They are included as part of large computer courseware 'Physics by Pictures'. The courseware 'Wave Optics on the Computer' consists of nine large simulation programs and the textbook. The programs are simulating basic phenomena of wave optics. parameters of optical systems can be varied by the user. The textbook contains theoretical considerations on studied optical phenomena, recommendations concerning work with computer programs, and, especially for those wishing to deeper understand wave optics, original problems for individual solution. At the Moscow Institute of Physics and Technology the course 'Wave Optics on the Computer' is used for teaching optics in the course of general physics. The course provides both the computer assisted teaching for lectures support and computer assisted learning for students during seminars in the computer classroom.

  8. Analysis of an Atom-Optical Architecture for Quantum Computation

    NASA Astrophysics Data System (ADS)

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

    Quantum technology based on photons has emerged as one of the most promising platforms for quantum information processing, having already been used in proof-of-principle demonstrations of quantum communication and quantum computation. However, the scalability of this technology depends on the successful integration of experimentally feasible devices in an architecture that tolerates realistic errors and imperfections. Here, we analyse an atom-optical architecture for quantum computation designed to meet the requirements of scalability. The architecture is based on a modular atom-cavity device that provides an effective photon-photon interaction, allowing for the rapid, deterministic preparation of a large class of entangled states. We begin our analysis at the physical level, where we outline the experimental cavity quantum electrodynamics requirements of the basic device. Then, we describe how a scalable network of these devices can be used to prepare a three-dimensional topological cluster state, sufficient for universal fault-tolerant quantum computation. We conclude at the application level, where we estimate the system-level requirements of the architecture executing an algorithm compiled for compatibility with the topological cluster state.

  9. 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).

  10. High-fidelity linear optical quantum computing with polarization encoding

    SciTech Connect

    Spedalieri, Federico M.; Lee, Hwang; Dowling, Jonathan P.

    2006-01-15

    We show that the KLM scheme [Knill, Laflamme, and Milburn, Nature 409, 46 (2001)] can be implemented using polarization encoding, thus reducing the number of path modes required by half. One of the main advantages of this new implementation is that it naturally incorporates a loss detection mechanism that makes the probability of a gate introducing a non-detected error, when non-ideal detectors are considered, dependent only on the detector dark-count rate and independent of its efficiency. Since very low dark-count rate detectors are currently available, a high-fidelity gate (probability of error of order 10{sup -6} conditional on the gate being successful) can be implemented using polarization encoding. The detector efficiency determines the overall success probability of the gate but does not affect its fidelity. This can be applied to the efficient construction of optical cluster states with very high fidelity for quantum computing.

  11. 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. PMID:25723196

  12. User-friendly computer-aided integrated optics simulator

    NASA Astrophysics Data System (ADS)

    Perrone, Guido; Petazzi, Diego; Montrosset, Ivo

    1993-04-01

    We have developed a user friendly program to analyze the electromagnetic behavior of general integrated optics circuits with a two-dimensional Beam Propagation Method. As a graphical interface for the description of the circuit under analysis we used a file produced by the optical layout generator Sigraph-Optik (copyright by Siemens-Nixdorf), while we acquire all the parameters necessary for the simulation via pop-up menus or a command file. The electromagnetic analysis is at the moment performed with the Beam Propagation Method based on FFT but we are working to extend it to a Crank-Nicholson finite difference scheme with transparent boundary conditions to minimize the computational window. The program final output are color maps and data files containing the effective refractive index and the field amplitude and phase. It is then possible to carry out a post processing on such files to make three dimensional graphs that summarize the circuit performance, to extract two dimensional plots at particular circuit sections and to project the field on the local normal modes of the waveguides. Examples of the simulation capabilities are given.

  13. 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. PMID:26974799

  14. Optical and hybrid computing; Proceedings of the Meeting, Leesburg, VA, Mar. 24-27, 1986

    NASA Astrophysics Data System (ADS)

    Szu, Harold H.

    The design, operation, and applications of optical and hybrid computer systems are discussed in reviews and reports of recent theoretical and experimental investigations. Topics examined include algorithms for linear and nonlinear systems, architectures based on bistable and molecular devices, neural networks for computing, and application-driven devices and system developments. Consideration is given to optical-computing advances in Japan, one-dimensional signal processing using the optical transfer function, parallel logic by spatial filtering, molecular computing and chemical logic, and optical pattern recognition and AI for scene analysis.

  15. Real-time in vivo computed optical interferometric tomography.

    PubMed

    Ahmad, Adeel; Shemonski, Nathan D; Adie, Steven G; Kim, Hee-Seok; Hwu, Wen-Mei W; Carney, P Scott; Boppart, Stephen A

    2013-06-01

    High-resolution real-time tomography of scattering tissues is important for many areas of medicine and biology(1-6). However, the compromise between transverse resolution and depth-of-field in addition to low sensitivity deep in tissue continue to impede progress towards cellular-level volumetric tomography. Computed imaging has the potential to solve these long-standing limitations. Interferometric synthetic aperture microscopy (ISAM)(7-9) is a computed imaging technique enabling high-resolution volumetric tomography with spatially invariant resolution. However, its potential for clinical diagnostics remains largely untapped since full volume reconstructions required lengthy postprocessing, and the phase-stability requirements have been difficult to satisfy in vivo. Here we demonstrate how 3-D Fourier-domain resampling, in combination with high-speed optical coherence tomography (OCT), can achieve high-resolution in vivo tomography. Enhanced depth sensitivity was achieved over a depth-of-field extended in real time by more than an order of magnitude. This work lays the foundation for high-speed volumetric cellular-level tomography. PMID:23956790

  16. Optical imaging of oral pathological tissue using optical coherence tomography and synchrotron radiation computed microtomography

    NASA Astrophysics Data System (ADS)

    Cânjǎu, Silvana; Todea, Carmen; Sinescu, Cosmin; Negrutiu, Meda L.; Duma, Virgil; Mǎnescu, Adrian; Topalǎ, Florin I.; Podoleanu, Adrian Gh.

    2013-06-01

    The efforts aimed at early diagnosis of oral cancer should be prioritized towards developing a new screening instrument, based on optical coherence tomography (OCT), to be used directly intraorally, able to perform a fast, real time, 3D and non-invasive diagnosis of oral malignancies. The first step in this direction would be to optimize the OCT image interpretation of oral tissues. Therefore we propose plastination as a tissue preparation method that better preserves three-dimensional structure for study by new optical imaging techniques. The OCT and the synchrotron radiation computed microtomography (micro-CT) were employed for tissue sample analyze. For validating the OCT results we used the gold standard diagnostic procedure for any suspicious lesion - histopathology. This is a preliminary study of comparing features provided by OCT and Micro-CT. In the conditions of the present study, OCT proves to be a highly promising imaging modality. The use of x-ray based topographic imaging of small biological samples has been limited by the low intrinsic x-ray absorption of non-mineralized tissue and the lack of established contrast agents. Plastination can be used to enhance optical imagies of oral soft tissue samples.

  17. 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

  18. 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.

  19. 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.

  20. Simulations of an Optical Tactile Sensor Based on Computer Tomography

    NASA Astrophysics Data System (ADS)

    Ohka, Masahiro; Sawamoto, Yasuhiro; Zhu, Ning

    In order to create a robotic tactile sensor of thin shape, a new optical tactile sensor is developed by applying a CT (Computer Tomography) algorithm. The present tactile sensor is comprised of infrared emitting diode arrays, receiving phototransistor arrays and a transparent acrylic plate and a black rubber sheet with projections. Infrared rays emitted from the diode array are directed into one end of the plate and their intensity distribution is measured by the phototransistor array mounted on the other end. If the CT algorithm is directly applied to the tactile sensor, there are two shortcomings: the shape of the sensing area is limited to a circular region and there is a long calculation time. Thus, a new CT algorithm oriented to tactile sensing is proposed for overcoming these problems. In the present algorithm, a square sensing area is divided into an N-by-N array and algebraic equations are derived from the relationship between the input and output light intensities on the assumed light projections. Several reconstruction methods are considered for obtaining pressure values caused in the squares. In the present study, the ART (Algebraic Reconstruction Technique) and LU decomposition methods were employed, and these methods were compared to select the best reconstruction method. In a series of simulations, it was found that the LU decomposition method held an advantage for the present type of tactile sensor because of its robustness against disturbance and short calculation time.

  1. Computer-automated program for calibration of optical tweezers

    NASA Astrophysics Data System (ADS)

    Taylor, C. D.; Foley, T. W.; Chang, A. N.; Mowa, S.; Burris, J. L.; Hester, B. C.

    2012-10-01

    An optical tweezers (OT) system uses focused laser light to contain and manipulate nano-scale to micro-scale particles. Trap stiffness is the quantitative measurement of the ability to trap a particle. For some techniques, this measurement depends on an accurate knowledge of the particle's position in time. A position sensing detector (PSD) is used to track particle motion by detecting laser light from the trapping region. The PSD outputs voltages corresponding to the x- and y-coordinates of particle motion, providing a means of knowing the location of the particle in time. An OT system requires a calibration to convert the measured voltages into accurate distances. This process is time-consuming and frequently needs to be repeated, however, with the growing availability of computer-aided data acquisition and control, the complete process can now be automated, reducing time spent by researchers and increasing level of accuracy of future measurements. We have developed a program written in LabVIEW that will, after initialization, 1) via image processing, calibrate the pixel size of the camera, 2) calibrate the optical tweezer position detector by controlling a motorized mirror to move a trapped bead through a detection laser with simultaneous position detector signal measurements, 3) re-align the trap beam and the detection beam by motorized mirror control, 4) measure position data for the same trapped particle being illuminated by the detection beam, and 5) analyze the position signal via the power spectrum method and equipartition method to give two trap stiffness values for comparison. Previous automated calibration methods require additional and sometimes costly equipment as well as some precalibration of stage motion or pixel size. Here, the user only needs to input the known size of the bead (provided by the manufacturer) into the program, insert their prepared slide into their microscope, input some parameters and make selections, and click "start" in order

  2. Fault tolerant topologies for fiber optic networks and computer interconnects operating in the severe avionics environment

    NASA Astrophysics Data System (ADS)

    Glista, Andrew S., Jr.

    1991-02-01

    The history of fiber optics technology development for naval aircraft is reviewed, and the current status of network and fly-by-light flight control development is examined. Fiber-optic component selection for aircraft is addressed, covering fiber and cables, optical sources, couplers, and connectors. Novel fault-tolerant network topologies for both analog and digital fiber optic transmission, which will permit both packet- and circuit-switched operation of robust fiber optic networks are discussed. The application of smart skin technology, i.e., fibers embedded in composite materials, to optical computer backplanes is briefly considered.

  3. COMPUTER MODEL OF TEMPERATURE DISTRIBUTION IN OPTICALLY PUMPED LASER RODS

    NASA Technical Reports Server (NTRS)

    Farrukh, U. O.

    1994-01-01

    Managing the thermal energy that accumulates within a solid-state laser material under active pumping is of critical importance in the design of laser systems. Earlier models that calculated the temperature distribution in laser rods were single dimensional and assumed laser rods of infinite length. This program presents a new model which solves the temperature distribution problem for finite dimensional laser rods and calculates both the radial and axial components of temperature distribution in these rods. The modeled rod is either side-pumped or end-pumped by a continuous or a single pulse pump beam. (At the present time, the model cannot handle a multiple pulsed pump source.) The optical axis is assumed to be along the axis of the rod. The program also assumes that it is possible to cool different surfaces of the rod at different rates. The user defines the laser rod material characteristics, determines the types of cooling and pumping to be modeled, and selects the time frame desired via the input file. The program contains several self checking schemes to prevent overwriting memory blocks and to provide simple tracing of information in case of trouble. Output for the program consists of 1) an echo of the input file, 2) diffusion properties, radius and length, and time for each data block, 3) the radial increments from the center of the laser rod to the outer edge of the laser rod, and 4) the axial increments from the front of the laser rod to the other end of the rod. This program was written in Microsoft FORTRAN77 and implemented on a Tandon AT with a 287 math coprocessor. The program can also run on a VAX 750 mini-computer. It has a memory requirement of about 147 KB and was developed in 1989.

  4. Predictors of Incomplete Optical Colonoscopy Using Computed Tomographic Colonography

    PubMed Central

    Sachdeva, Reetika; Tsai, Salina D.; El Zein, Mohamad H.; Tieu, Alan A.; Abdelgelil, Ahmed; Besharati, Sepideh; Khashab, Mouen A.; Kalloo, Anthony N.; Kumbhari, Vivek

    2016-01-01

    Background/Aims: Optical colonoscopy (OC) is the primary modality for investigation of colonic pathology. Although there is data on demographic factors for incomplete OC, paucity of data exists for anatomic variables that are associated with an incomplete OC. These anatomic variables can be visualized using computed tomographic colonography (CTC). We aim to retrospectively identify variables associated with incomplete OC using CTC and develop a scoring method to predict the outcome of OC. Patients and Methods: In this case–control study, 70 cases (with incomplete OC) and 70 controls (with complete OC) were identified. CTC images of cases and controls were independently reviewed by a single CTC radiologist. Demographic and anatomical parameters were recorded. Data was examined using descriptive linear statistics and multivariate logistic regression model. Results: On analysis, female gender (80% vs 58.6% P = 0.007), prior abdominal/pelvic surgeries (51.4% vs 14.3% P < 0.001), colonic length (187.6 ± 30.0 cm vs 163.8 ± 27.2 cm P < 0.001), and number of flexures (11.4 ± 3.1 vs 8.4 ± 2.9 P < 0.001) increased the risk for incomplete OC. No significant association was observed for increasing age (P = 0.881) and history of severe diverticulosis (P = 0.867) with incomplete OC. A scoring system to predict the outcome of OC is proposed based on CTC findings. Conclusion: Female gender, prior surgery, and increasing colonic length and tortuosity were associated with incomplete OC, whereas increasing age and history of severe diverticulosis were not. These factors may be used in the future to predict those patients who are at risk of incomplete OC. PMID:26831606

  5. 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.

  6. 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.

  7. Electron Optics: A Topic of a Computer Applications Course

    ERIC Educational Resources Information Center

    Romagnoli, R. J.

    1972-01-01

    Using elementary principles of electron optics, the student gains greater understanding of the classical similarities between particles and waves. A method of solution is illustrated, and the results appear more reliable than those existing in prior literature. (Author/TS)

  8. 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.

  9. 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.

  10. Three-dimensional motion correction using speckle and phase for in vivo computed optical interferometric tomography

    PubMed Central

    Shemonski, Nathan D.; Ahn, Shawn S.; Liu, Yuan-Zhi; South, Fredrick A.; Carney, P. Scott; Boppart, Stephen A.

    2014-01-01

    Over the years, many computed optical interferometric techniques have been developed to perform high-resolution volumetric tomography. By utilizing the phase and amplitude information provided with interferometric detection, post-acquisition corrections for defocus and optical aberrations can be performed. The introduction of the phase, though, can dramatically increase the sensitivity to motion (most prominently along the optical axis). In this paper, we present two algorithms which, together, can correct for motion in all three dimensions with enough accuracy for defocus and aberration correction in computed optical interferometric tomography. The first algorithm utilizes phase differences within the acquired data to correct for motion along the optical axis. The second algorithm utilizes the addition of a speckle tracking system using temporally- and spatially-coherent illumination to measure motion orthogonal to the optical axis. The use of coherent illumination allows for high-contrast speckle patterns even when imaging apparently uniform samples or when highly aberrated beams cannot be avoided. PMID:25574426

  11. 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.

  12. Half a century of optics in computing--a personal perspective [Invited].

    PubMed

    Shamir, Joseph

    2013-02-01

    Optical signal processing and computing was triggered by the invention of the laser. Starting practically in 1960, it really took off with the introduction of the spatial-matched filter in 1964. Almost half a century later, research and engineering activity in the field continues unabated but in directions that could not have been anticipated in those early days. This paper presents an overview of the developments in the field, discussing the advantages, disadvantages, and limitations of optics in computing paradigms to indicate where and how optics can be exploited in this area. Initially, optical methods were introduced for processing analog signals. Early attempts to extend optical methods toward digital processing failed because the differences between photons and electrons were not properly appreciated. In the last part of the paper we show that some novel concepts and advanced technology may revitalize also optical processes within the digital computing world. This latter development is demonstrated by digital logic functions implemented on simple electro-optic networks. (My personal perspective on the role of optics in computing is deeply rooted in many years of collaboration with my late friend, H. John Caulfield, and I dedicate this paper to his memory.). PMID:23385897

  13. 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.

  14. Stability in computed optical interferometric tomography (Part I): Stability requirements

    PubMed Central

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

    2014-01-01

    As imaging systems become more advanced and acquire data at faster rates, increasingly dynamic samples can be imaged without concern of motion artifacts. For optical interferometric techniques such as optical coherence tomography, it often follows that initially, only amplitude-based data are utilized due to unstable or unreliable phase measurements. As systems progress, stable phase maps can also be acquired, enabling more advanced, phase-dependent post-processing techniques. Here we report an investigation of the stability requirements for a class of phase-dependent post-processing techniques – numerical defocus and aberration correction with further extensions to techniques such as Doppler, phase-variance, and optical coherence elastography. Mathematical analyses and numerical simulations over a variety of instabilities are supported by experimental investigations. PMID:25321004

  15. 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)

  16. Reducing the phase sensitivity of laser-based optical reservoir computing systems.

    PubMed

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

    2016-01-25

    Optical implementations of reservoir computing systems are very promising because of their high processing speeds and the possibility to process several tasks in parallel. These systems can be implemented using semiconductor lasers subject to optical delayed feedback and optical injection. While the amount of the feedback/injection can be easily controlled, it is much more difficult to control the optical feedback/injection phase. We present extensive numerical investigations of the influence of the feedback/injection phases on laser-based reservoir computing systems with feedback. We show that a change in the phase can lead to a strong reduction in the reservoir computing system performance. We introduce a new readout layer design that -at least for some tasks- reduces this sensitivity to changes in the phase. It consists in optimizing the readout weights from a coherent combination of the reservoir's readout signal and its delayed version rather than only from the reservoir's readout signal as is usually done. PMID:26832506

  17. The earliest history of computer-aided optical design on large computers: the previously classified work by James G. Baker 1945-1954

    NASA Astrophysics Data System (ADS)

    Thompson, Kevin P.

    2007-09-01

    Optical design has always been conducted on the leading edge of computing hardware. In fact, the first significant run on the first large scale computer was made by James G. Baker, in 1945. Recently, a rare, complete set of reports on the earliest work to adapt optical design to large computers surfaced. This paper discusses specifically the early work aimed at automated optical design that is documented in these reports.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. Computer generated holograms design in null testing of optical freeform surfaces

    NASA Astrophysics Data System (ADS)

    Huang, Ya; Ma, Jun; Zhu, Rihong; Shen, Hua

    2013-06-01

    Optical freeform surfaces are complex surfaces with non-rotational symmetry that break through the limitations of conventional optical element, and are widely used in advanced optics application for system configuration simplifying and performance enhancing. Due to the geometrical complexity and optical particularity of optical freeform surfaces, there is, as yet, a lack of precision freeform surfaces testing. Computer generated hologram (CGH) null testing method are discussed in this paper to test the optical freeform surfaces such as off-axis aspheric surfaces. CGH design based on ray tracing and NURBS interpolation are included. Simuation in Zemax is given to verify the result of calculation. The alignment and fiducial sections are added to the CGH to lead the alignment of the freeform surface and CGH with sixdimensional adjustment. The CGH was designed and fabricated to test an off-axis aspheric with Fizeau configuration.

  3. Optical Design Methods: Your Head As A Personal Computer

    NASA Astrophysics Data System (ADS)

    Shafer, David

    1985-07-01

    Several design approaches are described which feature the use of your head as a design tool. This involves thinking about the design task at hand, trying to break it into separate, easily understood subtasks, and approaching these in a creative and intelligent fashion, as only humans can do. You and your computer can become a very powerful team when this design philosophy is adopted.

  4. Characterization of photochromic computer-generated holograms for optical testing

    NASA Astrophysics Data System (ADS)

    Pariani, Giorgio; Bertarelli, Chiara; Bianco, Andrea; Schaal, Frederik; Pruss, Christof

    2012-09-01

    We investigate the possibility to produce photochromic CGHs with maskless lithography methods. For this purpose, optical properties and requirements of photochromic materials will be shown. A diarylethene-based polyurethane is developed and characterized. The resolution limit and the in uence of the writing parameters on the produced patterns, namely speed rate and light power, have been determined. After the optimization of the writing process, gratings and Fresnel Zone Plates are produced on the photochromic layer and diraction eciencies are measured. Improvements and perspectives will be discussed.

  5. A computational toolbox for quantum and atomic optics

    NASA Astrophysics Data System (ADS)

    Tan, Sze M.

    1999-08-01

    A collection of routines is described which largely automates the process of generating the quantum mechanical equations of motion for problems involving systems with relatively few degrees of freedom. Their use allows the user to adopt a high-level approach to writing simulation programs which concentrates on the physics of the problem, rather than on the details of the solution. Examples are taken from the fields of quantum and atomic optics, but the toolbox is also useful for problems involving quantum information and in teaching quantum mechanics. The toolbox has been implemented using the Matlab programming language, but the ideas may be applied to any other object-oriented language.

  6. 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

    2015-01-01

    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. PMID:25826785

  7. 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.

  8. Optical quantum computation with cavities in the intermediate coupling region

    NASA Astrophysics Data System (ADS)

    Mei, F.; Yu, Y. F.; Feng, X. L.; Zhu, S. L.; Zhang, Z. M.

    2010-07-01

    Large-scale quantum computation is currently a hot area of research. The scalable quantum computation scheme with cavities originally proposed by Duan and Kimble (Phys. Rev. Lett., 92 (2004) 127902) is further developed here to operate in the intermediate coupling region, which not only greatly relaxes experimental demands on the Purcell factor, but also eliminates the need to consider internal trade-off between cavity quality and efficiency. In our scheme, by controlling the reflectivity of the input single-photon pulse in the cavity, we can realize local atom-photon and nonlocal atom-atom controlled phase-flip (CPF) gates. We also introduce a theoretical model to analyze the performance of our scheme under practical noise. Furthermore, we show that the nonlocal CPF gate can be used to realize a quantum repeater.

  9. 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.

  10. Stability in computed optical interferometric tomography (Part II): in vivo stability assessment

    PubMed Central

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

    2014-01-01

    Stability is of utmost importance to a wide range of phase-sensitive processing techniques. In Doppler optical coherence tomography and optical coherence elastography, in addition to defocus and aberration correction techniques such as interferometric synthetic aperture microscopy and computational/digital adaptive optics, a precise understanding of the system and sample stability helps to guide the system design and choice of imaging parameters. This article focuses on methods to accurately and quantitatively measure the stability of an imaging configuration in vivo. These methods are capable of partially decoupling axial from transverse motion and are compared against the stability requirements for computed optical interferometric tomography laid out in the first part of this article. PMID:25321016

  11. Imaging study on the optic canal using sixty four-slice spiral computed tomography

    PubMed Central

    Jiang, Peng-Fei; Dai, Xiu-Yu; Lv, Yongbin; Liu, Shaoyi; Mu, Xiao-Yan

    2015-01-01

    Background: Rapid advances in multislice computed tomography (MSCT) technology facilitate accurate clinical imaging. The newly developed 64-slice CT increases temporal and spatial resolution efficiently. Purpose: The purpose of this study is to evaluate the application of 64 slice spiral computed tomography (CT) on the imaging of the normal optics canal. Methods and materials: 100 healthy adults were investigated using 64 slice spiral CT. The optics canal was scanned, reconstructed and examined. Results: Among the four walls of the optic canal, the medial wall is the longest one. The upper wall and outer wall are inferior to the medial wall while the inferior wall is the shortest one. All the data accomplished by the 64 slice CT was consistent with the results of previous reports using other methods. Conclusion: The results suggested that the 64 slice spiral CT could be a valuable and accurate method for measuring the length of optics canal walls. PMID:26885062

  12. Simultaneous Computation of Two Independent Tasks Using Reservoir Computing Based on a Single Photonic Nonlinear Node With Optical Feedback.

    PubMed

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

    2015-12-01

    In this brief, we numerically demonstrate a photonic delay-based reservoir computing system, which processes, in parallel, two independent computational tasks even when the two tasks have unrelated input streams. Our approach is based on a single-longitudinal mode semiconductor ring laser (SRL) with optical feedback. The SRL emits in two directional optical modes. Each directional mode processes one individual task to mitigate possible crosstalk. We illustrate the feasibility of our scheme by analyzing the performance on two benchmark tasks: 1) chaotic time series prediction and 2) nonlinear channel equalization. We identify some feedback configurations for which the results for simultaneous prediction/classification indicate a good performance, but with slight degradation (as compared with the performance obtained for single task processing) due to nonlinear and linear interactions between the two directional modes of the laser. In these configurations, the system performs well on both tasks for a broad range of the parameters. PMID:25751880

  13. Optical scattering by biological aerosols: experimental and computational results on spore simulants

    NASA Astrophysics Data System (ADS)

    Sindoni, Orazio I.; Saija, Rosalba; Iatì, Maria Antonia; Borghese, Ferdinando; Denti, Paolo; Fernandes, Gustavo E.; Pan, Yong-Le; Chang, Richard K.

    2006-07-01

    We present both a computational and an experimental approach to the problem of biological aerosol characterization, joining the expertises reached in the field of theoretical optical scattering by complex, arbitrary shaped particles (multipole expansion of the electromagnetic fields and Transition Matrix), and a novel experimental technique based on two-dimensional angular optical scattering (TAOS). The good agreement between experimental and computational results, together with the possibility for a laboratory single-particle angle-resolved investigation, opens a new scenario in biological particle modelling, and might have major implications for a rapid discrimination of airborne particles.

  14. Optical testing of cylindrical surfaces with computer-generated holograms

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Guo, Pei-ji

    2013-08-01

    Increasing demands for highly accurate cylinders require more high-precision testing techniques. The existing methods of testing cylindrical surfaces can not ensure the highly-accuracy, efficiency, convenience and the overall cost. In order to acquire highly accurate cylindrical surfaces conveniently at a low cost, a new Fizeau interferometric optical testing utilizing CGH which is fabricated onto a wedge-shaped substrate is designed. In this test, a slit filter is placed in the center of the cylindrical curvature to filter out the undesired diffraction orders which occur when the beam hits the CGH. Meanwhile, the front side of the wedge-shaped substrate is as the reference flat, and the CGH is written onto the inclined surface, so that the real fringe pattern can not be affected by its reflected beam. Moreover, the design of cylindrical surfaces under test tilting and off-center relative to the diffraction surface of the CGH results that the required rays for interference can be obtained effectively from the pinhole filter in the interferometer. Furthermore, high-accuracy CGH in this test can be processed by conventional microlithography equipments. Corresponding to a cylindrical surface with 60mm in diameter and f-number of 1/7, the test has been successfully designed and optimized in Zemax whose testing accuracy is prior to 0.0019λ. Better interference pattern can be obtained because all the other disturbing rays image outside of aperture in a radius of 2mm. Experiment shows the method is efficient and predominant.

  15. Assignment of absolute stereochemistry by computation of optical rotation angles

    NASA Astrophysics Data System (ADS)

    Kondru, Rama Krishna

    We have developed simple wire and molecular orbital models to qualitatively and quantitatively understand optical rotation angles of molecules. We reported the first ab initio theoretical approach to determine the absolute stereochemistry of a complex natural product by calculating molar rotation angles, [M]D. We applied this method for an unambiguous assignment of the absolute stereochemistry of the hennoxazole A. A protocol analogous to population analysis was devised to analyze atomic contributions to the rotation angles for oxiranes, orthoesters, and other organic compounds. The molar rotations for an indoline, an indonone, menthol and menthone were calculated using ab inito methods and compared with experimental values. We reported the first prediction of the absolute configuration of a natural product, i.e. an a priori assignment of the relative and absolute stereochemistry of pitiamide A. Furthermore, we described a strategy that may help to establish structure-function relations for rotation angles by visualizing the electric and magnetic-field perturbations to a molecule's molecular orbitals.

  16. Optical quantum computing with photons of arbitrarily low fidelity and purity

    NASA Astrophysics Data System (ADS)

    Rohde, Peter P.

    2012-11-01

    Linear optics quantum computing (LOQC) is a leading candidate for the implementation of large scale quantum computers. Here quantum information is encoded into the quantum states of light and computation proceeds via a linear optics network. It is well known that in such schemes there are stringent requirements on the spatiotemporal structure of photons—they must be completely indistinguishable and of very high purity. We show that in the boson-sampling model for LOQC these conditions may be significantly relaxed. We present evidence that by increasing the size of the system we can implement a computationally hard algorithm even if our photons have arbitrarily low fidelity and purity. These relaxed conditions may make boson-sampling LOQC within reach of present-day technology.

  17. 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.

  18. 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.

  19. Demonstration of Deutsch's algorithm on a stable linear optical quantum computer

    SciTech Connect

    Zhang Pei; Liu Ruifeng; Gao Hong; Li Fuli; Huang Yunfeng

    2010-12-15

    We report an experimental demonstration of quantum Deutsch's algorithm using a linear-optical system. By employing photon polarization and spatial modes, we implement all balanced and constant functions for a quantum computer. The experimental system is very stable, and the experimental data are in excellent accordance with the theoretical results.

  20. 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…

  1. Solving System Of Linear Equations Using The Bimodal Optical Computer (Experimental Results)

    NASA Astrophysics Data System (ADS)

    Habli, M. A.; Abushagur, M. A. G.; Caulfield, H. J.

    1988-08-01

    Hardware and software design of the Bimodal Optical Computer (BOC) and its implementations are presented. Experimental results of the BOC for solving a system of linear equations Ax = b is reported. The effect of calibration, the convergence reliability of the BOC, and the convergence of problems with singular matrices are studied.

  2. 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 ...

  3. 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…

  4. 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

  5. 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.

  6. 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.

  7. 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.

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

    PubMed Central

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

    2015-01-01

    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 structures1,2. In ophthalmology, when combined with optical coherence tomography, HAO has enabled a detailed three-dimensional visualization of photoreceptor distributions3,4 and individual nerve fibre bundles5 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. PMID:26877761

  9. Passive Optical Bistability in Etalons with Diffusive Nonlinearities with Applications to Optical Computing

    NASA Astrophysics Data System (ADS)

    Godsalve, Christopher

    1992-01-01

    Available from UMI in association with The British Library. A theoretical study of optical bistability in passive nonlinear Fabry-Perot etalons is presented. The emphasis is on thermal nonlinearities. The analysis is also applied to etalons with competing thermal and electronic nonlinearities. Thermo-optic bistability is studied for liquid crystal filled etalons, and ZnSe interference filters. Electronic bistability and regenerative oscillations are modelled for InSb etalons. At the core of the thesis is a collection of analytical solutions for the time-dependent and steady-state diffusion equations. These are in cylindrical coordinates, and a large collection of boundary conditions are applied. This includes boundary conditions for combinations of highly conducting and poorly conducting thin films. On using a constant phase approximation of the illuminated area, switching dynamics are calculated through a Volterra equation after finding the appropriate Green's function. A fast numerical method is developed, and a way to extend the method to include the spatial variation in the phase is outlined. It is predicted that optically pixelated arrays of liquid-crystal switches larger than 64 x 64 could operate at 10kHz, and at 4muW power levels. Force cooling at 10kWm^{-1} must be used to achieve this. For optically pixelated ZnSe filters, 64 x 64 arrays could also operate at 10kHz, but at 4mW power levels. Again, force cooling at 10kWm^{-1} must be used, and the filter must be separated from a sapphire substrate by a polyimide or SiO_2 layer. If material pixelation is used, in combination with micro-bore forced cooling and thick spacer layers, switch energies as low as 500pJ are predicted for a 5 μm pixel radius. The switch powers can be as low as 10muW. Array sizes of 512 x 512 would require ~2W of laser power, and would operate at 10kHz. Taking the restricted power levels available for SEED array into account, it is predicted that thermo-optic switches could equal

  10. Optical computer aided tomography measurements of plasma uniformity in an inductively coupled discharge

    SciTech Connect

    Benck, E. C.; Roberts, J. R.

    1998-11-24

    Optical computer aided tomography (CAT) is being investigated as a potential in situ diagnostic for measuring plasma uniformity without making assumptions concerning the plasma symmetry. The presence of an opaque vacuum chamber wall severely limits the different directions from which optical emission measurements can be made of the plasma. The tomographic inversion problem with restricted optical access is being solved using Tikhonov regularization. The accuracy of this inversion process is investigated for several different observation geometries using theoretical test data generated from known distributions. Optical CAT is applied to an ICP-GEC plasma source, with all the measurements made through a single large 152 mm diameter window. Axially asymmetric plasma distributions are demonstrated as a function of gas flow rate and gas composition.

  11. 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.

  12. Optical Shared Memory Computing and Multiple Access Protocols for Photonic Networks

    NASA Astrophysics Data System (ADS)

    Li, Kuang-Yu.

    In this research we investigate potential applications of optics in massively parallel computer systems, especially focusing on design issues in three-dimensional optical data storage and free-space photonic networks. An optical implementation of a shared memory uses a single photorefractive crystal and can realize the set of memory modules in a digital shared memory computer. A complete instruction set consists of R sc EAD, W sc RITE, S sc ELECTIVE E sc RASE, and R sc EFRESH, which can be applied to any memory module independent of (and in parallel with) instructions to the other memory modules. In addition, a memory module can execute a sequence of R sc EAD operations simultaneously with the execution of a W sc RITE operation to accommodate differences in optical recording and readout times common to optical volume storage media. An experimental shared memory system is demonstrated and its projected performance is analyzed. A multiplexing technique is presented to significantly reduce both grating- and beam-degeneracy crosstalk in volume holographic systems, by incorporating space, angle, and wavelength as the multiplexing parameters. In this approach, each hologram, which results from the interference between a single input node and an object array, partially overlaps with the other holograms in its neighborhood. This technique can offer improved interconnection density, optical throughput, signal fidelity, and space-bandwidth product utilization. Design principles and numerical simulation results are presented. A free-space photonic cellular hypercube parallel computer, with emphasis on the design of a collisionless multiple access protocol, is presented. This design incorporates wavelength-, space-, and time-multiplexing to achieve multiple access, wavelength reuse, dense connectivity, collisionless communications, and a simple control mechanism. Analytic models based on semi-Markov processes are employed to analyze this protocol. The performance of the

  13. Generation of optical vortex based on computer-generated holographic gratings by photolithography

    NASA Astrophysics Data System (ADS)

    Li, Shaoxiang; Wang, Zhenwei

    2013-09-01

    The Laguerre-Gaussian beam is a typical example of the optical vortices, which can be generated by computer-generated holograms (CGHs) with the topological charge controlled. Here, we fabricated transmission-amplitude CGH gratings (up to 100 lines per millimeter) on metal film by photolithography technique. Such CGH grating grooves feature high resolution and fine smoothness, so that the gratings can be used to generate Laguerre-Gaussian beam with perfect mode. They are also applicable for the generation of femtosecond optical vortices due to the high damage threshold of the metal film.

  14. 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.

  15. Measurement of two-dimensional optical system MTF by computation of second order speckle statistics

    NASA Astrophysics Data System (ADS)

    Lund, G.; Azouit, M.

    1980-04-01

    An interferometric approach to the calculation of the two-dimensional MTF of an optical system is proposed. The technique, in some ways analogous to that of speckle interferometry used in astronomical situations, is based on the computation of the second-order spatio-temporal statistics of a fluctuating speckle pattern. The theorum of Van Cittert-Zernike is invoked to relate the speckle, due to the illumination of a perfect diffuser by the point spread function of an optical system, to the two-dimensional MTF of the system. The computed MTF is displayed in the form of a contour map and can also be represented in the conventional form of a one-dimensional vertical cut. Preliminary measurements have yielded qualitatively useful results and clearly illustrate the suitability of two-dimensional maps for the detection of transfer function anisotropies.

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

    NASA Astrophysics Data System (ADS)

    Luo, Ming-Xing; Wang, Xiaojun

    2014-07-01

    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.

  17. 1980 International Optical Computing Conference, Washington, DC, April 8-11, 1980, Proceedings. Books 1 & 2

    NASA Astrophysics Data System (ADS)

    Rhodes, W. T.

    1980-01-01

    Topics related to radio astronomy are discussed, taking into account Fourier reconstruction techniques in radio astronomy, methods of using closure phases in radio aperture synthesis, adaptive calibration of radio interferometer data, processing of three-dimensional data, acousto-optic spectrometer for radio astronomy, and an optical processor for the very large array radiotelescope. Other subjects reported are related to iterative methods for reconstructing images from incomplete data, holography and inverse scattering, and tomography. Attention is given to noise properties of images reconstructed from Fourier modulus, a numerical algorithm for 2-D wavefront reconstruction from intensity measurements in a single plane, computer simulation comparisons of speckle image reconstruction techniques, iterative coherent processor for bandlimited signal extrapolation, iterative reconstruction of space-limited images, image reconstruction from projections using circular harmonic expansion, polar sampling theorems and their application to computer-aided tomography, and Fourier multiaperture emission tomography.

  18. 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.

  19. Parallel photonic quantum computation assisted by quantum dots in one-side optical microcavities.

    PubMed

    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

  20. 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

  1. 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.

  2. Symbolic-computation study of bright solitons in the optical waveguides and Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Wang, Yun-Po; Tian, Bo; Wang, Yu-Feng; Huang, Zhi-Ruo; Sun, Ya; Cai, Hui-Ping

    2015-06-01

    We investigate solitons in optical waveguides and Bose-Einstein condensates (BECs) governed by a (3+1)-dimensional Gross-Pitaevskii system, which describes the propagation of electromagnetic waves in the optical waveguides and ground-state wave functions of the BECs. We use the symbolic computation and Hirota method to derive analytic bright one- and two-soliton solutions under certain conditions. Soliton amplitude/width amplification and the influence of time-modulated dispersion on the bright-soliton shape are studied via graphic analysis. Through the analysis of bright solitons in optical waveguides and BECs, we find that both the amplitude and the width of bright solitons can become larger during propagation with certain choices of time-modulated dispersion, and that the shape of the bright soliton can also be affected by the time-modulated dispersion; when the time-modulated dispersion is different, we can obtain bright parabolic-like and periodic-type solitons.

  3. DOC II 32-bit digital optical computer: optoelectronic hardware and software

    NASA Astrophysics Data System (ADS)

    Stone, Richard V.; Zeise, Frederick F.; Guilfoyle, Peter S.

    1991-12-01

    This paper describes current electronic hardware subsystems and software code which support OptiComp's 32-bit general purpose digital optical computer (DOC II). The reader is referred to earlier papers presented in this section for a thorough discussion of theory and application regarding DOC II. The primary optoelectronic subsystems include the drive electronics for the multichannel acousto-optic modulators, the avalanche photodiode amplifier, as well as threshold circuitry, and the memory subsystems. This device utilizes a single optical Boolean vector matrix multiplier and its VME based host controller interface in performing various higher level primitives. OptiComp Corporation wishes to acknowledge the financial support of the Office of Naval Research, the National Aeronautics and Space Administration, the Rome Air Development Center, and the Strategic Defense Initiative Office for the funding of this program under contracts N00014-87-C-0077, N00014-89-C-0266 and N00014-89-C- 0225.

  4. A computer model for the evaluation of the effect of corneal topography on optical performance.

    PubMed

    Camp, J J; Maguire, L J; Cameron, B M; Robb, R A

    1990-04-15

    We developed a method that models the effect of irregular corneal surface topography on corneal optical performance. A computer program mimics the function of an optical bench. The method generates a variety of objects (single point, standard Snellen letters, low contrast Snellen letters, arbitrarily complex objects) in object space. The lens is the corneal surface evaluated by a corneal topography analysis system. The objects are refracted by the cornea by using raytracing analysis to produce an image, which is displayed on a video monitor. Optically degraded images are generated by raytracing analysis of selected irregular corneal surfaces, such as those from patients with keratoconus and those from patients having undergone epikeratophakia for aphakia. PMID:2330940

  5. 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. PMID:23938640

  6. Photoinduced dichroism in Bacteriorhodopsin and its application to optical computing and information processing

    NASA Astrophysics Data System (ADS)

    Denis, Kevin; Aranda, Francisco J.

    1998-03-01

    The intensity dependence of the photoinduced dichroism in Bacteriorhodopsin (bR) films has potential application in optical image processing and optical computing. Under the illumination of linearly polarized actinic light of 570 nm wavelength, the photoinduced dichroism in a Bacteriorhodopsin film induces polarization rotation for a probe beam of the same wavelength. This behavior is a function of the life time of the M state in the Bacteriorhodopsin photocycle. We studied the dependence of the photoinduced dichroism on the pH environment in which the bR molecules are and on genetic mutation by replacement of the Aspartic amino acid in position 96 by Asparagine. The photoinduced probe polarization rotation can be exploited for optical Fourier processing and logic operations. The intensity dependence of the photoinduced dichroism in the different films has important implications on the applications for which they are suitable.

  7. 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).

  8. Computed optical interferometric tomography for high-speed volumetric cellular imaging

    PubMed Central

    Liu, Yuan-Zhi; Shemonski, Nathan D.; Adie, Steven G.; Ahmad, Adeel; Bower, Andrew J.; Carney, P. Scott; Boppart, Stephen A.

    2014-01-01

    Three-dimensional high-resolution imaging methods are important for cellular-level research. Optical coherence microscopy (OCM) is a low-coherence-based interferometry technology for cellular imaging with both high axial and lateral resolution. Using a high-numerical-aperture objective, OCM normally has a shallow depth of field and requires scanning the focus through the entire region of interest to perform volumetric imaging. With a higher-numerical-aperture objective, the image quality of OCM is affected by and more sensitive to aberrations. Interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO) are computed imaging techniques that overcome the depth-of-field limitation and the effect of optical aberrations in optical coherence tomography (OCT), respectively. In this work we combine OCM with ISAM and CAO to achieve high-speed volumetric cellular imaging. Experimental imaging results of ex vivo human breast tissue, ex vivo mouse brain tissue, in vitro fibroblast cells in 3D scaffolds, and in vivo human skin demonstrate the significant potential of this technique for high-speed volumetric cellular imaging. PMID:25401012

  9. Computational method for correcting complex optical distortion based on FOV division.

    PubMed

    Li, An; Wu, Yisi; Xia, Xinxing; Huang, Yuejin; Feng, Chaoqi; Zheng, Zhenrong

    2015-03-20

    We propose a computational method for correcting complex optical distortion in off-axis optical systems, such as the optical systems found in head-mounted and head-up displays. The proposed method divides the wide field of view (FOV) into subsections, thereby allowing the distortion to be calculated for each small FOV. Instead of applying the conventional distortion model, the distortion coefficients for each small FOV can be calculated using a simple linear polynomial. In addition, in contrast to the conventional distortion coefficients that refer to the deviation between the real and paraxial image, the distortion coefficients employed by this method directly characterize the relationship between the object and its image. Thus, using the polynomial in the reverse manner repeatedly for each small FOV with the corresponding distortion coefficients, a pixel lookup table is obtained, which can be used to accurately compensate for the distortion in the optical system. This method avoids complicated computations, and there are no requirements for intrinsic or extrinsic parameters. Our experiments verified the effectiveness of the method where the root-mean-square deviation of the projected distorted straight lines was corrected from 23 to 65 pixels to approximately 1 pixel. PMID:25968533

  10. Computed optical interferometric tomography for high-speed volumetric cellular imaging.

    PubMed

    Liu, Yuan-Zhi; Shemonski, Nathan D; Adie, Steven G; Ahmad, Adeel; Bower, Andrew J; Carney, P Scott; Boppart, Stephen A

    2014-09-01

    Three-dimensional high-resolution imaging methods are important for cellular-level research. Optical coherence microscopy (OCM) is a low-coherence-based interferometry technology for cellular imaging with both high axial and lateral resolution. Using a high-numerical-aperture objective, OCM normally has a shallow depth of field and requires scanning the focus through the entire region of interest to perform volumetric imaging. With a higher-numerical-aperture objective, the image quality of OCM is affected by and more sensitive to aberrations. Interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO) are computed imaging techniques that overcome the depth-of-field limitation and the effect of optical aberrations in optical coherence tomography (OCT), respectively. In this work we combine OCM with ISAM and CAO to achieve high-speed volumetric cellular imaging. Experimental imaging results of ex vivo human breast tissue, ex vivo mouse brain tissue, in vitro fibroblast cells in 3D scaffolds, and in vivo human skin demonstrate the significant potential of this technique for high-speed volumetric cellular imaging. PMID:25401012

  11. Optical computed tomography of radiochromic gels for accurate three-dimensional dosimetry

    NASA Astrophysics Data System (ADS)

    Babic, Steven

    In this thesis, three-dimensional (3-D) radiochromic Ferrous Xylenol-orange (FX) and Leuco Crystal Violet (LCV) micelles gels were imaged by laser and cone-beam (Vista(TM)) optical computed tomography (CT) scanners. The objective was to develop optical CT of radiochromic gels for accurate 3-D dosimetry of intensity-modulated radiation therapy (IMRT) and small field techniques used in modern radiotherapy. First, the cause of a threshold dose response in FX gel dosimeters when scanned with a yellow light source was determined. This effect stems from a spectral sensitivity to multiple chemical complexes that are at different dose levels between ferric ions and xylenol-orange. To negate the threshold dose, an initial concentration of ferric ions is needed in order to shift the chemical equilibrium so that additional dose results in a linear production of a coloured complex that preferentially absorbs at longer wavelengths. Second, a low diffusion leuco-based radiochromic gel consisting of Triton X-100 micelles was developed. The diffusion coefficient of the LCV micelle gel was found to be minimal (0.036 + 0.001 mm2 hr-1 ). Although a dosimetric characterization revealed a reduced sensitivity to radiation, this was offset by a lower auto-oxidation rate and base optical density, higher melting point and no spectral sensitivity. Third, the Radiological Physics Centre (RPC) head-and-neck IMRT protocol was extended to 3-D dose verification using laser and cone-beam (Vista(TM)) optical CT scans of FX gels. Both optical systems yielded comparable measured dose distributions in high-dose regions and low gradients. The FX gel dosimetry results were crossed checked against independent thermoluminescent dosimeter and GAFChromicRTM EBT film measurements made by the RPC. It was shown that optical CT scanned FX gels can be used for accurate IMRT dose verification in 3-D. Finally, corrections for FX gel diffusion and scattered stray light in the Vista(TM) scanner were developed to

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

    PubMed

    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

    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

  14. 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.

  15. Computational Optical Imaging Systems for Spectroscopy and Wide Field-of-View Gigapixel Photography

    NASA Astrophysics Data System (ADS)

    Kittle, David Scott

    This dissertation explores computational optical imaging methods to circumvent the physical limitations of classical sensing. An ideal imaging system would maximize resolution in time, spectral bandwidth, three-dimensional object space, and polarization. Practically, increasing any one parameter will correspondingly decrease the others. Spectrometers strive to measure the power spectral density of the object scene. Traditional pushbroom spectral imagers acquire high resolution spectral and spatial resolution at the expense of acquisition time. Multiplexed spectral imagers acquire spectral and spatial information at each instant of time. Using a coded aperture and dispersive element, the coded aperture snapshot spectral imagers (CASSI) here described leverage correlations between voxels in the spatial-spectral data cube to compressively sample the power spectral density with minimal loss in spatial-spectral resolution while maintaining high temporal resolution. Photography is limited by similar physical constraints. Low f/# systems are required for high spatial resolution to circumvent diffraction limits and allow for more photon transfer to the film plain, but require larger optical volumes and more optical elements. Wide field systems similarly suffer from increasing complexity and optical volume. Incorporating a multi-scale optical system, the f/#, resolving power, optical volume and wide field of view become much less coupled. This system uses a single objective lens that images onto a curved spherical focal plane which is relayed by small micro-optics to discrete focal planes. Using this design methodology allows for gigapixel designs at low f/# that are only a few pounds and smaller than a one-foot hemisphere. Computational imaging systems add the necessary step of forward modeling and calibration. Since the mapping from object space to image space is no longer directly readable, post-processing is required to display the required data. The CASSI system uses

  16. Modern numerical techniques and software for photo- and thermoemission electron optical systems computer-aided design

    NASA Astrophysics Data System (ADS)

    Monastyrski, Mikhail A.; Andreev, Sergei V.; Gaidukova, Inna S.; Tarasov, Victor A.; Filachev, Anatoly M.

    1997-09-01

    The paper is devoted to software development for simulation, optimization, and computer-aided design of photo/thermo- emission electron optical systems and units. The first part of the paper presents the applied program package (APP) 'ELIMDYNAMICS\\ intended for computer-aided design of dynamic photo-emission image tubes with electro/magnetostatic focusing and deflection (streak tubes). The developed software allows highly precise computation of basic image quality characteristics both in static and streak modes. One of the main advantages of the new program version presented is that 'through' electron beam computation from the photocathode to image receiver is available with regard to dynamic aberrations caused by scattering fields located nearby the edges of deflecting plates. In the second part, the possibility is shown to generalize some numerical techniques being effectively applied in photo-emission imaging electron optics (namely, the (tau) -variation - and the first kind integral equations techniques) to simulation of the thermo-emission electron beam technology units. Functions of the new APP 'CHARGE' are presented, and some numerical aspects of the self-coordinated problem are discussed.

  17. Linear-phase approximation in the triangular facet near-field physical optics computer program

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Hodges, R. E.

    1990-01-01

    Analyses of reflector antenna surfaces use a computer program based on a discrete approximation of the radiation integral. The calculation replaces the actual surface with a triangular facet representation; the physical optics current is assumed to be constant over each facet. Described here is a method of calculation using linear-phase approximation of the surface currents of parabolas, ellipses, and shaped subreflectors and compares results with a previous program that used a constant-phase approximation of the triangular facets. The results show that the linear-phase approximation is a significant improvement over the constant-phase approximation, and enables computation of 100 to 1,000 lambda reflectors within a reasonable time on a Cray computer.

  18. 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.

  19. Computational Electromagnetic Modeling of Optical Responses in Plasmonically Enhanced Nanoscale Devices Fabricated with Nanomasking Technique

    NASA Astrophysics Data System (ADS)

    Novak, Eric; Debu, Desalegn; Saylor, Cameron; Herzog, Joseph

    2015-03-01

    This work computationally explores plasmonic nanoscale devices fabricated with a recently developed nanomasking technique that is based on the self-aligned process. Computational electromagnetic modeling has determined enhancement factors and the plasmonic and optical properties of these structures. The nanomasking technique is a new process that is employed to overcome the resolution limits of traditional electron beam lithography and can also be used to increase resolution in photolithography fabrication as well. This technique can consistently produce accurate features with nanostructures and gaps smaller than 10 nm. These smaller dimensions can allow for increased and more localized plasmonically enhanced electric fields. These unique metal devices encompass tunable, enhanced plasmonic and optical properties that can be useful in a wide range of applications. Finite element methods are used to approximate the electromagnetic responses, giving the ability to alter the designs and dimensions in order to optimize the enhancement. Ultimately, we will fabricate devices and characterize the plasmonic properties with optical techniques, including dark-field spectroscopy, to confirm the properties with the goal of generating more efficient devices.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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. PMID:24514859

  8. 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.

  9. 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.

  10. Multivariate optical computing using a digital micromirror device for fluorescence and Raman spectroscopy.

    PubMed

    Smith, Zachary J; Strombom, Sven; Wachsmann-Hogiu, Sebastian

    2011-08-29

    A multivariate optical computer has been constructed consisting of a spectrograph, digital micromirror device, and photomultiplier tube that is capable of determining absolute concentrations of individual components of a multivariate spectral model. We present experimental results on ternary mixtures, showing accurate quantification of chemical concentrations based on integrated intensities of fluorescence and Raman spectra measured with a single point detector. We additionally show in simulation that point measurements based on principal component spectra retain the ability to classify cancerous from noncancerous T cells. PMID:21935055

  11. Unicursal random maze tool path for computer-controlled optical surfacing.

    PubMed

    Wang, Chunjin; Wang, Zhenzhong; Xu, Qiao

    2015-12-01

    A novel unicursal random maze tool path is proposed in this paper, which can not only implement uniform coverage of the polishing surfaces, but also possesses randomness and multidirectionality. The simulation experiments along with the practical polishing experiments are conducted to make the comparison of three kinds of paths, including maze path, raster path, and Hilbert path. The experimental results validate that the maze path can warrant uniform polishing and avoid the appearance of the periodical structures in the polished surface. It is also more effective than the Hilbert path in restraining the mid-spatial frequency error in computer-controlled optical surfacing process. PMID:26836670

  12. Computer-originated polarizing holographic optical element recorded in photopolymerizable layers.

    PubMed

    Carré, C; Habraken, S; Roose, S

    1993-05-01

    The photosensitive system that is used in most cases to produce holographic optical holograms is dichromated gelatin. Other materials may be used, in particular, photopolymerizable layers. In the present investigation, we set out to use the polymer developed in the Laboratoire de Photochimie Générale in Mulhouse in order to duplicate a computer-generated hologram. Our technique is intended to generate polarizing properties. We took into account the fact that no wet chemistry processing is required; grating fringe spacings are not distorted through chemical development. PMID:19802257

  13. 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.

  14. Spin-based all-optical quantum computation with quantum dots: Understanding and suppressing decoherence

    SciTech Connect

    Calarco, T.; Datta, A.; Fedichev, P.; Zoller, P.; Pazy, E.

    2003-07-01

    We present an all-optical implementation of quantum computation using semiconductor quantum dots. Quantum memory is represented by the spin of an excess electron stored in each dot. Two-qubit gates are realized by switching on trion-trion interactions between different dots. State selectivity is achieved via conditional laser excitation exploiting Pauli exclusion principle. Read out is performed via a quantum-jump technique. We analyze the effect on our scheme's performance of the main imperfections present in real quantum dots: exciton decay, hole mixing, and phonon decoherence. We introduce an adiabatic gate procedure that allows one to circumvent these effects and evaluate quantitatively its fidelity.

  15. 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.

  16. 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

    2016-04-01

    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. PMID:26988107

  17. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    PubMed Central

    Olding, Timothy; Holmes, Oliver; DeJean, Paul; McAuley, Kim B.; Nkongchu, Ken; Santyr, Giles; Schreiner, L. John

    2011-01-01

    This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM)-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI). For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low's gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery). When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low's gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a) from the same gel batch and (b) from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration. PMID:21430853

  18. 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.

  19. Computational studies on linear, second and third-order nonlinear optical properties of novel styrylquinolinium dyes

    NASA Astrophysics Data System (ADS)

    Karakas, A.; Karakaya, M.; Taser, M.; Ceylan, Y.; Gozutok, A.; Arof, A. K.; El Kouari, Y.; Sahraoui, B.

    2016-03-01

    The electric dipole moments (μ), static dipole polarizabilities (α) and first hyperpolarizabilities (β) of styrylquinolinium dyes, D8 and D21, have been computed by density functional theory (DFT). The one-photon absorption (OPA) characterizations have been investigated using UV-vis spectroscopy and further interpreted using computational chemistry. The time-dependent Hartree-Fock (TDHF) method has been used to describe the dynamic dipole polarizabilities, dynamic second-order and also static and dynamic third-order nonlinear optical (NLO) properties. D8-D21 have rather high β and second hyperpolarizabilities (γ). The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO-LUMO band gaps for D8-D21 have been evaluated by DFT.

  20. Optoelectronic array that computes error and weight modification for a bipolar optical neural network

    NASA Astrophysics Data System (ADS)

    Mao, C. C.; Johnson, K. M.

    1993-03-01

    The design, fabrication, and results of an optoelectronic device that computes the weight changes required by the delta-rule learning algorithm and encodes the result on a pair of optical beams are presented. This very-large-scale-integrated ferroelectric liquid-crystal array was designed specifically to permit bipolar optoelectronic neural network to learn without the limitations of an external controlling computer. The device contains 64 smart pixels, which represent the processing elements in an artificial neural network. Each processing element consists of two photodetectors, a current-to-voltage converter, two comparators, two switches, and two output liquid-crystal modulating pads. The device has a measured contrast ratio of 10:1, a 10-to-90-percent rise time of 350 microsec and a 90-to-10-percent fall time of 150 microsec.

  1. Computer-aided diagnosis of breast MRI with high accuracy optical flow estimation

    NASA Astrophysics Data System (ADS)

    Meyer-Baese, Anke; Barbu, Adrian; Lobbes, Marc; Hoffmann, Sebastian; Burgeth, Bernhard; Kleefeld, Andreas; Meyer-Bäse, Uwe

    2015-05-01

    Non-mass enhancing lesions represent a challenge for the radiological reading. They are not well-defined in both morphology (geometric shape) and kinetics (temporal enhancement) and pose a problem to lesion detection and classification. To enhance the discriminative properties of an automated radiological workflow, the correct preprocessing steps need to be taken. In an usual computer-aided diagnosis (CAD) system, motion compensation plays an important role. To this end, we employ a new high accuracy optical flow based motion compensation algorithm with robustification variants. An automated computer-aided diagnosis system evaluates the atypical behavior of these lesions, and additionally considers the impact of non-rigid motion compensation on a correct diagnosis.

  2. Fast computation of an optimal controller for large-scale adaptive optics.

    PubMed

    Massioni, Paolo; Kulcsár, Caroline; Raynaud, Henri-François; Conan, Jean-Marc

    2011-11-01

    The linear quadratic Gaussian regulator provides the minimum-variance control solution for a linear time-invariant system. For adaptive optics (AO) applications, under the hypothesis of a deformable mirror with instantaneous response, such a controller boils down to a minimum-variance phase estimator (a Kalman filter) and a projection onto the mirror space. The Kalman filter gain can be computed by solving an algebraic Riccati matrix equation, whose computational complexity grows very quickly with the size of the telescope aperture. This "curse of dimensionality" makes the standard solvers for Riccati equations very slow in the case of extremely large telescopes. In this article, we propose a way of computing the Kalman gain for AO systems by means of an approximation that considers the turbulence phase screen as the cropped version of an infinite-size screen. We demonstrate the advantages of the methods for both off- and on-line computational time, and we evaluate its performance for classical AO as well as for wide-field tomographic AO with multiple natural guide stars. Simulation results are reported. PMID:22048298

  3. Methods to improve the bus throughput of node computer in optical interconnection network

    NASA Astrophysics Data System (ADS)

    Tang, Feng; Jing, Wencai; Zhang, Yimo; Zhou, Ge; Jia, Dagong; Kong, Fanmin; Sun, Zhixiang

    2005-02-01

    Both hardware and software are optimized simultaneously to improve the bus throughput of node computer in cluster computing network. A cost effective optical interconnection ring network is established using off-the-shelf PCs with windows operating system. A network adapter card ONIC is developed. Using ETDM and field program technique, the full bandwidth of the 32bit×33MHz PCI bus is reached in physical layer. In order to overcome the hardware and software data bottlenecks induced by using of general purpose platform such as PCs and Windows 2000 system, several methods are adopted to maximum the bus throughput of node computer. A user-level interface is designed to blur the kernel/user mode boundary of the software system, and bypass the OS overhead. Zero-copy DMA is realized. The bandwidth in application level using PIO and DMA transfer mode is improved 17 and 26 times respectively. The sustained bandwidth in application layer can reach 437.6Mbit/s. It"s also shown theoretically and experimentally that the selection of main board chipset, using memory space map, reasonable using of PIO and DMA transfer mode, using polling and large MTU will also improve the bus throughput of node computer considerably.

  4. 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

  5. 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

  6. 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.

  7. Comparison of computed tomography- and optical image-based assessment of liposome distribution.

    PubMed

    Huang, Huang; Dunne, Michael; Lo, John; Jaffray, David A; Allen, Christine

    2013-05-01

    The use of multimodal imaging as a tool to assess the in vivo pharmacokinetics and biodistribution of nanocarriers is important in understanding the nature of their in vivo transport. The current study reports the development of a nano-sized liposomal computed tomographic (CT)/optical imaging probe carrying iohexol and Cy5.5 and its use in micro-CT and optical imaging to quantitatively assess the whole-body (macroscopic), intratumoral, and microscopic distribution over a period of 8 days. These multimodal liposomes have a vascular half-life of 30.3 ± 8.9 hours in mice bearing subcutaneous H520 non-small cell lung cancer tumors, with the maximum liposome accumulation in tumor achieved 48 hours postinjection. The in vivo liposome distribution and stability were quantitatively assessed using both micro-CT and fluorescence molecular tomography. The combination of CT and optical imaging enables visualization of the liposomes at the whole-body, tumor, and cellular scales with high sensitivity. Such noninvasive tracking of therapeutic vehicles at the macro- and microscale is important for informed and rational development of novel nanocarrier systems. PMID:23490441

  8. Optic nerve sheath diameters in healthy adults measured by computer tomography

    PubMed Central

    Vaiman, Michael; Abuita, Rani; Bekerman, Inessa

    2015-01-01

    AIM To measure optic nerve sheath diameters (ONSD) in different locations by computer tomography (CT) and to recommend the best location for cases when ONSD is used for intracranial pressure monitoring. METHODS In a prospective cohort study, CT data of 300 healthy adults were analyzed (600 eyes). In all cases, the CT investigation was performed at the Emergency Department because of the various conditions that proved not to be connected with ophthalmological or neurological pathology. The ONSD were measured at 3 mm and 8 mm distance from the globe, and 3 mm from the anterior opening of the optic canal. The correlation analysis was performed with gender, age, and ethnic background. RESULTS The right/left ONSD are 4.94±1.51/5.17±1.34 mm at 3 mm, 4.35±0.76/4.45±0.62 mm at 8 mm from the globe, and 3.55±0.82/3.65±0.7 mm at 3 mm from the optic canal. No significant differences correlated with gender of the patients, their age, and ethnic background were found. CONCLUSION In healthy persons, the ONSD varies from 5.17±1.34 mm to 3.55±0.82 mm in different locations within the intraorbital space. The most stable results with lesser standard deviation can be obtained if it is measured 8-10 mm from the globe. PMID:26682181

  9. Experimental and computational analysis of Doppler cooling and the magneto-optic trap.

    NASA Astrophysics Data System (ADS)

    Cowan, J. A., Jr.; Cline, R. A.

    1997-04-01

    Cold, dense clouds of cesium atoms have been produced in an undergraduate research lab using Doppler cooling and a vapor cell magneto-optic trap (MOT). Measurements of temperature, density, and filling of a MOT will be reported. In conjunction with this experiment, Windows-based software has been developed to simulate laser cooling and trapping. The program graphically depicts the position and velocity of a variable number of atoms in two dimensions as they are cooled and trapped. The algorithm accounts for absorption, spontaneous and stimulated emission, Doppler and Zeeman shifts, and radiation trapping. The user can adjust time step, atom velocity, laser intensity and detuning, and magnetic field gradient. The program can demonstrate optical molasses, a MOT, and a dark MOT. Simulations can be recorded and played back in the same graphical environment, along with movies from the actual experiment. The simulation is a useful educational tool for explaining and investigating Doppler cooling and the magneto-optic trap. The program allows anyone to obtain computational results and compare them with published experimental results. A beta version of Cool Simulation is downloadable off the World Wide Web.

  10. 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

  11. 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

  12. Hybrid system of optics and computer for 3-D object recognition

    NASA Astrophysics Data System (ADS)

    Li, Qun Z.; Miao, Peng C.; He, Anzhi

    1992-03-01

    In this paper, a hybrid system of optics and computer for 3D object recognition is presented. The system consists of a Twyman-Green interferometer, a He-Ne laser, a computer, a TV camera, and an image processor. The structured light produced by a Twyman-Green interferometer is split in and illuminates objects in two directions at the same time. Moire contour is formed on the surface of object. In order to delete unwanted patterns in moire contour, we don't utilize the moire contour on the surface of object. We place a TV camera in the middle of the angle between two illuminating directions and take two groups of deformed fringes on the surface of objects. Two groups of deformed fringes are processed using the digital image processing system controlled and operated by XOR logic in the computer, moire fringes are then extracted from the complicated environment. 3D coordinates of points of the object are obtained after moire fringe is followed, and points belonging to the same fringe are given the same altitude. The object is described by its projected drawings in three coordinate planes. The projected drawings in three coordinate planes of the known objects are stored in the library of judgment. The object can be recognized by inquiring the library of judgment.

  13. 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

  14. 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.

  15. Analysis of the disturbing diffraction orders of computer-generated holograms used for testing optical aspherics.

    PubMed

    Lindlein, N

    2001-06-01

    Aspheric surfaces are increasingly used in the design of high-quality optical imaging systems. Therefore accurate testing methods for aspherics are also necessary. One possibility is to use a computer-generated hologram (CGH) as a part of a null lens in an interferometric testing device. However, CGHs normally have more than one diffraction order, thus causing disturbing areas in the interferogram. Here a simple approximative analytical expression is given for the spatial frequencies of the disturbing light in the interferogram coming from the different diffraction orders of the CGH. This expression also enables one to calculate the size and the shape of the disturbing areas in the interferogram. Some design examples for CGHs are given in an application of the expression. PMID:18357287

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

    SciTech Connect

    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{close_quote}s track axis may be lost. The magnitude of the effect is dependent on the particle{close_quote}s track structure. {copyright} {ital 1997 American Institute of Physics.}

  17. 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.

  18. Development of a computer-controlled polishing process for x-ray optics

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    Future X-ray observatory missions require grazing-incidence X-ray optics with angular resolution of < 5 arcsec half power diameter. For X-ray mirrors fabricated using replication processes, the achievable resolution depends ultimately on the quality of the polished replication mandrels. With an aim to fabricate better mirror shells, and also to reduce the cost/time of mandrel production, a computer-controlled machine is being developed for deterministic and localized polishing of mandrels. A key component in this is software 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.

  19. Optically driven nanostructures as the basis for large-scale quantum computing

    NASA Astrophysics Data System (ADS)

    Tsukanov, Alexander V.

    2008-03-01

    We propose a large-scale quantum computer architecture based upon the regular arrays of dopant atoms implanted into the semiconductor host matrix. The singly-ionized pairs of donors represent charge qubits on which arbitrary quantum operations can be achieved by application of two strongly detuned laser pulses. The implementation of two-qubit operations as well as the qubit read-out utilize the intermediate circuit containing a probe electron that is able to shuttle along the array of ionized ancilla donors providing the indirect conditional coupling between the qubits. The quantum bus strategy enables us to handle the qubits connected in parallel and enhances the efficiency of the quantum information processing. We demonstrate that non-trivial multi-qubit operations in the quantum register (e.g., an entanglement generation) can be accomplished by the sequence of the optical pulses combined with an appropriate voltage gate pattern.

  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. Computationally efficient autoregressive method for generating phase screens with frozen flow and turbulence in optical simulations.

    PubMed

    Srinath, Srikar; Poyneer, Lisa A; Rudy, Alexander R; Ammons, S Mark

    2015-12-28

    We present a sample-based, autoregressive (AR) method for the generation and time evolution of atmospheric phase screens that is computationally efficient and uses a single parameter per Fourier mode to vary the power contained in the frozen flow and stochastic components. We address limitations of Fourier-based methods such as screen periodicity and low spatial frequency power content. Comparisons of adaptive optics (AO) simulator performance when fed AR phase screens and translating phase screens reveal significantly elevated residual closed-loop temporal power for small increases in added stochastic content at each time step, thus displaying the importance of properly modeling atmospheric "boiling". We present preliminary evidence that our model fits to AO telemetry are better reflections of real conditions than the pure frozen flow assumption. PMID:26831998

  2. 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.

  3. Holographic memory optical system based on computer-generated Fourier holograms.

    PubMed

    Betin, A Yu; Bobrinev, V I; Odinokov, S B; Evtikhiev, N N; Starikov, R S; Starikov, S N; Zlokazov, E Yu

    2013-11-20

    Holography is known to be a prospective tool for storing large amounts of digital information, providing long lasting safety and high speed data access. In this paper, we present a new approach to holographic memory system design. Our method is based on an application of discrete Fourier-transform calculations to encode two-dimensional binary data pages as computer-generated amplitude Fourier holograms (CGFHs). These CGFHs, represented as grayscale raster images, can be displayed with the use of a high resolution amplitude spatial light modulator (SLM) in an optical projection system and exposed on holographic medium with multiple reduction. The optical scheme required for the technical realization of this method appears significantly simpler compared with known holographic memory recording devices; moreover, it can be built using either coherent or incoherent light sources. Coding of data pages by precise pseudorandom phase masks during CGFH synthesis allows us to achieve about 3% of the recorded microholograms diffraction efficiency. The experimental results of CGFH projection recorded with a 20× reduction on photosensitive holographic medium and its reconstruction are presented. PMID:24513770

  4. 3-Phenylpyridinium hydrogen squarate: Experimental and computational study of a nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Korkmaz, Ufuk; Bulut, Ahmet; Bulut, İclal

    2015-04-01

    The detailed investigation of an organic nonlinear optical (NLO) squarate salt of 3-phenylpyridinium hydrogen squarate (1), C11H10N+·C4HO4-, was reported in this study. The XRD data indicates that the crystal structure of the title compound is in the triclinic P-1 space group. In the asymmetric unit, the 3-phenylpyridine molecule is protonated by one hydrogen atom donation of squaric acid molecule, forming the salt (1). The X-ray analysis shows that the crystal packing has hydrogen bonding ring pattern of D22 (10) (α-dimer) through Nsbnd H···O interactions. The structural and vibrational properties of the compound were also studied by computational methods of ab initio at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) levels of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 are presented and compared with the experimental results. Non-linear optical properties (NLO) of the title compound together with the molecular electrostatic potential (MEP), electronic absorption spectrum, frontier molecular orbitals (FMOs) and conformational flexibility were also studied at the 2 level and the results were reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained.

  5. 3-Phenylpyridinium hydrogen squarate: experimental and computational study of a nonlinear optical material.

    PubMed

    Korkmaz, Ufuk; Bulut, Ahmet; Bulut, İclal

    2015-04-01

    The detailed investigation of an organic nonlinear optical (NLO) squarate salt of 3-phenylpyridinium hydrogen squarate (1), C11H10N+·C4HO4(-), was reported in this study. The XRD data indicates that the crystal structure of the title compound is in the triclinic P-1 space group. In the asymmetric unit, the 3-phenylpyridine molecule is protonated by one hydrogen atom donation of squaric acid molecule, forming the salt (1). The X-ray analysis shows that the crystal packing has hydrogen bonding ring pattern of D2(2)(10) (α-dimer) through NH···O interactions. The structural and vibrational properties of the compound were also studied by computational methods of ab initio at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) levels of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 are presented and compared with the experimental results. Non-linear optical properties (NLO) of the title compound together with the molecular electrostatic potential (MEP), electronic absorption spectrum, frontier molecular orbitals (FMOs) and conformational flexibility were also studied at the 2 level and the results were reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained. PMID:25590828

  6. A fast inverse consistent deformable image registration method based on symmetric optical flow computation

    PubMed Central

    Li, Hua; Low, Daniel A; Deasy, Joseph O; Naqa, Issam El

    2014-01-01

    Deformable image registration is widely used in various radiation therapy applications including daily treatment planning adaptation to map planned tissue or dose to changing anatomy. In this work, a simple and efficient inverse consistency deformable registration method is proposed with aims of higher registration accuracy and faster convergence speed. Instead of registering image I to a second image J, the two images are symmetrically deformed toward one another in multiple passes, until both deformed images are matched and correct registration is therefore achieved. In each pass, a delta motion field is computed by minimizing a symmetric optical flow system cost function using modified optical flow algorithms. The images are then further deformed with the delta motion field in the positive and negative directions respectively, and then used for the next pass. The magnitude of the delta motion field is forced to be less than 0.4 voxel for every pass in order to guarantee smoothness and invertibility for the two overall motion fields that are accumulating the delta motion fields in both positive and negative directions, respectively. The final motion fields to register the original images I and J, in either direction, are calculated by inverting one overall motion field and combining the inversion result with the other overall motion field. The final motion fields are inversely consistent and this is ensured by the symmetric way that registration is carried out. The proposed method is demonstrated with phantom images, artificially deformed patient images and 4D-CT images. Our results suggest that the proposed method is able to improve the overall accuracy (reducing registration error by 30% or more, compared to the original and inversely inconsistent optical flow algorithms), reduce the inverse consistency error (by 95% or more) and increase the convergence rate (by 100% or more). The overall computation speed may slightly decrease, or increase in most cases

  7. Rapid computation of the amplitude and phase of tightly focused optical fields distorted by scattering particles.

    PubMed

    Ranasinghesagara, Janaka C; Hayakawa, Carole K; Davis, Mitchell A; Dunn, Andrew K; Potma, Eric O; Venugopalan, Vasan

    2014-07-01

    We develop an efficient method for accurately calculating the electric field of tightly focused laser beams in the presence of specific configurations of microscopic scatterers. This Huygens-Fresnel wave-based electric field superposition (HF-WEFS) method computes the amplitude and phase of the scattered electric field in excellent agreement with finite difference time-domain (FDTD) solutions of Maxwell's equations. Our HF-WEFS implementation is 2-4 orders of magnitude faster than the FDTD method and enables systematic investigations of the effects of scatterer size and configuration on the focal field. We demonstrate the power of the new HF-WEFS approach by mapping several metrics of focal field distortion as a function of scatterer position. This analysis shows that the maximum focal field distortion occurs for single scatterers placed below the focal plane with an offset from the optical axis. The HF-WEFS method represents an important first step toward the development of a computational model of laser-scanning microscopy of thick cellular/tissue specimens. PMID:25121440

  8. Rapid computation of the amplitude and phase of tightly focused optical fields distorted by scattering particles

    PubMed Central

    Ranasinghesagara, Janaka C.; Hayakawa, Carole K.; Davis, Mitchell A.; Dunn, Andrew K.; Potma, Eric O.; Venugopalan, Vasan

    2014-01-01

    We develop an efficient method for accurately calculating the electric field of tightly focused laser beams in the presence of specific configurations of microscopic scatterers. This Huygens–Fresnel wave-based electric field superposition (HF-WEFS) method computes the amplitude and phase of the scattered electric field in excellent agreement with finite difference time-domain (FDTD) solutions of Maxwell’s equations. Our HF-WEFS implementation is 2–4 orders of magnitude faster than the FDTD method and enables systematic investigations of the effects of scatterer size and configuration on the focal field. We demonstrate the power of the new HF-WEFS approach by mapping several metrics of focal field distortion as a function of scatterer position. This analysis shows that the maximum focal field distortion occurs for single scatterers placed below the focal plane with an offset from the optical axis. The HF-WEFS method represents an important first step toward the development of a computational model of laser-scanning microscopy of thick cellular/tissue specimens. PMID:25121440

  9. 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.

  10. 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.

  11. Optimization of compute unified device architecture for real-time ultrahigh-resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    We propose an optimized signal processing scheme that utilizes the compute unified device architecture (CUDA) for real-time spectral domain optical coherence tomography (OCT). Because linear spline interpolation and the direct spectral reshaping method have low data and control dependencies, these algorithms maximally utilize graphic processing unit (GPU) resources for dispersion control. In addition, data transfer between main memory and GPU, regarded as one of the most wasteful and time-consuming processes in GPU computing, is executed in parallel with the signal processing by overlapping kernel execution and data transfers. Experimental results obtained from application of the proposed scheme to a laboratory constructed OCT system comprising five spectrally shifted SLDs indicate that the OCT system has an axial resolution of 4.8 μm and transverse resolution of 13 μm in air. Further, coherence artifacts are reduced by 3-14 dB over the side-lobes in the point spread function. The optimization of CUDA enables OCT imaging rates up to 350 kHz (A-lines/sec) with a single GTX680 GPU.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26626797

  13. 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

    2015-01-01

    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. PMID:26626797

  14. Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging

    NASA Astrophysics Data System (ADS)

    Kim, E.; Bowsher, J.; Thomas, A. S.; Sakhalkar, H.; Dewhirst, M.; Oldham, M.

    2008-10-01

    Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the 'self'-attenuation of photons emitted within the sample. The correction is analogous to a method commonly applied in single-photon-emission computed tomography reconstruction. The performance of the correction method was investigated by application to a transparent cylindrical gelatin phantom, containing a known distribution of attenuation (a central ink-doped gelatine core) and a known distribution of fluorescing fibres. Attenuation corrected and uncorrected optical-ECT images were reconstructed on the phantom to enable an evaluation of the effectiveness of the correction. Significant attenuation artefacts were observed in the uncorrected images where the central fibre appeared ~24% less intense due to greater attenuation from the surrounding ink-doped gelatin. This artefact was almost completely removed in the attenuation-corrected image, where the central fibre was within ~4% of the others. The successful phantom test enabled application of attenuation correction to optical-ECT images of an unsectioned human breast xenograft tumour grown subcutaneously on the hind leg of a nude mouse. This tumour cell line had been genetically labelled (pre-implantation) with fluorescent reporter genes such that all viable tumour cells expressed constitutive red fluorescent protein and hypoxia-inducible factor 1 transcription-produced green fluorescent protein. In addition to the fluorescent reporter labelling of gene expression, the tumour microvasculature was labelled by a light-absorbing vasculature contrast agent delivered in vivo by tail-vein injection. Optical-CT transmission images yielded high-resolution 3D images of the absorbing contrast agent, and

  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. Computational optical-sectioning microscopy for 3D quantization of cell motion: results and challenges

    NASA Astrophysics Data System (ADS)

    McNally, James G.

    1994-09-01

    How cells move and navigate within a 3D tissue mass is of central importance in such diverse problems as embryonic development, wound healing and metastasis. This locomotion can now be visualized and quantified by using computation optical-sectioning microscopy. In this approach, a series of 2D images at different depths in a specimen are stacked to construct a 3D image, and then with a knowledge of the microscope's point-spread function, the actual distribution of fluorescent intensity in the specimen is estimated via computation. When coupled with wide-field optics and a cooled CCD camera, this approach permits non-destructive 3D imaging of living specimens over long time periods. With these techniques, we have observed a complex diversity of motile behaviors in a model embryonic system, the cellular slime mold Dictyostelium. To understand the mechanisms which control these various behaviors, we are examining motion in various Dictyostelium mutants with known defects in proteins thought to be essential for signal reception, cell-cell adhesion or locomotion. This application of computational techniques to analyze 3D cell locomotion raises several technical challenges. Image restoration techniques must be fast enough to process numerous 1 Gbyte time-lapse data sets (16 Mbytes per 3D image X 60 time points). Because some cells are weakly labeled and background intensity is often high due to unincorporated dye, the SNR in some of these images is poor. Currently, the images are processed by a regularized linear least- squares restoration method, and occasionally by a maximum-likelihood method. Also required for these studies are accurate automated- tracking procedures to generate both 3D trajectories for individual cells and 3D flows for a group of cells. Tracking is currently done independently for each cell, using a cell's image as a template to search for a similar image at the next time point. Finally, sophisticated visualization techniques are needed to view the

  17. FORTRAN programs for computation of optical properties of the sea from radiation data collected by in situ spectrometers

    NASA Astrophysics Data System (ADS)

    Sathe, P. V.; Sathyendranath, Shubha

    Measurement of spectral composition of the radiation field pervading above and below the seasurface is gaining increasing importance in recent years. It plays a significant role in ocean remote sensing to determine the constituents of seawater. An accurate description of the radiation field inside the waterbody also holds the key to solving problems of radiation transfer in the ocean. This paper presents computer programs in FORTRAN 77 which process the radiation data collected in the sea by in situ spectrometers, apply the necessary corrections to them and compute optical properties of the sea at spectral intervals of 4 nm each, within the entire visible region of electromagnetic spectrum. The programs compute the solar zenith and azimuth angles at a given location in the sea from astronomical considerations for use in computing the optical properties. The programs are useful in computing the spectral quality of upwelling light emerging out from within the sea, which forms the basic signal in remote sensing of ocean color. They also may be used by marine biologists to compute the vertical diffuse attenuation coefficients and absorption coefficients for different water types in studies on marine productivity requiring the amount of energy available for photosynthesis in different optical channels at different depths in the sea.

  18. Towards athermal optically-interconnected computing system using slotted silicon microring resonators and RF-photonic comb generation

    NASA Astrophysics Data System (ADS)

    Zhou, Linjie; Kashiwagi, Ken; Okamoto, Katsunari; Scott, R. P.; Fontaine, N. K.; Ding, Dan; Akella, Venkatesh; Yoo, S. J. B.

    2009-06-01

    We report that completely athermal design of a slotted silicon waveguide is possible by combining the negative thermo-optic (TO) coefficient of, for example, polymethyl methacrylate (PMMA) with the positive TO coefficient of silicon. When used in a microring resonator structure, the filled overcladding slotted waveguide and the unfilled (air-filled) overcladding slotted waveguide can both achieve athermal characteristics. Simulations indicate a wide range of realizations with proper design parameters of the slotted waveguides, namely, the silicon strip and slot widths. Preliminary experimental results on fabricated devices demonstrate that the temperature dependence is reduced from 91 pm/°C for a regular microring resonator to 52 pm/°C for the PMMA-clad microring resonator. Completely athermal realization is expectable in similar devices with improved fabrication techniques. For the external optical source, we demonstrate a stable 3.5 THz wide (175 modes×20 GHz) optical comb source with nearly flat spectral phase. Adjustable mode spacing and wavelength tunability across the C-band are maintained so that comb lines can be matched to the specified wavelength grid of the computing system. With such schemes, temperature controls of individual optical components in the optically interconnected computing chips become unnecessary, greatly reducing the complexity of the computing system.

  19. 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.

  20. A computational approach to high-resolution imaging of the living human retina without hardware adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    We demonstrate high-resolution imaging of the living human retina by computationally correcting highorder ocular aberrations. These corrections are performed post-acquisition and without the need for a deformable mirror or wavefront sensor that are commonly employed in hardware adaptive optics (HAO) systems. With the introduction of HAO to ophthalmic imaging, high-resolution near diffraction-limited imaging of the living human retina has become possible. The combination of a deformable mirror, wavefront sensor, and supporting hardware/software, though, can more than double the cost of the underlying imaging modality, in addition to significantly increasing the system complexity and sensitivity to misalignment. Optical coherence tomography (OCT) allows 3-D imaging in addition to naturally providing the complex optical field of backscattered light. This is unlike a scanning laser ophthalmoscope which measures only the intensity of the backscattered light. Previously, our group has demonstrated the utility of a technique called computational adaptive optics (CAO) which utilizes the complex field measured with OCT to computationally correct for optical aberrations in a manner similar to HAO. Until now, CAO has been applied to ex vivo imaging and in vivo skin imaging. Here, we demonstrate in vivo imaging of cone photoreceptors using CAO. Additional practical considerations such as imaging speed, and stability are discussed.

  1. 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.

  2. 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.

  3. 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

  4. 2-Pyridinium propanol hydrogen squarate: Experimental and computational study of a nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Korkmaz, Ufuk; Bulut, Ahmet

    2015-02-01

    The experimental and theoretical investigation of a novel organic nonlinear optical (NLO) squarate salt of 2-pyridinium propanol hydrogen squarate (1), C8H12ON+ ·C4HO4-, were reported in this study. The crystal structure of the title compound was found to crystallize in the triclinic P-1 space group. In the asymmetric unit each squaric acid molecules have donated one H atom to the pyridines N1 and N2 atoms of a 2-pyridine propanol molecule, forming the salt (1). The X-ray analysis clearly indicated that the crystal packing has shown the hydrogen bonding ring pattern of D22 (10) (α-dimer) through Nsbnd H⋯O interactions. The structural and vibrational properties of the compound were also studied by computational methods of ab initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 are presented and compared with the X-ray analysis result. The molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained.

  5. 2-Pyridinium propanol hydrogen squarate: experimental and computational study of a nonlinear optical material.

    PubMed

    Korkmaz, Ufuk; Bulut, Ahmet

    2015-02-01

    The experimental and theoretical investigation of a novel organic nonlinear optical (NLO) squarate salt of 2-pyridinium propanol hydrogen squarate (1), C8H12ON(+)·C4HO4(-), were reported in this study. The crystal structure of the title compound was found to crystallize in the triclinic P-1 space group. In the asymmetric unit each squaric acid molecules have donated one H atom to the pyridines N1 and N2 atoms of a 2-pyridine propanol molecule, forming the salt (1). The X-ray analysis clearly indicated that the crystal packing has shown the hydrogen bonding ring pattern of D2(2)(10) (α-dimer) through N-H⋯O interactions. The structural and vibrational properties of the compound were also studied by computational methods of ab initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 are presented and compared with the X-ray analysis result. The molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained. PMID:25459503

  6. 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

  7. Computational Code to Determinate the Optical Constants of Materials with Atrophysical Importance

    NASA Astrophysics Data System (ADS)

    Robson Rocha, Will; Pilling, Sergio

    Several environments in the interstellar medium (ISM) are composed by dust grains (e.g. silicates), that in somewhere can be covered by astrophysical ices (frozen molecular species). The presence of this materials inside dense and cold regions in space such as molecular clouds and circumstellar disks around young stars is proven by space telescopes (e. g. Herschel, Spitzer, ISO) using infrared spectroscopy. In such environments, molecules such as H _{2}O, CO, CO _{2}, NH _{3}, CH _{3}OH among others, may exist in the solid phase and constitute what we call as the interstellar ices. In this work we present a code called NKABS (acronym for “N and K determination from ABSorbance data”) to calculate the optical constants of materials with astrophysical importance directly from absorbance data in the infrared. It is a free code, developed in Python Programing Language, available for Windows (®) operating system. The parameters obtained using the NKABS code are essentials to perform studies involving computational modeling of star forming regions in the infrared. The experimental data have been obtained using a high vacuum portable chamber from the Laboratorio de Astroquímica e Astrobiologia (LASA/UNIVAP). The samples used to calculate the optical constants presented here, were obtained from the condensation of pure gases (e.g. CO, CO _{2} , NH _{3} , SO _{2}), from the sublimation in vacuum of pure liquids (e.g. water, acetone, acetonitrile, acetic acid, formic acid, ethanol and methanol) and from mixtures of different species (e.g. H _{2}O:CO _{2}, H _{2}O:CO:NH _{3}, H _{2}O:CO _{2}:NH _{3}:CH _{4}). Additionally films of solid biomolecules samples of astrochemistry/astrobiology interest (e.g. glycine, adenine) were probed. The NKABS code may also calculate the optical constants of materials processed by the radiation, a scenario very common in star forming regions. Authors would like to thanks the agencies FAPESP (JP#2009/18304-0 and PHD#2013/07657-5), FVE

  8. 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

    2014-01-01

    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. PMID:24302357

  9. Computing approximate blocking probability of inverse multiplexing and sub-band conversion in the flexible-grid optical networks

    NASA Astrophysics Data System (ADS)

    Gu, Yamei; You, Shanhong

    2016-07-01

    With the rapid growth of data rate, the optical network is evolving from fixed-grid to flexible-grid to provide spectrum-efficient and scalable transport of 100 Gb/s services and beyond. Also, the deployment of wavelength converter in the existing network can increase the flexibility of routing and wavelength allocation (RWA) and improve blocking performance of the optical networks. In this paper, we present a methodology for computing approximate blocking probabilities of the provision of multiclass services in the flexible-grid optical networks with sub-band spectrum conversion and inverse multiplexing respectively. Numerical calculation results based on the model are compared to the simulation results for the different cases. It is shown that the calculation results match well with the simulation results for the flexible-grid optical networks at different scenarios.

  10. 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.