Chromatic-free spatially resolved optical emission spectroscopy diagnostics for microplasma

International Nuclear Information System (INIS)

Zhu Liguo; Chen Wencong; Zhu Ximing; Pu Yikang; Li Zeren

2009-01-01

A chromatic-free spatially resolved diagnostic system for microplasma measurement is proposed and demonstrated, which consists of an optical chromatic-free microscope mirror system, an electron multiplying charge coupled device (EMCCD), and bandpass filters. The diagnostic system free of chromatic aberrations with a spatial resolution of about 6 μm is achieved. The factors that limit the resolution of this diagnostic system have been analyzed, which are optical diffraction, the pixel size of the EMCCD, and the thickness of the microplasma. In this paper, the optimal condition for achieving a maximum resolution power has been analyzed. With this diagnostic system, we revealed the spatial nonuniformity of a microwave atmospheric-pressure argon microplasma. Furthermore, the spatial distribution of the time-averaged effective electron temperature has been estimated from the intensity distributions of 750.4 and 415.8 nm emissions.

Introduction of Spectrally and Spatially Flexible Optical Networks

DEFF Research Database (Denmark)

Xia, Tiejun J.; Fevrier, Herve; Wang, Ting

2015-01-01

Given the introduction of coherent 100G systems has provided enough fiber capacity to meet data traffic growth in the near term, enhancing network efficiency will be service providers' high priority. Adding flexibility at the optical layer is a key step to increasing network efficiency, and both...... spectral and spatial functionality will be considered in next generation optical networks along with advanced network management to effectively harness the new capabilities....

Designs of Optoelectronic Trinary Signed-Digit Multiplication by use of Joint Spatial Encodings and Optical Correlation

Science.gov (United States)

Cherri, Abdallah K.

1999-02-01

Trinary signed-digit (TSD) symbolic-substitution-based (SS-based) optical adders, which were recently proposed, are used as the basic modules for designing highly parallel optical multiplications by use of cascaded optical correlators. The proposed multiplications perform carry-free generation of the multiplication partial products of two words in constant time. Also, three different multiplication designs are presented, and new joint spatial encodings for the TSD numbers are introduced. The proposed joint spatial encodings allow one to reduce the SS computation rules involved in optical multiplication. In addition, the proposed joint spatial encodings increase the space bandwidth product of the spatial light modulators of the optical system. This increase is achieved by reduction of the numbers of pixels in the joint spatial encodings for the input TSD operands as well as reduction of the number of pixels used in the proposed matched spatial filters for the optical multipliers.

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

Science.gov (United States)

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

2018-01-01

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

Optical remote sensing

CERN Document Server

Prasad, Saurabh; Chanussot, Jocelyn

2011-01-01

Optical remote sensing relies on exploiting multispectral and hyper spectral imagery possessing high spatial and spectral resolutions respectively. These modalities, although useful for most remote sensing tasks, often present challenges that must be addressed for their effective exploitation. This book presents current state-of-the-art algorithms that address the following key challenges encountered in representation and analysis of such optical remotely sensed data: challenges in pre-processing images, storing and representing high dimensional data, fusing different sensor modalities, patter

High Speed and High Spatial Density Parameter Measurement Using Fiber Optic Sensing Technology

Science.gov (United States)

Parker, Allen R. Jr. (Inventor); Chan, Hon Man (Inventor); Richards, William Lance (Inventor); Piazza, Anthony (Inventor); Hamory, Philip J (Inventor)

2017-01-01

The present invention is an improved fiber optic sensing system (FOSS) having the ability to provide both high spatial resolution and high frequency strain measurements. The inventive hybrid FOSS fiber combines sensors from high acquisition speed and low spatial resolution Wavelength-Division Multiplexing (WDM) systems and from low acquisition speed and high spatial resolution Optical Frequency Domain Reflection (OFDR) systems. Two unique light sources utilizing different wavelengths are coupled with the hybrid FOSS fiber to generate reflected data from both the WDM sensors and OFDR sensors operating on a single fiber optic cable without incurring interference from one another. The two data sets are then de-multiplexed for analysis, optionally with conventionally-available WDM and OFDR system analyzers.

Spatial light modulators for full cross-connections in optical networks

Science.gov (United States)

Juday, Richard D. (Inventor)

2004-01-01

A polarization-independent optical switch is disclosed for switching at least one incoming beam from at least one input source to at least one output drain. The switch includes a polarizing beam splitter to split each of the at least one incoming beam into a first input beam and a second input beam, wherein the first input beam and the second input beams are independently polarized; a wave plate optically coupled to the second input beam for converting the polarization of the second input beam to an appropriately polarized second input beam; a beam combiner optically coupled to the first input beam and the modified second input beam, wherein the beam combiner accepts the first input beam and the modified second input beam to produce a combined beam; the combined beam is invariant to the polarization state of the input source's polarization; and a controllable spatial light modulator optically coupled to the combined beam, wherein the combined beam is diffracted by the controllable spatial light modulator to place light at a plurality of output locations.

Allocation of spectral and spatial modes in multidimensional metro-access optical networks

Science.gov (United States)

Gao, Wenbo; Cvijetic, Milorad

2018-04-01

Introduction of spatial division multiplexing (SDM) has added a new dimension in an effort to increase optical fiber channel capacity. At the same time, it can also be explored as an advanced optical networking tool. In this paper, we have investigated the resource allocation to end-users in multidimensional networking structure with plurality of spectral and spatial modes actively deployed in different networking segments. This presents a more comprehensive method as compared to the common practice where the segments of optical network are analyzed independently since the interaction between network hierarchies is included into consideration. We explored the possible transparency from the metro/core network to the optical access network, analyzed the potential bottlenecks from the network architecture perspective, and identified an optimized network structure. In our considerations, the viability of optical grooming through the entire hierarchical all-optical network is investigated by evaluating the effective utilization and spectral efficiency of the network architecture.

Gas refractometry based on an all-fiber spatial optical filter.

Science.gov (United States)

Silva, Susana; Coelho, L; André, R M; Frazão, O

2012-08-15

A spatial optical filter based on splice misalignment between optical fibers with different diameters is proposed for gas refractometry. The sensing head is formed by a 2 mm long optical fiber with 50 μm diameter that is spliced with a strong misalignment between two single-mode fibers (SMF28) and interrogated in transmission. The misalignment causes a Fabry-Perot behavior along the reduced-size fiber and depending on the lead-out SMF28 position, it is possible to obtain different spectral responses, namely, bandpass or band-rejection filters. It is shown that the spatial filter device is highly sensitive to refractive index changes on a nitrogen environment by means of the gas pressure variation. A maximum sensitivity of -1390 nm/RIU for the bandpass filter was achieved. Both devices have shown similar temperature responses with an average sensitivity of 25.7 pm/°C.

Virtual experiment of optical spatial filtering in Matlab environment

Science.gov (United States)

Ji, Yunjing; Wang, Chunyong; Song, Yang; Lai, Jiancheng; Wang, Qinghua; Qi, Jing; Shen, Zhonghua

2017-08-01

The principle of spatial filtering experiment has been introduced, and the computer simulation platform with graphical user interface (GUI) has been made out in Matlab environment. Using it various filtering processes for different input image or different filtering purpose will be completed accurately, and filtering effect can be observed clearly with adjusting experimental parameters. The physical nature of the optical spatial filtering can be showed vividly, and so experimental teaching effect will be promoted.

Multiport optical circulator by using polarizing beam splitter cubes as spatial walk-off polarizers.

Science.gov (United States)

Chen, Jing-Heng; Chen, Kun-Huang; Lin, Jiun-You; Hsieh, Hsiang-Yung

2010-03-10

Optical circulators are necessary passive devices applied in optical communication systems. In the design of optical circulators, the implementation of the function of spatial walk-off polarizers is a key technique that significantly influences the performance and cost of a device. This paper proposes a design of a multiport optical circulator by using polarizing beam splitter cubes as spatial walk-off polarizers. To show the feasibility of the design, a prototype of a six-port optical circulator was fabricated. The insertion losses are 0.94-1.49 dB, the isolations are 25-51 dB, and return losses are 27.72 dB.

Multi-wavelength and multi-colour temporal and spatial optical solitons

DEFF Research Database (Denmark)

Kivshar, Y. S.; Sukhorukov, A. A.; Ostrovskaya, E. A.

2000-01-01

We present an overview of several novel types of multi- component envelope solitary waves that appear in fiber and waveguide nonlinear optics. In particular, we describe multi-channel solitary waves in bit-parallel-wavelength fiber transmission systems for high performance computer networks, multi......-color parametric spatial solitary waves due to cascaded nonlinearities of quadratic materials, and quasiperiodic envelope solitons in Fibonacci optical superlattices....

Optical network scaling: roles of spectral and spatial aggregation.

Science.gov (United States)

Arık, Sercan Ö; Ho, Keang-Po; Kahn, Joseph M

2014-12-01

As the bit rates of routed data streams exceed the throughput of single wavelength-division multiplexing channels, spectral and spatial traffic aggregation become essential for optical network scaling. These aggregation techniques reduce network routing complexity by increasing spectral efficiency to decrease the number of fibers, and by increasing switching granularity to decrease the number of switching components. Spectral aggregation yields a modest decrease in the number of fibers but a substantial decrease in the number of switching components. Spatial aggregation yields a substantial decrease in both the number of fibers and the number of switching components. To quantify routing complexity reduction, we analyze the number of multi-cast and wavelength-selective switches required in a colorless, directionless and contentionless reconfigurable optical add-drop multiplexer architecture. Traffic aggregation has two potential drawbacks: reduced routing power and increased switching component size.

Linear optical quantum computing in a single spatial mode.

Science.gov (United States)

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

2013-10-11

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

Technologies for Elastic Optical Networking Systems in Spatial, Temporal and Spectral Domains

Science.gov (United States)

Qin, Chuan

wavelength to track the signal wavelength, thus providing a technique for authentically automatic wavelength tracking. I also explored different materials and crystal orientations to reduce the radio-frequency (RF) power consumption required to shift the wavelengths. Based on the elastic optical networking in the temporal, spectral and spatial domains, an additional degree of freedom has been investigated recently to increase the data capacity. The exploration to use the spatial domain to carry more data is termed as spatial division multiplexing (SDM). One such SDM method is orbital angular momentum(OAM), which is a group of orthogonal light beams carrying orbital angular momentum exhibiting an azimuthal phase variation. The utilization of OAM states has the potential to significantly increase the spectral efficiency and channel capacity. The thesis also includes the demonstration to establish a connection by exploiting the elasticity steering in spatial, temporal and spectral domains. Beam steering based on optical phased array (OPA) is also a potential candidate of SDM to carry information when a different linear phase will distribute light to different spatial locations. The states are intrinsically orthogonal to one another. Using 4x4 3-D waveguides written by ultrafast laser inscription (ULI), we demonstrated 2-D optical phased array (OPA) beam steering that shows steering in both vertical and horizontal directions. Enabling technologies provide future pathways for elastic optical networking and will fundamentally impact optical communication systems in many ways.

Semiconductor nanoparticles with spatial separation of charge carriers: synthesis and optical properties

International Nuclear Information System (INIS)

Vasiliev, Roman B; Dirin, Dmitry N; Gaskov, Alexander M

2011-01-01

The results of studies on core/shell semiconductor nanoparticles with spatial separation of photoexcited charge carriers are analyzed and generalized. Peculiarities of the electronic properties of semiconductor/semiconductor heterojunctions formed inside such particles are considered. Data on the effect of spatial separation of charge carriers on the optical properties of nanoparticles including spectral shifts of the exciton bands, absorption coefficients and electron–hole pair recombination times are presented. Methods of synthesis of core/shell semiconductor nanoparticles in solutions are discussed. Specific features of the optical properties of anisotropic semiconductor nanoparticles with the semiconductor/semiconductor junctions are noted. The bibliography includes 165 references.

Spatial-temporal-covariance-based modeling, analysis, and simulation of aero-optics wavefront aberrations.

Science.gov (United States)

Vogel, Curtis R; Tyler, Glenn A; Wittich, Donald J

2014-07-01

We introduce a framework for modeling, analysis, and simulation of aero-optics wavefront aberrations that is based on spatial-temporal covariance matrices extracted from wavefront sensor measurements. Within this framework, we present a quasi-homogeneous structure function to analyze nonhomogeneous, mildly anisotropic spatial random processes, and we use this structure function to show that phase aberrations arising in aero-optics are, for an important range of operating parameters, locally Kolmogorov. This strongly suggests that the d5/3 power law for adaptive optics (AO) deformable mirror fitting error, where d denotes actuator separation, holds for certain important aero-optics scenarios. This framework also allows us to compute bounds on AO servo lag error and predictive control error. In addition, it provides us with the means to accurately simulate AO systems for the mitigation of aero-effects, and it may provide insight into underlying physical processes associated with turbulent flow. The techniques introduced here are demonstrated using data obtained from the Airborne Aero-Optics Laboratory.

Neural-network-directed alignment of optical systems using the laser-beam spatial filter as an example

Science.gov (United States)

Decker, Arthur J.; Krasowski, Michael J.; Weiland, Kenneth E.

1993-01-01

This report describes an effort at NASA Lewis Research Center to use artificial neural networks to automate the alignment and control of optical measurement systems. Specifically, it addresses the use of commercially available neural network software and hardware to direct alignments of the common laser-beam-smoothing spatial filter. The report presents a general approach for designing alignment records and combining these into training sets to teach optical alignment functions to neural networks and discusses the use of these training sets to train several types of neural networks. Neural network configurations used include the adaptive resonance network, the back-propagation-trained network, and the counter-propagation network. This work shows that neural networks can be used to produce robust sequencers. These sequencers can learn by example to execute the step-by-step procedures of optical alignment and also can learn adaptively to correct for environmentally induced misalignment. The long-range objective is to use neural networks to automate the alignment and operation of optical measurement systems in remote, harsh, or dangerous aerospace environments. This work also shows that when neural networks are trained by a human operator, training sets should be recorded, training should be executed, and testing should be done in a manner that does not depend on intellectual judgments of the human operator.

Remote Raman microimaging using an AOTF and a spatially coherent microfiber optical probe

International Nuclear Information System (INIS)

Trey Skinner, H.; Cooney, T.F.; Sharma, S.K.; Angel, S.M.

1996-01-01

A fiber-optic Raman microimaging probe is described that is suitable for acquiring high-spatial-resolution Raman images in sampling situations with no clear line of sight. A high-power near-infrared diode laser combined with an acousto-optic tunable filter and a spatially coherent optical fiber bundle allow fluorescence-free Raman images of remotely located samples to be acquired at distances up to several meters. The feasibility of this technique is demonstrated with Raman images of (1) a pellet containing a mixture of a highly scattering sample, bis-methylstyrylbenzene (BMSB), KCl, and graphite, and (2) a partially graphitized diamond. These images clearly show phase boundaries over an area of approximately 0.1 mm 2 with ∼4-μm resolution. copyright 1996 Society for Applied Spectroscopy

On the theory of spatial localization of photons

International Nuclear Information System (INIS)

Keller, Ole

2005-01-01

In the quantum physics of near-field optics and optical tunneling light-matter interactions are studied on a length scale (much) smaller than the wavelength of light, and questions regarding the possibilities for strong spatial localization of electromagnetic fields are here in focus. Some of these questions relate to the spatial resolution problem in optics, a problem which has gained considerable attention in connection to optical investigations of mesoscopic systems. Optics beyond the classical diffraction limit has renewed our interest in the various theories for spatial localization of single photons. In the present work aspects of these theories of particular importance for light-matter interaction on the microscopic and mesoscopic length scales are reviewed. Photon wave mechanics, i.e. the (rather unknown) first quantized theory of the photon, allows us to address the spatial field localization problem in a flexible manner which links smoothly to classical electromagnetics. The wave mechanics of free photons is discussed both in the momentum-time domain (Part A) and in the space-time domain (Part B). The first-quantized theory of spatial localization of photons subjected to field-matter interaction is described in Part C, paying particular attendance to the so-called photon energy wave function concept. In Part D, the spatial localization of photons are studied on a field theoretic (second-quantized) basis. The coarse-grained photon localization theory and the spatial localization perceived in various representations (gauges) here are core issues. In the two last parts of the review I describe photon fields in near-field optics (Part E), and the optical tunneling phenomenon, here seen as a fingerprint of weak photon localizability (Part F)

Few-mode fiber, splice and SDM component characterization by spatially-diverse optical vector network analysis

DEFF Research Database (Denmark)

Rommel, Simon; Mendinueta, José Manuel Delgado; Klaus, Werner

2017-01-01

This paper discusses spatially diverse optical vector network analysis for space division multiplexing (SDM) component and system characterization, which is becoming essential as SDM is widely considered to increase the capacity of optical communication systems. Characterization of a 108-channel ...... in the few-mode multi-core fiber and their impact on system IL and MDL are analyzed, finding splices to cause significant mode-mixing and to be non-negligible in system capacity analysis.......This paper discusses spatially diverse optical vector network analysis for space division multiplexing (SDM) component and system characterization, which is becoming essential as SDM is widely considered to increase the capacity of optical communication systems. Characterization of a 108-channel...... photonic lantern spatial multiplexer, coupled to a 36-core 3-mode fiber, is experimentally demonstrated, extracting the full impulse response and complex transfer function matrices as well as insertion loss (IL) and mode-dependent loss (MDL) data. Moreover, the mode-mixing behavior of fiber splices...

Coherent Addressing of Individual Neutral Atoms in a 3D Optical Lattice.

Science.gov (United States)

Wang, Yang; Zhang, Xianli; Corcovilos, Theodore A; Kumar, Aishwarya; Weiss, David S

2015-07-24

We demonstrate arbitrary coherent addressing of individual neutral atoms in a 5×5×5 array formed by an optical lattice. Addressing is accomplished using rapidly reconfigurable crossed laser beams to selectively ac Stark shift target atoms, so that only target atoms are resonant with state-changing microwaves. The effect of these targeted single qubit gates on the quantum information stored in nontargeted atoms is smaller than 3×10^{-3} in state fidelity. This is an important step along the path of converting the scalability promise of neutral atoms into reality.

Spatial and Temporal Variations of Aerosol Optical Properties during KORUS-AQ

Science.gov (United States)

Choi, Y.; Ghim, Y. S.; Segal-Rosenhaimer, M.; Redemann, J.

2017-12-01

As part of the KORUS-AQ campaign, Aerosol Robotic Networks (AERONET) Cimel sunphotometers were deployed at more than 20 sites over Korea including the Seoul Metropolitan Area (SMA) and rural/background areas. We analyzed hourly mean values of fine and coarse mode aerosol optical depths (AODs), and fine mode fraction (FMF) from spectral deconvolution algorithm retrievals. The AERONET sites over Korea were classified into four groups - those in SMA, southeastern and southwestern parts of Korea, and background sites, which distribute similar results from particulate matter (PM) stations in Korea. Temporal and spatial variations of aerosol optical properties (AOPs) from the four groups were further examined using AODs from the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), which can provide denser spatial resolution than AERONET sites and PM stations. AOPs from more than 30 flights over SMA were also investigated to distinguish the characteristics of diurnal variations upwind and downwind of SMA. The spatial and temporal homogeneity and/or heterogeneity of AOPs are discussed in terms of meteorological variables, other pollutants and nearby emission sources.

Longterm and spatial variability of Aerosol optical properties measured by sky radiometer in Japan sites

Science.gov (United States)

Aoki, K.

2016-12-01

Aerosols and cloud play an important role in the climate change. We started the long-term monitoring of aerosol and cloud optical properties since 1990's by using sky radiometer (POM-01, 02; Prede Co. Ltd., Japan). We provide the information, in this presentation, on the aerosol optical properties with respect to their temporal and spatial variability in Japan site (ex. Sapporo, Toyama, Kasuga and etc). The global distributions of aerosols have been derived from earth observation satellite and have been simulated in numerical models, which assume optical parameters. However, these distributions are difficult to derive because of variability in time and space. Therefore, Aerosol optical properties were investigated using the measurements from ground-based and ship-borne sky radiometer. The sky radiometer is an automatic instrument that takes observations only in daytime under the clear sky conditions. Observation of diffuse solar intensity interval was made every ten or five minutes by once. The aerosol optical properties were computed using the SKYRAD.pack version 4.2. The obtained Aerosol optical properties (Aerosol optical thickness, Ångström exponent, Single scattering albedo, and etc.) and size distribution volume clearly showed spatial and temporal variability in Japan area. In this study, we present the temporal and spatial variability of Aerosol optical properties at several Japan sites, applied to validation of satellite and numerical models. This project is validation satellite of GCOM-C, JAXA. The GCOM-C satellite scheduled to be launched in early 2017.

Spatial confinement of acoustic and optical waves in stubbed slab structure as optomechanical resonator

Energy Technology Data Exchange (ETDEWEB)

Li, Changsheng, E-mail: lcs135@163.com; Huang, Dan; Guo, Jierong

2015-02-20

We theoretically demonstrate that acoustic waves and optical waves can be spatially confined in the same micro-cavity by specially designed stubbed slab structure. The proposed structure presents both phononic and photonic band gaps from finite element calculation. The creation of cavity mode inside the band gap region provides strong localization of phonon and photon in the defect region. The practical parameters to inject cavity and work experimentally at telecommunication range are discussed. This structure can be precisely fabricated, hold promises to enhance acousto-optical interactions and design new applications as optomechanical resonator. - Highlights: • A resonator simultaneously supports acoustic and optical modes. • Strong spatial confinement and slow group velocity. • Potential to work as active optomechanical resonator.

Diffuse optical imaging using spatially and temporally modulated light

Science.gov (United States)

O'Sullivan, Thomas D.; Cerussi, Albert E.; Cuccia, David J.; Tromberg, Bruce J.

2012-07-01

The authors describe the development of diffuse optical imaging (DOI) technologies, specifically the use of spatial and temporal modulation to control near infrared light propagation in thick tissues. We present theory and methods of DOI focusing on model-based techniques for quantitative, in vivo measurements of endogenous tissue absorption and scattering properties. We specifically emphasize the common conceptual framework of the scalar photon density wave for both temporal and spatial frequency-domain approaches. After presenting the history, theoretical foundation, and instrumentation related to these methods, we provide a brief review of clinical and preclinical applications from our research as well as our outlook on the future of DOI technology.

Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

International Nuclear Information System (INIS)

Ott, Dino; Oddershede, Lene B.; Reihani, S. Nader S.

2014-01-01

In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Here we present a simple and easy-to-implement method to efficiently eliminate crosstalk. The method is based on spatial filtering by simply inserting a pinhole at the correct position and is highly compatible with standard back focal plane photodiode based detection of position and force. Our spatial filtering method reduces crosstalk up to five times better than polarization filtering alone. The effectiveness is dependent on pinhole size and distance between the traps and is here quantified experimentally and reproduced by theoretical modeling. The method here proposed will improve the accuracy of force-distance measurements, e.g., of single molecules, performed by dual-beam optical traps and hence give much more scientific value for the experimental efforts

Linear and nonlinear optical spectroscopy: Spectral, temporal and spatial resolution

DEFF Research Database (Denmark)

Hvam, Jørn Marcher

1997-01-01

Selected linear and nonlinear optical spectroscopies are being described with special emphasis on the possibility of obtaining simultaneous spectral, temporal and spatial resolution. The potential of various experimental techniques is being demonstrated by specific examples mostly taken from inve...... investigations of the electronic, and opto-electronic, properties of semiconductor nanostructures....

Perfect pattern formation of neutral atoms in an addressable optical lattice

International Nuclear Information System (INIS)

Vala, J.; Whaley, K.B.; Thapliyal, A.V.; Vazirani, U.; Myrgren, S.; Weiss, D.S.

2005-01-01

We propose a physical scheme for formation of an arbitrary pattern of neutral atoms in an addressable optical lattice. We focus specifically on the generation of a perfect optical lattice of simple orthorhombic structure with unit occupancy, as required for initialization of a neutral atom quantum computer. The scheme employs a compacting process that is accomplished by sequential application of two types of operations: a flip operator that changes the internal state of the atoms, and a shift operator that selectively moves the atoms in one internal state along the lattice principal axis. Realizations of these elementary operations and their physical limitations are analyzed. The complexity of the compacting scheme is analyzed and we show that this scales linearly with the number of lattice sites per row of the lattice

Manipulating qudits spatial using programmable diffractive optical devices

International Nuclear Information System (INIS)

Lima, G.; Neves, L.; Saavedra, C.; Vargas, A.; Guzman, R.

2009-01-01

The generation of high-dimensional quantum states (qudits) is justified by the advantages that they can bring for the field of quantum information. These states for practical application in quantum communication must be of simple manipulation. Qudits can be generated by controlling the transverse momentum of the parametric down-converted photons. In this work, we show a simple technique for modifying these sates based on the use of programmable diffractive optical devices, which can act as spatial light modulators. (Author)

Optical Interconnection Via Computer-Generated Holograms

Science.gov (United States)

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.

Feasibility of spatial frequency domain imaging (SFDI) for optically characterizing a preclinical oncology model.

Science.gov (United States)

Tabassum, Syeda; Zhao, Yanyu; Istfan, Raeef; Wu, Junjie; Waxman, David J; Roblyer, Darren

2016-10-01

Determination of chemotherapy efficacy early during treatment would provide more opportunities for physicians to alter and adapt treatment plans. Diffuse optical technologies may be ideally suited to track early biological events following chemotherapy administration due to low cost and high information content. We evaluated the use of spatial frequency domain imaging (SFDI) to characterize a small animal tumor model in order to move towards the goal of endogenous optical monitoring of cancer therapy in a controlled preclinical setting. The effects of key measurement parameters including the choice of imaging spatial frequency and the repeatability of measurements were evaluated. The precision of SFDI optical property extractions over repeat mouse measurements was determined to be within 3.52% for move and replace experiments. Baseline optical properties and chromophore values as well as intratumor heterogeneity were evaluated over 25 tumors. Additionally, tumor growth and chemotherapy response were monitored over a 45 day longitudinal study in a small number of mice to demonstrate the ability of SFDI to track treatment effects. Optical scattering and oxygen saturation increased as much as 70% and 25% respectively in treated tumors, suggesting SFDI may be useful for preclinical tracking of cancer therapies.

Spatial gradient tuning in metamaterials

Science.gov (United States)

Driscoll, Tom; Goldflam, Michael; Jokerst, Nan; Basov, Dimitri; Smith, David

2011-03-01

Gradient Index (GRIN) metamaterials have been used to create devices inspired by, but often surpassing the potential of, conventional GRIN optics. The unit-cell nature of metamaterials presents the opportunity to exert much greater control over spatial gradients than is possible in natural materials. This is true not only during the design phase but also offers the potential for real-time reconfiguration of the metamaterial gradient. This ability fits nicely into the picture of transformation-optics, in which spatial gradients can enable an impressive suite of innovative devices. We discuss methods to exert control over metamaterial response, focusing on our recent demonstrations using Vanadium Dioxide. We give special attention to role of memristance and mem-capacitance observed in Vanadium Dioxide, which simplify the demands of stimuli and addressing, as well as intersecting metamaterials with the field of memory-materials.

Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma

International Nuclear Information System (INIS)

Oh, Changhoon; Ryoo, Hoonchul; Lee, Hyungwoo; Hahn, Jae W.; Kim, Se-Yeon; Yi, Hun-Jung

2010-01-01

We proposed a spatially resolved optical emission spectrometer (SROES) for analyzing the uniformity of plasma density for semiconductor processes. To enhance the spatial resolution of the SROES, we constructed a SROES system using a series of lenses, apertures, and pinholes. We calculated the spatial resolution of the SROES for the variation of pinhole size, and our calculated results were in good agreement with the measured spatial variation of the constructed SROES. The performance of the SROES was also verified by detecting the correlation between the distribution of a fluorine radical in inductively coupled plasma etch process and the etch rate of a SiO 2 film on a silicon wafer.

Spatial transformation-enabled electromagnetic devices: from radio frequencies to optical wavelengths

Science.gov (United States)

Jiang, Zhi Hao; Turpin, Jeremy P.; Morgan, Kennith; Lu, Bingqian; Werner, Douglas H.

2015-01-01

Transformation optics provides scientists and engineers with a new powerful design paradigm to manipulate the flow of electromagnetic waves in a user-defined manner and with unprecedented flexibility, by controlling the spatial distribution of the electromagnetic properties of a medium. Using this approach, over the past decade, various previously undiscovered physical wave phenomena have been revealed and novel electromagnetic devices have been demonstrated throughout the electromagnetic spectrum. In this paper, we present versatile theoretical and experimental investigations on designing transformation optics-enabled devices for shaping electromagnetic wave radiation and guidance, at both radio frequencies and optical wavelengths. Different from conventional coordinate transformations, more advanced and versatile coordinate transformations are exploited here to benefit diverse applications, thereby providing expanded design flexibility, enhanced device performance, as well as reduced implementation complexity. These design examples demonstrate the comprehensive capability of transformation optics in controlling electromagnetic waves, while the associated novel devices will open up new paths towards future integrated electromagnetic component synthesis and design, from microwave to optical spectral regimes. PMID:26217054

Spatial transformation-enabled electromagnetic devices: from radio frequencies to optical wavelengths.

Science.gov (United States)

Jiang, Zhi Hao; Turpin, Jeremy P; Morgan, Kennith; Lu, Bingqian; Werner, Douglas H

2015-08-28

Transformation optics provides scientists and engineers with a new powerful design paradigm to manipulate the flow of electromagnetic waves in a user-defined manner and with unprecedented flexibility, by controlling the spatial distribution of the electromagnetic properties of a medium. Using this approach, over the past decade, various previously undiscovered physical wave phenomena have been revealed and novel electromagnetic devices have been demonstrated throughout the electromagnetic spectrum. In this paper, we present versatile theoretical and experimental investigations on designing transformation optics-enabled devices for shaping electromagnetic wave radiation and guidance, at both radio frequencies and optical wavelengths. Different from conventional coordinate transformations, more advanced and versatile coordinate transformations are exploited here to benefit diverse applications, thereby providing expanded design flexibility, enhanced device performance, as well as reduced implementation complexity. These design examples demonstrate the comprehensive capability of transformation optics in controlling electromagnetic waves, while the associated novel devices will open up new paths towards future integrated electromagnetic component synthesis and design, from microwave to optical spectral regimes. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Photosensitized production of singlet oxygen: spatially-resolved optical studies in single cells

DEFF Research Database (Denmark)

Breitenbach, Thomas; Kuimova, Marina; Gbur, Peter

2009-01-01

be monitored using viability assays. Time- and spatially-resolved optical measurements of both singlet oxygen and its precursor, the excited state sensitizer, reflect the complex and dynamic morphology of the cell. These experiments help elucidate photoinduced, oxygen-dependent events that compromise cell...

Comparison of spatially and temporally resolved diffuse transillumination measurement systems for extraction of optical properties of scattering media.

Science.gov (United States)

Ortiz-Rascón, E; Bruce, N C; Garduño-Mejía, J; Carrillo-Torres, R; Hernández-Paredes, J; Álvarez-Ramos, M E

2017-11-20

This paper discusses the main differences between two different methods for determining the optical properties of tissue optical phantoms by fitting the spatial and temporal intensity distribution functions to the diffusion approximation theory. The consistency in the values of the optical properties is verified by changing the width of the recipient containing the turbid medium; as the optical properties are an intrinsic value of the scattering medium, independently of the recipient width, the stability in these values for different widths implies a better measurement system for the acquisition of the optical properties. It is shown that the temporal fitting method presents higher stability than the spatial fitting method; this is probably due to the addition of the time of flight parameter into the diffusion theory.

Improved algorithm for estimating optical properties of food and biological materials using spatially-resolved diffuse reflectance

Science.gov (United States)

In this research, the inverse algorithm for estimating optical properties of food and biological materials from spatially-resolved diffuse reflectance was optimized in terms of data smoothing, normalization and spatial region of reflectance profile for curve fitting. Monte Carlo simulation was used ...

An electro-optic spatial light modulator for thermoelastic generation of programmably focused ultrasound

Science.gov (United States)

1984-12-01

The concept proposed is an electro-optic technique that would make it possible to spatially modulate a high power pulsed laser beam to thermoelastically induce focused ultrasound in a test material. Being a purely electro-optic device, the modulator, and therefore the depth at which the acoustic focus occurs, can be programmed electronically at electronic speeds. If successful, it would become possible to scan ultrasound continuously in three dimensions within the component or structure under test.

Graph-state preparation and quantum computation with global addressing of optical lattices

International Nuclear Information System (INIS)

Kay, Alastair; Pachos, Jiannis K.; Adams, Charles S.

2006-01-01

We present a way to manipulate ultracold atoms where four atomic levels are trapped by appropriately tuned optical lattices. When employed to perform quantum computation via global control, this unique structure dramatically reduces the number of steps involved in the control procedures, either for the standard, network, model, or for one-way quantum computation. The use of a far-blue-detuned lattice and a magnetically insensitive computational basis makes the scheme robust against decoherence. The present scheme is a promising candidate for experimental implementation of quantum computation and for graph-state preparation in one, two, or three spatial dimensions

Calculation of spatial distribution of optical escape factor and its application to He I collisional-radiative model

International Nuclear Information System (INIS)

Iida, Yohei; Kado, Shinichiro; Tanaka, Satoru

2010-01-01

An integral analytical formula for a spatial distribution of the optical escape factor (OEF) in an infinite cylindrical plasma is derived as a function of an arbitrary upper state spatial density profile, the temperature ratio of the upper state to the lower state, and the optical depth of the corresponding transition. Test calculations are carried out for three different upper state profiles, i.e., uniform (rectangular), parabolic, and Gaussian upper state profiles. The OEF takes on negative values at the periphery of the parabolic and Gaussian upper state profiles. These characteristics cannot be expressed by the conventional OEF formulas derived for the center of the plasma, even though the optical depth is increased. In addition to the analytical derivation of the formula, two practical formulas are proposed: an empirical formula of the spatial distribution of the OEF for the Gaussian upper state density profile and a linear formula of the OEF distribution for upper state profiles that are expressed as linear combinations. These formulas enable us to calculate the spatial distribution of the OEF for the multiple-Gaussian upper state profile without the need for time-consuming integral calculations.

Study the effects of varying interference upon the optical properties of turbid samples using NIR spatial light modulation

Science.gov (United States)

Shaul, Oren; Fanrazi-Kahana, Michal; Meitav, Omri; Pinhasi, Gad A.; Abookasis, David

2018-03-01

Optical properties of biological tissues are valuable diagnostic parameters which can provide necessary information regarding tissue state during disease pathogenesis and therapy. However, different sources of interference, such as temperature changes may modify these properties, introducing confounding factors and artifacts to data, consequently skewing their interpretation and misinforming clinical decision-making. In the current study, we apply spatial light modulation, a type of diffuse reflectance hyperspectral imaging technique, to monitor the variation in optical properties of highly scattering turbid media in the presence varying levels of the following sources of interference: scattering concentration, temperature, and pressure. Spatial near-infrared (NIR) light modulation is a wide-field, non-contact emerging optical imaging platform capable of separating the effects of tissue scattering from those of absorption, thereby accurately estimating both parameters. With this technique, periodic NIR illumination patterns at alternately low and high spatial frequencies, at six discrete wavelengths between 690 to 970 nm, were sequentially projected upon the medium while a CCD camera collects the diffusely reflected light. Data analysis based assumptions is then performed off-line to recover the medium's optical properties. We conducted a series of experiments demonstrating the changes in absorption and reduced scattering coefficients of commercially available fresh milk and chicken breast tissue under different interference conditions. In addition, information on the refractive index was study under increased pressure. This work demonstrates the utility of NIR spatial light modulation to detect varying sources of interference upon the optical properties of biological samples.

Optical trapping and tweezing using a spatial light modulator

CSIR Research Space (South Africa)

Ismail, Y

2009-07-01

Full Text Available using a spatial light modulator Y.Ismail1,2, M. G. Mclaren1,3, A. Forbes1,2,4 1 CSIR National Laser Centre 2 School of Physics, University of KwaZulu-Natal 3 School of Physics, University of the Witwatersrand 4 School of Physics, University... of Stellenbosch Presented at the 2009 South African Institute of Physics Annual Conference University of KwaZulu-Natal Durban, South Africa 6-10 July 2009 Optical tweezing is based on the manipulation of micron sized particles in 3 dimensions 100X...

Dynamic virtual optical network embedding in spectral and spatial domains over elastic optical networks with multicore fibers

Science.gov (United States)

Zhu, Ruijie; Zhao, Yongli; Yang, Hui; Tan, Yuanlong; Chen, Haoran; Zhang, Jie; Jue, Jason P.

2016-08-01

Network virtualization can eradicate the ossification of the infrastructure and stimulate innovation of new network architectures and applications. Elastic optical networks (EONs) are ideal substrate networks for provisioning flexible virtual optical network (VON) services. However, as network traffic continues to increase exponentially, the capacity of EONs will reach the physical limitation soon. To further increase network flexibility and capacity, the concept of EONs is extended into the spatial domain. How to map the VON onto substrate networks by thoroughly using the spectral and spatial resources is extremely important. This process is called VON embedding (VONE).Considering the two kinds of resources at the same time during the embedding process, we propose two VONE algorithms, the adjacent link embedding algorithm (ALEA) and the remote link embedding algorithm (RLEA). First, we introduce a model to solve the VONE problem. Then we design the embedding ability measurement of network elements. Based on the network elements' embedding ability, two VONE algorithms were proposed. Simulation results show that the proposed VONE algorithms could achieve better performance than the baseline algorithm in terms of blocking probability and revenue-to-cost ratio.

Generalized radiative transfer theory for scattering by particles in an absorbing gas: Addressing both spatial and spectral integration in multi-angle remote sensing of optically thin aerosol layers

Science.gov (United States)

Davis, Anthony B.; Xu, Feng; Diner, David J.

2018-01-01

We demonstrate the computational advantage gained by introducing non-exponential transmission laws into radiative transfer theory for two specific situations. One is the problem of spatial integration over a large domain where the scattering particles cluster randomly in a medium uniformly filled with an absorbing gas, and only a probabilistic description of the variability is available. The increasingly important application here is passive atmospheric profiling using oxygen absorption in the visible/near-IR spectrum. The other scenario is spectral integration over a region where the absorption cross-section of a spatially uniform gas varies rapidly and widely and, moreover, there are scattering particles embedded in the gas that are distributed uniformly, or not. This comes up in many applications, O2 A-band profiling being just one instance. We bring a common framework to solve these problems both efficiently and accurately that is grounded in the recently developed theory of Generalized Radiative Transfer (GRT). In GRT, the classic exponential law of transmission is replaced by one with a slower power-law decay that accounts for the unresolved spectral or spatial variability. Analytical results are derived in the single-scattering limit that applies to optically thin aerosol layers. In spectral integration, a modest gain in accuracy is obtained. As for spatial integration of near-monochromatic radiance, we find that, although both continuum and in-band radiances are affected by moderate levels of sub-pixel variability, only extreme variability will affect in-band/continuum ratios.

Few-mode fiber, splice and SDM component characterization by spatially-diverse optical vector network analysis.

Science.gov (United States)

Rommel, Simon; Mendinueta, José Manuel Delgado; Klaus, Werner; Sakaguchi, Jun; Olmos, Juan José Vegas; Awaji, Yoshinari; Monroy, Idelfonso Tafur; Wada, Naoya

2017-09-18

This paper discusses spatially diverse optical vector network analysis for space division multiplexing (SDM) component and system characterization, which is becoming essential as SDM is widely considered to increase the capacity of optical communication systems. Characterization of a 108-channel photonic lantern spatial multiplexer, coupled to a 36-core 3-mode fiber, is experimentally demonstrated, extracting the full impulse response and complex transfer function matrices as well as insertion loss (IL) and mode-dependent loss (MDL) data. Moreover, the mode-mixing behavior of fiber splices in the few-mode multi-core fiber and their impact on system IL and MDL are analyzed, finding splices to cause significant mode-mixing and to be non-negligible in system capacity analysis.

Diffuse optical tomography with physiological and spatial a priori constraints

International Nuclear Information System (INIS)

Intes, Xavier; Maloux, Clemence; Guven, Murat; Yazici, Birzen; Chance, Britton

2004-01-01

Diffuse optical tomography is a typical inverse problem plagued by ill-condition. To overcome this drawback, regularization or constraining techniques are incorporated in the inverse formulation. In this work, we investigate the enhancement in recovering functional parameters by using physiological and spatial a priori constraints. More accurate recovery of the two main functional parameters that are the blood volume and the relative saturation is demonstrated through simulations by using our method compared to actual techniques. (note)

Spatial Aspects of Multi-Sensor Data Fusion: Aerosol Optical Thickness

Science.gov (United States)

Leptoukh, Gregory; Zubko, V.; Gopalan, A.

2007-01-01

The Goddard Earth Sciences Data and Information Services Center (GES DISC) investigated the applicability and limitations of combining multi-sensor data through data fusion, to increase the usefulness of the multitude of NASA remote sensing data sets, and as part of a larger effort to integrate this capability in the GES-DISC Interactive Online Visualization and Analysis Infrastructure (Giovanni). This initial study focused on merging daily mean Aerosol Optical Thickness (AOT), as measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites, to increase spatial coverage and produce complete fields to facilitate comparison with models and station data. The fusion algorithm used the maximum likelihood technique to merge the pixel values where available. The algorithm was applied to two regional AOT subsets (with mostly regular and irregular gaps, respectively) and a set of AOT fields that differed only in the size and location of artificially created gaps. The Cumulative Semivariogram (CSV) was found to be sensitive to the spatial distribution of gap areas and, thus, useful for assessing the sensitivity of the fused data to spatial gaps.

A fully-integrated 12.5-Gb/s 850-nm CMOS optical receiver based on a spatially-modulated avalanche photodetector

NARCIS (Netherlands)

Lee, M.J.; Youn, J.S.; Park, K.Y.; Choi, W.Y.

2014-01-01

We present a fully integrated 12.5-Gb/s optical receiver fabricated with standard 0.13-µm complementary metal-oxide-semiconductor (CMOS) technology for 850-nm optical interconnect applications. Our integrated optical receiver includes a newly proposed CMOS-compatible spatially-modulated avalanche

Spatial optic multiplexer/diplexer

International Nuclear Information System (INIS)

Tremblay, P.L.

1991-01-01

An apparatus is described for simultaneous transmission of optic signals having different wavelengths over a single optic fiber. Multiple light signals are transmitted through optic fibers that are formed into a circumference surrounding a central core fiber. The multiple light signals are directed by a lens into a single receiving fiber where the light combines and is then focused into the central core fiber which transmits the light to a wavelength discriminating receiver assembly

Towards breaking the spatial resolution barriers: An optical flow and super-resolution approach for sea ice motion estimation

Science.gov (United States)

Petrou, Zisis I.; Xian, Yang; Tian, YingLi

2018-04-01

Estimation of sea ice motion at fine scales is important for a number of regional and local level applications, including modeling of sea ice distribution, ocean-atmosphere and climate dynamics, as well as safe navigation and sea operations. In this study, we propose an optical flow and super-resolution approach to accurately estimate motion from remote sensing images at a higher spatial resolution than the original data. First, an external example learning-based super-resolution method is applied on the original images to generate higher resolution versions. Then, an optical flow approach is applied on the higher resolution images, identifying sparse correspondences and interpolating them to extract a dense motion vector field with continuous values and subpixel accuracies. Our proposed approach is successfully evaluated on passive microwave, optical, and Synthetic Aperture Radar data, proving appropriate for multi-sensor applications and different spatial resolutions. The approach estimates motion with similar or higher accuracy than the original data, while increasing the spatial resolution of up to eight times. In addition, the adopted optical flow component outperforms a state-of-the-art pattern matching method. Overall, the proposed approach results in accurate motion vectors with unprecedented spatial resolutions of up to 1.5 km for passive microwave data covering the entire Arctic and 20 m for radar data, and proves promising for numerous scientific and operational applications.

Frequency-addressed tunable transmission in optically thin metallic nanohole arrays with dual-frequency liquid crystals

International Nuclear Information System (INIS)

Hao Qingzhen; Zhao Yanhui; Juluri, Bala Krishna; Kiraly, Brian; Huang, Tony Jun; Liou, Justin; Khoo, Iam Choon

2011-01-01

Frequency-addressed tunable transmission is demonstrated in optically thin metallic nanohole arrays embedded in dual-frequency liquid crystals (DFLCs). The optical properties of the composite system are characterized by the transmission spectra of the nanoholes, and a prominent transmission peak is shown to originate from the resonance of localized surface plasmons at the edges of the nanoholes. An ∼17 nm shift in the transmission peak is observed between the two alignment configurations of the liquid crystals. This DFLC-based active plasmonic system demonstrates excellent frequency-dependent switching behavior and could be useful in future nanophotonic applications.

Experimental demonstration of spatially coherent beam combining using optical parametric amplification.

Science.gov (United States)

Kurita, Takashi; Sueda, Keiichi; Tsubakimoto, Koji; Miyanaga, Noriaki

2010-07-05

We experimentally demonstrated coherent beam combining using optical parametric amplification with a nonlinear crystal pumped by random-phased multiple-beam array of the second harmonic of a Nd:YAG laser at 10-Hz repetition rate. In the proof-of-principle experiment, the phase jump between two pump beams was precisely controlled by a motorized actuator. For the demonstration of multiple-beam combining a random phase plate was used to create random-phased beamlets as a pump pulse. Far-field patterns of the pump, the signal, and the idler indicated that the spatially coherent signal beams were obtained on both cases. This approach allows scaling of the intensity of optical parametric chirped pulse amplification up to the exa-watt level while maintaining diffraction-limited beam quality.

Optical wall dynamics induced by coexistence of monostable and bistable spatial regions.

Science.gov (United States)

Odent, V; Louvergneaux, E; Clerc, M G; Andrade-Silva, I

2016-11-01

When nonequilibrium extended homogeneous systems exhibit multistability, it leads to the presence of domain walls between the existing equilibria. Depending on the stability of the steady states, the dynamics differs. Here, we consider the interface dynamics in the case of a spatially inhomogeneous system, namely, an optical system where the control parameter is spatially Gaussian. Then interfaces connect the monostable and the bistable nonuniform states that are associated with two distinct spatial regions. The coexistence of these two regions of different stability induces relaxation dynamics and the propagation of a wall with a time-dependent speed. We emphasize analytically these two dynamical behaviors using a generic bistable model. Experimentally, an inhomogeneous Gaussian light beam traveling through either a dye-doped liquid crystal cell or a Kerr cavity depicts these behaviors, in agreement with the theoretical predictions.

Method for spatially modulating X-ray pulses using MEMS-based X-ray optics

Science.gov (United States)

Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

2015-03-10

A method and apparatus are provided for spatially modulating X-rays or X-ray pulses using microelectromechanical systems (MEMS) based X-ray optics. A torsionally-oscillating MEMS micromirror and a method of leveraging the grazing-angle reflection property are provided to modulate X-ray pulses with a high-degree of controllability.

Electro-optic spatial decoding on the spherical-wavefront Coulomb fields of plasma electron sources.

Science.gov (United States)

Huang, K; Esirkepov, T; Koga, J K; Kotaki, H; Mori, M; Hayashi, Y; Nakanii, N; Bulanov, S V; Kando, M

2018-02-13

Detections of the pulse durations and arrival timings of relativistic electron beams are important issues in accelerator physics. Electro-optic diagnostics on the Coulomb fields of electron beams have the advantages of single shot and non-destructive characteristics. We present a study of introducing the electro-optic spatial decoding technique to laser wakefield acceleration. By placing an electro-optic crystal very close to a gas target, we discovered that the Coulomb field of the electron beam possessed a spherical wavefront and was inconsistent with the previously widely used model. The field structure was demonstrated by experimental measurement, analytic calculations and simulations. A temporal mapping relationship with generality was derived in a geometry where the signals had spherical wavefronts. This study could be helpful for the applications of electro-optic diagnostics in laser plasma acceleration experiments.

Electroluminescence analysis for spatial characterization of parasitic optical losses in silicon heterojunction solar cells

Science.gov (United States)

Ahmed, Nuha; Zhang, Lei; Sriramagiri, Gowri; Das, Ujjwal; Hegedus, Steven

2018-04-01

Electroluminescence (EL) coupled with reflection measurements are used to spatially quantify optical losses in silicon heterojunction solar cells due to plasmonic absorption in the metal back contacts. The effect of indium tin oxide back reflector in decreasing this plasmonic absorption is found to increase the reflection from the back nickel (Ni)-aluminum (Al) and Al metals by ˜12% and ˜41%, respectively, in both bifacial and front junction silicon solar cells. Losses due to back reflection are calculated by comparison between the EL emission signals in high and low back reflection samples and are shown to be in agreement with standard reflection measurements. We conclude that the optical properties of the back contact can significantly influence the EL intensity which complicates the interpretation of EL as being primarily due to recombination especially when comparing two different devices with spatially varying back surface structures.

Algorithm of extraction optics properties from the measurement of spatially resolved diffuse reflectance

International Nuclear Information System (INIS)

Cunill Rodriguez, Margarita; Delgado Atencio, Jose Alberto; Castro Ramos, Jorge; Vazquez y Montiel, Sergio

2009-01-01

There are several methods to obtain the optical parameters of biological tissues from the measurement of spatially resolved diffuse reflectance. One of them is well-known as Video Reflectometry in which a camera CCD is used as detection and recording system of the lateral distribution of diffuse reflectance Rd(r) when an infinitely narrow light beam impinges on the tissue. In this paper, we present an algorithm that we have developed for the calibration and application of an experimental set-up of Video Reflectometry destined to extract the optical properties of models of biological tissues with optical properties similar to the human skin. The results of evaluation of the accuracy of the algorithm for optical parameters extraction is shown for a set of proofs reflectance curves with known values of these parameters. In the generation of these curves the simulation of measurement errors was also considered. The results show that it is possible to extract the optical properties with an accuracy error of less than 1% for all the proofs curves. (Author)

Microcomputer-based real-time optical signal processing system

Science.gov (United States)

Yu, F. T. S.; Cao, M. F.; Ludman, J. E.

1986-01-01

A microcomputer-based real-time programmable optical signal processing system utilizing a Magneto-Optic Spatial Light Modulator (MOSLM) and a Liquid Crystal Light Valve (LCLV) is described. This system can perform a myriad of complicated optical operations, such as image correlation, image subtraction, matrix multiplication and many others. The important assets of this proposed system must be the programmability and the capability of real-time addressing. The design specification and the progress toward practical implementation of this proposed system are discussed. Some preliminary experimental demonstrations are conducted. The feasible applications of this proposed system to image correlation for optical pattern recognition, image subtraction for IC chip inspection and matrix multiplication for optical computing are demonstrated.

High Spatial Resolution Imaging Mass Spectrometry of Human Optic Nerve Lipids and Proteins

Science.gov (United States)

Anderson, David M. G.; Spraggins, Jeffrey M.; Rose, Kristie L.; Schey, Kevin L.

2015-06-01

The human optic nerve carries signals from the retina to the visual cortex of the brain. Each optic nerve is comprised of approximately one million nerve fibers that are organized into bundles of 800-1200 fibers surrounded by connective tissue and supportive glial cells. Damage to the optic nerve contributes to a number of blinding diseases including: glaucoma, neuromyelitis optica, optic neuritis, and neurofibromatosis; however, the molecular mechanisms of optic nerve damage and death are incompletely understood. Herein we present high spatial resolution MALDI imaging mass spectrometry (IMS) analysis of lipids and proteins to define the molecular anatomy of the human optic nerve. The localization of a number of lipids was observed in discrete anatomical regions corresponding to myelinated and unmyelinated nerve regions as well as to supporting connective tissue, glial cells, and blood vessels. A protein fragment from vimentin, a known intermediate filament marker for astrocytes, was observed surrounding nerved fiber bundles in the lamina cribrosa region. S100B was also found in supporting glial cell regions in the prelaminar region, and the hemoglobin alpha subunit was observed in blood vessel areas. The molecular anatomy of the optic nerve defined by MALDI IMS provides a firm foundation to study biochemical changes in blinding human diseases.

Sub-spatial resolution position estimation for optical fibre sensing applications

DEFF Research Database (Denmark)

Zibar, Darko; Werzinger, Stefan; Schmauss, Bernhard

2017-01-01

Methods from machine learning community are employed for estimating the position of fibre Bragg gratings in an array. Using the conventional methods for position estimation, based on inverse discrete Fourier transform (IDFT), it is required that two-point spatial resolution is less than gratings...... of reflection coefficients and the positions is performed. From the practical point of view, we can demonstrate the reduction of the interrogator's bandwidth by factor of 2. The technique is demonstrated for incoherent optical frequency domain reflectometry (IOFDR). However, the approach is applicable to any...

A high spatial resolution distributed optical fiber grating sensing system based on OFDR

Science.gov (United States)

Dong, Ke; Xiong, Yuchuan; Wen, Hongqiao; Tong, Xinlin; Zhang, Cui; Deng, Chengwei

2017-10-01

A distributed optical fiber grating sensing system with large capacity and high spatial resolution is presented. Since highdensity identical weak grating array was utilized as sensing fiber, the multiplexing number was greatly increased, meanwhile, optical frequency domain reflectometry (OFDR) technology was used to implement high resolution distributed sensing system. In order to eliminate the nonlinear effect of tunable light source, a windowed FFT algorithm based on cubic spline interpolation was applied. The feasibility of the algorithm was experimentally testified, ultimately, the spatial resolution of system can reach mm-level. The influence of the crosstalk signal in the grating array on the OFDR system was analyzed. A method that a long enough delay fiber was added before the first FBG to remove crosstalk signal was proposed. The experiment was verified using an optical fiber with 113 uniform Bragg gratings at an interval of 10cm whose reflectivity are less than 1%. It demonstrates that crosstalk signal and measurement signal can be completely separated in the distance domain after adding a long enough delay fiber. Finally, the temperature experiment of distributed grating sensing system was carried out. The results display that each raster's center wavelength in the fiber link is independent of each other and the center wavelength drift has a good linear relationship with the temperature. The sensitivity of linear fitting is equal to 11.1pm/°C.

Reconfigurable Optical Interconnections Via Dynamic Computer-Generated Holograms

Science.gov (United States)

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.

Matter-wave solitons and finite-amplitude Bloch waves in optical lattices with a spatially modulated nonlinearity

OpenAIRE

Zhang, Jie-Fang; Li, Yi-Shen; Meng, Jianping; Wu, Lei; Malomed, Boris A.

2010-01-01

We investigate solitons and nonlinear Bloch waves in Bose-Einstein condensates trapped in optical lattices. By introducing specially designed localized profiles of the spatial modulation of the attractive nonlinearity, we construct an infinite number of exact soliton solutions in terms of the Mathieu and elliptic functions, with the chemical potential belonging to the semi-infinite bandgap of the optical-lattice-induced spectrum. Starting from the exact solutions, we employ the relaxation met...

Investigation of the spatial distribution of second-order nonlinearity in thermally poled optical fibers.

Science.gov (United States)

An, Honglin; Fleming, Simon

2005-05-02

The spatial distribution of second-order nonlinearity in thermally poled optical fibers was characterized by second-harmonic microscopy. The second-order nonlinearity was found to be confined to a thin layer close to the anode surface and progressed further into the silica as the poling time increased. Position uncertainty of the anode metal wire was observed to have an effect, as the nonlinear layers were found not always symmetrically located around the nearest points between the anode and cathode. Optical microscopy results were obtained on etched poled fiber cross-sections and compared with those from second-harmonic microscopy.

Quantum diffraction and interference of spatially correlated photon pairs and its Fourier-optical analysis

International Nuclear Information System (INIS)

Shimizu, Ryosuke; Edamatsu, Keiichi; Itoh, Tadashi

2006-01-01

We present one- and two-photon diffraction and interference experiments involving parametric down-converted photon pairs. By controlling the divergence of the pump beam in parametric down-conversion, the diffraction-interference pattern produced by an object changes from a quantum (perfectly correlated) case to a classical (uncorrelated) one. The observed diffraction and interference patterns are accurately reproduced by Fourier-optical analysis taking into account the quantum spatial correlation. We show that the relation between the spatial correlation and the object size plays a crucial role in the formation of both one- and two-photon diffraction-interference patterns

Fast spatial beam shaping by acousto-optic diffraction for 3D non-linear microscopy.

Science.gov (United States)

Akemann, Walther; Léger, Jean-François; Ventalon, Cathie; Mathieu, Benjamin; Dieudonné, Stéphane; Bourdieu, Laurent

2015-11-02

Acousto-optic deflection (AOD) devices offer unprecedented fast control of the entire spatial structure of light beams, most notably their phase. AOD light modulation of ultra-short laser pulses, however, is not straightforward to implement because of intrinsic chromatic dispersion and non-stationarity of acousto-optic diffraction. While schemes exist to compensate chromatic dispersion, non-stationarity remains an obstacle. In this work we demonstrate an efficient AOD light modulator for stable phase modulation using time-locked generation of frequency-modulated acoustic waves at the full repetition rate of a high power laser pulse amplifier of 80 kHz. We establish the non-local relationship between the optical phase and the generating acoustic frequency function and verify the system for temporal stability, phase accuracy and generation of non-linear two-dimensional phase functions.

Content-addressable memory processing: Multilevel coding, logical minimization, and an optical implementation

International Nuclear Information System (INIS)

Mirsalehi, M.M.; Gaylord, T.K.

1986-01-01

This paper describes the effect of coding scheme on the number of reference patterns that need to be stored in a content-addressable memory. It is shown that residue number system in conjunction with multilevel coding and logical minimization significantly reduces the number of reference patterns required for implementation of an operation. The number of reference patterns and the total amount of information that needs to be stored are determined for practical cases of 16-bit and 32-bit fixed-point addition and multiplication. The storage requirements were found to be achievable with the state-of-the-art memory technologies. An optical holographical processor capable of parallel-input/parallel-output operation is described

Computation of the optical properties of turbid media from slope and curvature of spatially resolved reflectance curves

International Nuclear Information System (INIS)

Jäger, Marion; Foschum, Florian; Kienle, Alwin

2013-01-01

The optical properties of turbid media were calculated from the curvature at the radial distance ρ O and the slope at the radial distance ρ* of simulated spatially resolved reflectance curves (ρ O (ρ*) denotes a decrease of the spatially resolved reflectance curve of 0.75 (2.4) orders of magnitude relative to the reflectance value at 1.2 mm). We found correlations between the curvature at ρ O and the reduced scattering coefficient as well as the slope at ρ* and the absorption coefficient. For the determination of the optical properties we used these two correlations. The calculation of the reduced scattering coefficient from the curvature at ρ O is practically independent from the absorption coefficient. Knowing the reduced scattering coefficient within a certain accuracy allows the determination of the absorption coefficient from the slope at ρ*. Additionally, we investigated the performance of an artificial neural network for the determination of the optical properties using the above explained correlations. This means we used the derivatives as input data. Our artificial neural network was capable to learn the mapping between the optical properties and the derivatives. In effect, the results for the determined optical properties improved in comparison to the above explained method. Finally, the procedure was compared to an artificial neural network that was trained without using the derivatives. (note)

Spatial-temporal bio-optical classification of dynamic semi-estuarine waters in western North America

Science.gov (United States)

Phillips, Stephen Robert; Costa, Maycira

2017-12-01

The use of standard ocean colour reflectance based algorithms to derive surface chlorophyll may have limited applicability for optically dynamic coastal waters due to the pre-defined coefficients based on global datasets. Reflectance based algorithms adjusted to regional optical water characteristics are a promising alternative. A class-based definition of optically diverse coastal waters was investigated as a first step towards the development of temporal and spatial constrained reflectance based algorithms for optically variable coastal waters. A large set of bio-optical data were collected as part of five research cruises and bi-weekly trips aboard a ship of opportunity in the west coast of Canada, to assess the spatial and temporal variability of above-water reflectance in this contrasted coastal environment. To accomplish this, in situ biophysical and optical measurements were collected in conjunction with above-water hyperspectral remote sensing reflectance (Rrs) at 145 stations. The concentrations of measured biophysical data varied considerably; chlorophyll a (Chla) (mean = 1.64, range: 0.10-7.20 μg l-1), total suspended matter (TSM) (3.09, 0.82-20.69 mg l-1), and absorption by chromophoric dissolved organic matter (CDOM) (acdom(443 nm)) (0.525, 0.007-3.072 m-1), thus representing the spatio-temporal variability of the Salish Sea. Optically, a similar large range was also found; particulate scattering (bp(650 nm)) (1.316, 0.250-7.450 m-1), particulate backscattering (bbp(650 nm)) (0.022, 0.005-0.097 m-1), total beam attenuation coefficient (ct(650)) (1.675, 0.371-9.537 m-1) and particulate absorption coefficient (ap(650 nm)) (0.345, 0.048-2.020 m-1). An empirical orthogonal function (EOF) analysis revealed that Rrs variability was highly correlated to bp (r = 0.90), bbp (r = 0.82) and concentration of TSM (r = 0.80), which highlighted the dominant role of water turbidity in this region. Hierarchical clustering analysis was applied to the normalized Rrs

Extending the Effective Ranging Depth of Spectral Domain Optical Coherence Tomography by Spatial Frequency Domain Multiplexing

Directory of Open Access Journals (Sweden)

Tong Wu

2016-11-01

Full Text Available We present a spatial frequency domain multiplexing method for extending the imaging depth range of a spectral domain optical coherence tomography (SDOCT system without any expensive device. This method uses two galvo scanners with different pivot-offset distances in two independent reference arms for spatial frequency modulation and multiplexing. The spatial frequency contents corresponding to different depth regions of the sample can be shifted to different frequency bands. The spatial frequency domain multiplexing SDOCT system provides an approximately 1.9-fold increase in the effective ranging depth compared with that of a conventional full-range SDOCT system. The reconstructed images of phantom and biological tissue demonstrate the expected increase in ranging depth. The parameters choice criterion for this method is discussed.

Dynamic illumination of spatially restricted or large brain volumes via a single tapered optical fiber.

Science.gov (United States)

Pisanello, Ferruccio; Mandelbaum, Gil; Pisanello, Marco; Oldenburg, Ian A; Sileo, Leonardo; Markowitz, Jeffrey E; Peterson, Ralph E; Della Patria, Andrea; Haynes, Trevor M; Emara, Mohamed S; Spagnolo, Barbara; Datta, Sandeep Robert; De Vittorio, Massimo; Sabatini, Bernardo L

2017-08-01

Optogenetics promises precise spatiotemporal control of neural processes using light. However, the spatial extent of illumination within the brain is difficult to control and cannot be adjusted using standard fiber optics. We demonstrate that optical fibers with tapered tips can be used to illuminate either spatially restricted or large brain volumes. Remotely adjusting the light input angle to the fiber varies the light-emitting portion of the taper over several millimeters without movement of the implant. We use this mode to activate dorsal versus ventral striatum of individual mice and reveal different effects of each manipulation on motor behavior. Conversely, injecting light over the full numerical aperture of the fiber results in light emission from the entire taper surface, achieving broader and more efficient optogenetic activation of neurons, compared to standard flat-faced fiber stimulation. Thus, tapered fibers permit focal or broad illumination that can be precisely and dynamically matched to experimental needs.

A New Method of Chinese Address Extraction Based on Address Tree Model

Directory of Open Access Journals (Sweden)

KANG Mengjun

2015-01-01

Full Text Available Address is a spatial location encoding method of individual geographical area. In China, address planning is relatively backward due to the rapid development of the city, resulting in the presence of large number of non-standard address. The space constrain relationship of standard address model is analyzed in this paper and a new method of standard address extraction based on the tree model is proposed, which regards topological relationship as consistent criteria of space constraints. With this method, standard address can be extracted and errors can be excluded from non-standard address. Results indicate that higher math rate can be obtained with this method.

A fully-integrated 12.5-Gb/s 850-nm CMOS optical receiver based on a spatially-modulated avalanche photodetector.

Science.gov (United States)

Lee, Myung-Jae; Youn, Jin-Sung; Park, Kang-Yeob; Choi, Woo-Young

2014-02-10

We present a fully integrated 12.5-Gb/s optical receiver fabricated with standard 0.13-µm complementary metal-oxide-semiconductor (CMOS) technology for 850-nm optical interconnect applications. Our integrated optical receiver includes a newly proposed CMOS-compatible spatially-modulated avalanche photodetector, which provides larger photodetection bandwidth than previously reported CMOS-compatible photodetectors. The receiver also has high-speed CMOS circuits including transimpedance amplifier, DC-balanced buffer, equalizer, and limiting amplifier. With the fabricated optical receiver, detection of 12.5-Gb/s optical data is successfully achieved at 5.8 pJ/bit. Our receiver achieves the highest data rate ever reported for 850-nm integrated CMOS optical receivers.

Spatial light modulators and applications III; Proceedings of the Meeting, San Diego, CA, Aug. 7, 8, 1989

Science.gov (United States)

Efron, Uzi (Editor)

1990-01-01

Recent advances in the technology and applications of spatial light modulators (SLMs) are discussed in review essays by leading experts. Topics addressed include materials for SLMs, SLM devices and device technology, applications to optical data processing, and applications to artificial neural networks. Particular attention is given to nonlinear optical polymers, liquid crystals, magnetooptic SLMs, multiple-quantum-well SLMs, deformable-mirror SLMs, three-dimensional optical memories, applications of photorefractive devices to optical computing, photonic neurocomputers and learning machines, holographic associative memories, SLMs as parallel memories for optoelectronic neural networks, and coherent-optics implementations of neural-network models.

A novel power and offset allocation method for spatial multiplexing MIMO Systems in optical wireless channels

KAUST Repository

Park, Kihong

2011-12-01

We consider optical wireless communication which can be utilized for illumination and communication by relying on lighting devices. Due to the limited bandwidth of optical sources, it is challenging to achieve high data rate in optical wireless systems. In order to obtain a multiplexing gain and high spectral efficiency, we design an optical multi-input multi-output (MIMO) system utilizing a singular value decomposition-based spatial multiplexing and adaptive modulation. We note that the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels. In this paper, we generalize the result of power allocation method in [1] for arbitrary number of transmit and receive antennas in optical wireless MIMO systems. Based on three constraints, namely, the nonnegativity, the aggregate optical power, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size for maximum sum rate. From some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency than the method that allocates the optical power equally for each data stream. © 2011 IEEE.

Nano-optical conveyor belt with waveguide-coupled excitation.

Science.gov (United States)

Wang, Guanghui; Ying, Zhoufeng; Ho, Ho-pui; Huang, Ying; Zou, Ningmu; Zhang, Xuping

2016-02-01

We propose a plasmonic nano-optical conveyor belt for peristaltic transport of nano-particles. Instead of illumination from the top, waveguide-coupled excitation is used for trapping particles with a higher degree of precision and flexibility. Graded nano-rods with individual dimensions coded to have resonance at specific wavelengths are incorporated along the waveguide in order to produce spatially addressable hot spots. Consequently, by switching the excitation wavelength sequentially, particles can be transported to adjacent optical traps along the waveguide. The feasibility of this design is analyzed using three-dimensional finite-difference time-domain and Maxwell stress tensor methods. Simulation results show that this system is capable of exciting addressable traps and moving particles in a peristaltic fashion with tens of nanometers resolution. It is the first, to the best of our knowledge, report about a nano-optical conveyor belt with waveguide-coupled excitation, which is very important for scalability and on-chip integration. The proposed approach offers a new design direction for integrated waveguide-based optical manipulation devices and its application in large scale lab-on-a-chip integration.

Spatially-resolved measurement of optically stimulated luminescence and time-resolved luminescence

International Nuclear Information System (INIS)

Bailiff, I.K.; Mikhailik, V.B.

2003-01-01

Spatially-resolved measurements of optically stimulated luminescence (OSL) were performed using a two-dimensional scanning system designed for use with planar samples. The scanning system employs a focused laser beam to stimulate a selected area of the sample, which is moved under the beam by a motorised stage. Exposure of the sample is controlled by an electronic shutter. Mapping of the distribution of OSL using a continuous wave laser source was obtained with sub-millimeter resolution for samples of sliced brick, synthetic single crystal quartz, concrete and dental ceramic. These revealed sporadic emission in the case of brick or concrete and significant spatial variation of emission for quartz and dental ceramic slices. Determinations of absorbed dose were performed for quartz grains within a slice of modern brick. Reconfiguration of the scanner with a pulsed laser source enabled quartz and feldspathic minerals within a ceramic sample to be thinner region. about 6 nm from the extrapolation of themeasuring the time-resolved luminescence spectrum

Spatial optical (2+1)-dimensional scalar- and vector-solitons in saturable nonlinear media

Energy Technology Data Exchange (ETDEWEB)

Weilnau, C.; Traeger, D.; Schroeder, J.; Denz, C. [Institute of Applied Physics, Westfaelische Wilhelms-Universitaet Muenster, Corrensstr. 2/4, 48149 Muenster (Germany); Ahles, M.; Petter, J. [Institute of Applied Physics, Technische Universitaet Darmstadt, Hochschulstr. 6, 64289 Darmstadt (Germany)

2002-10-01

(2+1)-dimensional optical spatial solitons have become a major field of research in nonlinear physics throughout the last decade due to their potential in adaptive optical communication technologies. With the help of photorefractive crystals that supply the required type of nonlinearity for soliton generation, we are able to demonstrate experimentally the formation, the dynamic properties, and especially the interaction of solitary waves, which were so far only known from general soliton theory. Among the complex interaction scenarios of scalar solitons, we reveal a distinct behavior denoted as anomalous interaction, which is unique in soliton-supporting systems. Further on, we realize highly parallel, light-induced waveguide configurations based on photorefractive screening solitons that give rise to technical applications towards waveguide couplers and dividers as well as all-optical information processing devices where light is controlled by light itself. Finally, we demonstrate the generation, stability and propagation dynamics of multi-component or vector solitons, multipole transverse optical structures bearing a complex geometry. In analogy to the particle-light dualism of scalar solitons, various types of vector solitons can - in a broader sense - be interpreted as molecules of light. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

Spatial optical (2+1)-dimensional scalar- and vector-solitons in saturable nonlinear media

International Nuclear Information System (INIS)

Weilnau, C.; Traeger, D.; Schroeder, J.; Denz, C.; Ahles, M.; Petter, J.

2002-01-01

(2+1)-dimensional optical spatial solitons have become a major field of research in nonlinear physics throughout the last decade due to their potential in adaptive optical communication technologies. With the help of photorefractive crystals that supply the required type of nonlinearity for soliton generation, we are able to demonstrate experimentally the formation, the dynamic properties, and especially the interaction of solitary waves, which were so far only known from general soliton theory. Among the complex interaction scenarios of scalar solitons, we reveal a distinct behavior denoted as anomalous interaction, which is unique in soliton-supporting systems. Further on, we realize highly parallel, light-induced waveguide configurations based on photorefractive screening solitons that give rise to technical applications towards waveguide couplers and dividers as well as all-optical information processing devices where light is controlled by light itself. Finally, we demonstrate the generation, stability and propagation dynamics of multi-component or vector solitons, multipole transverse optical structures bearing a complex geometry. In analogy to the particle-light dualism of scalar solitons, various types of vector solitons can - in a broader sense - be interpreted as molecules of light. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

Spatial beam shaping using a micro-structured optical fiber and all-fiber laser amplification system for large-scale laser facilities seeding

International Nuclear Information System (INIS)

Calvet, Pierre

2014-01-01

Spatial beam shaping is an important topic for the lasers applications. For various industrial areas (marking, drilling, laser-matter interaction, high-power laser seeding...) the optical beam has to be flattened. Currently, the state of the art of the beam shaping: 'free-space' solutions or highly multimode fibers, are not fully suitable. The first ones are very sensitive to any perturbations and the maintenance is challenging, the second ones cannot deliver a coherent beam. For this reason, we present in this manuscript a micro-structured optical single-mode fiber delivering a spatially flattened beam. This 'Top-Hat' fiber can shape any beam in a spatially coherent beam what is a progress with respect to the highly multimode fibers used in the state of the art. The optical fibers are easy to use and very robust, what is a strong benefit with respect to the 'free-space' solutions. Thanks to this fiber, we could realize an all-fiber multi-stage laser chain to amplify a 10 ns pulse to 100 μJ. Moreover the temporal, spectral and spatial properties were preserved. We adapted this 'Top-Hat' fiber to this multi-stage laser chain, we proved the capability and the interest of this fiber for the spatial beam shaping of the laser beams in highly performing and robust laser systems. (author) [fr

Ergodic channel capacity of spatial correlated multiple-input multiple-output free space optical links using multipulse pulse-position modulation

Science.gov (United States)

Wang, Huiqin; Wang, Xue; Cao, Minghua

2017-02-01

The spatial correlation extensively exists in the multiple-input multiple-output (MIMO) free space optical (FSO) communication systems due to the channel fading and the antenna space limitation. Wilkinson's method was utilized to investigate the impact of spatial correlation on the MIMO FSO communication system employing multipulse pulse-position modulation. Simulation results show that the existence of spatial correlation reduces the ergodic channel capacity, and the reception diversity is more competent to resist this kind of performance degradation.

Numerical simulation and experimental study of factors influencing the optical characteristics of a spatial target

International Nuclear Information System (INIS)

Zhu Dingqiang; Shen Wentao; Cai Guobiao; Ke Weina

2013-01-01

The optical properties of a spatial target are important characteristics for its detection, identification, tracking and interception. A homeostatic model of the temperature and infrared characteristics of the target has been developed considering the radiation of the environmental background. The heat conduction inside the wall and the effect of an internal heat source are included in the model. The reflection characteristics of the target are calculated with bi-directional reflection distribution function (BRDF) models. The temperature and infrared radiation have been measured in the simulating space environment in the ground tests. The comparisons between the theoretical results and experimental data demonstrate a good agreement. Applying the developed model, the influences of several parameters (such as spin frequency, absorptivity/emissivity and thermal conductivity) of the target have been investigated. Highlights: ► A mathematical model was developed to predict the optical characteristics of a spatial target. ► The temperature and infrared radiation are measured in ground tests. ► The simulation results and the test results are consistent. ► The effects of several target parameters were analysed.

Self-error-rejecting photonic qubit transmission in polarization-spatial modes with linear optical elements

Science.gov (United States)

Jiang, YuXiao; Guo, PengLiang; Gao, ChengYan; Wang, HaiBo; Alzahrani, Faris; Hobiny, Aatef; Deng, FuGuo

2017-12-01

We present an original self-error-rejecting photonic qubit transmission scheme for both the polarization and spatial states of photon systems transmitted over collective noise channels. In our scheme, we use simple linear-optical elements, including half-wave plates, 50:50 beam splitters, and polarization beam splitters, to convert spatial-polarization modes into different time bins. By using postselection in different time bins, the success probability of obtaining the uncorrupted states approaches 1/4 for single-photon transmission, which is not influenced by the coefficients of noisy channels. Our self-error-rejecting transmission scheme can be generalized to hyperentangled n-photon systems and is useful in practical high-capacity quantum communications with photon systems in two degrees of freedom.

Trinary flip-flops using Savart plate and spatial light modulator for optical computation in multivalued logic

Science.gov (United States)

Ghosh, Amal K.; Basuray, Amitabha

2008-11-01

The memory devices in multi-valued logic are of most significance in modern research. This paper deals with the implementation of basic memory devices in multi-valued logic using Savart plate and spatial light modulator (SLM) based optoelectronic circuits. Photons are used here as the carrier to speed up the operations. Optical tree architecture (OTA) has been also utilized in the optical interconnection network. We have exploited the advantages of Savart plates, SLMs and OTA and proposed the SLM based high speed JK, D-type and T-type flip-flops in a trinary system.

Combining spatial domain multiplexing and orbital angular momentum of photon-based multiplexing to increase the bandwidth of optical fiber communication systems

Science.gov (United States)

Murshid, Syed; Alanzi, Saud; Hridoy, Arnob; Lovell, Gregory L.; Parhar, Gurinder; Chakravarty, Abhijit; Chowdhury, Bilas

2016-06-01

Spatial domain multiplexing/space division multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single-mode pigtail laser sources of the same wavelength into a carrier multimode fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. We launch light from five different single-mode pigtail laser sources (of same wavelength) at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation, five distinct concentric donut-shaped rings with negligible crosstalk at the output end of the fiber were obtained. These SDM channels also exhibit orbital angular momentum (OAM), thereby adding an extradegree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.

Computer simulation of the spatial distribution of optical radiation arising from knocked-out excited particles

International Nuclear Information System (INIS)

Gokov, S.P.; Gritsyna, V.V.; Koval', A.G.; Kovtunenko, Yu.I.; Shevchenko, D.I.

2004-01-01

The new approach for the explanation of the spatial distribution of the optical radiation arising from knocked-out excited particles is given. Calculated and experimental data for Al (λ=396.1 nm) and Mg (λ=383.8 nm) knocked-out by Ar + (20 keV) beam from MgAl 2 O 4 surface are compared [ru

Zero-crossing detection algorithm for arrays of optical spatial filtering velocimetry sensors

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Pedersen, Finn; Hanson, Steen Grüner

2008-01-01

This paper presents a zero-crossing detection algorithm for arrays of compact low-cost optical sensors based on spatial filtering for measuring fluctuations in angular velocity of rotating solid structures. The algorithm is applicable for signals with moderate signal-to-noise ratios, and delivers...... repeating the same measurement error for each revolution of the target, and to gain high performance measurement of angular velocity. The traditional zero-crossing detection is extended by 1) inserting an appropriate band-pass filter before the zero-crossing detection, 2) measuring time periods between zero...

The potential of diffraction grating for spatial applications

Science.gov (United States)

Jourlin, Y.; Parriaux, O.; Pigeon, F.; Tischenko, A. V.

2017-11-01

Diffraction gratings are know, and have been fabricated for more than one century. They are now making a come back for two reasons: first, because they are now better understood which leads to the efficient exploitation of what was then called their "anomalies"; secondly, because they are now fabricable by means of the modern manufacturing potential of planar technologies. Novel grating can now perform better than conventional gratings, and address new application fields which were not expected to be theirs. This is the case of spatial applications where they can offer multiple optical functions, low size, low weight and mechanical robustness. The proposed contribution will briefly discuss the use of gratings for spatial applications. One of the most important applications is in the measurement of displacement. Usual translation and rotation sensors are bulky devices, which impose a system breakdown leading to cumbersome and heavy assemblies. We are proposing a miniaturized version of the traditional moving grating technique using submicron gratings and a specific OptoASIC which enables the measurement function to be non-obtrusively inserted into light and compact electro-mechanical systems. Nanometer resolution is possible with no compromise on the length of the measurement range. Another family of spatial application is in the field of spectrometers where new grating types allow a more flexible processing of the optical spectrum. Another family of applications addresses the question of inter-satellite communications: the introduction of gratings in laser cavities or in the laser mirrors enables the stabilization of the emitted polarization, the stabilization of the frequency as well as wide range frequency sweeping without mobile parts.

Adaptive optics improves multiphoton super-resolution imaging

Science.gov (United States)

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

2018-02-01

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

Optically Addressed Nanostructures for High Density Data Storage

Science.gov (United States)

2005-10-14

beam to sub-wavelength resolutions. X. Refereed Journal Publications I. M. D. Stenner , D. J. Gauthier, and M. A. Neifeld, "The speed of information in a...profiles for high-density optical data storage," Optics Communications, Vol.253, pp.56-69, 2005. 5. M. D. Stenner , D. J. Gauthier, and M. A. Neifeld, "Fast...causal information transmission in a medium with a slow group velocity," Physical Review Letters, Vol.94, February 2005. 6. M. D. Stenner , M. A

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

Science.gov (United States)

Huang, Aiping; Tao, Linwei; Niu, Yilong

2018-04-01

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

A recent history of science cases for optical interferometry

Science.gov (United States)

Defrère, Denis; Aerts, Conny; Kishimoto, Makoto; Léna, Pierre

2018-04-01

Optical long-baseline interferometry is a unique and powerful technique for astronomical research. Since the 1980's (with I2T, GI2T, Mark I to III, SUSI, ...), optical interferometers have produced an increasing number of scientific papers covering various fields of astrophysics. As current interferometric facilities are reaching their maturity, we take the opportunity in this paper to summarize the conclusions of a few key meetings, workshops, and conferences dedicated to interferometry. We present the most persistent recommendations related to science cases and discuss some key technological developments required to address them. In the era of extremely large telescopes, optical long-baseline interferometers will remain crucial to probe the smallest spatial scales and make breakthrough discoveries.

Optical Array Processor: Laboratory Results

Science.gov (United States)

Casasent, David; Jackson, James; Vaerewyck, Gerard

1987-01-01

A Space Integrating (SI) Optical Linear Algebra Processor (OLAP) is described and laboratory results on its performance in several practical engineering problems are presented. The applications include its use in the solution of a nonlinear matrix equation for optimal control and a parabolic Partial Differential Equation (PDE), the transient diffusion equation with two spatial variables. Frequency-multiplexed, analog and high accuracy non-base-two data encoding are used and discussed. A multi-processor OLAP architecture is described and partitioning and data flow issues are addressed.

DLP technolgy: applications in optical networking

Science.gov (United States)

Yoder, Lars A.; Duncan, Walter M.; Koontz, Elisabeth M.; So, John; Bartlett, Terry A.; Lee, Benjamin L.; Sawyers, Bryce D.; Powell, Donald; Rancuret, Paul

2001-11-01

For the past five years, Digital Light Processing (DLP) technology from Texas Instruments has made significant inroads in the projection display market. With products encompassing the world's smallest data & video projectors, HDTVs, and digital cinema, DLP is an extremely flexible technology. At the heart of these display solutions is Texas Instruments Digital Micromirror Device (DMD), a semiconductor-based light switch array of thousands of individually addressable, tiltable, mirror-pixels. With success of the DMD as a spatial light modulator in the visible regime, the use of DLP technology under the constraints of coherent, infrared light for optical networking applications is being explored. As a coherent light modulator, the DMD device can be used in Dense Wavelength Division Multiplexed (DWDM) optical networks to dynamically manipulate and shape optical signals. This paper will present the fundamentals of using DLP with coherent wavefronts, discuss inherent advantages of the technology, and present several applications for DLP in dynamic optical networks.

Spatial Frequency Multiplexing of Fiber-Optic Interferometric Refractive Index Sensors Based on Graded-Index Multimode Fibers

Science.gov (United States)

Liu, Li; Gong, Yuan; Wu, Yu; Zhao, Tian; Wu, Hui-Juan; Rao, Yun-Jiang

2012-01-01

Fiber-optic interferometric sensors based on graded-index multimode fibers have very high refractive-index sensitivity, as we previously demonstrated. In this paper, spatial-frequency multiplexing of this type of fiber-optic refractive index sensors is investigated. It is estimated that multiplexing of more than 10 such sensors is possible. In the multiplexing scheme, one of the sensors is used to investigate the refractive index and temperature responses. The fast Fourier transform (FFT) of the combined reflective spectra is analyzed. The intensity of the FFT spectra is linearly related with the refractive index and is not sensitive to the temperature.

Wave optics modeling of real-time holographic wavefront compensation systems using OSSim

Science.gov (United States)

Carbon, Margarita A.; Guthals, Dennis M.; Logan, Jerry D.

2005-08-01

OSSim (Optical System Simulation) is a wave-optics, time-domain simulation toolbox with both optical and data processing components developed for adaptive optics (AO) systems. Diffractive wavefront control elements have recently been added that accurately model optically and electrically addressed spatial light modulators as real time holographic (RTH) devices in diffractive wavefront control systems. The developed RTH toolbox has found multiple applications for a variety of Boeing programs in solving problems of AO system analysis and design. Several complex diffractive wavefront control systems have been modeled for compensation of static and dynamic aberrations such as imperfect segmented primary mirrors and atmospheric and boundary layer turbulence. The results of OSSim simulations of RTH wavefront compensation show very good agreement with available experimental data.

Gray Scale Operation Of A Multichannel Optical Convolver Using The Semetex Magnetooptic Spatial Light Modulator

Science.gov (United States)

Davis, Jeffrey A.; Day, Timothy; Lilly, Roger A.; Taber, Donald B.; Liu, Hua-Kuang; Davis, J. A.; Day, T.; Lilly, R. A.; Taber, D. B.; Liu, H.-K.

1988-02-01

We present a new multichannel optical correlator/convolver architecture which uses an acoustooptic light modulator (AOLM) for the input channel and a Semetex magnetooptic spatial light modulator (MOSLM) for the set of parallel reference channels. Details of the anamorphic optical system are discussed. Experimental results illustrate use of the system as a convolver for performing digital multiplication by analog convolution (DMAC). A limited gray scale capability for data stored by the MOSLM is demonstrated by implementing this DMAC algorithm with trinary logic. Use of the MOSLM allows the number of parallel channels for the convolver to be increased significantly compared with previously reported techniques while retaining the capability for updating both channels at high speeds.

Equating spatial summation in visual field testing reveals greater loss in optic nerve disease.

Science.gov (United States)

Kalloniatis, Michael; Khuu, Sieu K

2016-07-01

To test the hypothesis that visual field assessment in ocular disease measured with target stimuli within or close to complete spatial summation results in larger threshold elevation compared to when measured with the standard Goldmann III target size. The hypothesis predicts a greater loss will be identified in ocular disease. Additionally, we sought to develop a theoretical framework that would allow comparisons of thresholds with disease progression when using different Goldmann targets. The Humphrey Field Analyser (HFA) 30-2 grid was used in 13 patients with early/established optic nerve disease using the current Goldmann III target size or a combination of the three smallest stimuli (target size I, II and III). We used data from control subjects at each of the visual field locations for the different target sizes to establish the number of failed points (events) for the patients with optic nerve disease, as well as global indices for mean deviation (MD) and pattern standard deviation (PSD). The 30-2 visual field testing using alternate target size stimuli showed that all 13 patients displayed more defects (events) compared to the standard Goldmann III target size. The median increase for events was seven additional failed points: (range 1-26). The global indices also increased when the new testing approach was used (MD -3.47 to -6.25 dB and PSD 4.32 to 6.63 dB). Spatial summation mapping showed an increase in critical area (Ac) in disease and overall increase in thresholds when smaller target stimuli were used. When compared to the current Goldmann III paradigm, the use of alternate sized targets within the 30-2 testing protocol revealed a greater loss in patients with optic nerve disease for both event analysis and global indices (MD and PSD). We therefore provide evidence in a clinical setting that target size is important in visual field testing. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Trinary arithmetic and logic unit (TALU) using savart plate and spatial light modulator (SLM) suitable for optical computation in multivalued logic

Science.gov (United States)

Ghosh, Amal K.; Bhattacharya, Animesh; Raul, Moumita; Basuray, Amitabha

2012-07-01

Arithmetic logic unit (ALU) is the most important unit in any computing system. Optical computing is becoming popular day-by-day because of its ultrahigh processing speed and huge data handling capability. Obviously for the fast processing we need the optical TALU compatible with the multivalued logic. In this regard we are communicating the trinary arithmetic and logic unit (TALU) in modified trinary number (MTN) system, which is suitable for the optical computation and other applications in multivalued logic system. Here the savart plate and spatial light modulator (SLM) based optoelectronic circuits have been used to exploit the optical tree architecture (OTA) in optical interconnection network.

Spatial Factor Analysis for Aerosol Optical Depth in Metropolises in China with Regard to Spatial Heterogeneity

Directory of Open Access Journals (Sweden)

Hui Shi

2018-04-01

Full Text Available A substantial number of studies have analyzed how driving factors impact aerosols, but they have been little concerned with the spatial heterogeneity of aerosols and the factors that impact aerosols. The spatial distributions of the aerosol optical depth (AOD retrieved by Moderate Resolution Imaging Spectrometer (MODIS data at 550-nm and 3-km resolution for three highly developed metropolises, the Beijing-Tianjin-Hebei (BTH region, the Yangtze River Delta (YRD, and the Pearl River Delta (PRD, in China during 2015 were analyzed. Different degrees of spatial heterogeneity of the AOD were found, which were indexed by Moran’s I index giving values of 0.940, 0.715, and 0.680 in BTH, YRD, and PRD, respectively. For the spatial heterogeneity, geographically weighted regression (GWR was employed to carry out a spatial factor analysis, where terrain, climate condition, urban development, and vegetation coverage were taken as the potential driving factors. The results of the GWR imply varying relationships between the AOD and the factors. The results were generally consistent with existing studies, but the results suggest the following: (1 Elevation increase would more likely lead to a strong negative impact on aerosols (with most of the coefficients ranging from −1.5~0 in the BTH, −1.5~0 in the YRD, and −1~0 in the PRD in the places with greater elevations where the R-squared values are always larger than 0.5. However, the variation of elevations cannot explain the variation of aerosols in the places with relatively low elevations (with R-squared values approximately 0.1, ranging from 0 to 0.3, and approximately 0.1 in the BTH, YRD, and PRD, such as urban areas in the BTH and YRD. (2 The density of the built-up areas made a strong and positive impact on aerosols in the urban areas of the BTH (R-squared larger than 0.5, while the R-squared dropped to 0.1 in the places far away from the urban areas. (3 The vegetation coverage led to a stronger

Influence of macular pigment optical density spatial distribution on intraocular scatter.

Science.gov (United States)

Putnam, Christopher M; Bland, Pauline J; Bassi, Carl J

This study evaluated the summed measures of macular pigment optical density (MPOD) spatial distribution and their effects on intraocular scatter using a commercially available device (C-Quant, Oculus, USA). A customized heterochromatic flicker photometer (cHFP) device was used to measure MPOD spatial distribution across the central 16° using a 1° stimulus. MPOD was calculated as a discrete measure and summed measures across the central 1°, 3.3°, 10° and 16° diameters. Intraocular scatter was determined as a mean of 5 trials in which reliability and repeatability measures were met using the C-Quant. MPOD spatial distribution maps were constructed and the effects of both discrete and summed values on intraocular scatter were examined. Spatial mapping identified mean values for discrete MPOD [0.32 (s.d.=0.08)], MPOD summed across central 1° [0.37 (s.d.=0.11)], MPOD summed across central 3.3° [0.85 (s.d.=0.20)], MPOD summed across central 10° [1.60 (s.d.=0.35)] and MPOD summed across central 16° [1.78 (s.d.=0.39)]. Mean intraocular scatter was 0.83 (s.d.=0.16) log units. While there were consistent trends for an inverse relationship between MPOD and scatter, these relationships were not statistically significant. Correlations between the highest and lowest quartiles of MPOD within the central 1° were near significance. While there was an overall trend of decreased intraocular forward scatter with increased MPOD consistent with selective short wavelength visible light attenuation, neither discrete nor summed values of MPOD significantly influence intraocular scatter as measured by the C-Quant device. Published by Elsevier España, S.L.U.

Laboratory simulation of atmospheric turbulence induced optical wavefront distortion

Science.gov (United States)

Taylor, Travis Shane

1999-11-01

Many creative approaches have been taken in the past for simulating the effect that atmospheric turbulence has on optical beams. Most of the experimental architectures have been complicated and consisted of many optical elements as well as moving components. These techniques have shown a modicum of success; however, they are not completely controllable or predictable. A benchtop technique for experimentally producing one important effect that atmospheric turbulence has on optical beams (phase distortion) is presented here. The system is completely controllable and predictable while accurately representing the statistical nature of the problem. Previous experimentation in optical processing through turbulent media has demonstrated that optical wavefront distortions can be produced via spatial light modulating (SLM) devices, and most turbulence models and experimental results indicate that turbulence can be represented as a phase fluctuation. The amplitude distributions in the resulting far field are primarily due to propagation of the phase. Operating a liquid crystal television (LCTV) in the ``phase- mostly'' mode, a phase fluctuation type model for turbulence is utilized in the present investigation, and a real-time experiment for demonstrating the effects was constructed. For an optical system to simulate optical wavefront distortions due to atmospheric turbulence, the following are required: (1)An optical element that modulates the phasefront of an optical beam (2)A model and a technique for generating spatially correlated turbulence simulating distributions (3)Hardware and software for displaying and manipulating the information addressing the optical phase modulation device The LCTV is ideal for this application. When operated in the ``phase-mostly'' mode some LCTVs can modulate the phasefront of an optical beam by as much as 2π and an algorithm for generating spatially correlated phase screens can be constructed via mathematical modeling software such as

A light writable microfluidic "flash memory": optically addressed actuator array with latched operation for microfluidic applications.

Science.gov (United States)

Hua, Zhishan; Pal, Rohit; Srivannavit, Onnop; Burns, Mark A; Gulari, Erdogan

2008-03-01

This paper presents a novel optically addressed microactuator array (microfluidic "flash memory") with latched operation. Analogous to the address-data bus mediated memory address protocol in electronics, the microactuator array consists of individual phase-change based actuators addressed by localized heating through focused light patterns (address bus), which can be provided by a modified projector or high power laser pointer. A common pressure manifold (data bus) for the entire array is used to generate large deflections of the phase change actuators in the molten phase. The use of phase change material as the working media enables latched operation of the actuator array. After the initial light "writing" during which the phase is temporarily changed to molten, the actuated status is self-maintained by the solid phase of the actuator without power and pressure inputs. The microfluidic flash memory can be re-configured by a new light illumination pattern and common pressure signal. The proposed approach can achieve actuation of arbitrary units in a large-scale array without the need for complex external equipment such as solenoid valves and electrical modules, which leads to significantly simplified system implementation and compact system size. The proposed work therefore provides a flexible, energy-efficient, and low cost multiplexing solution for microfluidic applications based on physical displacements. As an example, the use of the latched microactuator array as "normally closed" or "normally open" microvalves is demonstrated. The phase-change wax is fully encapsulated and thus immune from contamination issues in fluidic environments.

Generalizing optical geometry

International Nuclear Information System (INIS)

Jonsson, Rickard; Westman, Hans

2006-01-01

We show that by employing the standard projected curvature as a measure of spatial curvature, we can make a certain generalization of optical geometry (Abramowicz M A and Lasota J-P 1997 Class. Quantum Grav. A 14 23-30). This generalization applies to any spacetime that admits a hypersurface orthogonal shearfree congruence of worldlines. This is a somewhat larger class of spacetimes than the conformally static spacetimes assumed in standard optical geometry. In the generalized optical geometry, which in the generic case is time dependent, photons move with unit speed along spatial geodesics and the sideways force experienced by a particle following a spatially straight line is independent of the velocity. Also gyroscopes moving along spatial geodesics do not precess (relative to the forward direction). Gyroscopes that follow a curved spatial trajectory precess according to a very simple law of three-rotation. We also present an inertial force formalism in coordinate representation for this generalization. Furthermore, we show that by employing a new sense of spatial curvature (Jonsson R 2006 Class. Quantum Grav. 23 1)) closely connected to Fermat's principle, we can make a more extensive generalization of optical geometry that applies to arbitrary spacetimes. In general this optical geometry will be time dependent, but still geodesic photons move with unit speed and follow lines that are spatially straight in the new sense. Also, the sideways experienced (comoving) force on a test particle following a line that is straight in the new sense will be independent of the velocity

Optical holography

CERN Document Server

Collier, Robert J; Lin, Lawrence H

1971-01-01

Optical Holography deals with the use of optical holography to solve technical problems, with emphasis on the properties of holograms formed with visible light. Topics covered include the Fourier transform, propagation and diffraction, pulsed-laser holography, and optical systems with spherical lenses. A geometric analysis of point-source holograms is also presented, and holograms and hologram spatial filters formed with spatially modulated reference waves are described. This book is comprised of 20 chapters and begins with an introduction to concepts that are basic to understanding hologr

A comparative study of the enhancement of molecular emission in a spatially confined plume through optical emission spectroscopy and probe beam deflection measurements

Energy Technology Data Exchange (ETDEWEB)

Ding, Dayu; Liang, Peipei; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian, E-mail: jsun@fudan.edu.cn

2013-01-01

The spatial confinement effects of shock wave on the expansion of a carbon plume induced by pulsed laser ablation of graphite in air and the enhancement of the plume emission were studied by optical emission spectroscopy and probe beam deflection measurements. A metal disk was set in the way of the ablation-generated shock wave to block and reflect the supersonically propagating shock wave. The reflected shock wave propagated backwards and confined the expanding plume. The optical emission of CN molecules was enhanced in contrast to the case without the block disk and the emission enhancement was dependent on the position of the disk. Based on the results of time-integrated and -resolved optical emission spectroscopy, and the time- and space-resolved probe beam deflection measurements, the processes occurring in the plume were discussed and the mechanisms responsible for the enhancement of molecular emission in the spatially confined plume were investigated. - Highlights: ► Spatial confinement and optical emission enhancement of carbon plume were studied. ► Ablation-generated shockwave propagating in air was reflected by a block disk. ► The effects of reflected shockwave on the emission enhancement were confirmed. ► The reflect shockwave confined the carbon plume and enhanced the plume emission.

A comparative study of the enhancement of molecular emission in a spatially confined plume through optical emission spectroscopy and probe beam deflection measurements

International Nuclear Information System (INIS)

Ding, Dayu; Liang, Peipei; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian

2013-01-01

The spatial confinement effects of shock wave on the expansion of a carbon plume induced by pulsed laser ablation of graphite in air and the enhancement of the plume emission were studied by optical emission spectroscopy and probe beam deflection measurements. A metal disk was set in the way of the ablation-generated shock wave to block and reflect the supersonically propagating shock wave. The reflected shock wave propagated backwards and confined the expanding plume. The optical emission of CN molecules was enhanced in contrast to the case without the block disk and the emission enhancement was dependent on the position of the disk. Based on the results of time-integrated and -resolved optical emission spectroscopy, and the time- and space-resolved probe beam deflection measurements, the processes occurring in the plume were discussed and the mechanisms responsible for the enhancement of molecular emission in the spatially confined plume were investigated. - Highlights: ► Spatial confinement and optical emission enhancement of carbon plume were studied. ► Ablation-generated shockwave propagating in air was reflected by a block disk. ► The effects of reflected shockwave on the emission enhancement were confirmed. ► The reflect shockwave confined the carbon plume and enhanced the plume emission

Hybrid optical CDMA-FSO communications network under spatially correlated gamma-gamma scintillation.

Science.gov (United States)

Jurado-Navas, Antonio; Raddo, Thiago R; Garrido-Balsells, José María; Borges, Ben-Hur V; Olmos, Juan José Vegas; Monroy, Idelfonso Tafur

2016-07-25

In this paper, we propose a new hybrid network solution based on asynchronous optical code-division multiple-access (OCDMA) and free-space optical (FSO) technologies for last-mile access networks, where fiber deployment is impractical. The architecture of the proposed hybrid OCDMA-FSO network is thoroughly described. The users access the network in a fully asynchronous manner by means of assigned fast frequency hopping (FFH)-based codes. In the FSO receiver, an equal gain-combining technique is employed along with intensity modulation and direct detection. New analytical formalisms for evaluating the average bit error rate (ABER) performance are also proposed. These formalisms, based on the spatially correlated gamma-gamma statistical model, are derived considering three distinct scenarios, namely, uncorrelated, totally correlated, and partially correlated channels. Numerical results show that users can successfully achieve error-free ABER levels for the three scenarios considered as long as forward error correction (FEC) algorithms are employed. Therefore, OCDMA-FSO networks can be a prospective alternative to deliver high-speed communication services to access networks with deficient fiber infrastructure.

Spatial discrimination against background with different optical systems for collection of fluorescence in laser-excited atomic fluorescence spectrometry with a graphite tube electrothermal atomizer.

Science.gov (United States)

Yuzefovsky, A I; Lonardo, R F; Michel, R G

1995-07-01

A single 90 degrees off-axis ellipsoidal mirror fragment was used in a dispersive detection system for electrothermal atomization laser-excited atomic fluorescence spectrometry. The performance of the new optical arrangement was compared with those of optical arrangements that employed a plane mirror in combination with biconvex or plano-convex lenses. All the optical arrangements collected fluorescence in a scheme called front surface illustration. BEAM-4, an optical ray tracing program, was used for calculations of spatial ray distributions and optical collection efficiency for the various optical configurations. Experimentally, the best collection efficiency was obtained by use of the ellipsoidal mirror, in qualitative agreement with simulations done by use of the BEAM-4 software. The best detection limit for cobalt with the new optical arrangement was 20 fg, which was a factor of 5 better than that obtained with conventional optical arrangements with otherwise the same instrumentation. The signal-to-background ratio and the fluorescence collection efficiency were also studied as a function of position of the optical components for the various optical arrangements. For both cobalt and phosphorus, the signal-to-background ratio with the new optical arrangement remained stable within 10-20% during +/- 8 mm shifts in the position of the detection system from the focal plane of the optics. Overall, the new optical arrangement offered high collection efficiency, excellent sensitivity, and facile optical alignment due to efficient spatial separation between the fluorescence signal and the background radiation. The advantages of the new optical arrangement were particularly important during measurements in the presence of high levels of blackbody radiation.

On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

KAUST Repository

Park, Kihong

2013-04-01

In this paper, we consider resource allocation method in the visible light communication. It is challenging to achieve high data rate due to the limited bandwidth of the optical sources. In order to increase the spectral efficiency, we design a suitable multiple-input multiple-output (MIMO) system utilizing spatial multiplexing based on singular value decomposition and adaptive modulation. More specifically, after explaining why the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels, we theoretically derive a power allocation method for an arbitrary number of transmit and receive antennas for optical wireless MIMO systems. Based on three key constraints: the nonnegativity of the intensity-modulated signal, the aggregate optical power budget, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size. Based on some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency at the expense of an increased computational complexity in comparison to a simple method that allocates the optical power equally among all the data streams. © 2013 IEEE.

On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

KAUST Repository

Park, Kihong; Ko, Youngchai; Alouini, Mohamed-Slim

2013-01-01

In this paper, we consider resource allocation method in the visible light communication. It is challenging to achieve high data rate due to the limited bandwidth of the optical sources. In order to increase the spectral efficiency, we design a suitable multiple-input multiple-output (MIMO) system utilizing spatial multiplexing based on singular value decomposition and adaptive modulation. More specifically, after explaining why the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels, we theoretically derive a power allocation method for an arbitrary number of transmit and receive antennas for optical wireless MIMO systems. Based on three key constraints: the nonnegativity of the intensity-modulated signal, the aggregate optical power budget, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size. Based on some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency at the expense of an increased computational complexity in comparison to a simple method that allocates the optical power equally among all the data streams. © 2013 IEEE.

Theoretical limit of spatial resolution in diffuse optical tomography using a perturbation model

International Nuclear Information System (INIS)

Konovalov, A B; Vlasov, V V

2014-01-01

We have assessed the limit of spatial resolution of timedomain diffuse optical tomography (DOT) based on a perturbation reconstruction model. From the viewpoint of the structure reconstruction accuracy, three different approaches to solving the inverse DOT problem are compared. The first approach involves reconstruction of diffuse tomograms from straight lines, the second – from average curvilinear trajectories of photons and the third – from total banana-shaped distributions of photon trajectories. In order to obtain estimates of resolution, we have derived analytical expressions for the point spread function and modulation transfer function, as well as have performed a numerical experiment on reconstruction of rectangular scattering objects with circular absorbing inhomogeneities. It is shown that in passing from reconstruction from straight lines to reconstruction using distributions of photon trajectories we can improve resolution by almost an order of magnitude and exceed the accuracy of reconstruction of multi-step algorithms used in DOT. (optical tomography)

New development in optical fibers for data center applications

Science.gov (United States)

Sun, Yi; Shubochkin, Roman; Zhu, Benyuan

2015-01-01

VCSEL-multimode optical fiber based links is the most successful optical technology in Data Centers. Laser-optimized multimode optical fibers, OM3 and OM4, have been the primary choice of physical media for 10 G serial, 4 x 10 G parallel, 10 x 10 G parallel, and 4 x 25 G parallel optical solutions in IEEE 802.3 standards. As the transition of high-end servers from 10 Gb/s to 40 Gb/s is driving the aggregation of speeds to 40 Gb/s now, and to 100 Gb/s and 400 Gb/s in near future, industry experts are coming together in IEEE 802.3bs 400 Gb/s study group and preliminary discussion of Terabit transmission for datacom applications has also been commenced. To meet the requirement of speed, capacity, density, power consumption and cost for next generation datacom applications, optical fiber design concepts beyond the standard OM3 and OM4 MMFs have a revived research and developmental interest, for example, wide band multimode optical fiber using multiple dopants for coarse wavelength division multiplexing; multicore multimode optical fiber using plural multimode cores in a single fiber strand to improve spatial density; and perhaps 50 Gb/s per lane and few mode fiber in spatial division multiplexing for ultimate capacity increase in far future. This talk reviews the multitude of fiber optic media being developed in the industry to address the upcoming challenges of datacom growth. We conclude that multimode transmission using low cost VCSEL technology will continue to be a viable solution for datacom applications.

Improved Selectivity From a Wavelength Addressable Device for Wireless Stimulation of Neural Tissue

Directory of Open Access Journals (Sweden)

Elif Ç. Seymour

2014-02-01

Full Text Available Electrical neural stimulation with micro electrodes is a promising technique for restoring lost functions in the central nervous system as a result of injury or disease. One of the problems related to current neural stimulators is the tissue response due to the connecting wires and the presence of a rigid electrode inside soft neural tissue. We have developed a novel, optically activated, microscale photovoltaic neurostimulator based on a custom layered compound semiconductor heterostructure that is both wireless and has a comparatively small volume. Optical activation provides a wireless means of energy transfer to the neurostimulator, eliminating wires and the associated complications. This neurostimulator was shown to evoke action potentials and a functional motor response in the rat spinal cord. In this work, we extend our design to include wavelength selectivity and thus allowing independent activation of devices. As a proof of concept, we fabricated two different microscale devices with different spectral responsivities in the near-infrared region. We assessed the improved addressability of individual devices via wavelength selectivity as compared to spatial selectivity alone through on-bench optical measurements of the devices in combination with an in vivo light intensity profile in the rat cortex obtained in a previous study. We show that wavelength selectivity improves the individual addressability of the floating stimulators, thus increasing the number of devices that can be implanted in close proximity to each other.

Control and manipulation of cold atoms in optical tweezers

International Nuclear Information System (INIS)

Muldoon, Cecilia; Brandt, Lukas; Dong Jian; Stuart, Dustin; Brainis, Edouard; Himsworth, Matthew; Kuhn, Axel

2012-01-01

Neutral atoms trapped by laser light are among the most promising candidates for storing and processing information in a quantum computer or simulator. The application certainly calls for a scalable and flexible scheme for addressing and manipulating the atoms. We have now made this a reality by implementing a fast and versatile method to dynamically control the position of neutral atoms trapped in optical tweezers. The tweezers result from a spatial light modulator (SLM) controlling and shaping a large number of optical dipole-force traps. Trapped atoms adapt to any change in the potential landscape, such that one can rearrange and randomly access individual sites within atom-trap arrays. (paper)

The spatial-temporal evolution of aerosol optical depth and the analysis of influence factors in Bohai Rim

International Nuclear Information System (INIS)

Hou, Chunliang; Jiang, Hong; Wang, Xiaoyan; Pei, Huan

2014-01-01

Aerosol Optical Depth (AOD) is an important parameter of aerosol optical properties and it is an important physical parameter quantity to understanding the atmospheric environment. Bohai Rim is one of the three major urban agglomeration regions with rapidly developing economy in China. The study of AOD over this region is important to understand the environment and climate in Bohai Rim. Firstly, aerosol product data from 2000 to 2010, published by NASA, were used to analyze the temporal-spatial evolution of AOD in Bohai Rim with precision evaluation. The results showed that the spatial distribution of AOD had an obvious regional characteristic. The spatial distribution characterized that a much high value existed at urban areas and plain areas. On the contrary, the low value data existed in some mountainous regions which had higher percentages of forest coverage. The AOD values fluctuated somewhat each year in the region, from the minimum annual mean in 2003 to the maximum in 2009. Generally, the highest AOD value was in summer, followed by spring, autumn and winter. In terms of monthly variation, the value of AOD reached its peak in June and the lowest value was in December. This study analyzed the relation between AOD and some influence factors such as land use types, elevation, and distribution of urban agglomeration and so on. These results provide an important basic dataset for climate and environmental research

In-situ optical and acoustical measurements of the buoyant cyanobacterium p. Rubescens: spatial and temporal distribution patterns.

Directory of Open Access Journals (Sweden)

Hilmar Hofmann

Full Text Available Optical (fluorescence and acoustic in-situ techniques were tested in their ability to measure the spatial and temporal distribution of plankton in freshwater ecosystems with special emphasis on the harmful and buoyant cyanobacterium P. rubescens. Fluorescence was measured with the multi-spectral FluoroProbe (Moldaenke FluoroProbe, MFP and a Seapoint Chlorophyll Fluorometer (SCF. In-situ measurements of the acoustic backscatter strength (ABS were conducted with three different acoustic devices covering multiple acoustic frequencies (614 kHz ADCP, 2 MHz ADP, and 6 MHz ADV. The MFP provides a fast and reliable technique to measure fluorescence at different wavelengths in situ, which allows discriminating between P. rubescens and other phytoplankton species. All three acoustic devices are sensitive to P. rubescens even if other scatterers, e.g., zooplankton or suspended sediment, are present in the water column, because P. rubescens containing gas vesicles has a strong density difference and hence acoustic contrast to the ambient water and other scatterers. After calibration, the combination of optical and acoustical measurements not only allows qualitative and quantitative observation of P. rubescens, but also distinction between P. rubescens, other phytoplankton, and zooplankton. As the measuring devices can sample in situ at high rates they enable assessment of plankton distributions at high temporal (minutes and spatial (decimeters resolution or covering large temporal (seasonal and spatial (basin scale scales.

Maximum-likelihood-based extended-source spatial acquisition and tracking for planetary optical communications

Science.gov (United States)

Tsou, Haiping; Yan, Tsun-Yee

1999-04-01

This paper describes an extended-source spatial acquisition and tracking scheme for planetary optical communications. This scheme uses the Sun-lit Earth image as the beacon signal, which can be computed according to the current Sun-Earth-Probe angle from a pre-stored Earth image or a received snapshot taken by other Earth-orbiting satellite. Onboard the spacecraft, the reference image is correlated in the transform domain with the received image obtained from a detector array, which is assumed to have each of its pixels corrupted by an independent additive white Gaussian noise. The coordinate of the ground station is acquired and tracked, respectively, by an open-loop acquisition algorithm and a closed-loop tracking algorithm derived from the maximum likelihood criterion. As shown in the paper, the optimal spatial acquisition requires solving two nonlinear equations, or iteratively solving their linearized variants, to estimate the coordinate when translation in the relative positions of onboard and ground transceivers is considered. Similar assumption of linearization leads to the closed-loop spatial tracking algorithm in which the loop feedback signals can be derived from the weighted transform-domain correlation. Numerical results using a sample Sun-lit Earth image demonstrate that sub-pixel resolutions can be achieved by this scheme in a high disturbance environment.

Spatial chaos of trapped Bose-Einstein condensate in one-dimensional weak optical lattice potential

International Nuclear Information System (INIS)

Chong Guishu; Hai Wenhua; Xie Qiongtao

2004-01-01

The spatially chaotic attractor in an elongated cloud of Bose-Einstein condensed atoms perturbed by a weak optical lattice potential is studied. The analytical insolvability and numerical incomputability of the atomic number density are revealed by a perturbed solution that illustrates the unpredictability of the deterministic chaos. Although this could lead the nonphysical explosion and unboundedness to the numerical solution, the theoretical analysis offers a criterion to avoid them. Moreover, the velocity field is investigated that exhibits the superfluid property of the chaotic system

An order of magnitude improvement in optical fiber bandwidth using spatial domain multiplexing/space division multiplexing (SDM) in conjunction with orbital angular momentum (OAM)

Science.gov (United States)

Murshid, Syed; Alanzi, Saud; Hridoy, Arnob; Lovell, Greg; Parhar, Gurinder; Chakravarty, Abhijit; Chowdhury, Bilas

2014-09-01

Spatial Domain Multiplexing/Space Division Multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single mode pigtail laser sources of same wavelength into a carrier fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. In this endeavor we launch light from five different single mode pigtail laser sources at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation we get five distinct concentric donut shaped rings with negligible crosstalk at the output end of the fiber. These SDM channels also exhibit Orbital Angular Momentum (OAM), thereby adding an extra degree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.

Single-spin stochastic optical reconstruction microscopy.

Science.gov (United States)

Pfender, Matthias; Aslam, Nabeel; Waldherr, Gerald; Neumann, Philipp; Wrachtrup, Jörg

2014-10-14

We experimentally demonstrate precision addressing of single-quantum emitters by combined optical microscopy and spin resonance techniques. To this end, we use nitrogen vacancy (NV) color centers in diamond confined within a few ten nanometers as individually resolvable quantum systems. By developing a stochastic optical reconstruction microscopy (STORM) technique for NV centers, we are able to simultaneously perform sub-diffraction-limit imaging and optically detected spin resonance (ODMR) measurements on NV spins. This allows the assignment of spin resonance spectra to individual NV center locations with nanometer-scale resolution and thus further improves spatial discrimination. For example, we resolved formerly indistinguishable emitters by their spectra. Furthermore, ODMR spectra contain metrology information allowing for sub-diffraction-limit sensing of, for instance, magnetic or electric fields with inherently parallel data acquisition. As an example, we have detected nuclear spins with nanometer-scale precision. Finally, we give prospects of how this technique can evolve into a fully parallel quantum sensor for nanometer resolution imaging of delocalized quantum correlations.

Diffraction from the perspective of the spatial coherence wavelets

International Nuclear Information System (INIS)

Castaneda, R.; Carrasquilla-Alvarez, J.; Garcia-Sucerquia, J.

2005-10-01

The diffraction of spatially partially coherent optical fields is analysed by using two concepts recently introduced by the authors: the spatial coherence wavelets and the effective diffracting aperture. Within this framework, the intimate link between the spatial properties of the optical field and the aperture's edges in the diffraction phenomena is studied. New insight is proposed in regard to the diffraction in the Fresnel - Fraunhofer approximation. Our ideas are supported by numerical calculations and analysis of the diffraction patterns obtained when an optical field with adjustable spatial coherence impinges upon a circular aperture (author)

Spatial Attention Is Attracted in a Sustained Fashion toward Singular Points in the Optic Flow

Science.gov (United States)

Wang, Shuo; Fukuchi, Masaki; Koch, Christof; Tsuchiya, Naotsugu

2012-01-01

While a single approaching object is known to attract spatial attention, it is unknown how attention is directed when the background looms towards the observer as s/he moves forward in a quasi-stationary environment. In Experiment 1, we used a cued speeded discrimination task to quantify where and how spatial attention is directed towards the target superimposed onto a cloud of moving dots. We found that when the motion was expansive, attention was attracted towards the singular point of the optic flow (the focus of expansion, FOE) in a sustained fashion. The effects were less pronounced when the motion was contractive. The more ecologically valid the motion features became (e.g., temporal expansion of each dot, spatial depth structure implied by distribution of the size of the dots), the stronger the attentional effects. Further, the attentional effects were sustained over 1000 ms. Experiment 2 quantified these attentional effects using a change detection paradigm by zooming into or out of photographs of natural scenes. Spatial attention was attracted in a sustained manner such that change detection was facilitated or delayed depending on the location of the FOE only when the motion was expansive. Our results suggest that focal attention is strongly attracted towards singular points that signal the direction of forward ego-motion. PMID:22905096

Spatial dynamics of picosecond CO2 laser pulses produced by optical switching in Ge

International Nuclear Information System (INIS)

Pogorelsky, I.; Fisher, A.S.; Veligdan, J.; Russell, P.

1991-01-01

The design, test and optimization of a picosecond CO 2 pulse-forming system are presented. The system switches a semiconductor's optical characteristics at 10 μm under the control of a synchronized 1.06-μm Nd:YAG picosecond laser pulse. An energy-efficient version of such a system using collimated beams is described. A simple, semi-empirical approach is used to simulate the switching process, specifically including the spatial distributions of the laser energy and phase, which are relevant for experiments in laser-driven electron acceleration. 11 refs., 7 figs

Assembly and alignment method for optimized spatial resolution of off-axis three-mirror fore optics of hyperspectral imager.

Science.gov (United States)

Kim, Youngsoo; Hong, Jinsuk; Choi, Byungin; Lee, Jong-Ung; Kim, Yeonsoo; Kim, Hyunsook

2017-08-21

A fore optics for the hyperspectral spectrometer is designed, manufactured, assembled, and aligned. The optics has a telecentric off-axis three-mirror configuration with a field of view wider than 14 degrees and an f-number as small as 2.3. The primary mirror (M1) and the secondary mirror (M2) are axially symmetric aspheric surfaces to minimize the sensitivity. The tertiary mirror (M3) is a decentered aspheric surface to minimize the coma and astigmatism aberration. The M2 also has a hole for the slit to maintain the optical performance while maximizing the telecentricity. To ensure the spatial resolution performance of the optical system, an alignment procedure is established to assemble and align the entrance slit of the spectrometer to the rear end of the fore optics. It has a great advantage to confirm and maintain the alignment integrity of the fore optics module throughout the alignment procedure. To perform the alignment procedure successfully, the precision movement control requirements are calculated and applied. As a result, the alignment goal of the RMS wave front error (WFE) to be smaller than 90 nm at all fields is achieved.

Crossed Optical Fiber Sensor Arrays for High-Spatial-Resolution Sensing: Application to Dissolved Oxygen Concentration Measurements

Directory of Open Access Journals (Sweden)

M. Veronica Rigo

2012-01-01

Full Text Available Optical fiber sensors using luminescent probes located along an optical fiber in the cladding of this fiber are of great interest for monitoring physical and chemical properties in their environment. The interrogation of a luminophore with a short laser pulse propagating through the fiber core allows for the measurement of the location of these luminophores. To increase the spatial resolution of such a measurements and to measure multiple analytes and properties in a confined space, a crossed optical fiber sensing platform can be employed. Here we describe the application of this platform to measuring the concentration of dissolved oxygen. The sensor is based on luminescence quenching of a ruthenium complex immobilized in a highly crosslinked film and covalently attached to the optical fibers. Both luminescence-intensity and luminescence-lifetime changes of the sensor molecules in response to changes in the concentration of oxygen dissolved in water are reported. For luminescence-intensity measurements, a second adjacent sensor region is employed as reference to account for laser pulse energy fluctuations. Enhanced quenching response in water is demonstrated by the use of organically modified poly(ethylene glycol precursors, which increase the hydrophobicity of the film surface.

Spatial-phase code-division multiple-access system with multiplexed Fourier holography switching for reconfigurable optical interconnection

Science.gov (United States)

Takasago, Kazuya; Takekawa, Makoto; Shirakawa, Atsushi; Kannari, Fumihiko

2000-05-01

A new, to our knowledge, space-variant optical interconnection system based on a spatial-phase code-division multiple-access technique with multiplexed Fourier holography is described. In this technique a signal beam is spread over wide spatial frequencies by an M -sequence pseudorandom phase code. At a receiver side a selected signal beam is properly decoded, and at the same time its spatial pattern is shaped with a Fourier hologram, which is recorded by light that is encoded with the same M -sequence phase mask as the desired signal beam and by light whose spatial beam pattern is shaped to a signal routing pattern. Using the multiplexed holography, we can simultaneously route multisignal flows into individually specified receiver elements. The routing pattern can also be varied by means of switching the encoding phase code or replacing the hologram. We demonstrated a proof-of-principle experiment with a doubly multiplexed hologram that enables simultaneous routing of two signal beams. Using a numerical model, we showed that the proposed scheme can manage more than 250 routing patterns for one signal flow with one multiplexed hologram at a signal-to-noise ratio of 5.

Macular pigment optical density spatial distribution measured in a subject with oculocutaneous albinism.

Science.gov (United States)

Putnam, Christopher M; Bland, Pauline J

2014-01-01

Previous studies of macular pigment optical density (MPOD) distribution in individuals with oculocutaneous albinism (OCA) have primarily used objective measurement techniques including fundus reflectometry and autofluorescence. We report here on a subject with OCA and their corresponding MPOD distribution assessed through heterochromatic flicker photometry (HFP). A subject with a history of OCA presented with an ocular history including strabismus surgery of the LE with persistent amblyopia and mild, latent nystagmus. Best corrected visual acuity was 20/25- RE and 20/40- LE. Spectral domain optical coherence tomography (SD-OCT) and fundus photography were also obtained. Evaluation of MPOD spatial distribution up to 8 degrees eccentricity from the fovea was performed using HFP. SD-OCT indicated a persistence of multiple inner retinal layers within the foveal region in the RE and LE including symmetric foveal thickening consistent with foveal hypoplasia. Fundus photography showed mild retinal pigmented epithelial (RPE) hypopigmentation and a poorly demarcated macula. OriginPro 9 was used to plot MPOD spatial distribution of the subject and a 33-subject sample. The OCA subject demonstrated a foveal MPOD of 0.10 with undetectable levels at 6 degrees eccentricity. The study sample showed a mean foveal MPOD of 0.34 and mean 6 degree eccentricity values of 0.03. Consistent with previous macular pigment (MP) studies of OCA, overall MPOD is reduced in our subject. Mild phenotypic expression of OCA with high functional visual acuity may represent a Henle fiber layer amenable to additional MP deposition. Further study of MP supplementation in OCA patients is warranted. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Spectral/spatial optical CDMA code based on Diagonal Eigenvalue Unity

Science.gov (United States)

Najjar, Monia; Jellali, Nabiha; Ferchichi, Moez; Rezig, Houria

2017-11-01

A new two dimensional Diagonal Eigenvalue Unity (2D-DEU) code is developed for the spectral⧹spatial optical code division multiple access (OCDMA) system. It has a lower cross correlation value compared to two dimensional diluted perfect difference (2D-DPD), two dimensional Extended Enhanced Double Weight (2D-Extended-EDW) codes. Also, for the same code length, the number of users can be generated by the 2D-DEU code is higher than that provided by the others codes. The Bit Error Rate (BER) numerical analysis is developed by considering the effects of shot noise, phase induced intensity noise (PIIN), and thermal noise. The main result shows that BER is strongly affected by PIIN for the higher source power. The 2D-DEU code performance is compared with 2D-DPD, 2D-Extended-EDW and two dimensional multi-diagonals (2D-MD) codes. This comparison proves that the proposed 2D-DEU system outperforms the related codes.

Nonlinear Optics: Materials, Fundamentals, and Applications. Postdeadline papers

Science.gov (United States)

1992-08-01

The Nonlinear Optics: Materials, Fundamentals, and Applications conference was held on 17-21 Aug. 1992. The following topics were addressed: subpicosecond time resolved four-wave mixing spectroscopy in heteroepitaxial ZnSe thin layers; anisotropic two-photon transition in GaAs/AlGaAs multiple quantum well waveguides; two picosecond, narrow-band, tunable, optical parametric systems using BBO and LBO; second generation in an optically active liquid: experimental observation of a fourth-order optical nonlinearity due to molecular chirality; optical image recognition system implemented with a 3-D memory disk; phase-matched second-harmonic generation in waveguides of polymeric Langmuir-Blodgett films; fluence dependent dynamics observed in the resonant third-order optical response of C60 and C70 films; temporal modulation of spatial optical solitons: a variational approach; measurements of light-scattering noise during two-wave mixing in a Kerr medium; excess noise introduced by beam propagation through an atomic vapor; an approach to all-optical switching based on second-order nonlinearities; multilayer, nonlinear ARROW waveguides for surface emitted sum-frequency mixing; energy scaling of SBS phase conjugate mirrors to 4J; vector versus scalar theory for the double phase conjugate mirror; cross-talk and error probability in counter-beam lambda-multiplexed digital holograms; and modal growth of SHG in doped silica thin film waveguides.

Single molecule optical measurements of orientation and rotations of biological macromolecules.

Science.gov (United States)

Shroder, Deborah Y; Lippert, Lisa G; Goldman, Yale E

2016-11-22

Subdomains of macromolecules often undergo large orientation changes during their catalytic cycles that are essential for their activity. Tracking these rearrangements in real time opens a powerful window into the link between protein structure and functional output. Site-specific labeling of individual molecules with polarized optical probes and measurement of their spatial orientation can give insight into the crucial conformational changes, dynamics, and fluctuations of macromolecules. Here we describe the range of single molecule optical technologies that can extract orientation information from these probes, review the relevant types of probes and labeling techniques, and highlight the advantages and disadvantages of these technologies for addressing specific inquiries.

Reflective Optics for Microdiffraction

International Nuclear Information System (INIS)

Ice, G.E.

2007-01-01

Nondispersive optics are essential for emerging microdiffraction and nanobeam research. Here we describe extensions to traditional Kirkpatrick Baez optics required to develop nondispersive microdiffraction and nanoprobe optics with 1-10 nm spatial resolution

On the local field method with the account of spatial dispersion. Application to the optical activity theory

Science.gov (United States)

Tyu, N. S.; Ekhilevsky, S. G.

1992-07-01

For the perfect molecular crystals the equations of the local field method (LFM) with the account of spatial dispersion are formulated. They are used to derive the expression for the crystal polarizability tensor. For the first time within the framework of this method the formula for the gyrotropy tensor of an arbitrary optically active molecular crystal is obtained. This formula is analog of well known relationships of Lorentz-Lorenz.

Optical design of the lightning imager for MTG

Science.gov (United States)

Lorenzini, S.; Bardazzi, R.; Di Giampietro, M.; Feresin, F.; Taccola, M.; Cuevas, L. P.

2017-11-01

The Lightning Imager for Meteosat Third Generation is an optical payload with on-board data processing for the detection of lightning. The instrument will provide a global monitoring of lightning events over the full Earth disk from geostationary orbit and will operate in day and night conditions. The requirements of the large field of view together with the high detection efficiency with small and weak optical pulses superimposed to a much brighter and highly spatial and temporal variable background (full operation during day and night conditions, seasonal variations and different albedos between clouds oceans and lands) are driving the design of the optical instrument. The main challenge is to distinguish a true lightning from false events generated by random noise (e.g. background shot noise) or sun glints diffusion or signal variations originated by microvibrations. This can be achieved thanks to a `multi-dimensional' filtering, simultaneously working on the spectral, spatial and temporal domains. The spectral filtering is achieved with a very narrowband filter centred on the bright lightning O2 triplet line (777.4 nm +/- 0.17 nm). The spatial filtering is achieved with a ground sampling distance significantly smaller (between 4 and 5 km at sub satellite pointing) than the dimensions of a typical lightning pulse. The temporal filtering is achieved by sampling continuously the Earth disk within a period close to 1 ms. This paper presents the status of the optical design addressing the trade-off between different configurations and detailing the design and the analyses of the current baseline. Emphasis is given to the discussion of the design drivers and the solutions implemented in particular concerning the spectral filtering and the optimisation of the signal to noise ratio.

Thermally induced optical deformation of a Nd:YVO4 active disk under the action of multi-beam spatially periodic diode pumping

Science.gov (United States)

Guryev, D. A.; Nikolaev, D. A.; Tsvetkov, V. B.; Shcherbakov, I. A.

2018-05-01

A study of how the transverse distribution of an optical path changes in a Nd:YVO4 active disk was carried out in a ten-beam spatially periodic diode pumping in the one-dimensional case. The pumping beams’ transverse dimensions were comparable with the distances between them. The investigations were carried out using laser interferometry methods. It was found that the optical thickness changing in the active disk along the line of pumping spots was well described by a Gaussian function.

Asymptotic analysis of spatial discretizations in implicit Monte Carlo

International Nuclear Information System (INIS)

Densmore, Jeffery D.

2009-01-01

We perform an asymptotic analysis of spatial discretizations in Implicit Monte Carlo (IMC). We consider two asymptotic scalings: one that represents a time step that resolves the mean-free time, and one that corresponds to a fixed, optically large time step. We show that only the latter scaling results in a valid spatial discretization of the proper diffusion equation, and thus we conclude that IMC only yields accurate solutions when using optically large spatial cells if time steps are also optically large. We demonstrate the validity of our analysis with a set of numerical examples.

High-efficiency and flexible generation of vector vortex optical fields by a reflective phase-only spatial light modulator.

Science.gov (United States)

Cai, Meng-Qiang; Wang, Zhou-Xiang; Liang, Juan; Wang, Yan-Kun; Gao, Xu-Zhen; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

2017-08-01

The scheme for generating vector optical fields should have not only high efficiency but also flexibility for satisfying the requirements of various applications. However, in general, high efficiency and flexibility are not compatible. Here we present and experimentally demonstrate a solution to directly, flexibly, and efficiently generate vector vortex optical fields (VVOFs) with a reflective phase-only liquid crystal spatial light modulator (LC-SLM) based on optical birefringence of liquid crystal molecules. To generate the VVOFs, this approach needs in principle only a half-wave plate, an LC-SLM, and a quarter-wave plate. This approach has some advantages, including a simple experimental setup, good flexibility, and high efficiency, making the approach very promising in some applications when higher power is need. This approach has a generation efficiency of 44.0%, which is much higher than the 1.1% of the common path interferometric approach.

Area PEc Neurons Use a Multiphasic Pattern of Activity to Signal the Spatial Properties of Optic Flow

Directory of Open Access Journals (Sweden)

Milena Raffi

2017-01-01

Full Text Available The cortical representation of visual perception requires the integration of several-signal processing distributed across many cortical areas, but the neural substrates of such perception are largely unknown. The type of firing pattern exhibited by single neurons is an important indicator of dynamic circuitry within or across cortical areas. Neurons in area PEc are involved in the spatial mapping of the visual field; thus, we sought to analyze the firing pattern of activity of PEc optic flow neurons to shed some light on the cortical processing of visual signals. We quantified the firing activity of 152 optic flow neurons using a spline interpolation function, which allowed determining onset, end, and latency of each neuronal response. We found that many PEc neurons showed multiphasic activity, which is strictly related to the position of the eye and to the position of the focus of expansion (FOE of the flow field. PEc neurons showed a multiphasic activity comprised of excitatory phases interspersed with inhibitory pauses. This phasic pattern seems to be a very efficient way to signal the spatial location of visual stimuli, given that the same neuron sends different firing patterns according to a specific combination of FOE/eye position.

Optical Pattern Recognition

Science.gov (United States)

Yu, Francis T. S.; Jutamulia, Suganda

2008-10-01

Contributors; Preface; 1. Pattern recognition with optics Francis T. S. Yu and Don A. Gregory; 2. Hybrid neural networks for nonlinear pattern recognition Taiwei Lu; 3. Wavelets, optics, and pattern recognition Yao Li and Yunglong Sheng; 4. Applications of the fractional Fourier transform to optical pattern recognition David Mendlovic, Zeev Zalesky and Haldum M. Oxaktas; 5. Optical implementation of mathematical morphology Tien-Hsin Chao; 6. Nonlinear optical correlators with improved discrimination capability for object location and recognition Leonid P. Yaroslavsky; 7. Distortion-invariant quadratic filters Gregory Gheen; 8. Composite filter synthesis as applied to pattern recognition Shizhou Yin and Guowen Lu; 9. Iterative procedures in electro-optical pattern recognition Joseph Shamir; 10. Optoelectronic hybrid system for three-dimensional object pattern recognition Guoguang Mu, Mingzhe Lu and Ying Sun; 11. Applications of photrefractive devices in optical pattern recognition Ziangyang Yang; 12. Optical pattern recognition with microlasers Eung-Gi Paek; 13. Optical properties and applications of bacteriorhodopsin Q. Wang Song and Yu-He Zhang; 14. Liquid-crystal spatial light modulators Aris Tanone and Suganda Jutamulia; 15. Representations of fully complex functions on real-time spatial light modulators Robert W. Cohn and Laurence G. Hassbrook; Index.

Plasmonic computing of spatial differentiation

Science.gov (United States)

Zhu, Tengfeng; Zhou, Yihan; Lou, Yijie; Ye, Hui; Qiu, Min; Ruan, Zhichao; Fan, Shanhui

2017-05-01

Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.

Plasmonic computing of spatial differentiation.

Science.gov (United States)

Zhu, Tengfeng; Zhou, Yihan; Lou, Yijie; Ye, Hui; Qiu, Min; Ruan, Zhichao; Fan, Shanhui

2017-05-19

Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.

Phase space treatment of optical beams

International Nuclear Information System (INIS)

Nemes, G.; Teodorescu, I.E.; Nemes, M.

1984-01-01

The lecture reveals the possibility of treating optical beams and systems using the PS concept. In the first part some well-known concepts and results of charged particle optics are applied to optical beam and systems. Attention is paid to the PSE concept as to beina a beam invariant according to Liouville's theorem. In the second part some simple optical sources, their PSE and their transforms through simple optical elements are theoretically presented. An experimental method and a device for PSE measurements are presented in the third part. In the fourth part the main problems of the linear system theory which were applied to electrical circuits in the time (or freo.uency) domain and to optical systems in the bidimensional space of spatial coordinates (or spatial frequencies) are applied to stigmatic optical systems in the bidimensional PS (spatial coordinate, angle). Some examples of applying PS concepts in optics are presented in the fifth part. The lecture is mainly based on original results some of them being previously unpublished. (authors)

Advanced optical instruments technology

Science.gov (United States)

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

1992-08-01

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

Optical Manipulation System Using a Plurality of Optical Traps

DEFF Research Database (Denmark)

2006-01-01

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

Optical implementation of multifocal programmable lens with single and multiple axes

Energy Technology Data Exchange (ETDEWEB)

Romero, Lenny A; Millan, Maria S; Perez-Cabre, Elisabet, E-mail: lenny.alexandra.romero@upc.edu [Optics and Optometry Dep. Technical University of Catalonia Violinista Vellsola 37, 08222 Terrassa (Spain)

2011-01-01

In this work we analyse the generation of a diffractive optical element (DOE) consisting of a multifocal Fresnel lens by means of an LCoS (liquid cristal on silicon) spatial light modulator (SLM). The multifocal lens is composed of a set of lenses of different focal length that share a common optical axis (coaxial combination) or have different axes in parallel (multi-axis combination). For both configurations, we present several ways to combine the phase distributions for three lenses with different focal lengths (f1, f2, f3), into a single-phase distribution addressed to the SLM. Numerical simulations were carried out along with the experimental analysis to corroborate the results.

Spatial Terahertz Modulator

Science.gov (United States)

Xie, Zhenwei; Wang, Xinke; Ye, Jiasheng; Feng, Shengfei; Sun, Wenfeng; Akalin, Tahsin; Zhang, Yan

2013-11-01

Terahertz (THz) technology is a developing and promising candidate for biological imaging, security inspection and communications, due to the low photon energy, the high transparency and the broad band properties of the THz radiation. However, a major encountered bottleneck is lack of efficient devices to manipulate the THz wave, especially to modulate the THz wave front. A wave front modulator should allow the optical or electrical control of the spatial transmission (or reflection) of an input THz wave and hence the ability to encode the information in a wave front. Here we propose a spatial THz modulator (STM) to dynamically control the THz wave front with photo-generated carriers. A computer generated THz hologram is projected onto a silicon wafer by a conventional spatial light modulator (SLM). The corresponding photo-generated carrier spatial distribution will be induced, which forms an amplitude hologram to modulate the wave front of the input THz beam. Some special intensity patterns and vortex beams are generated by using this method. This all-optical controllable STM is structure free, high resolution and broadband. It is expected to be widely used in future THz imaging and communication systems.

Spatial Computation

Science.gov (United States)

2003-12-01

Computation and today’s microprocessors with the approach to operating system architecture, and the controversy between microkernels and monolithic kernels...Both Spatial Computation and microkernels break away a relatively monolithic architecture into in- dividual lightweight pieces, well specialized...for their particular functionality. Spatial Computation removes global signals and control, in the same way microkernels remove the global address

Pattern formation in optical resonators

International Nuclear Information System (INIS)

Weiss, C O; Larionova, Ye

2007-01-01

We review pattern formation in optical resonators. The emphasis is on 'particle-like' structures such as vortices or spatial solitons. On the one hand, similarities impose themselves with other fields of physics (condensed matter, phase transitions, particle physics, fluds/super fluids). On the other hand the feedback is led by the resonator mirrors to bi- and multi-stability of the spatial field structure, which is the basic ingredient for optical information processing. The spatial dimension or the 'parallelism' is the strength of optics compared to electronics (and will have to be employed to fully use the advantages optics offers in information processing). But even in the 'serial' processing tasks of telecoms (e.g. information buffering) spatial resonator solitons can do better than the schemes proposed so far-including 'slow light'. Pattern formation in optical resonators will likely be the key to brain-like information processing like cognition, learning and association; to complement the precise but limited algorithmic capabilities of electronic processing. But even in the short term it will be useful for solving serial optical processing problems. The prospects for technical uses of pattern formation in resonators are one motivation for this research. The fundamental similarities with other fields of physics, on the other hand, inspire transfer of concepts between fields; something that has always proven fruitful for gaining deeper insights or for solving technical problems

Diurnal spatial distributions of aerosol optical and cloud micro-macrophysics properties in Africa based on MODIS observations

Science.gov (United States)

Ntwali, Didier; Chen, Hongbin

2018-06-01

The diurnal spatial distribution of both natural and anthropogenic aerosols, as well as liquid and ice cloud micro-macrophysics have been evaluated over Africa using Terra and Aqua MODIS collection 6 products. The variability of aerosol optical depth (AOD), Ångström exponent (AE), liquid and ice cloud microphysics (Liquid cloud effective radius LCER, Ice cloud effective radius ICER) and cloud macrophysics (Liquid cloud optical thickness LCOT, Liquid cloud water path LCWP, Ice cloud optical thickness ICOT, Ice cloud water path ICWP) parameters were investigated from the morning to afternoon over Africa from 2010 to 2014. In both the morning (Terra) and afternoon (Aqua) heavy pollution (AOD ≥ 0.6) occurs in the coastal and central areas (between 120 N-170 N and 100 E-150 E) of West of Africa (WA), Central of Africa (CA) (0.50 S-70S and 100 E-250 E),. Moderate pollution (0.3 1.2) aerosols. The mixture of dust and biomass burning aerosols (0.7 improve aerosol and cloud remote sensing retrieval.

Integrated optical transceiver with electronically controlled optical beamsteering

Science.gov (United States)

Davids, Paul; DeRose, Christopher; Tauke-Pedretti, Anna

2017-08-22

A beam-steering optical transceiver is provided. The transceiver includes one or more modules, each comprising an antenna chip and a control chip bonded to the antenna chip. Each antenna chip has a feeder waveguide, a plurality of row waveguides that tap off from the feeder waveguide, and a plurality of metallic nanoantenna elements arranged in a two-dimensional array of rows and columns such that each row overlies one of the row waveguides. Each antenna chip also includes a plurality of independently addressable thermo-optical phase shifters, each configured to produce a thermo-optical phase shift in a respective row. Each antenna chip also has, for each row, a row-wise heating circuit configured to produce a respective thermo-optic phase shift at each nanoantenna element along its row. The control chip includes controllable current sources for the independently addressable thermo-optical phase shifters and the row-wise heating circuits.

An auxiliary graph based dynamic traffic grooming algorithm in spatial division multiplexing enabled elastic optical networks with multi-core fibers

Science.gov (United States)

Zhao, Yongli; Tian, Rui; Yu, Xiaosong; Zhang, Jiawei; Zhang, Jie

2017-03-01

A proper traffic grooming strategy in dynamic optical networks can improve the utilization of bandwidth resources. An auxiliary graph (AG) is designed to solve the traffic grooming problem under a dynamic traffic scenario in spatial division multiplexing enabled elastic optical networks (SDM-EON) with multi-core fibers. Five traffic grooming policies achieved by adjusting the edge weights of an AG are proposed and evaluated through simulation: maximal electrical grooming (MEG), maximal optical grooming (MOG), maximal SDM grooming (MSG), minimize virtual hops (MVH), and minimize physical hops (MPH). Numeric results show that each traffic grooming policy has its own features. Among different traffic grooming policies, an MPH policy can achieve the lowest bandwidth blocking ratio, MEG can save the most transponders, and MSG can obtain the fewest cores for each request.

Optically controlled reflection modulator using GaAs-AlGaAs n-i-p-i/multiple-quantum-well structures

Science.gov (United States)

Law, K.-K.; Simes, R. J.; Coldren, L. A.; Gossard, A. C.; Maserjian, J.

1989-01-01

An optically controlled reflection modulator has been demonstrated that consists of a combination of a GaAs-AlGaAs n-i-p-i doping structure with a multiple-quantum-well structures on top of a distributed Bragg reflector, all grown by MBE. A modulation of approximately 60 percent is obtained on the test structure, corresponding to a differential change of absorption coefficient in the quantum wells of approximately 7500/cm. Changes in reflectance can be observed with a control beam power as low as 1.5 microW. This device structure has the potential of being developed as an optically addressed spatial light modulator for optical information processing.

Optical image reconstruction using DC data: simulations and experiments

International Nuclear Information System (INIS)

Huabei Jiang; Paulsen, K.D.; Oesterberg, U.L.

1996-01-01

In this paper, we explore optical image formation using a diffusion approximation of light propagation in tissue which is modelled with a finite-element method for optically heterogeneous media. We demonstrate successful image reconstruction based on absolute experimental DC data obtained with a continuous wave 633 nm He-Ne laser system and a 751 nm diode laser system in laboratory phantoms having two optically distinct regions. The experimental systems used exploit a tomographic type of data collection scheme that provides information from which a spatially variable optical property map is deduced. Reconstruction of scattering coefficient only and simultaneous reconstruction of both scattering and absorption profiles in tissue-like phantoms are obtained from measured and simulated data. Images with different contrast levels between the heterogeneity and the background are also reported and the results show that although it is possible to obtain qualitative visual information on the location and size of a heterogeneity, it may not be possible to quantitatively resolve contrast levels or optical properties using reconstructions from DC data only. Sensitivity of image reconstruction to noise in the measurement data is investigated through simulations. The application of boundary constraints has also been addressed. (author)

Spatially Correlated, Single Nanomaterial-Level Structural and Optical Profiling of Cu-Doped ZnO Nanorods Synthesized via Multifunctional Silicides

Directory of Open Access Journals (Sweden)

Johnson Truong

2018-04-01

Full Text Available We demonstrate a straightforward and effective method to synthesize vertically oriented, Cu-doped ZnO nanorods (NRs using a novel multipurpose platform of copper silicide nanoblocks (Cu3Si NBs preformed laterally in well-defined directions on Si. The use of the surface-organized Cu3Si NBs for ZnO NR growth successfully results in densely assembled Cu-doped ZnO NRs on each NB platform, whose overall structures resemble thick bristles on a brush head. We show that Cu3Si NBs can uniquely serve as a catalyst for ZnO NRs, a local dopant source of Cu, and a prepatterned guide to aid the local assembly of the NRs on the growth substrate. We also ascertain the crystalline structures, optical properties, and spectroscopic signatures of the Cu-doped ZnO NRs produced on the NBs, both at each module of NRs/NB and at their ensemble level. Subsequently, we determine their augmented properties relative to the pristine form of undoped ZnO NRs and the source material of Cu3Si NBs. We provide spatially correlated structural and optical data for individual modules of Cu-doped ZnO NRs assembled on a Cu3Si NB by resolving them along the different positions on the NB. Ensemble-averaged versus individual behaviors of Cu-doped ZnO NRs on Cu3Si NBs are then compared. We further discuss the potential impact of such ZnO-derived NRs on their relatively unexplored biological and biomedical applications. Our efforts will be particularly useful when exploiting each integrated module of self-aligned, Cu-doped ZnO NRs on a NB as a discretely addressable, active element in solid-state sensors and miniaturized luminescent bioprobes.

Digital polarization holography advancing geometrical phase optics.

Science.gov (United States)

De Sio, Luciano; Roberts, David E; Liao, Zhi; Nersisyan, Sarik; Uskova, Olena; Wickboldt, Lloyd; Tabiryan, Nelson; Steeves, Diane M; Kimball, Brian R

2016-08-08

Geometrical phase or the fourth generation (4G) optics enables realization of optical components (lenses, prisms, gratings, spiral phase plates, etc.) by patterning the optical axis orientation in the plane of thin anisotropic films. Such components exhibit near 100% diffraction efficiency over a broadband of wavelengths. The films are obtained by coating liquid crystalline (LC) materials over substrates with patterned alignment conditions. Photo-anisotropic materials are used for producing desired alignment conditions at the substrate surface. We present and discuss here an opportunity of producing the widest variety of "free-form" 4G optical components with arbitrary spatial patterns of the optical anisotropy axis orientation with the aid of a digital spatial light polarization converter (DSLPC). The DSLPC is based on a reflective, high resolution spatial light modulator (SLM) combined with an "ad hoc" optical setup. The most attractive feature of the use of a DSLPC for photoalignment of nanometer thin photo-anisotropic coatings is that the orientation of the alignment layer, and therefore of the fabricated LC or LC polymer (LCP) components can be specified on a pixel-by-pixel basis with high spatial resolution. By varying the optical magnification or de-magnification the spatial resolution of the photoaligned layer can be adjusted to an optimum for each application. With a simple "click" it is possible to record different optical components as well as arbitrary patterns ranging from lenses to invisible labels and other transparent labels that reveal different images depending on the side from which they are viewed.

Advances in optical structure systems; Proceedings of the Meeting, Orlando, FL, Apr. 16-19, 1990

Science.gov (United States)

Breakwell, John; Genberg, Victor L.; Krumweide, Gary C.

Various papers on advances in optical structure systems are presented. Individual topics addressed include: beam pathlength optimization, thermal stress in glass/metal bond with PR 1578 adhesive, structural and optical properties for typical solid mirror shapes, parametric study of spinning polygon mirror deformations, simulation of small structures-optics-controls system, spatial PSDs of optical structures due to random vibration, mountings for a four-meter glass mirror, fast-steering mirrors in optical control systems, adaptive state estimation for control of flexible structures, surface control techniques for large segmented mirrors, two-time-scale control designs for large flexible structures, closed-loop dynamic shape control of a flexible beam. Also discussed are: inertially referenced pointing for body-fixed payloads, sensor blending line-of-sight stabilization, controls/optics/structures simulation development, transfer functions for piezoelectric control of a flexible beam, active control experiments for large-optics vibration alleviation, composite structures for a large-optical test bed, graphite/epoxy composite mirror for beam-steering applications, composite structures for optical-mirror applications, thin carbon-fiber prepregs for dimensionally critical structures.

Optical wedge method for spatial reconstruction of particle trajectories

International Nuclear Information System (INIS)

Asatiani, T.L.; Alchudzhyan, S.V.; Gazaryan, K.A.; Zograbyan, D.Sh.; Kozliner, L.I.; Krishchyan, V.M.; Martirosyan, G.S.; Ter-Antonyan, S.V.

1978-01-01

A technique of optical wedges allowing the full reconstruction of pictures of events in space is considered. The technique is used for the detection of particle tracks in optical wide-gap spark chambers by photographing in one projection. The optical wedges are refracting right-angle plastic prisms positioned between the camera and the spark chamber so that through them both ends of the track are photographed. A method for calibrating measurements is given, and an estimate made of the accuracy of the determination of the second projection with the help of the optical wedges

Improvement of diffraction efficiency of three-dimensional magneto-optic spatial light modulator with magnetophotonic crystal

Energy Technology Data Exchange (ETDEWEB)

Nakamura, K.; Takagi, H., E-mail: takagi@ee.tut.ac.jp; Lim, P. B.; Inoue, M., E-mail: inoue@tut.ac.jp [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441 8580 (Japan); Goto, Taichi [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441 8580 (Japan); JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Horimai, H. [HolyMine Corporation, Atsugi, Kanagawa 243 0813 (Japan); Yoshikawa, H. [Department of Computer Engineering, College of Science and Technology, Nihon University, Funabashi, Chiba 274 8501 (Japan); Bove, V. M. [MIT Media Lab, Cambridge, Massachusetts 02139 (United States)

2016-01-11

We have developed three-dimensional magneto-optic spatial light modulators (3D-MOSLMs) that use magnetic domains as submicron scale pixels to represent holograms. Our display system uses a submicron-scale magnetic pixel array on an amorphous TbFe film to create a wide viewing angle hologram. However, in previous work the reconstructed images had a low intensity and a low optical contrast; brightness of the reconstructed image was 4.4 × 10{sup −2 }cd/m{sup 2} with 532 nm illumination light at 10.8 mW/cm{sup 2}, while display standard ISO13406 recommends 100 cd/m{sup 2} or more. In this paper, we describe our development of a 3D-MOSLM composed of an artificial magnetic lattice structure of magnetophotonic crystals (MPCs). The MPCs enhance the diffraction efficiency of reconstructed 3D images and reduce the power consumption for controlling the magnetic pixels by a light localization effect. We demonstrate reconstructed 3D images using the MPC and show significant brightness improvement.

Vectorial optical fields fundamentals and applications

CERN Document Server

2014-01-01

Polarization is a vector nature of light that plays an important role in optical science and engineering. While existing textbook treatments of light assume beams with spatially homogeneous polarization, there is an increasing interest in vectorial optical fields with spatially engineered states of polarization. New effects and phenomena have been predicted and observed for light beams with these unconventional polarization states. This edited review volume aims to provide a comprehensive overview and summarize the latest developments in this important emerging field of optics. This book will cover the fundamentals including mathematical and physical descriptions, experimental generation, manipulation, focusing, propagation, and the applications of the engineered vectorial optical fields in focal field engineering, plasmonic focusing and optical antenna, single molecular imaging, optical tweezers/trapping, as well as optical measurements and instrumentations. Readership: Students, professionals, post-graduat...

Global spectroscopic survey of cloud thermodynamic phase at high spatial resolution, 2005-2015

Science.gov (United States)

Thompson, David R.; Kahn, Brian H.; Green, Robert O.; Chien, Steve A.; Middleton, Elizabeth M.; Tran, Daniel Q.

2018-02-01

The distribution of ice, liquid, and mixed phase clouds is important for Earth's planetary radiation budget, impacting cloud optical properties, evolution, and solar reflectivity. Most remote orbital thermodynamic phase measurements observe kilometer scales and are insensitive to mixed phases. This under-constrains important processes with outsize radiative forcing impact, such as spatial partitioning in mixed phase clouds. To date, the fine spatial structure of cloud phase has not been measured at global scales. Imaging spectroscopy of reflected solar energy from 1.4 to 1.8 µm can address this gap: it directly measures ice and water absorption, a robust indicator of cloud top thermodynamic phase, with spatial resolution of tens to hundreds of meters. We report the first such global high spatial resolution survey based on data from 2005 to 2015 acquired by the Hyperion imaging spectrometer onboard NASA's Earth Observer 1 (EO-1) spacecraft. Seasonal and latitudinal distributions corroborate observations by the Atmospheric Infrared Sounder (AIRS). For extratropical cloud systems, just 25 % of variance observed at GCM grid scales of 100 km was related to irreducible measurement error, while 75 % was explained by spatial correlations possible at finer resolutions.

Stochastic Optical Reconstruction Microscopy (STORM).

Science.gov (United States)

Xu, Jianquan; Ma, Hongqiang; Liu, Yang

2017-07-05

Super-resolution (SR) fluorescence microscopy, a class of optical microscopy techniques at a spatial resolution below the diffraction limit, has revolutionized the way we study biology, as recognized by the Nobel Prize in Chemistry in 2014. Stochastic optical reconstruction microscopy (STORM), a widely used SR technique, is based on the principle of single molecule localization. STORM routinely achieves a spatial resolution of 20 to 30 nm, a ten-fold improvement compared to conventional optical microscopy. Among all SR techniques, STORM offers a high spatial resolution with simple optical instrumentation and standard organic fluorescent dyes, but it is also prone to image artifacts and degraded image resolution due to improper sample preparation or imaging conditions. It requires careful optimization of all three aspects-sample preparation, image acquisition, and image reconstruction-to ensure a high-quality STORM image, which will be extensively discussed in this unit. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Determination of the transfer function for optical surface topography measuring instruments—a review

International Nuclear Information System (INIS)

Foreman, Matthew R; Török, Peter; Giusca, Claudiu L; Leach, Richard K; Coupland, Jeremy M

2013-01-01

A significant number of areal surface topography measuring instruments, largely based on optical techniques, are commercially available. However, implementation of optical instrumentation into production is currently difficult due to the lack of understanding of the complex interaction between the light and the component surface. Studying the optical transfer function of the instrument can help address this issue. Here a review is given of techniques for the measurement of optical transfer functions. Starting from the basis of a spatially coherent, monochromatic confocal scanning imaging system, the theory of optical transfer functions in three-dimensional (3D) imaging is presented. Further generalizations are reviewed allowing the extension of the theory to the description of conventional and interferometric 3D imaging systems. Polychromatic transfer functions and surface topography measurements are also discussed. Following presentation of theoretical results, experimental methods to measure the optical transfer function of each class of system are presented, with a focus on suitable methods for the establishment of calibration standards in 3D imaging and surface topography measurements. (topical review)

Progress in nano-electro optics characterization of nano-optical materials and optical near-field interactions

CERN Document Server

Ohtsu, Motoichi

2005-01-01

This volume focuses on the characterization of nano-optical materials and optical-near field interactions. It begins with the techniques for characterizing the magneto-optical Kerr effect and continues with methods to determine structural and optical properties in high-quality quantum wires with high spatial uniformity. Further topics include: near-field luminescence mapping in InGaN/GaN single quantum well structures in order to interpret the recombination mechanism in InGaN-based nano-structures; and theoretical treatment of the optical near field and optical near-field interactions, providing the basis for investigating the signal transport and associated dissipation in nano-optical devices. Taken as a whole, this overview will be a valuable resource for engineers and scientists working in the field of nano-electro-optics.

Deterministic photonic spatial-polarization hyper-controlled-not gate assisted by a quantum dot inside a one-side optical microcavity

International Nuclear Information System (INIS)

Ren, Bao-Cang; Wei, Hai-Rui; Deng, Fu-Guo

2013-01-01

To date, all work concerning the construction of quantum logic gates, an essential part of quantum computing, has focused on operating in one degree of freedom (DOF) for quantum systems. Here, we investigate the possibility of achieving scalable photonic quantum computing based on two DOFs for quantum systems. We construct a deterministic hyper-controlled-not (hyper-CNOT) gate operating in both the spatial mode and polarization DOFs for a photon pair simultaneously, using the giant optical Faraday rotation induced by a single-electron spin in a quantum dot inside a one-side optical microcavity as a result of cavity quantum electrodynamics. With this hyper-CNOT gate and linear optical elements, two-photon four-qubit cluster entangled states can be prepared and analyzed, which give an application to manipulate more information with less resources. We analyze the experimental feasibility of this hyper-CNOT gate and show that it can be implemented with current technology. (letter)

Correlation characteristics of optical coherence tomography images of turbid media with statistically inhomogeneous optical parameters

International Nuclear Information System (INIS)

Dolin, Lev S.; Sergeeva, Ekaterina A.; Turchin, Ilya V.

2012-01-01

Noisy structure of optical coherence tomography (OCT) images of turbid medium contains information about spatial variations of its optical parameters. We propose analytical model of statistical characteristics of OCT signal fluctuations from turbid medium with spatially inhomogeneous coefficients of absorption and backscattering. Analytically predicted correlation characteristics of OCT signal from spatially inhomogeneous medium are in good agreement with the results of correlation analysis of OCT images of different biological tissues. The proposed model can be efficiently applied for quantitative evaluation of statistical properties of absorption and backscattering fluctuations basing on correlation characteristics of OCT images.

The development of a colour liquid crystal display spatial light modulator and applications in polychromatic optical data processing

Science.gov (United States)

Aiken, John Charles

The development of a colour Spatial Light Modulator (SLM) and its application to optical information processing is described. Whilst monochrome technology has been established for many years, this is not the case for colour where commercial systems are unavailable. A main aspect of this study is therefore, how the use of colour can add an additional dimension to optical information processing. A well established route to monochrome system development has been the use of (black and white) liquid crystal televisions (LCTV) as SLM, providing useful performance at a low-cost. This study is based on the unique use of a colour display removed from a LCTV and operated as a colour SLM. A significant development has been the replacement of the original TV electronics operating the display with enhanced drive electronics specially developed for this application. Through a computer interface colour images from a drawing package or video camera can now be readily displayed on the LCD as input to an optical system. A detailed evaluation of the colour LCD optical properties, indicates that the new drive electronics have considerably improved the operation of the display for use as a colour SLM. Applications are described employing the use of colour in Fourier plane filtering, image correlation and speckle metrology. The SLM (and optical system) developed demonstrates, how the addition of colour has greatly enhanced its capabilities to implement principles of optical data processing, conventionally performed monochromatically. The hybrid combination employed, combining colour optical data processing with electronic techniques has resulted in a capable development system. Further development of the system using current colour LCDs and the move towards a portable system, is considered in the study conclusion.

Spatial mode discriminator based on leaky waveguides

Science.gov (United States)

Xu, Jing; Liu, Jialing; Shi, Hongkang; Chen, Yuntian

2018-06-01

We propose a conceptually simple and experimentally compatible configuration to discriminate the spatial mode based on leaky waveguides, which are inserted in-between the transmission link. The essence of such a spatial mode discriminator is to introduce the leakage of the power flux on purpose for detection. Importantly, the leaky angle of each individual spatial mode with respect to the propagation direction are different for non-degenerated modes, while the radiation patterns of the degenerated spatial modes in the plane perpendicular to the propagation direction are also distinguishable. Based on these two facts, we illustrate the operation principle of the spatial mode discriminators via two concrete examples; a w-type slab leaky waveguide without degeneracy, and a cylindrical leaky waveguide with degeneracy. The correlation between the leakage angle and the spatial mode distribution for a slab leaky waveguide, as well as differences between the in-plane radiation patterns of degenerated modes in a cylindrical leaky waveguide, are verified numerically and analytically. Such findings can be readily useful in discriminating the spatial modes for optical communication or optical sensing.

Phase-image-based content-addressable holographic data storage

Science.gov (United States)

John, Renu; Joseph, Joby; Singh, Kehar

2004-03-01

We propose and demonstrate the use of phase images for content-addressable holographic data storage. Use of binary phase-based data pages with 0 and π phase changes, produces uniform spectral distribution at the Fourier plane. The absence of strong DC component at the Fourier plane and more intensity of higher order spatial frequencies facilitate better recording of higher spatial frequencies, and improves the discrimination capability of the content-addressable memory. This improves the results of the associative recall in a holographic memory system, and can give low number of false hits even for small search arguments. The phase-modulated pixels also provide an opportunity of subtraction among data pixels leading to better discrimination between similar data pages.

Optical signal processing for enabling high-speed, highly spectrally efficient and high capacity optical systems

Science.gov (United States)

Fazal, Muhammad Irfan

may be possible. Recently, interest has increased in exploring the spatial dimension of light to increase capacity, both in fiber as well as free-space communication channels. The orbital angular momentum (OAM) of light, carried by Laguerre-Gaussian (LG) beams have the interesting property that, in theory, an infinite number of OAMs can be transmitted; which due to its inherent orthogonality will not affect each other. Thus, in theory, one can increase the channel capacity arbitrarily. However, in practice, the device dimensions will reduce the number of OAMs used. In addition to advanced modulation formats, it is expected that optical signal processing may play a role in the future development of more efficient optical transmission systems. The hope is that performing signal processing in the optical domain may reduce optical-to-electronic conversion inefficiencies, eliminate bottlenecks and take advantage of the ultrahigh bandwidth inherent in optics. While 40 to 50 Gbit/s electronic components are the peak of commercial technology and 100 Gbit/s capable RF components are still in their infancy, optical signal processing of these high-speed data signals may provide a potential solution. Furthermore, any optical processing system or sub-system must be capable of handling the wide array of data formats and data rates that networks may employ. The work presented in this Ph.D. dissertation attempts at addressing the issue of optical processing for advanced optical modulation formats, and particularly explores the state of the art in increasing the capacity of an optical link by a combination of wavelength/phase/polarization/OAM dimensions of light. Spatial multiplexing and demultiplexing of both coherently and directly detected signals at the 100 Gbit/s Ethernet standard is addressed. The application of a continuously tunable all-optical delay for all-optical functionality like time-slot interchange at high data-rates is presented. Moreover the interplay of chirp

Deterministic ion beam material adding technology for high-precision optical surfaces.

Science.gov (United States)

Liao, Wenlin; Dai, Yifan; Xie, Xuhui; Zhou, Lin

2013-02-20

Although ion beam figuring (IBF) provides a highly deterministic method for the precision figuring of optical components, several problems still need to be addressed, such as the limited correcting capability for mid-to-high spatial frequency surface errors and low machining efficiency for pit defects on surfaces. We propose a figuring method named deterministic ion beam material adding (IBA) technology to solve those problems in IBF. The current deterministic optical figuring mechanism, which is dedicated to removing local protuberances on optical surfaces, is enriched and developed by the IBA technology. Compared with IBF, this method can realize the uniform convergence of surface errors, where the particle transferring effect generated in the IBA process can effectively correct the mid-to-high spatial frequency errors. In addition, IBA can rapidly correct the pit defects on the surface and greatly improve the machining efficiency of the figuring process. The verification experiments are accomplished on our experimental installation to validate the feasibility of the IBA method. First, a fused silica sample with a rectangular pit defect is figured by using IBA. Through two iterations within only 47.5 min, this highly steep pit is effectively corrected, and the surface error is improved from the original 24.69 nm root mean square (RMS) to the final 3.68 nm RMS. Then another experiment is carried out to demonstrate the correcting capability of IBA for mid-to-high spatial frequency surface errors, and the final results indicate that the surface accuracy and surface quality can be simultaneously improved.

Mobile quantum sensing with spins in optically trapped nanodiamonds

Science.gov (United States)

Awschalom, David D.

2013-03-01

The nitrogen-vacancy (NV) color center in diamond has emerged as a powerful, optically addressable, spin-based probe of electromagnetic fields and temperature. For nanoscale sensing applications, the NV center's atom-like nature enables the close-range interactions necessary for both high spatial resolution and the detection of fields generated by proximal nuclei, electrons, or molecules. Using a custom-designed optical tweezers apparatus, we demonstrate three-dimensional position control of nanodiamonds in solution with simultaneous optical measurement of electron spin resonance (ESR)[3]. Despite the motion and random orientation of NV centers suspended in the optical trap, we observe distinct peaks in the ESR spectra from the ground-state spin transitions. Accounting for the random dynamics of the trapped nanodiamonds, we model the ESR spectra observed in an applied magnetic field and estimate the dc magnetic sensitivity based on the ESR line shapes to be 50 μT/√{ Hz }. We utilize the optically trapped nanodiamonds to characterize the magnetic field generated by current-carrying wires and ferromagnetic structures in microfluidic circuits. These measurements provide a pathway to spin-based sensing in fluidic environments and biophysical systems that are inaccessible to existing scanning probe techniques, such as the interiors of living cells. This work is supported by AFOSR and DARPA.

Spatial dispersion in atom-surface quantum friction

International Nuclear Information System (INIS)

Reiche, D.; Dalvit, D. A. R.; Busch, K.; Intravaia, F.

2017-01-01

We investigate the influence of spatial dispersion on atom-surface quantum friction. We show that for atom-surface separations shorter than the carrier's mean free path within the material, the frictional force can be several orders of magnitude larger than that predicted by local optics. In addition, when taking into account spatial dispersion effects, we show that the commonly used local thermal equilibrium approximation underestimates by approximately 95% the drag force, obtained by employing the recently reported nonequilibrium fluctuation-dissipation relation for quantum friction. Unlike the treatment based on local optics, spatial dispersion in conjunction with corrections to local thermal equilibrium change not only the magnitude but also the distance scaling of quantum friction.

Distributed Optical Fiber Sensors Based on Optical Frequency Domain Reflectometry: A review.

Science.gov (United States)

Ding, Zhenyang; Wang, Chenhuan; Liu, Kun; Jiang, Junfeng; Yang, Di; Pan, Guanyi; Pu, Zelin; Liu, Tiegen

2018-04-03

Distributed optical fiber sensors (DOFS) offer unprecedented features, the most unique one of which is the ability of monitoring variations of the physical and chemical parameters with spatial continuity along the fiber. Among all these distributed sensing techniques, optical frequency domain reflectometry (OFDR) has been given tremendous attention because of its high spatial resolution and large dynamic range. In addition, DOFS based on OFDR have been used to sense many parameters. In this review, we will survey the key technologies for improving sensing range, spatial resolution and sensing performance in DOFS based on OFDR. We also introduce the sensing mechanisms and the applications of DOFS based on OFDR including strain, stress, vibration, temperature, 3D shape, flow, refractive index, magnetic field, radiation, gas and so on.

Miniature Optical Isolator, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — To address NASA's need for miniature optical isolators in atom interferometry applications, Physical Optics Corporation (POC) proposes to develop a miniature optical...

Spatial Language Facilitates Spatial Cognition: Evidence from Children Who Lack Language Input

Science.gov (United States)

Gentner, Dedre; Ozyurek, Asli; Gurcanli, Ozge; Goldin-Meadow, Susan

2013-01-01

Does spatial language influence how people think about space? To address this question, we observed children who did not know a conventional language, and tested their performance on nonlinguistic spatial tasks. We studied deaf children living in Istanbul whose hearing losses prevented them from acquiring speech and whose hearing parents had not…

Polycrystalline magnetic garnet films comprising weakly coupled crystallites for piezoelectrically-driven magneto-optic spatial light modulators

Energy Technology Data Exchange (ETDEWEB)

Mito, S.; Sakurai, H.; Takagi, H.; Inoue, M. [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Baryshev, A. V. [Electronics-Inspired Interdisciplinary Research Institute Toyohashi, Aichi 441-8580 (Japan); Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation)

2012-04-01

We have investigated the magnetization process of the polycrystalline magnetic garnet films in order to determine the most suitable composition of garnet films for piezoelectrically-driven magneto-optic spatial light modulators (MOSLMs). For experiment, the bismuth-dysprosium-aluminum-substituted yttrium iron (Bi{sub 1.3}Dy{sub 0.7}Y{sub 1.0}Fe{sub 3.1}Al{sub 1.9}O{sub 12}) garnet films were deposited by an RF magnetron sputter and annealed at 700 deg. C in air. The annealing time was varied in a range of several minutes to control the grain size. The saturation magnetization, the remanent magnetization and the composition of the fabricated garnet films slightly changed versus the annealing time. Experiments showed that the coercivity and the grain size increased at longer annealing; the coercivity was larger for films with bigger grains. This work shows that garnet films with smaller coercivity are most suitable for controlling the magnetization of garnet and, correspondingly, the magneto-optical rotation of MOSLM pixels driven by piezoelectrics.

Miniature Optical Isolator, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — To address NASA's need for compact optical isolators, Physical Optics Corporation (POC) proposes to continue the development of a new Miniature Optical Isolator...

Role of high-order aberrations in senescent changes in spatial vision

Energy Technology Data Exchange (ETDEWEB)

Elliot, S; Choi, S S; Doble, N; Hardy, J L; Evans, J W; Werner, J S

2009-01-06

The contributions of optical and neural factors to age-related losses in spatial vision are not fully understood. We used closed-loop adaptive optics to test the visual benefit of correcting monochromatic high-order aberrations (HOAs) on spatial vision for observers ranging in age from 18-81 years. Contrast sensitivity was measured monocularly using a two-alternative forced choice (2AFC) procedure for sinusoidal gratings over 6 mm and 3 mm pupil diameters. Visual acuity was measured using a spatial 4AFC procedure. Over a 6 mm pupil, young observers showed a large benefit of AO at high spatial frequencies, whereas older observers exhibited the greatest benefit at middle spatial frequencies, plus a significantly larger increase in visual acuity. When age-related miosis is controlled, young and old observers exhibited a similar benefit of AO for spatial vision. An increase in HOAs cannot account for the complete senescent decline in spatial vision. These results may indicate a larger role of additional optical factors when the impact of HOAs is removed, but also lend support for the importance of neural factors in age-related changes in spatial vision.

Optical computing, optical memory, and SBIRs at Foster-Miller

Science.gov (United States)

Domash, Lawrence H.

1994-03-01

A desktop design and manufacturing system for binary diffractive elements, MacBEEP, was developed with the optical researcher in mind. Optical processing systems for specialized tasks such as cellular automation computation and fractal measurement were constructed. A new family of switchable holograms has enabled several applications for control of laser beams in optical memories. New spatial light modulators and optical logic elements have been demonstrated based on a more manufacturable semiconductor technology. Novel synthetic and polymeric nonlinear materials for optical storage are under development in an integrated memory architecture. SBIR programs enable creative contributions from smaller companies, both product oriented and technology oriented, and support advances that might not otherwise be developed.

ICALEO '89 - Optical methods in flow and particle diagnostics; Proceedings of the Meeting, Orlando, FL, Oct. 15-20, 1989

Science.gov (United States)

Long, Marshall B.

Various papers on optical methods in flow and particle diagnostics are presented. Individual topics addressed include: swirl effects on confined flows in a model of a dump combustor, new analog optical method for data evaluation in laser Doppler anemometry, catadioptric optics for laser Doppler velocimeter applications, mapping of velocity flow field using the laser two-focus technique, engineering applications of particle image velocimeters, quantitative fluid flow analysis by laser velocimetry and numerical processing, optical analysis of particle image velocimetry data. Also discussed are: measuring turbulence in reversing flows by particle image velocimeter, two-color particle velocimetry, data evaluation in particle image velocimetry using spatial light modulator, statistical investigation of errors in particle image velocimetry, optimization of particle image velocimeters, visualization of internal structure in volumetric data, scalar measurements in two, three, and four dimensions.

Hyperentanglement concentration for polarization-spatial-time-bin hyperentangled photon systems with linear optics

Science.gov (United States)

Wang, Hong; Ren, Bao-Cang; Alzahrani, Faris; Hobiny, Aatef; Deng, Fu-Guo

2017-10-01

Hyperentanglement has significant applications in quantum information processing. Here we present an efficient hyperentanglement concentration protocol (hyper-ECP) for partially hyperentangled Bell states simultaneously entangled in polarization, spatial-mode and time-bin degrees of freedom (DOFs) with the parameter-splitting method, where the parameters of the partially hyperentangled Bell states are known to the remote parties. In this hyper-ECP, only one remote party is required to perform some local operations on the three DOFs of a photon, only the linear optical elements are considered, and the success probability can achieve the maximal value. Our hyper-ECP can be easily generalized to concentrate the N-photon partially hyperentangled Greenberger-Horne-Zeilinger states with known parameters, where the multiple DOFs have largely improved the channel capacity of long-distance quantum communication. All of these make our hyper-ECP more practical and useful in high-capacity long-distance quantum communication.

Microscale optical cryptography using a subdiffraction-limit optical key

Science.gov (United States)

Ogura, Yusuke; Aino, Masahiko; Tanida, Jun

2018-04-01

We present microscale optical cryptography using a subdiffraction-limit optical pattern, which is finer than the diffraction-limit size of the decrypting optical system, as a key and a substrate with a reflectance distribution as an encrypted image. Because of the subdiffraction-limit spatial coding, this method enables us to construct a secret image with the diffraction-limit resolution. Simulation and experimental results demonstrate, both qualitatively and quantitatively, that the secret image becomes recognizable when and only when the substrate is illuminated with the designed key pattern.

Multi-component optical solitary waves

DEFF Research Database (Denmark)

Kivshar, Y. S.; Sukhorukov, A. A.; Ostrovskaya, E. A.

2000-01-01

We discuss several novel types of multi-component (temporal and spatial) envelope solitary waves that appear in fiber and waveguide nonlinear optics. In particular, we describe multi-channel solitary waves in bit-parallel-wavelength fiber transmission systems for highperformance computer networks......, multi-color parametric spatial solitary waves due to cascaded nonlinearities of quadratic materials, and quasiperiodic envelope solitons due to quasi-phase-matching in Fibonacci optical superlattices. (C) 2000 Elsevier Science B.V. All rights reserved....

Metaoptics for Spectral and Spatial Beam Manipulation

Science.gov (United States)

Raghu Srimathi, Indumathi

Laser beam combining and beam shaping are two important areas with applications in optical communications, high power lasers, and atmospheric propagation studies. In this dissertation, metaoptical elements have been developed for spectral and spatial beam shaping, and multiplexing. Beams carrying orbital angular momentum (OAM), referred to as optical vortices, have unique propagation properties. Optical vortex beams carrying different topological charges are orthogonal to each other and have low inter-modal crosstalk which allows for them to be (de)multiplexed. Efficient spatial (de)multiplexing of these beams have been carried out by using diffractive optical geometrical coordinate transformation elements. The spatial beam combining technique shown here is advantageous because the efficiency of the system is not dependent on the number of OAM states being combined. The system is capable of generating coaxially propagating beams in the far-field and the beams generated can either be incoherently or coherently multiplexed with applications in power scaling and dynamic intensity profile manipulations. Spectral beam combining can also be achieved with the coordinate transformation elements. The different wavelengths emitted by fiber sources can be spatially overlapped in the far-field plane and the generated beams are Bessel-Gauss in nature with enhanced depth of focus properties. Unique system responses and beam shapes in the far-field can be realized by controlling amplitude, phase, and polarization at the micro-scale. This has been achieved by spatially varying the structural parameters at the subwavelength scale and is analogous to local modification of material properties. With advancements in fabrication technology, it is possible to control not just the lithographic process, but also the deposition process. In this work, a unique combination of spatial structure variations in conjunction with the conformal coating properties of an atomic layer deposition tool

Distributed Optical Fiber Sensors Based on Optical Frequency Domain Reflectometry: A review

Directory of Open Access Journals (Sweden)

Zhenyang Ding

2018-04-01

Full Text Available Distributed optical fiber sensors (DOFS offer unprecedented features, the most unique one of which is the ability of monitoring variations of the physical and chemical parameters with spatial continuity along the fiber. Among all these distributed sensing techniques, optical frequency domain reflectometry (OFDR has been given tremendous attention because of its high spatial resolution and large dynamic range. In addition, DOFS based on OFDR have been used to sense many parameters. In this review, we will survey the key technologies for improving sensing range, spatial resolution and sensing performance in DOFS based on OFDR. We also introduce the sensing mechanisms and the applications of DOFS based on OFDR including strain, stress, vibration, temperature, 3D shape, flow, refractive index, magnetic field, radiation, gas and so on.

Distributed Optical Fiber Sensors Based on Optical Frequency Domain Reflectometry: A review

Science.gov (United States)

Wang, Chenhuan; Liu, Kun; Jiang, Junfeng; Yang, Di; Pan, Guanyi; Pu, Zelin; Liu, Tiegen

2018-01-01

Distributed optical fiber sensors (DOFS) offer unprecedented features, the most unique one of which is the ability of monitoring variations of the physical and chemical parameters with spatial continuity along the fiber. Among all these distributed sensing techniques, optical frequency domain reflectometry (OFDR) has been given tremendous attention because of its high spatial resolution and large dynamic range. In addition, DOFS based on OFDR have been used to sense many parameters. In this review, we will survey the key technologies for improving sensing range, spatial resolution and sensing performance in DOFS based on OFDR. We also introduce the sensing mechanisms and the applications of DOFS based on OFDR including strain, stress, vibration, temperature, 3D shape, flow, refractive index, magnetic field, radiation, gas and so on. PMID:29614024

Characterization of a Fiber-Coupled 36-Core 3-Mode Photonic Lantern Spatial Multiplexer

DEFF Research Database (Denmark)

Rommel, Simon; Mendinueta, José Manuel Delgado; Klaus, Werner

2017-01-01

A fiber-coupled 108-port photonic lantern spatial-MUX is characterized with a spatially-diverse optical vector network analyzer. Insertion loss, mode-dependent losses, and time response are measured, showing significant mode mixing at a fiber splice.......A fiber-coupled 108-port photonic lantern spatial-MUX is characterized with a spatially-diverse optical vector network analyzer. Insertion loss, mode-dependent losses, and time response are measured, showing significant mode mixing at a fiber splice....

Intelligent Optical Systems Using Adaptive Optics

Science.gov (United States)

Clark, Natalie

2012-01-01

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

MATCHING ALTERNATIVE ADDRESSES: A SEMANTIC WEB APPROACH

Directory of Open Access Journals (Sweden)

S. Ariannamazi

2015-12-01

Full Text Available Rapid development of crowd-sourcing or volunteered geographic information (VGI provides opportunities for authoritatives that deal with geospatial information. Heterogeneity of multiple data sources and inconsistency of data types is a key characteristics of VGI datasets. The expansion of cities resulted in the growing number of POIs in the OpenStreetMap, a well-known VGI source, which causes the datasets to outdate in short periods of time. These changes made to spatial and aspatial attributes of features such as names and addresses might cause confusion or ambiguity in the processes that require feature’s literal information like addressing and geocoding. VGI sources neither will conform specific vocabularies nor will remain in a specific schema for a long period of time. As a result, the integration of VGI sources is crucial and inevitable in order to avoid duplication and the waste of resources. Information integration can be used to match features and qualify different annotation alternatives for disambiguation. This study enhances the search capabilities of geospatial tools with applications able to understand user terminology to pursuit an efficient way for finding desired results. Semantic web is a capable tool for developing technologies that deal with lexical and numerical calculations and estimations. There are a vast amount of literal-spatial data representing the capability of linguistic information in knowledge modeling, but these resources need to be harmonized based on Semantic Web standards. The process of making addresses homogenous generates a helpful tool based on spatial data integration and lexical annotation matching and disambiguating.

Spatiotemporal optical solitons

International Nuclear Information System (INIS)

Malomed, Boris A; Mihalache, Dumitru; Wise, Frank; Torner, Lluis

2005-01-01

In the course of the past several years, a new level of understanding has been achieved about conditions for the existence, stability, and generation of spatiotemporal optical solitons, which are nondiffracting and nondispersing wavepackets propagating in nonlinear optical media. Experimentally, effectively two-dimensional (2D) spatiotemporal solitons that overcome diffraction in one transverse spatial dimension have been created in quadratic nonlinear media. With regard to the theory, fundamentally new features of light pulses that self-trap in one or two transverse spatial dimensions and do not spread out in time, when propagating in various optical media, were thoroughly investigated in models with various nonlinearities. Stable vorticity-carrying spatiotemporal solitons have been predicted too, in media with competing nonlinearities (quadratic-cubic or cubic-quintic). This article offers an up-to-date survey of experimental and theoretical results in this field. Both achievements and outstanding difficulties are reviewed, and open problems are highlighted. Also briefly described are recent predictions for stable 2D and 3D solitons in Bose-Einstein condensates supported by full or low-dimensional optical lattices. (review article)

Diffractive beam shaping, tracking and coupling for wave-guided optical waveguides (WOWs)

DEFF Research Database (Denmark)

Villangca, Mark Jayson; Bañas, Andrew Rafael; Aabo, Thomas

2014-01-01

techniques to create multiple focal spots that can be coupled into light manipulated WOWs. This is done by using a spatial light modulator to project the necessary phase to generate the multiple coupling light spots. We incorporate a diffractive setup in our Biophotonics Workstation (BWS) and demonstrate......We have previously proposed and demonstrated the targeted-light delivery capability of wave-guided optical waveguides (WOWs). The full strength of this structure-mediated paradigm can be harnessed by addressing multiple WOWs and manipulating them to work in tandem. We propose the use of diffractive...

Dynamically tunable optical bottles from an optical fiber

DEFF Research Database (Denmark)

Chen, Yuhao; Yan, Lu; Rishøj, Lars Søgaard

2012-01-01

Optical fibers have long been used to impose spatial coherence to shape free-space optical beams. Recent work has shown that one can use higher order fiber modes to create more exotic beam profiles. We experimentally generate optical bottles from Talbot imaging in the coherent superposition of two...... fiber modes excited with long period gratings, and obtain a 28 μm × 6 μm bottle with controlled contrast up to 10.13 dB. Our geometry allows for phase tuning of one mode with respect to the other, which enables us to dynamically move the bottle in free space....

Near infrared spatial frequency domain fluorescence imaging of tumor phantoms containing erythrocyte-derived optical nanoplatforms

Science.gov (United States)

Burns, Joshua M.; Schaefer, Elise; Anvari, Bahman

2018-02-01

Light-activated theranostic constructs provide a multi-functional platform for optical imaging and phototherapeutic applications. Our group has engineered nano-sized vesicles derived from erythrocytes that encapsulate the FDAapproved near infrared (NIR) absorber indocyanine green (ICG). We refer to these constructs as NIR erythrocytemimicking transducers (NETs). Once photo-excited by NIR light these constructs can transduce the photons energy to emit fluorescence, generate heat, or induce chemical reactions. In this study, we investigated fluorescence imaging of NETs embedded within tumor phantoms using spatial frequency domain imaging (SFDI). Using SFDI, we were able to fluorescently image simulated tumors doped with different concentration of NETs. These preliminary results suggest that NETs can be used in conjunction with SFDI for potential tumor imaging applications.

Matter-wave solitons and finite-amplitude Bloch waves in optical lattices with spatially modulated nonlinearity

Science.gov (United States)

Zhang, Jie-Fang; Li, Yi-Shen; Meng, Jianping; Wu, Lei; Malomed, Boris A.

2010-09-01

We investigate solitons and nonlinear Bloch waves in Bose-Einstein condensates trapped in optical lattices (OLs). By introducing specially designed localized profiles of the spatial modulation of the attractive nonlinearity, we construct an infinite set of exact soliton solutions in terms of Mathieu and elliptic functions, with the chemical potential belonging to the semi-infinite gap of the OL-induced spectrum. Starting from the particular exact solutions, we employ the relaxation method to construct generic families of soliton solutions in a numerical form. The stability of the solitons is investigated through the computation of the eigenvalues for small perturbations, and also by direct simulations. Finally, we demonstrate a virtually exact (in the numerical sense) composition relation between nonlinear Bloch waves and solitons.

Matter-wave solitons and finite-amplitude Bloch waves in optical lattices with spatially modulated nonlinearity

International Nuclear Information System (INIS)

Zhang Jiefang; Meng Jianping; Wu Lei; Li Yishen; Malomed, Boris A.

2010-01-01

We investigate solitons and nonlinear Bloch waves in Bose-Einstein condensates trapped in optical lattices (OLs). By introducing specially designed localized profiles of the spatial modulation of the attractive nonlinearity, we construct an infinite set of exact soliton solutions in terms of Mathieu and elliptic functions, with the chemical potential belonging to the semi-infinite gap of the OL-induced spectrum. Starting from the particular exact solutions, we employ the relaxation method to construct generic families of soliton solutions in a numerical form. The stability of the solitons is investigated through the computation of the eigenvalues for small perturbations, and also by direct simulations. Finally, we demonstrate a virtually exact (in the numerical sense) composition relation between nonlinear Bloch waves and solitons.

Spatial Preference Modelling for equitable infrastructure provision: an application of Sen's Capability Approach

Science.gov (United States)

Wismadi, Arif; Zuidgeest, Mark; Brussel, Mark; van Maarseveen, Martin

2014-01-01

To determine whether the inclusion of spatial neighbourhood comparison factors in Preference Modelling allows spatial decision support systems (SDSSs) to better address spatial equity, we introduce Spatial Preference Modelling (SPM). To evaluate the effectiveness of this model in addressing equity, various standardisation functions in both Non-Spatial Preference Modelling and SPM are compared. The evaluation involves applying the model to a resource location-allocation problem for transport infrastructure in the Special Province of Yogyakarta in Indonesia. We apply Amartya Sen's Capability Approach to define opportunity to mobility as a non-income indicator. Using the extended Moran's I interpretation for spatial equity, we evaluate the distribution output regarding, first, `the spatial distribution patterns of priority targeting for allocation' (SPT) and, second, `the effect of new distribution patterns after location-allocation' (ELA). The Moran's I index of the initial map and its comparison with six patterns for SPT as well as ELA consistently indicates that the SPM is more effective for addressing spatial equity. We conclude that the inclusion of spatial neighbourhood comparison factors in Preference Modelling improves the capability of SDSS to address spatial equity. This study thus proposes a new formal method for SDSS with specific attention on resource location-allocation to address spatial equity.

A multi-scale spatial approach to address environmental effects of small hydropower development.

Science.gov (United States)

McManamay, Ryan A; Samu, Nicole; Kao, Shih-Chieh; Bevelhimer, Mark S; Hetrick, Shelaine C

2015-01-01

Hydropower development continues to grow worldwide in developed and developing countries. While the ecological and physical responses to dam construction have been well documented, translating this information into planning for hydropower development is extremely difficult. Very few studies have conducted environmental assessments to guide site-specific or widespread hydropower development. Herein, we propose a spatial approach for estimating environmental effects of hydropower development at multiple scales, as opposed to individual site-by-site assessments (e.g., environmental impact assessment). Because the complex, process-driven effects of future hydropower development may be uncertain or, at best, limited by available information, we invested considerable effort in describing novel approaches to represent environmental concerns using spatial data and in developing the spatial footprint of hydropower infrastructure. We then use two case studies in the US, one at the scale of the conterminous US and another within two adjoining rivers basins, to examine how environmental concerns can be identified and related to areas of varying energy capacity. We use combinations of reserve-design planning and multi-metric ranking to visualize tradeoffs among environmental concerns and potential energy capacity. Spatial frameworks, like the one presented, are not meant to replace more in-depth environmental assessments, but to identify information gaps and measure the sustainability of multi-development scenarios as to inform policy decisions at the basin or national level. Most importantly, the approach should foster discussions among environmental scientists and stakeholders regarding solutions to optimize energy development and environmental sustainability.

Diffractive optical elements for transformation of modes in lasers

Science.gov (United States)

Sridharan, Arun K.; Pax, Paul H.; Heebner, John E.; Drachenberg, Derrek R.; Armstrong, James P.; Dawson, Jay W.

2015-09-01

Spatial mode conversion modules are described, with the capability of efficiently transforming a given optical beam profile, at one plane in space into another well-defined optical beam profile at a different plane in space, whose detailed spatial features and symmetry properties can, in general, differ significantly. The modules are comprised of passive, high-efficiency, low-loss diffractive optical elements, combined with Fourier transform optics. Design rules are described that employ phase retrieval techniques and associated algorithms to determine the necessary profiles of the diffractive optical components. System augmentations are described that utilize real-time adaptive optical techniques for enhanced performance as well as power scaling.

Spatial mode discrimination using second harmonic generation

DEFF Research Database (Denmark)

Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David

2007-01-01

Second harmonic generation can be used as a technique for controlling the spatial mode structure of optical beams. We demonstrate experimentally the generation of higher order spatial modes, and that it is possible to use nonlinear phase matching as a predictable and robust technique for the conv...

A study on the optimization of optical guide of gamma camera detector

International Nuclear Information System (INIS)

Chung, Yong Hyun; Cho, Gyu Seong; Kim, Ho Kyung; Lee, Wan No; Kim, Young Soo

2000-01-01

An optical guide, which is a light guide located between NaI(Tl) scintillation-crystal and array of photo-multiplier tubes (PMTs) in the gamma camera detector system, is an essential component to deliver the spatial information recorded in scintillator to the PMTs. Without the optical guide, the spatial information within the range of a single PMT could not be obtained. For the design of the optimal optical guide, it is necessary to characterize its properties, especially sensitivity and spatial resolution of detector. In this study, the thickness and the refractive index of optical guide, which affect not only on the sensitivity but also on the spatial resolution of gamma-camera detector, were investigated by using Monte Carlo simulation. A 12'x12'x3/8' NaI(Tl) and 23 PMTs with each 5' diameter were considered as a gamma-camera detector components. Interactions of optical photons in the scintillator and the optical guide were simulated using a commercial code DETECT97, and the spatial resolution, mainly interfered by the intrinsic inward distortion within the PMT, was investigated using our own ANGER program, which was developed to calculate positions of incident photons in the gamma camera. From the simulation results, it was found that an optical guide with 1.6 of refractive index and 10 mm of thickness give maximum sensitivity and minimum spatial distortion, respectively

Using an Optimized Chinese Address Matching Method to Develop a Geocoding Service: A Case Study of Shenzhen, China

Directory of Open Access Journals (Sweden)

Qin Tian

2016-05-01

Full Text Available With the coming era of big data and the rapid development and widespread applications of Geographical Information Systems (GISs, geocoding technology is playing an increasingly important role in bridging the gap between non-spatial data resources and spatial data in various fields. However, Chinese geocoding faces great challenges because of the complexity of the address string format in Chinese, which contains no delimiters between Chinese words, and the poor address management resulting from the existence of multiple address authorities spread among different governmental agencies. This paper presents a geocoding service based on an optimized Chinese address matching method, including address modeling, address standardization and address matching. The address model focuses on the spatial semantics of each address element, and the address standardization process is based on an address tree model. A geocoding service application is implemented in practice using a large quantity of data from Shenzhen Municipality. More than 1,460,000 data records were used to test the geocoding service, and good matching rates were achieved with good adaptability and intelligence.

Determination of the spatial resolution of an aperture-type near-field scanning optical microscope using a standard sample of a quantum-dot-embedded polymer film

International Nuclear Information System (INIS)

Kim, J. Y.; Kim, D. C.; Nakajima, K.; Mitsui, T.; Aoki, H.

2010-01-01

The near-field scanning optical microscope (NSOM) is a form of scanning probe microscope that achieves, through the use of the near-field, a spatial resolution significantly superior to that defined by the Abbe diffraction limit. Although the term spatial resolution has a clear meaning, it is often used in different ways in characterizing the NSOM instrument. In this paper, we describe the concept, the cautions, and the general guidelines of a method to measure the spatial resolution of an aperture-type NSOM instrument. As an example, a quantum dot embedded polymer film was prepared and imaged as a test sample, and the determination of the lateral resolution was demonstrated using the described method.

Spatial frequency domain spectroscopy of two layer media

Science.gov (United States)

Yudovsky, Dmitry; Durkin, Anthony J.

2011-10-01

Monitoring of tissue blood volume and oxygen saturation using biomedical optics techniques has the potential to inform the assessment of tissue health, healing, and dysfunction. These quantities are typically estimated from the contribution of oxyhemoglobin and deoxyhemoglobin to the absorption spectrum of the dermis. However, estimation of blood related absorption in superficial tissue such as the skin can be confounded by the strong absorption of melanin in the epidermis. Furthermore, epidermal thickness and pigmentation varies with anatomic location, race, gender, and degree of disease progression. This study describes a technique for decoupling the effect of melanin absorption in the epidermis from blood absorption in the dermis for a large range of skin types and thicknesses. An artificial neural network was used to map input optical properties to spatial frequency domain diffuse reflectance of two layer media. Then, iterative fitting was used to determine the optical properties from simulated spatial frequency domain diffuse reflectance. Additionally, an artificial neural network was trained to directly map spatial frequency domain reflectance to sets of optical properties of a two layer medium, thus bypassing the need for iteration. In both cases, the optical thickness of the epidermis and absorption and reduced scattering coefficients of the dermis were determined independently. The accuracy and efficiency of the iterative fitting approach was compared with the direct neural network inversion.

Theory and optical design of x-ray echo spectrometers

Science.gov (United States)

Shvyd'ko, Yuri

2017-08-01

X-ray echo spectroscopy, a space-domain counterpart of neutron spin echo, is a recently proposed inelastic x-ray scattering (IXS) technique. X-ray echo spectroscopy relies on imaging IXS spectra and does not require x-ray monochromatization. Due to this, the echo-type IXS spectrometers are broadband, and thus have a potential to simultaneously provide dramatically increased signal strength, reduced measurement times, and higher resolution compared to the traditional narrow-band scanning-type IXS spectrometers. The theory of x-ray echo spectrometers presented earlier [Yu. Shvyd'ko, Phys. Rev. Lett. 116, 080801 (2016), 10.1103/PhysRevLett.116.080801] is developed here further with a focus on questions of practical importance, which could facilitate optical design and assessment of the feasibility and performance of the echo spectrometers. Among others, the following questions are addressed: spectral resolution, refocusing condition, echo spectrometer tolerances, refocusing condition adjustment, effective beam size on the sample, spectral window of imaging and scanning range, impact of the secondary source size on the spectral resolution, angular dispersive optics, focusing and collimating optics, and detector's spatial resolution. Examples of optical designs and characteristics of echo spectrometers with 1-meV and 0.1-meV resolutions are presented.

Fourier synthesis of asymmetrical optical potentials for atoms

International Nuclear Information System (INIS)

Ritt, G.

2007-01-01

In this work a dissipationless asymmetrical optical potential for cold atoms was produced. In a first step a new type of optical lattice was generated, whose spatial periodicity only corresponds to a quarter of the wavelength of the light used for the generation. This corresponds to the half of the periodicity of a conventional optical lattice, which is formed by the light of the same wavelength. The generation of this new type of optical lattice was reached by the use of two degenerated raman transitions. Virtual processes occur, in which four photons are involved. In conventional optical lattices however virtual two-photon processes occur. By spatially superimposing this optical lattice with a conventional optical lattice an asymmetrical optical potential could be formed. By diffraction of a Bose Einstein condensate of rubidium atoms at the transient activated asymmetrical potential the asymmetrical structure was proven. (orig.)

Hybrid content addressable memory MSD arithmetic

Science.gov (United States)

Li, Yao; Kim, Dai Hyun; Kostrzewski, Andrew A.; Eichmann, George

1990-07-01

The modified signed-digit (MSD) number system, because of its inherent weak interdigit dependance, has been suggested as a useful means for a fast and parallel digital arithmetic. To maintain a fast processing speed, a single-stage holographic optical content-addressable memory (CAM) based MSD algorithm was suggested. In this paper, a novel non-holographic opto-electronic CAM based fast MSD addition processing architecture is proposed. The proposed concept has been verified with our first-order proof-of-principle experiments. A figure of merit comparison of this and other existing approaches is also presented. Based on this key opto-electronic CAM element, implementation of more sophisticated I'VISD arithmetic, such as optical MSD subtraction and multiplication operations, are proposed.

Spiral intensity patterns in the internally pumped optical parametric oscillator

DEFF Research Database (Denmark)

Lodahl, Peter; Bache, Morten; Saffman, Mark

2001-01-01

We describe a nonlinear optical system that supports spiral pattern solutions in the field intensity. This new spatial structure is found to bifurcate above a secondary instability in the internally pumped optical parametric oscillator. The analytical predictions of threshold and spatial scale...

Ultrafast Single-Shot Optical Oscilloscope based on Time-to-Space Conversion due to Temporal and Spatial Walk-Off Effects in Nonlinear Mixing Crystal

Science.gov (United States)

Takagi, Yoshihiro; Yamada, Yoshifumi; Ishikawa, Kiyoshi; Shimizu, Seiji; Sakabe, Shuji

2005-09-01

A simple method for single-shot sub-picosecond optical pulse diagnostics has been demonstrated by imaging the time evolution of the optical mixing onto the beam cross section of the sum-frequency wave when the interrogating pulse passes over the tested pulse in the mixing crystal as a result of the combined effect of group-velocity difference and walk-off beam propagation. A high linearity of the time-to-space projection is deduced from the process solely dependent upon the spatial uniformity of the refractive indices. A snap profile of the accidental coincidence between asynchronous pulses from separate mode-locked lasers has been detected, which demonstrates the single-shot ability.

Nano-optical conveyor belt, part I: Theory.

Science.gov (United States)

Hansen, Paul; Zheng, Yuxin; Ryan, Jason; Hesselink, Lambertus

2014-06-11

We propose a method for peristaltic transport of nanoparticles using the optical force field over a nanostructured surface. Nanostructures may be designed to produce strong near-field hot spots when illuminated. The hot spots function as optical traps, separately addressable by their resonant wavelengths and polarizations. By activating closely packed traps sequentially, nanoparticles may be handed off between adjacent traps in a peristaltic fashion. A linear repeating structure of three separately addressable traps forms a "nano-optical conveyor belt"; a unit cell with four separately addressable traps permits controlled peristaltic transport in the plane. Using specifically designed activation sequences allows particle sorting.

Measuring heart rate with optical sensor

NARCIS (Netherlands)

Barachi, M. (Mitra)

2014-01-01

The problem addressed in this report is to verify the possibility of using an optical sensor in the SaxShirt in order to extract the heart rate. There are specifically three questions that we try to address. 1) How is it possible to extract heart rate (BPM) from the optical sensor? 2) Is it

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

Science.gov (United States)

Liu, Zhuolin

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

Accuracies Of Optical Processors For Adaptive Optics

Science.gov (United States)

Downie, John D.; Goodman, Joseph W.

1992-01-01

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

Noise Characterization of Devices for Optical Computing

National Research Council Canada - National Science Library

Walkup, John

1998-01-01

The major objective of the research effort is to investigate the noise characteristics of advanced optical Sources, spatial light modulators, and other devices which are candidates for applications in optical computers...

Femtosecond Nanofocusing with Full Optical Waveform Control

International Nuclear Information System (INIS)

Berweger, Samuel; Atkin, Joanna M.; Xu, Xiaoji G.; Olmon, Robert L.; Raschke, Markus Bernd

2011-01-01

The simultaneous nanometer spatial confinement and femtosecond temporal control of an optical excitation has been a long-standing challenge in optics. Previous approaches using surface plasmon polariton (SPP) resonant nanostructures or SPP waveguides have suffered from, for example, mode mismatch, or possible dependence on the phase of the driving laser field to achieve spatial localization. Here we take advantage of the intrinsic phase- and amplitude-independent nanofocusing ability of a conical noble metal tip with weak wavelength dependence over a broad bandwidth to achieve a 10 nm spatially and few-femtosecond temporally confined excitation. In combination with spectral pulse shaping and feedback on the second-harmonic response of the tip apex, we demonstrate deterministic arbitrary optical waveform control. In addition, the high efficiency of the nanofocusing tip provided by the continuous micro- to nanoscale mode transformation opens the door for spectroscopy of elementary optical excitations in matter on their natural length and time scales and enables applications from ultrafast nano-opto-electronics to single molecule quantum coherent control.

Illusions in the spatial sense of the eye: geometrical-optical illusions and the neural representation of space.

Science.gov (United States)

Westheimer, Gerald

2008-09-01

Differences between the geometrical properties of simple configurations and their visual percept are called geometrical-optical illusions. They can be differentiated from illusions in the brightness or color domains, from ambiguous figures and impossible objects, from trompe l'oeil and perspective drawing with perfectly valid views, and from illusory contours. They were discovered independently by several scientists in a short time span in the 1850's. The clear distinction between object and visual space that they imply allows the question to be raised whether the transformation between the two spaces can be productively investigated in terms of differential geometry and metrical properties. Perceptual insight and psychophysical research prepares the ground for investigation of the neural representation of space but, because visual attributes are processed separately in parallel, one looks in vain for a neural map that is isomorphic with object space or even with individual forms it contains. Geometrical-optical illusions help reveal parsing rules for sensory signals by showing how conflicts are resolved when there is mismatch in the output of the processing modules for various primitives as a perceptual pattern's unitary structure is assembled. They point to a hierarchical ordering of spatial primitives: cardinal directions and explicit contours predominate over oblique orientation and implicit contours (Poggendorff illusion); rectilinearity yields to continuity (Hering illusion), point position and line length to contour orientation (Ponzo). Hence the geometrical-optical illusions show promise as analytical tools in unraveling neural processing in vision.

A precategorical spatial-data metamodel

OpenAIRE

Steven A Roberts; G Brent Hall; Paul H Calamai

2006-01-01

Increasing recognition of the extent and speed of habitat fragmentation and loss, particularly in the urban fringe, is driving the need to analyze qualitatively and quantitatively regional landscape structure for decision support in land-use planning and environmental-policy implementation. The spatial analysis required in this area is not well served by existing spatial-data models. In this paper a new theoretical spatial-data metamodel is introduced as a tool for addressing such needs and a...

Experimental study of coherence vortices: Local properties of phase singularities in a spatial coherence function

DEFF Research Database (Denmark)

Wang, W.; Duan, Z.H.; Hanson, Steen Grüner

2006-01-01

By controlling the irradiance of an extended quasimonochromatic, spatially incoherent source, an optical field is generated that exhibits spatial coherence with phase singularities, called coherence vortices. A simple optical geometry for direct visualization of coherence vortices is proposed, an...

An investigation of the potential of optical computed tomography for imaging of synchrotron-generated x-rays at high spatial resolution

International Nuclear Information System (INIS)

Doran, Simon J; Brochard, Thierry; Braeuer-Krisch, Elke; Adamovics, John; Krstajic, Nikola

2010-01-01

X-ray microbeam radiation therapy (MRT) is a novel form of treatment, currently in its preclinical stage, which uses microplanar x-ray beams from a synchrotron radiation source. It is important to perform accurate dosimetry on these microbeams, but, to date, there has been no accurate enough method available for making 3D dose measurements with isotropic, high spatial resolution to verify the results of Monte Carlo dose simulations. Here, we investigate the potential of optical computed tomography for satisfying these requirements. The construction of a simple optical CT microscopy (optical projection tomography) system from standard commercially available hardware is described. The measurement of optical densities in projection data is shown to be highly linear (r 2 = 0.999). The depth-of-field (DOF) of the imaging system is calculated based on the previous literature and measured experimentally using a commercial DOF target. It is shown that high quality images can be acquired despite the evident lack of telecentricity and despite DOF of the system being much lower than the sample diameter. Possible reasons for this are discussed. Results are presented for a complex irradiation of a 22 mm diameter cylinder of the radiochromic polymer PRESAGE(TM), demonstrating the exquisite 'dose-painting' abilities available in the MRT hutch of beamline ID-17 at the European Synchrotron Radiation Facility. Dose distributions in this initial experiment are equally well resolved on both an optical CT scan and a corresponding transmission image of radiochromic film, down to a line width of 83 μm (6 lp mm -1 ) with an MTF value of 0.40. A group of 33 μm wide lines was poorly resolved on both the optical CT and film images, and this is attributed to an incorrect exposure time calculation, leading to under-delivery of dose. Image artefacts in the optical CT scan are discussed. PRESAGE(TM) irradiated using the microbeam facility is proposed as a suitable material for producing

Some aspects of optical spatial solitons in photorefractive media and ...

Indian Academy of Sciences (India)

medium thereby creating an optical waveguide which subsequently guides the beam. Pramana .... Exposure of a photorefractive (PR) material with optical field of non-uniform intensity leads to ...... This work is supported by SAP programme of the University Grants Commission. (UGC) ... Press, San Diego, California, 2003).

Spatial Interpolation of Aerosol Optical Depth Pollution: Comparison of Methods for the Development of Aerosol Distribution

Science.gov (United States)

Safarpour, S.; Abdullah, K.; Lim, H. S.; Dadras, M.

2017-09-01

Air pollution is a growing problem arising from domestic heating, high density of vehicle traffic, electricity production, and expanding commercial and industrial activities, all increasing in parallel with urban population. Monitoring and forecasting of air quality parameters are important due to health impact. One widely available metric of aerosol abundance is the aerosol optical depth (AOD). The AOD is the integrated light extinction coefficient over a vertical atmospheric column of unit cross section, which represents the extent to which the aerosols in that vertical profile prevent the transmission of light by absorption or scattering. Seasonal aerosol optical depth (AOD) values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's Terra satellites, for the 10 years period of 2000 - 2010 were used to test 7 different spatial interpolation methods in the present study. The accuracy of estimations was assessed through visual analysis as well as independent validation based on basic statistics, such as root mean square error (RMSE) and correlation coefficient. Based on the RMSE and R values of predictions made using measured values from 2000 to 2010, Radial Basis Functions (RBFs) yielded the best results for spring, summer and winter and ordinary kriging yielded the best results for fall.

SPATIAL INTERPOLATION OF AEROSOL OPTICAL DEPTH POLLUTION: COMPARISON OF METHODS FOR THE DEVELOPMENT OF AEROSOL DISTRIBUTION

Directory of Open Access Journals (Sweden)

S. Safarpour

2017-09-01

Full Text Available Air pollution is a growing problem arising from domestic heating, high density of vehicle traffic, electricity production, and expanding commercial and industrial activities, all increasing in parallel with urban population. Monitoring and forecasting of air quality parameters are important due to health impact. One widely available metric of aerosol abundance is the aerosol optical depth (AOD. The AOD is the integrated light extinction coefficient over a vertical atmospheric column of unit cross section, which represents the extent to which the aerosols in that vertical profile prevent the transmission of light by absorption or scattering. Seasonal aerosol optical depth (AOD values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS sensor onboard NASA’s Terra satellites, for the 10 years period of 2000 - 2010 were used to test 7 different spatial interpolation methods in the present study. The accuracy of estimations was assessed through visual analysis as well as independent validation based on basic statistics, such as root mean square error (RMSE and correlation coefficient. Based on the RMSE and R values of predictions made using measured values from 2000 to 2010, Radial Basis Functions (RBFs yielded the best results for spring, summer and winter and ordinary kriging yielded the best results for fall.

Photon propagation in heterogeneous optical media with spatial correlations: enhanced mean-free-paths and wider-than-exponential free-path distributions

International Nuclear Information System (INIS)

Davis, A.B.; Marshak, Alexander

2004-01-01

Beer's law of exponential decay in direct transmission is well-known but its break-down in spatially variable optical media has been discussed only sporadically in the literature. We document here this break-down in three-dimensional (3D) media with complete generality and explore its ramifications for photon propagation. We show that effective transmission laws and their associated free-path distributions (FPDs) are in fact never exactly exponential in variable media of any kind. Moreover, if spatial correlations in the extinction field extend at least to the scale of the mean-free-path (MFP), FPDs are necessarily wider-than-exponential in the sense that all higher-order moments of the relevant mean-field FPDs exceed those of the exponential FPD, even if it is tuned to yield the proper MFP. The MFP itself is always larger than the inverse of average extinction in a variable medium. In a vast and important class of spatially-correlated random media, the MFP is indeed the average of the inverse of extinction. We translate these theoretical findings into a practical method for deciding a priori when 3D effects become important. Finally, we discuss an obvious but limited analogy between our analysis of spatial variability and the well-known effects of strong spectral variability in gaseous media when observed or modeled at moderate resolution

Optical design of Kirkpatrick-Baez microscope for ICF

International Nuclear Information System (INIS)

Mu Baozhong; Yi Shengzhen; Huang Shengling; Wang Zhanshan

2008-01-01

A new flux-resolution optical design method of Kirkpatrick-Baez microscope (KB microscope) is proposed. In X-ray imaging diagnostics of inertial confinement fusion(ICF), spatial resolution and flux are always the key parameters. While the traditional optical design of KB microscope is to correct on-axis spherical aberration and astigmatic aberration, flux-resolution method is based on lateral aberration of full field and astigmatic aberration. Thus the spatial resolution related to field dimension and light flux can be estimated. By the expressions of spatial resolution and actual limits in ICF, rules of how to set original structure and optical design flow are summarized. An instance is presented and it shows that the design has met the original targets and overcome the shortcomings of image characterization in compressed core by traditional spherical aberration correction. (authors)

Heterodyne spatial interferometry of circumstellar dust shells at a wavelength of 11 microns

International Nuclear Information System (INIS)

Sutton, E.C.

1979-01-01

The spatial distribution of the 11 micron thermal emission from circumstellar dust envelopes has been studied using an infrared heterodyne interferometer. Circumstellar dust envelopes often exist around cool, late-type stars. These envelopes radiate strongly at 11 microns, particularly if they are composed of silicate grains, which have a strong emission feature near this wavelength. By measuring the spatial distribution of this dust emission it is possible to probe the temperatures and densities of the circumstellar material and thereby to gain an understanding of the structures of circumstellar envelopes. Among the sources which have been observed with this interferometer are α Orionis, o Ceti, VY Canis Majoris, and IRC + 10216. The 11 micron brightness distributions of these objects all have spatially extended dust-emission components which are resolved in these measurements. The dust envelopes of α Orionis and o Ceti are optically thin, having optical depths at 11 microns of 0.02 and 0.04, respectively. In addition, variations are seen in the 11 micron brightness distribution of o Ceti which correlate with the stellar variability. These variations primarily represent changes in the relative amount of spatially compact photospheric emission and spatially extended dust emission. The source VY Canis Majoris, on the other had, has a dust envelope which is optically thick at 11 microns. The dust envelope of IRC + 10216, although optically thick at visible wavelengths, does not seem to be optically thick at 11 microns since there is a spatially compact component of the 11 micron brightness distribution which presumably represents emission from the central star

Investigation of the thermal and optical performance of a spatial light modulator with high average power picosecond laser exposure for materials processing applications

Science.gov (United States)

Zhu, G.; Whitehead, D.; Perrie, W.; Allegre, O. J.; Olle, V.; Li, Q.; Tang, Y.; Dawson, K.; Jin, Y.; Edwardson, S. P.; Li, L.; Dearden, G.

2018-03-01

Spatial light modulators (SLMs) addressed with computer generated holograms (CGHs) can create structured light fields on demand when an incident laser beam is diffracted by a phase CGH. The power handling limitations of these devices based on a liquid crystal layer has always been of some concern. With careful engineering of chip thermal management, we report the detailed optical phase and temperature response of a liquid cooled SLM exposed to picosecond laser powers up to 〈P〉  =  220 W at 1064 nm. This information is critical for determining device performance at high laser powers. SLM chip temperature rose linearly with incident laser exposure, increasing by only 5 °C at 〈P〉  =  220 W incident power, measured with a thermal imaging camera. Thermal response time with continuous exposure was 1-2 s. The optical phase response with incident power approaches 2π radians with average power up to 〈P〉  =  130 W, hence the operational limit, while above this power, liquid crystal thickness variations limit phase response to just over π radians. Modelling of the thermal and phase response with exposure is also presented, supporting experimental observations well. These remarkable performance characteristics show that liquid crystal based SLM technology is highly robust when efficiently cooled. High speed, multi-beam plasmonic surface micro-structuring at a rate R  =  8 cm2 s-1 is achieved on polished metal surfaces at 〈P〉  =  25 W exposure while diffractive, multi-beam surface ablation with average power 〈P〉  =100 W on stainless steel is demonstrated with ablation rate of ~4 mm3 min-1. However, above 130 W, first order diffraction efficiency drops significantly in accord with the observed operational limit. Continuous exposure for a period of 45 min at a laser power of 〈P〉  =  160 W did not result in any detectable drop in diffraction efficiency, confirmed afterwards by the efficient

Investigation of local thermodynamic equilibrium of laser induced Al2O3–TiC plasma in argon by spatially resolved optical emission spectroscopy

Directory of Open Access Journals (Sweden)

K. Alnama

2016-06-01

Full Text Available Plasma plume of Al2O3–TiC is generated by third harmonic Q-switched Nd:YAG nanosecond laser. It is characterized using Optical Emission Spectroscopy (OES at different argon background gas pressures 10, 102, 103, 104 and 105 Pa. Spatial evolution of excitation and ionic temperatures is deduced from spectral data analysis. Temporal evolution of Ti I emission originated from different energy states is probed. The correlation between the temporal behavior and the spatial temperature evolution are investigated under LTE condition for the possibility to use the temporal profile of Ti I emission as an indicator for LTE validity in the plasma.

Spatial cognitive rehabilitation and motor recovery after stroke

Science.gov (United States)

Barrett, A.M.; Muzaffar, Tufail

2014-01-01

Purpose of review Stroke rehabilitation needs to take major steps forward to reduce functional disability for survivors. In this article, we suggest that spatial retraining might greatly increase the efficiency and efficacy of motor rehabilitation, directly addressing the burden and cost of paralysis after stroke. Recent findings Combining motor and cognitive treatment may be practical, as well as addressing needs after moderate–to-severe stroke. Spatial neglect could suppress motor recovery and reduce motor learning, even when patients receive appropriate rehabilitation to build strength, dexterity, and endurance. Spatial neglect rehabilitation acts to promote motor as well as visual-perceptual recovery. These findings, and previous underemphasized studies, make a strong case for combining spatial neglect treatment with traditional exercise training. Spatial neglect therapies might also help people who cannot participate in intensive movement therapies because of limited strength and endurance after stroke. Summary Spatial retraining, currently used selectively after right brain stroke, may be broadly useful after stroke to promote rapid motor recovery. PMID:25364954

Optical see-through head-mounted display with occlusion capability

Science.gov (United States)

Gao, Chunyu; Lin, Yuxiang; Hua, Hong

2013-05-01

Lack of mutual occlusion capability between computer-rendered and real objects is one of fundamental problems for most existing optical see-through head-mounted displays (OST-HMD). Without the proper occlusion management, the virtual view through an OST-HMD appears "ghost-like", floating in the real world. To address this challenge, we have developed an innovative optical scheme that uniquely combines the eyepiece and see-through relay optics to achieve an occlusion-capable OST-HMD system with a very compelling form factor and high optical performances. The proposed display system was based on emerging freeform optical design technologies and was designed for highly efficient liquid crystal on silicon (LCoS) type spatial light modulator (SLM) and bright Organic LED (OLED) microdisplay. The proposed display technology was capable of working in both indoor and outdoor environments. Our current design offered a 1280x1024 color resolution based on 0.8" microdisplay and SLM. The MTF values for the majority of the fields at the cutoff frequency of 40lps/mm, which is determined by the pixel size of the microdisplay, are better than 15%. The design achieved a diagonal FOV of 40 degrees, 31.7 degrees horizontally and 25.6 degrees vertically, an exit pupil diameter of 8mm (non-vignetted), and an eye clearance of 18mm. The optics weights about 20 grams per eye. Our proposed occlusion capable OST-HMD system can easily find myriads of applications in various military and commercial sectors such as military training, gaming and entertainment.

Two-dimensional metamaterial optics

International Nuclear Information System (INIS)

Smolyaninov, I I

2010-01-01

While three-dimensional photonic metamaterials are difficult to fabricate, many new concepts and ideas in the metamaterial optics can be realized in two spatial dimensions using planar optics of surface plasmon polaritons. In this paper we review recent progress in this direction. Two-dimensional photonic crystals, hyperbolic metamaterials, and plasmonic focusing devices are demonstrated and used in novel microscopy and waveguiding schemes

Creating spatial organizations

NARCIS (Netherlands)

Lekanne Deprez, F.R.E.; Tissen, R.J.

2009-01-01

This paper addresses the spatial design of modern organizations in the context of a fundamental change which is currently taking place in the way companies view their organizations and the inherent performance expectations, requirements and results underlying these. This change involves a managerial

Simulation the spatial resolution of an X-ray imager based on zinc oxide nanowires in anodic aluminium oxide membrane by using MCNP and OPTICS Codes

Science.gov (United States)

Samarin, S. N.; Saramad, S.

2018-05-01

The spatial resolution of a detector is a very important parameter for x-ray imaging. A bulk scintillation detector because of spreading of light inside the scintillator does't have a good spatial resolution. The nanowire scintillators because of their wave guiding behavior can prevent the spreading of light and can improve the spatial resolution of traditional scintillation detectors. The zinc oxide (ZnO) scintillator nanowire, with its simple construction by electrochemical deposition in regular hexagonal structure of Aluminum oxide membrane has many advantages. The three dimensional absorption of X-ray energy in ZnO scintillator is simulated by a Monte Carlo transport code (MCNP). The transport, attenuation and scattering of the generated photons are simulated by a general-purpose scintillator light response simulation code (OPTICS). The results are compared with a previous publication which used a simulation code of the passage of particles through matter (Geant4). The results verify that this scintillator nanowire structure has a spatial resolution less than one micrometer.

Gradient-index optics fundamentals and applications

CERN Document Server

Gomez-Reino, Carlos; Bao, Carmen

2010-01-01

Gradient-Index (GRIN) optics provides a comprehensive and thorough treatment on fundamentals and applications of light propagation through inhomogeneous media. The book can be used both as a classroom text for students in physics and engineering and as a reference for specialists. A description of the phenomena, components and technology used in GRIN Optics are presented. The relationship to lenses, waveguides, optical connections, spatial solitons and vision is demonstrated. Applications of GRIN components and hybrid structures for optical connections, optical sensing and Talbot effect are analyzed.

Cost-Effective Brillouin Optical Time-Domain Analysis Sensor Using a Single Optical Source and Passive Optical Filtering

Directory of Open Access Journals (Sweden)

H. Iribas

2016-01-01

Full Text Available We present a simplified configuration for distributed Brillouin optical time-domain analysis sensors that aims to reduce the cost of the sensor by reducing the number of components required for the generation of the two optical waves involved in the sensing process. The technique is based on obtaining the pump and probe waves by passive optical filtering of the spectral components generated in a single optical source that is driven by a pulsed RF signal. The optical source is a compact laser with integrated electroabsorption modulator and the optical filters are based on fiber Bragg gratings. Proof-of-concept experiments demonstrate 1 m spatial resolution over a 20 km sensing fiber with a 0.9 MHz precision in the measurement of the Brillouin frequency shift, a performance similar to that of much more complex setups. Furthermore, we discuss the factors limiting the sensor performance, which are basically related to residual spectral components in the filtering process.

Optical computer switching network

Science.gov (United States)

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.

Initial results of the spatial distribution of rubber trees in Peninsular Malaysia using remotely sensed data for biomass estimate

International Nuclear Information System (INIS)

Shidiq, I P A; Ismail, M H; Kamarudin, N

2014-01-01

The preservation and sustainable management of forest and other land cover ecosystems such as rubber trees will help addressing two major recent issues: climate change and bio-resource energy. The rubber trees are dominantly distributed in the Negeri Sembilan and Kedah on the west coast side of Peninsular Malaysia. This study is aimed to analyse the spatial distribution and biomass of rubber trees in Peninsular Malaysia with special emphasis in Negeri Sembilan State. Geospatial data from remote sensors are used to tackle the time and labour consuming problem due to the large spatial coverage and the need of continuous temporal data. Remote sensing imagery used in this study is a Landsat 5 TM. The image from optical sensor was used to sense the rubber trees and further classified rubber tree by different age

Initial results of the spatial distribution of rubber trees in Peninsular Malaysia using remotely sensed data for biomass estimate

Science.gov (United States)

Shidiq, I. P. A.; Ismail, M. H.; Kamarudin, N.

2014-02-01

The preservation and sustainable management of forest and other land cover ecosystems such as rubber trees will help addressing two major recent issues: climate change and bio-resource energy. The rubber trees are dominantly distributed in the Negeri Sembilan and Kedah on the west coast side of Peninsular Malaysia. This study is aimed to analyse the spatial distribution and biomass of rubber trees in Peninsular Malaysia with special emphasis in Negeri Sembilan State. Geospatial data from remote sensors are used to tackle the time and labour consuming problem due to the large spatial coverage and the need of continuous temporal data. Remote sensing imagery used in this study is a Landsat 5 TM. The image from optical sensor was used to sense the rubber trees and further classified rubber tree by different age.

15x optical zoom and extreme optical image stabilisation: diffraction limited integral field spectroscopy with the Oxford SWIFT spectrograph

Science.gov (United States)

Tecza, Matthias; Thatte, Niranjan; Clarke, Fraser; Lynn, James; Freeman, David; Roberts, Jennifer; Dekany, Richard

2012-09-01

When commissioned in November 2008 at the Palomar 200 inch Hale Telescope, the Oxford SWIFT I and z band integral field spectrograph, fed by the adaptive optics system PALAO, provided a wide (3×) range of spatial resolutions: three plate scales of 235 mas, 160 mas, and 80 mas per spaxel over a contiguous field-of-view of 89×44 pixels. Depending on observing conditions and guide star brightness we can choose a seeing limited scale of 235 mas per spaxel, or 160 mas and 80 mas per spaxel for very bright guide star AO with substantial increase of enclosed energy. Over the last two years PALAO was upgraded to PALM-3000: an extreme, high-order adaptive optics system with two deformable mirrors with more than 3000 actuators, promising diffraction limited performance in SWIFT's wavelength range. In order to take advantage of this increased spatial resolution we upgraded SWIFT with new pre-optics allowing us to spatially Nyquist sample the diffraction limited PALM-3000 point spread function with 16 mas resolution, reducing the spaxel scale by another factor of 5×. We designed, manufactured, integrated and tested the new pre-optics in the first half of 2011 and commissioned it in December 2011. Here we present the opto-mechanical design and assembly of the new scale changing optics, as well as laboratory and on-sky commissioning results. In optimal observing conditions we achieve substantial Strehl ratios, delivering the near diffraction limited spatial resolution in the I and z bands.

Distributed strain measurement in perfluorinated polymer optical fibres using optical frequency domain reflectometry

International Nuclear Information System (INIS)

Liehr, Sascha; Wendt, Mario; Krebber, Katerina

2010-01-01

We present the latest advances in distributed strain measurement in perfluorinated polymer optical fibres (POFs) using backscatter techniques. Compared to previously introduced poly(methyl methacrylate) POFs, the measurement length can be extended to more than 500 m at improved spatial resolution of a few centimetres. It is shown that strain in a perfluorinated POF can be measured up to 100%. In parallel to these investigations, the incoherent optical frequency domain reflectometry (OFDR) technique is introduced to detect strained fibre sections and to measure distributed length change along the fibre with sub-millimetre resolution by applying a cross-correlation algorithm to the backscatter signal. The overall superior performance of the OFDR technique compared to the optical time domain reflectometry in terms of accuracy, dynamic range, spatial resolution and measurement speed is presented. The proposed sensor system is a promising technique for use in structural health monitoring applications where the precise detection of high strain is required

Two-photon interference : spatial aspects of two-photon entanglement, diffraction, and scattering

NARCIS (Netherlands)

Peeters, Wouter Herman

2010-01-01

This dissertation contains scientific research within the realm of quantum optics, which is a branch of physics. An experimental and theoretical study is made of two-photon interference phenomena in various optical systems. Spatially entangled photon pairs are produced via the nonlinear optical

Ex vivo investigation of tissue optical properties using an optical fibre sensor

OpenAIRE

Warncke, Dennis

2014-01-01

peer-reviewed Biomedical research has become a strong growing sector in recent years. Moreover the interdisciplinary background involves novel possibilities and measurement techniques. Light propagation in turbid media like human tissue is a central aspect to many medical and biomedical applications. This is a very complex process and depends on parameters, which are called optical properties. The spatial distribution of light is determined by those optical properties. A maj...

Comparing multiple model-derived aerosol optical properties to spatially collocated ground-based and satellite measurements

Science.gov (United States)

Ocko, Ilissa B.; Ginoux, Paul A.

2017-04-01

Anthropogenic aerosols are a key factor governing Earth's climate and play a central role in human-caused climate change. However, because of aerosols' complex physical, optical, and dynamical properties, aerosols are one of the most uncertain aspects of climate modeling. Fortunately, aerosol measurement networks over the past few decades have led to the establishment of long-term observations for numerous locations worldwide. Further, the availability of datasets from several different measurement techniques (such as ground-based and satellite instruments) can help scientists increasingly improve modeling efforts. This study explores the value of evaluating several model-simulated aerosol properties with data from spatially collocated instruments. We compare aerosol optical depth (AOD; total, scattering, and absorption), single-scattering albedo (SSA), Ångström exponent (α), and extinction vertical profiles in two prominent global climate models (Geophysical Fluid Dynamics Laboratory, GFDL, CM2.1 and CM3) to seasonal observations from collocated instruments (AErosol RObotic NETwork, AERONET, and Cloud-Aerosol Lidar with Orthogonal Polarization, CALIOP) at seven polluted and biomass burning regions worldwide. We find that a multi-parameter evaluation provides key insights on model biases, data from collocated instruments can reveal underlying aerosol-governing physics, column properties wash out important vertical distinctions, and improved models does not mean all aspects are improved. We conclude that it is important to make use of all available data (parameters and instruments) when evaluating aerosol properties derived by models.

Field guide to nonlinear optics

CERN Document Server

Powers, Peter E

2013-01-01

Optomechanics is a field of mechanics that addresses the specific design challenges associated with optical systems. This [i]Field Guide [/i]describes how to mount optical components, as well as how to analyze a given design. It is intended for practicing optical and mechanical engineers whose work requires knowledge in both optics and mechanics. This Field Guide is designed for those looking for a condensed and concise source of key concepts, equations, and techniques for nonlinear optics. Topics covered include technologically important effects, recent developments in nonlinear optics

Local Optical Spectroscopies for Subnanometer Spatial Resolution Chemical Imaging

Energy Technology Data Exchange (ETDEWEB)

Weiss, Paul

2014-01-20

The evanescently coupled photon scanning tunneling microscopes (STMs) have special requirements in terms of stability and optical access. We have made substantial improvements to the stability, resolution, and noise floor of our custom-built visible-photon STM, and will translate these advances to our infrared instrument. Double vibration isolation of the STM base with a damping system achieved increased rigidity, giving high tunneling junction stability for long-duration and high-power illumination. Light frequency modulation with an optical chopper and phase-sensitive detection now enhance the signal-to-noise ratio of the tunneling junction during irradiation.

Spatial patterns of persistent neural activity vary with the behavioral context of short-term memory.

Science.gov (United States)

Daie, Kayvon; Goldman, Mark S; Aksay, Emre R F

2015-02-18

A short-term memory can be evoked by different inputs and control separate targets in different behavioral contexts. To address the circuit mechanisms underlying context-dependent memory function, we determined through optical imaging how memory is encoded at the whole-network level in two behavioral settings. Persistent neural activity maintaining a memory of desired eye position was imaged throughout the oculomotor integrator after saccadic or optokinetic stimulation. While eye position was encoded by the amplitude of network activity, the spatial patterns of firing were context dependent: cells located caudally generally were most persistent following saccadic input, whereas cells located rostrally were most persistent following optokinetic input. To explain these data, we computationally identified four independent modes of network activity and found these were differentially accessed by saccadic and optokinetic inputs. These results show how a circuit can simultaneously encode memory value and behavioral context, respectively, in its amplitude and spatial pattern of persistent firing. Copyright © 2015 Elsevier Inc. All rights reserved.

Towards an integrated strategy for monitoring wetland inundation with virtual constellations of optical and radar satellites

Science.gov (United States)

DeVries, B.; Huang, W.; Huang, C.; Jones, J. W.; Lang, M. W.; Creed, I. F.; Carroll, M.

2017-12-01

The function of wetlandscapes in hydrological and biogeochemical cycles is largely governed by surface inundation, with small wetlands that experience periodic inundation playing a disproportionately large role in these processes. However, the spatial distribution and temporal dynamics of inundation in these wetland systems are still poorly understood, resulting in large uncertainties in global water, carbon and greenhouse gas budgets. Satellite imagery provides synoptic and repeat views of the Earth's surface and presents opportunities to fill this knowledge gap. Despite the proliferation of Earth Observation satellite missions in the past decade, no single satellite sensor can simultaneously provide the spatial and temporal detail needed to adequately characterize inundation in small, dynamic wetland systems. Surface water data products must therefore integrate observations from multiple satellite sensors in order to address this objective, requiring the development of improved and coordinated algorithms to generate consistent estimates of surface inundation. We present a suite of algorithms designed to detect surface inundation in wetlands using data from a virtual constellation of optical and radar sensors comprising the Landsat and Sentinel missions (DeVries et al., 2017). Both optical and radar algorithms were able to detect inundation in wetlands without the need for external training data, allowing for high-efficiency monitoring of wetland inundation at large spatial and temporal scales. Applying these algorithms across a gradient of wetlands in North America, preliminary findings suggest that while these fully automated algorithms can detect wetland inundation at higher spatial and temporal resolutions than currently available surface water data products, limitations specific to the satellite sensors and their acquisition strategies are responsible for uncertainties in inundation estimates. Further research is needed to investigate strategies for

Autoregressive spatially varying coefficients model for predicting daily PM2.5 using VIIRS satellite AOT

Science.gov (United States)

Schliep, E. M.; Gelfand, A. E.; Holland, D. M.

2015-12-01

There is considerable demand for accurate air quality information in human health analyses. The sparsity of ground monitoring stations across the United States motivates the need for advanced statistical models to predict air quality metrics, such as PM2.5, at unobserved sites. Remote sensing technologies have the potential to expand our knowledge of PM2.5 spatial patterns beyond what we can predict from current PM2.5 monitoring networks. Data from satellites have an additional advantage in not requiring extensive emission inventories necessary for most atmospheric models that have been used in earlier data fusion models for air pollution. Statistical models combining monitoring station data with satellite-obtained aerosol optical thickness (AOT), also referred to as aerosol optical depth (AOD), have been proposed in the literature with varying levels of success in predicting PM2.5. The benefit of using AOT is that satellites provide complete gridded spatial coverage. However, the challenges involved with using it in fusion models are (1) the correlation between the two data sources varies both in time and in space, (2) the data sources are temporally and spatially misaligned, and (3) there is extensive missingness in the monitoring data and also in the satellite data due to cloud cover. We propose a hierarchical autoregressive spatially varying coefficients model to jointly model the two data sources, which addresses the foregoing challenges. Additionally, we offer formal model comparison for competing models in terms of model fit and out of sample prediction of PM2.5. The models are applied to daily observations of PM2.5 and AOT in the summer months of 2013 across the conterminous United States. Most notably, during this time period, we find small in-sample improvement incorporating AOT into our autoregressive model but little out-of-sample predictive improvement.

Fiber-Optic Magnetometry and Thermometry Using Optically Detected Magnetic Resonance With Nitrogen-Vacancy Centers in Diamond

Science.gov (United States)

Blakley, Sean Michael

Nitrogen--vacancy diamond (NVD) quantum sensors are an emerging technology that has shown great promise in areas like high-resolution thermometry and magnetometry. Optical fibers provide attractive new application paradigms for NVD technology. A detailed description of the fabrication processes associated with the development of novel fiber-optic NVD probes are presented in this work. The demonstrated probes are tested on paradigmatic model systems designed to ascertain their suitability for use in challenging biological environments. Methods employing optically detected magnetic resonance (ODMR) are used to accurately measure and map temperature distributions of small objects and to demonstrate emergent temperature-dependent phenomena in genetically modified living organisms. These methods are also used to create detailed high resolution spatial maps of both magnetic scalar and magnetic vector field distributions of spatially localized weak field features in the presence of a noisy, high-field background.

Highly spatially resolved structural and optical investigation of Bi nanoparticles in Y-Er disilicate thin films

Energy Technology Data Exchange (ETDEWEB)

Scarangella, A. [CNR IMM-MATIS, Via S. Sofia 64, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy); Amiard, G.; Boninelli, S., E-mail: simona.boninelli@ct.infn.it; Miritello, M. [CNR IMM-MATIS, Via S. Sofia 64, 95123 Catania (Italy); Reitano, R. [Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy); Priolo, F. [CNR IMM-MATIS, Via S. Sofia 64, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy); Scuola Superiore di Catania, Università di Catania, Via Valdisavoia 9, 95123 Catania (Italy)

2016-08-08

Er-containing silicon compatible materials have been widely used as infrared emitters for microphotonics application. In this field, the additional introduction of a proper sensitizer permits to increase the Er excitation cross sections, thus increasing its optical efficiency. This work aims to investigate the influence of a post-transition metal, bismuth, on the optical properties of erbium-yttrium disilicate thin films synthesized by magnetron co-sputtering. After thermal treatments at 1000 °C in O{sub 2} or N{sub 2} environment, the presence of small precipitates, about 6 nm in diameter, was evidenced by transmission electron microscopy analyses. The spatially resolved chemical nature of the nanoparticles was discerned in the Si and O rich environments by means of scanning transmission electron microscopy–energy dispersive X-ray and scanning transmission electron microscopy–electron energy loss spectroscopy analyses performed with nanometric resolution. In particular, metallic Bi nanoparticles were stabilized in the N{sub 2} environment, being strongly detrimental for the Er emission. A different scenario was instead observed in O{sub 2}, where the formation of Bi silicate nanoparticles was demonstrated with the support of photoluminescence excitation spectroscopy. In particular, a broad band peaked at 255 nm, correlated to the excitation band of Bi silicate nanoparticles, was identified in Er excitation spectrum. Thus Bi silicate clusters act as sensitizer for Er ions, permitting to improve Er emission up to 250 times with respect to the resonant condition. Moreover, the Er decay time increases in the presence of the Bi silicate nanoparticles that act as cages for Er ions. These last results permit to further increase Er optical efficiency in the infrared range, suggesting (Bi + Er)-Y disilicate as a good candidate for applications in microphotonics.

Standoff Laser-Induced Breakdown Spectroscopy (LIBS) Using a Miniature Wide Field of View Spatial Heterodyne Spectrometer with Sub-Microsteradian Collection Optics.

Science.gov (United States)

Barnett, Patrick D; Lamsal, Nirmal; Angel, S Michael

2017-04-01

A spatial heterodyne spectrometer (SHS) is described for standoff laser-induced breakdown spectroscopy (LIBS) measurements. The spatial heterodyne LIBS spectrometer (SHLS) is a diffraction grating based interferometer with no moving parts that offers a very large field of view, high light throughput, and high spectral resolution in a small package. The field of view of the SHLS spectrometer is shown to be ∼1° in standoff LIBS measurements. In the SHLS system described here, the collection aperture was defined by the 10 mm diffraction gratings in the SHS and standoff LIBS measurements were made up to 20 m with no additional collection optics, corresponding to a collection solid angle of 0.2 μsr, or f/2000, and also using a small telescope to increase the collection efficiency. The use of a microphone was demonstrated to rapidly optimize laser focus for 20 m standoff LIBS measurements.

Comprehensive long distance and real-time pipeline monitoring system based on fiber optic sensing

Energy Technology Data Exchange (ETDEWEB)

Nikles, Marc; Ravet, Fabien; Briffod, Fabien [Omnisens S.A., Morges (Switzerland)

2009-07-01

An increasing number of pipelines are constructed in remote regions affected by harsh environmental conditions. These pipeline routes often cross mountain areas which are characterized by unstable grounds and where soil texture changes between winter and summer increase the probability of hazards. Due to the long distances to be monitored and the linear nature of pipelines, distributed fiber optic sensing techniques offer significant advantages and the capability to detect and localize pipeline disturbance with great precision. Furthermore pipeline owner/operators lay fiber optic cable parallel to transmission pipelines for telecommunication purposes and at minimum additional cost monitoring capabilities can be added to the communication system. The Brillouin-based Omnisens DITEST monitoring system has been used in several long distance pipeline projects. The technique is capable of measuring strain and temperature over 100's kilometers with meter spatial resolution. Dedicated fiber optic cables have been developed for continuous strain and temperature monitoring and their deployment along the pipeline has enabled permanent and continuous pipeline ground movement, intrusion and leak detection. This paper presents a description of the fiber optic Brillouin-based DITEST sensing technique, its measurement performance and limits, while addressing future perspectives for pipeline monitoring. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Mortazavi, M.; Urzay, J., E-mail: jurzay@stanford.edu; Mani, A. [Center for Turbulence Research, Stanford University, Stanford, California 94305-3024 (United States)

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

Addressing the needs of the telecoms industry for optical fibre communication in Africa

Science.gov (United States)

Leitch, Andrew W. R.; Conibear, Ann B.

2005-10-01

We report on a successful partnership between the Department of Physics at the Nelson Mandela Metropolitan University (NMMU) and Telkom, South Africa's national telecommunications company, to train physics students in the important fields related to optical fibre technology. The partnership, which began in 2001 and forms part of Telkom's Centre of Excellence program in South Africa, is currently being extended to other countries in Africa. The training being conducted in the Physics Department has as one of its main goals an increased understanding of polarisation mode dispersion (PMD), an effect that will ultimately limit the transmission speeds through optical fibre.

Visible-Frequency Metasurface for Structuring and Spatially Multiplexing Optical Vortices.

Science.gov (United States)

Mehmood, M Q; Mei, Shengtao; Hussain, Sajid; Huang, Kun; Siew, S Y; Zhang, Lei; Zhang, Tianhang; Ling, Xiaohui; Liu, Hong; Teng, Jinghua; Danner, Aaron; Zhang, Shuang; Qiu, Cheng-Wei

2016-04-06

A multifocus optical vortex metalens, with enhanced signal-to-noise ratio, is presented, which focuses three longitudinal vortices with distinct topological charges at different focal planes. The design largely extends the flexibility of tuning the number of vortices and their focal positions for circularly polarized light in a compact device, which provides the convenience for the nanomanipulation of optical vortices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Uncertainty in spatial planning proceedings

Directory of Open Access Journals (Sweden)

Aleš Mlakar

2009-01-01

Full Text Available Uncertainty is distinctive of spatial planning as it arises from the necessity to co-ordinate the various interests within the area, from the urgency of adopting spatial planning decisions, the complexity of the environment, physical space and society, addressing the uncertainty of the future and from the uncertainty of actually making the right decision. Response to uncertainty is a series of measures that mitigate the effects of uncertainty itself. These measures are based on two fundamental principles – standardization and optimization. The measures are related to knowledge enhancement and spatial planning comprehension, in the legal regulation of changes, in the existence of spatial planning as a means of different interests co-ordination, in the active planning and the constructive resolution of current spatial problems, in the integration of spatial planning and the environmental protection process, in the implementation of the analysis as the foundation of spatial planners activities, in the methods of thinking outside the parameters, in forming clear spatial concepts and in creating a transparent management spatial system and also in the enforcement the participatory processes.

IP- -: A Reduced Internet Protocol for Optical Packet Networking

Science.gov (United States)

Ohta, Masataka; Fujikawa, Kenji

IP- - is proposed as an Internet Protocol suitable for optical packet networking. As optical routers require much faster control than electric ones and lack of optical buffers other than those by fiber delay lines requires fixed time control, Internet Protocols must be at least as simple as IPv4 and much simpler than IPv6. IP- - also addresses issues of IP address space exhaustion and IP routing table explosion.

Catching Attention in Fiber Optics Class

OpenAIRE

Kezerashvili, R. Ya.; Leng, L.

2004-01-01

Following a brief review on the history and the current development of fiber optics, the significance of teaching fiber optics for science and non-science major college students is addressed. Several experimental demonstrations designed to aid the teaching and learning process in fiber optics lectures are presented. Sample laboratory projects are also proposed to help the students to understand the physical principles of fiber optics.

Helmholtz Natural Modes: the universal and discrete spatial fabric of electromagnetic wavefields

International Nuclear Information System (INIS)

El Gawhary, Omar

2017-01-01

The interaction of electromagnetic waves with matter is at the foundation of the way we perceive and explore the world around us. In fact, when a field interacts with an object, signatures on the object’s geometry and physical properties are recorded in the resulting scattered field and are transported away from the object, where they can eventually be detected and processed. An optical field can transport information through its spectral content, its polarization state, and its spatial distribution. Generally speaking, the field’s spatial structure is typically subjected to changes under free-space propagation and any information therein encoded gets reshuffled by the propagation process. We must ascribe to this fundamental reason the fact that spectroscopy was known to the ancient civilizations already, and founded as modern science in the middle of seventeenth century, while to date we do not have an established scientific of field of ‘spatial spectroscopy’ yet. In this work we tackle this issue and we show how any field, whose evolution is dictated by Helmholtz equation, contains a universal and invariant spatial structure. When expressed in the framework of this spatial fabric, the spatial information content carried by any field reveals its invariant nature. This opens the way to novel paradigms in optical digital communications, inverse scattering, materials inspection, nanometrology and quantum optics. (paper)

Constraints on spatially oscillating sub-mm forces from the Stanford Optically Levitated Microsphere Experiment data

Science.gov (United States)

Antoniou, I.; Perivolaropoulos, L.

2017-11-01

A recent analysis by one of the authors [L. Perivolaropoulos, Phys. Rev. D 95, 084050 (2017), 10.1103/PhysRevD.95.084050] has indicated the presence of a 2 σ signal of spatially oscillating new force residuals in the torsion balance data of the Washington experiment. We extend that study and analyze the data of the Stanford Optically Levitated Microsphere Experiment (SOLME) [A. D. Rider et al., Phys. Rev. Lett. 117, 101101 (2016), 10.1103/PhysRevLett.117.101101] (kindly provided by A. D. Rider et al.) searching for sub-mm spatially oscillating new force signals. We find a statistically significant oscillating signal for a force residual of the form F (z )=α cos (2/π λ z +c ) where z is the distance between the macroscopic interacting masses (levitated microsphere and cantilever). The best fit parameter values are α =(1.1 ±0.4 )×10-17N , λ =(35.2 ±0.6 ) μ m . Monte Carlo simulation of the SOLME data under the assumption of zero force residuals has indicated that the statistical significance of this signal is at about 2 σ level. The improvement of the χ2 fit compared to the null hypothesis (zero residual force) corresponds to Δ χ2=13.1 . There are indications that this previously unnoticed signal is indeed in the data but is most probably induced by a systematic effect caused by diffraction of non-Gaussian tails of the laser beam. Thus the amplitude of this detected signal can only be useful as an upper bound to the amplitude of new spatially oscillating forces on sub-mm scales. In the context of gravitational origin of the signal emerging from a fundamental modification of the Newtonian potential of the form Veff(r )=-G M/r (1 +αOcos (2/π λ r +θ ))≡VN(r )+Vosc(r ) , we evaluate the source integral of the oscillating macroscopically induced force. If the origin of the SOLME oscillating signal is systematic, the parameter αO is bounded as αOchameleon oscillating potentials etc.).

Optical design of transmitter lens for asymmetric distributed free space optical networks

Science.gov (United States)

Wojtanowski, Jacek; Traczyk, Maciej

2018-05-01

We present a method of transmitter lens design dedicated for light distribution shaping on a curved and asymmetric target. In this context, target is understood as a surface determined by hypothetical optical detectors locations. In the proposed method, ribbon-like surfaces of arbitrary shape are considered. The designed lens has the task to transform collimated and generally non-uniform input beam into desired irradiance distribution on such irregular targets. Desired irradiance is associated with space-dependant efficiency of power flow between the source and receivers distributed on the target surface. This unconventional nonimaging task is different from most illumination or beam shaping objectives, where constant or prescribed irradiance has to be produced on a flat target screen. The discussed optical challenge comes from the applications where single transmitter cooperates with multitude of receivers located in various positions in space and oriented in various directions. The proposed approach is not limited to optical networks, but can be applied in a variety of other applications where nonconventional irradiance distribution has to be engineered. The described method of lens design is based on geometrical optics, radiometry and ray mapping philosophy. Rays are processed as a vector field, each of them carrying a certain amount of power. Having the target surface shape and orientation of receivers distribution, the rays-surface crossings map is calculated. It corresponds to the output rays vector field, which is referred to the calculated input rays spatial distribution on the designed optical surface. The application of Snell's law in a vector form allows one to obtain surface local normal vector and calculate lens profile. In the paper, we also present the case study dealing with exemplary optical network. The designed freeform lens is implemented in commercially available optical design software and irradiance three-dimensional spatial distribution is

Quantum optics

International Nuclear Information System (INIS)

Flytzanis, C.

1988-01-01

The 1988 progress report of the Quantum Optics laboratory (Polytechnic School, France) is presented. The research program is focused on the behavior of dense and dilute materials submitted to short and high-intensity light radiation fields. Nonlinear optics techniques, with time and spatial resolution, are developed. An important research activity concerns the investigations on the interactions between the photon beams and the inhomogeneous or composite materials, as well as the artificial microstructures. In the processes involving molecular beams and surfaces, the research works on the photophysics of surfaces and the molecule-surface interactions, are included [fr

Speckle reduction in optical coherence tomography images of human skin by a spatial diversity method - art. no. 66270P

DEFF Research Database (Denmark)

Jørgensen, Thomas Martini; Thrane, Lars; Mogensen, M.

2007-01-01

the scheme with a mobile fiber-based time-domain real-time OCT system. Essential enhancement was obtained in image contrast when performing in vivo imaging of normal skin and lesions. Resulting images show improved delineation of structure in correspondence with the observed improvements in contrast...... system. Here, we consider a method that in principle can be fitted to most OCT systems without major modifications. Specifically, we address a spatial diversity technique for suppressing speckle noise in OCT images of human skin. The method is a variant of changing the position of the sample relative...

Optical loop framing

International Nuclear Information System (INIS)

Kalibjian, R.; Chong, Y.P.; Prono, D.S.; Cavagnolo, H.R.

1984-06-01

The ATA provides an electron beam pulse of 70-ns duration at a 1-Hz rate. Our present optical diagnostics technique involve the imaging of the visible light generated by the beam incident onto the plant of a thin sheet of material. It has already been demonstrated that the light generated has a sufficiently fast temporal reponse in performing beam diagnostics. Notwithstanding possible beam emittance degradation due to scattering in the thin sheet, the observation of beam spatial profiles with relatively high efficiencies has provided data complementary to that obtained from beam wall current monitors and from various x-ray probes and other electrical probes. The optical image sensor consists of a gated, intensified television system. The gate pulse of the image intensifier can be appropriately delayed to give frames that are time-positioned from the head to the tail of the beam with a minimum gate time of 5-ns. The spatial correlation of the time frames from pulse to pulse is very good for a stable electron beam; however, when instabilities do occur, it is difficult to properly assess the spatial composition of the head and the tail of the beam on a pulse-to-pulse basis. Multiple gating within a pulse duration becomes desirable but cannot be performed because the recycle time (20-ms) of the TV system is much longer than the beam pulse. For this reason we have developed an optical-loop framing technique that will allow the recording of two frames within one pulse duration with our present gated/intensified TV system

Illusion optics via one-dimensional ultratransparent photonic crystals with shifted spatial dispersions.

Science.gov (United States)

Yao, Zhongqi; Luo, Jie; Lai, Yun

2017-12-11

In this work, we propose that one-dimensional ultratransparent dielectric photonic crystals with wide-angle impedance matching and shifted elliptical equal frequency contours are promising candidate materials for illusion optics. The shift of the equal frequency contour does not affect the refractive behaviors, but enables a new degree of freedom in phase modulation. With such ultratransparent photonic crystals, we demonstrate some applications in illusion optics, including creating illusions of a different-sized scatterer and a shifted source with opposite phase. Such ultratransparent dielectric photonic crystals may establish a feasible platform for illusion optics devices at optical frequencies.

Specification of optical components using Wigner distribution function

International Nuclear Information System (INIS)

Xu Jiancheng; Li Haibo; Xu Qiao; Chai Liqun; Fan Changjiang

2010-01-01

In order to characterize and specify small-scale local wavefront deformation of optical component, a method based on Wigner distribution function has been proposed, which can describe wavefront deformation in spatial and spatial frequency domain. The relationship between Wigner distribution function and power spectral density is analyzed and thus the specification of small-scale local wavefront deformation is obtained by Wigner distribution function. Simulation and experiment demonstrate the effectiveness of the proposed method. The proposed method can not only identify whether the optical component meets the requirement of inertial confinement fusion (ICF), but also determine t he location where small-scale wavefront deformation is unqualified. Thus it provides an effective guide to the revision of unqualified optical components. (authors)

Nonlinear Photonics and Novel Optical Phenomena

CERN Document Server

Morandotti, Roberto

2012-01-01

Nonlinear Photonics and Novel Optical Phenomena contains contributed chapters from leading experts in nonlinear optics and photonics, and provides a comprehensive survey of fundamental concepts as well as hot topics in current research on nonlinear optical waves and related novel phenomena. The book covers self-accelerating airy beams, integrated photonics based on high index doped-silica glass, linear and nonlinear spatial beam dynamics in photonic lattices and waveguide arrays, polariton solitons and localized structures in semiconductor microcavities, terahertz waves, and other novel phenomena in different nanophotonic and optical systems.

The optical smoothing for high power laser chain. Fundamental concepts and analytical modeling, computerized simulations, experiments on smoothing by multimode optical fiber

International Nuclear Information System (INIS)

Videau, Laurent

1998-01-01

Laser-plasma interaction experiments require a focal spot whose spatial width is imposed and whose energy distribution is uniform. Optical smoothing techniques have been developed for high power laser chains in order to reach the required uniformity level. We present theoretical principles for optical smoothing and we develop a statistical approach which allows a precise study of smoothing techniques. This study deals with the contrast of the time-integrated pattern and with the hot spot motion and their life time. We give more details about the technique of Smoothing by Optical Fiber (SOF). A broadband pulse is injected into a multimode optical fiber. At the output of the fiber, the spatial modes, correlated to a propagation angle in the core of the fiber, are statistically independent and produce a speckle pattern. The speckles move because of the temporal incoherence and the time-integrated pattern is smoothed. The smoothing is characterized by the spectral correlation width defined as the width of the spectral correlation function. We show a smoothing difference between the fiber image plane and the convergence one which is the Fourier plane. Furthermore, we analyze the mode coupling into the core of the fiber which allows an explanation of experimental results compared to theoretical ones. A second study presents experimental results of Smoothing by Optical Fiber on a high power laser chain. In fact, SOF implies amplitude modulations in spatial and temporal domains which induce nonlinear effects. We show that the amplification efficiency decreases and we compare experimental results with an analytic model which takes into account spatial and temporal incoherencies. Finally, we propose a different setup using the cascading effect which creates spatially and/or temporally incoherent pulses. (author) [fr

Analysis of waveguide architectures of InGaN/GaN diode lasers by nearfield optical microscopy

Science.gov (United States)

Friede, Sebastian; Tomm, Jens W.; Kühn, Sergei; Hoffmann, Veit; Wenzel, Hans

2017-02-01

Waveguide (WG) architectures of 420-nm emitting InAlGaN/GaN diode lasers are analyzed by photoluminescence (PL) and photocurrent (PC) spectroscopy using a nearfield scanning optical microscope (NSOM) for excitation and detection. The measurements with a spatial resolution of 100 nm are implemented by scanning the fiber tip along the unprepared front facets of standard devices. PL is collected by the fiber tip, whereas PCs are extracted from the contacts that are anyway present for power supply. The mechanisms of signal generation are addressed in detail. The components of the `optical active region', multiple quantum wells (MQW), WGs, and cladding layers are separately inspected. Even separate analysis of p- and n-sections of the WG become possible. Defect levels are detected in the p-part of the WG. Their presence is consistent with the doping by Mg. An increased efficiency of carrier capture into InGaN/GaN WGs compared to GaN WGs is observed. Thus, beyond the improved optical confinement, the electrical confinement is improved, as well. NSOM PL and PC at GaN based devices do not reach the clarity and spatial resolution for WG mode analysis as seen before for GaAs based devices. This is due to higher modal absorption and higher WG losses. NSOM based optical analysis turns out to be an efficient tool for analysis of single layers grown into InAlGaN/GaN diode laser structures, even if this analysis is done at a packaged ready-to-work device.

Spatial domain decomposition for neutron transport problems

International Nuclear Information System (INIS)

Yavuz, M.; Larsen, E.W.

1989-01-01

A spatial Domain Decomposition method is proposed for modifying the Source Iteration (SI) and Diffusion Synthetic Acceleration (DSA) algorithms for solving discrete ordinates problems. The method, which consists of subdividing the spatial domain of the problem and performing the transport sweeps independently on each subdomain, has the advantage of being parallelizable because the calculations in each subdomain can be performed on separate processors. In this paper we describe the details of this spatial decomposition and study, by numerical experimentation, the effect of this decomposition on the SI and DSA algorithms. Our results show that the spatial decomposition has little effect on the convergence rates until the subdomains become optically thin (less than about a mean free path in thickness)

Enhancing spatial detection accuracy for syndromic surveillance with street level incidence data

Directory of Open Access Journals (Sweden)

Alemi Farrokh

2010-01-01

Full Text Available Abstract Background The Department of Defense Military Health System operates a syndromic surveillance system that monitors medical records at more than 450 non-combat Military Treatment Facilities (MTF worldwide. The Electronic Surveillance System for Early Notification of Community-based Epidemics (ESSENCE uses both temporal and spatial algorithms to detect disease outbreaks. This study focuses on spatial detection and attempts to improve the effectiveness of the ESSENCE implementation of the spatial scan statistic by increasing the spatial resolution of incidence data from zip codes to street address level. Methods Influenza-Like Illness (ILI was used as a test syndrome to develop methods to improve the spatial accuracy of detected alerts. Simulated incident clusters of various sizes were superimposed on real ILI incidents from the 2008/2009 influenza season. Clusters were detected using the spatial scan statistic and their displacement from simulated loci was measured. Detected cluster size distributions were also evaluated for compliance with simulated cluster sizes. Results Relative to the ESSENCE zip code based method, clusters detected using street level incidents were displaced on average 65% less for 2 and 5 mile radius clusters and 31% less for 10 mile radius clusters. Detected cluster size distributions for the street address method were quasi normal and sizes tended to slightly exceed simulated radii. ESSENCE methods yielded fragmented distributions and had high rates of zero radius and oversized clusters. Conclusions Spatial detection accuracy improved notably with regard to both location and size when incidents were geocoded to street addresses rather than zip code centroids. Since street address geocoding success rates were only 73.5%, zip codes were still used for more than one quarter of ILI cases. Thus, further advances in spatial detection accuracy are dependant on systematic improvements in the collection of individual

Piezo-optic surfaces of lithium niobate crystals

International Nuclear Information System (INIS)

Mytsyk, B. G.; Dem'yanyshyn, N. M.

2006-01-01

A method of construction of the spatial distribution of the piezo-optic effect in crystals is proposed. A particular case of this method is the known technique of construction of indicator surfaces of the piezo-optic effect. The essence of the proposed method consists in determining the difference in the radius vectors of the optical indicatrix perturbed by stress and the free optical indicatrix. It is shown that this difference in the radius vectors is mathematically identical to the law of transformation of the piezo-optic tensor during the rotation of the coordinate system

Optic neuropathies--importance of spatial distribution of mitochondria as well as function.

Science.gov (United States)

Yu Wai Man, C Y; Chinnery, P F; Griffiths, P G

2005-01-01

Optic neuropathies such as Leber's hereditary optic neuropathy, dominant optic atrophy and toxic amblyopia are an important cause of irreversible visual failure. Although they are associated with a defect of mitochondrial energy production, their pathogenesis is poorly understood. A common feature to all these disorders is relatively selective degeneration of the papillomacular bundle of retinal ganglion cells resulting central or caecocentral visual field defects. The striking similarity in the pattern of clinical involvement seen with these disparate disorders suggests a common pathway in their aetiology. The existing hypothesis that the optic nerve head has higher energy demands than other tissues making it uniquely dependent on oxidative phosporylation is not satisfactory. First, other ocular tissues such as photoreceptors, which are more dependent on oxidative phosporylation are not affected. Second, other mitochondrial disorders, which have a greater impact on mitochondrial energy function, do not affect the optic nerve. The optic nerve head has certain unique ultra structural features. Ganglion cell axons exit the eye through a perforated collagen plate, the lamina cribrosa. There is a sharp discontinuity in the density of mitochondria at the optic nerve head, with a very high concentration in the prelaminar nerve fibre layer and low concentration behind the lamina. This has previously been attributed to a mechanical hold up of axoplasmic flow, which has itself been proposed as a factor in the pathogenesis of a number of optic neuropathies. More recent evidence shows that mitochondrial distribution reflects the different energy requirements of the unmyelinated prelaminar axons in comparison to the myelinated retrolaminar axons. The heterogeous distribution of mitochondria is actively maintained to support conduction through the optic nerve head. We propose that factors that disrupt the heterogeneous distribution of mitochondria can result in ganglion cell

Developing and setting up optical methods to study the speckle patterns created by optical beam smoothing

International Nuclear Information System (INIS)

Surville, J.

2005-12-01

We have developed three main optical methods to study the speckles generated by a smoothed laser source. The first method addresses the measurement of the temporal and spatial correlation functions of the source, with a modified Michelson interferometer. The second one is a pump-probe technique created to shoot a picture of a speckle pattern generated at a set time. And the third one is an evolution of the second method dedicated to time-frequency coding, thanks to a frequency chirped probe pulse. Thus, the speckles can be followed in time and their motion can be described. According to these three methods, the average size and duration of the speckles can be measured. It is also possible to measure the size and the duration of each of them and mostly their velocity in a given direction. All the results obtained have been confronted to the different existing theories. We show that the statistical distributions of the measured speckles'size and speckles'intensity agree satisfactorily with theoretical values

Specification of optical components for a high average-power laser environment

Energy Technology Data Exchange (ETDEWEB)

Taylor, J.R.; Chow, R.; Rinmdahl, K.A.; Willis, J.B.; Wong, J.N.

1997-06-25

Optical component specifications for the high-average-power lasers and transport system used in the Atomic Vapor Laser Isotope Separation (AVLIS) plant must address demanding system performance requirements. The need for high performance optics has to be balanced against the practical desire to reduce the supply risks of cost and schedule. This is addressed in optical system design, careful planning with the optical industry, demonstration of plant quality parts, qualification of optical suppliers and processes, comprehensive procedures for evaluation and test, and a plan for corrective action.

An Analysis of an Ultra-High Speed Content-Addressable Database Retrieval System

National Research Council Canada - National Science Library

Costianes, Peter

2001-01-01

This work presents a model for assessing the performance of a paradigm and its implementation first proposed by Chou, Detofsky, and Louri entitled Multiwavelength Optical Content-Addressable Parallel Processor (MW-OCAPP...

Novel concepts in near-field optics: from magnetic near-field to optical forces

Science.gov (United States)

Yang, Honghua

Driven by the progress in nanotechnology, imaging and spectroscopy tools with nanometer spatial resolution are needed for in situ material characterizations. Near-field optics provides a unique way to selectively excite and detect elementary electronic and vibrational interactions at the nanometer scale, through interactions of light with matter in the near-field region. This dissertation discusses the development and applications of near-field optical imaging techniques, including plasmonic material characterization, optical spectral nano-imaging and magnetic field detection using scattering-type scanning near-field optical microscopy (s-SNOM), and exploring new modalities of optical spectroscopy based on optical gradient force detection. Firstly, the optical dielectric functions of one of the most common plasmonic materials---silver is measured with ellipsometry, and analyzed with the Drude model over a broad spectral range from visible to mid-infrared. This work was motivated by the conflicting results of previous measurements, and the need for accurate values for a wide range of applications of silver in plasmonics, optical antennas, and metamaterials. This measurement provides a reference for dielectric functions of silver used in metamaterials, plasmonics, and nanophotonics. Secondly, I implemented an infrared s-SNOM instrument for spectroscopic nano-imaging at both room temperature and low temperature. As one of the first cryogenic s-SNOM instruments, the novel design concept and key specifications are discussed. Initial low-temperature and high-temperature performances of the instrument are examined by imaging of optical conductivity of vanadium oxides (VO2 and V2O 3) across their phase transitions. The spectroscopic imaging capability is demonstrated on chemical vibrational resonances of Poly(methyl methacrylate) (PMMA) and other samples. The third part of this dissertation explores imaging of optical magnetic fields. As a proof-of-principle, the magnetic

Altered Functional Connectivity Following an Inflammatory White Matter Injury in the Newborn Rat: A High Spatial and Temporal Resolution Intrinsic Optical Imaging Study

Directory of Open Access Journals (Sweden)

Edgar Guevara

2017-07-01

Full Text Available Very preterm newborns have an increased risk of developing an inflammatory cerebral white matter injury that may lead to severe neuro-cognitive impairment. In this study we performed functional connectivity (fc analysis using resting-state optical imaging of intrinsic signals (rs-OIS to assess the impact of inflammation on resting-state networks (RSN in a pre-clinical model of perinatal inflammatory brain injury. Lipopolysaccharide (LPS or saline injections were administered in postnatal day (P3 rat pups and optical imaging of intrinsic signals were obtained 3 weeks later. (rs-OIS fc seed-based analysis including spatial extent were performed. A support vector machine (SVM was then used to classify rat pups in two categories using fc measures and an artificial neural network (ANN was implemented to predict lesion size from those same fc measures. A significant decrease in the spatial extent of fc statistical maps was observed in the injured group, across contrasts and seeds (*p = 0.0452 for HbO2 and **p = 0.0036 for HbR. Both machine learning techniques were applied successfully, yielding 92% accuracy in group classification and a significant correlation r = 0.9431 in fractional lesion volume prediction (**p = 0.0020. Our results suggest that fc is altered in the injured newborn brain, showing the long-standing effect of inflammation.

All-Optical Network Subsystems Using Integrated SOA-Based Optical Gates and Flip-Flops for Label-Swapped Netorks

DEFF Research Database (Denmark)

Seoane, Jorge; Holm-Nielsen, Pablo Villanueva; Kehayas, E.

2006-01-01

In this letter, we demonstrate that all-optical network subsystems, offering intelligence in the optical layer, can be constructed by functional integration of integrated all-optical logic gates and flip-flops. In this context, we show 10-Gb/s all-optical 2-bit label address recognition......-level advantages of these all-optical subsystems combined with their realization with compact integrated devices, suggest that they are strong candidates for future packet/label switched optical networks....... by interconnecting two optical gates that perform xor operation on incoming optical labels. We also demonstrate 40-Gb/s all-optical wavelength-switching through an optically controlled wavelength converter, consisting of an integrated flip-flop prototype device driven by an integrated optical gate. The system...

Measurement of Spatial Coherence of Light Propagating in a Turbulent Atmosphere

Directory of Open Access Journals (Sweden)

P. Barcik

2013-04-01

Full Text Available A lot of issues have to be taken into account when designing a reliable free space optical communication link. Among these are e.g.,beam wander, fluctuation of optical intensity and loss of spatial coherence that are caused by atmospheric turbulence. This paper presents experimental measurements of spatial coherence of a laser beam. The experimental setup is based on Young's double pinhole experiment. Fringe patterns under atmospheric turbulence for four different pinhole separations are presented. From these fringe patterns, visibility is determined and the coherence radius is estimated.

Slow light enhanced optical nonlinearity in a silicon photonic crystal coupled-resonator optical waveguide.

Science.gov (United States)

Matsuda, Nobuyuki; Kato, Takumi; Harada, Ken-Ichi; Takesue, Hiroki; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya

2011-10-10

We demonstrate highly enhanced optical nonlinearity in a coupled-resonator optical waveguide (CROW) in a four-wave mixing experiment. Using a CROW consisting of 200 coupled resonators based on width-modulated photonic crystal nanocavities in a line defect, we obtained an effective nonlinear constant exceeding 10,000 /W/m, thanks to slow light propagation combined with a strong spatial confinement of light achieved by the wavelength-sized cavities.

Long-distance super-resolution imaging assisted by enhanced spatial Fourier transform.

Science.gov (United States)

Tang, Heng-He; Liu, Pu-Kun

2015-09-07

A new gradient-index (GRIN) lens that can realize enhanced spatial Fourier transform (FT) over optically long distances is demonstrated. By using an anisotropic GRIN metamaterial with hyperbolic dispersion, evanescent wave in free space can be transformed into propagating wave in the metamaterial and then focused outside due to negative-refraction. Both the results based on the ray tracing and the finite element simulation show that the spatial frequency bandwidth of the spatial FT can be extended to 2.7k(0) (k(0) is the wave vector in free space). Furthermore, assisted by the enhanced spatial FT, a new long-distance (in the optical far-field region) super-resolution imaging scheme is also proposed and the super resolved capability of λ/5 (λ is the wavelength in free space) is verified. The work may provide technical support for designing new-type high-speed microscopes with long working distances.

Morphogenetic and histogenetic roles of the temporal-spatial organization of cell proliferation in the vertebrate corticogenesis as revealed by inter-specific analyses of the optic tectum cortex development

Directory of Open Access Journals (Sweden)

Melina eRapacioli

2016-03-01

Full Text Available The central nervous system areas displaying the highest structural and functional complexity correspond to the so called cortices, i.e. concentric alternating neuronal and fibrous layers. Corticogenesis, i.e. the development of the cortical organization, depends on the temporal-spatial organization of several developmental events: (a the duration of the proliferative phase of the neuroepithelium, (b the relative duration of symmetric (expansive versus asymmetric (neuronogenic sub phases, (c the spatial organization of each kind of cell division, (e the time of determination and cell cycle exit and (f the time of onset of the postmitotic neuronal migration and (g the time of onset of the neuronal structural and functional differentiation. The first five events depend on molecular mechanisms that perform a fine tuning of the proliferative activity. Changes in any of them significantly influence the cortical size or volume (tangential expansion and radial thickness, morphology, architecture and also impact on neuritogenesis and synaptogenesis affecting the cortical wiring. This paper integrates information, obtained in several species, on the developmental roles of cell proliferation in the development of the optic tectum cortex, a multilayered associative area of the dorsal (alar midbrain. The present review (1 compiles relevant information on the temporal and spatial organization of cell proliferation in different species (fish, amphibians, birds and mammals, (2 revises the main molecular events involved in the isthmic organizer determination and localization, (3 describes how the patterning installed by isthmic organizer is translated into spatially organized neural stem cell proliferation (i.e. by means of growth factors, receptors, transcription factors, signaling pathways, etc. and (4 describes the morpho- and histogenetic effect of a spatially organized cell proliferation in the above mentioned species. A brief section on the optic tectum

Roadmap on optical sensors

Science.gov (United States)

Ferreira, Mário F. S.; Castro-Camus, Enrique; Ottaway, David J.; López-Higuera, José Miguel; Feng, Xian; Jin, Wei; Jeong, Yoonchan; Picqué, Nathalie; Tong, Limin; Reinhard, Björn M.; Pellegrino, Paul M.; Méndez, Alexis; Diem, Max; Vollmer, Frank; Quan, Qimin

2017-08-01

Sensors are devices or systems able to detect, measure and convert magnitudes from any domain to an electrical one. Using light as a probe for optical sensing is one of the most efficient approaches for this purpose. The history of optical sensing using some methods based on absorbance, emissive and florescence properties date back to the 16th century. The field of optical sensors evolved during the following centuries, but it did not achieve maturity until the demonstration of the first laser in 1960. The unique properties of laser light become particularly important in the case of laser-based sensors, whose operation is entirely based upon the direct detection of laser light itself, without relying on any additional mediating device. However, compared with freely propagating light beams, artificially engineered optical fields are in increasing demand for probing samples with very small sizes and/or weak light-matter interaction. Optical fiber sensors constitute a subarea of optical sensors in which fiber technologies are employed. Different types of specialty and photonic crystal fibers provide improved performance and novel sensing concepts. Actually, structurization with wavelength or subwavelength feature size appears as the most efficient way to enhance sensor sensitivity and its detection limit. This leads to the area of micro- and nano-engineered optical sensors. It is expected that the combination of better fabrication techniques and new physical effects may open new and fascinating opportunities in this area. This roadmap on optical sensors addresses different technologies and application areas of the field. Fourteen contributions authored by experts from both industry and academia provide insights into the current state-of-the-art and the challenges faced by researchers currently. Two sections of this paper provide an overview of laser-based and frequency comb-based sensors. Three sections address the area of optical fiber sensors, encompassing both

Roadmap on optical sensors.

Science.gov (United States)

Ferreira, Mário F S; Castro-Camus, Enrique; Ottaway, David J; López-Higuera, José Miguel; Feng, Xian; Jin, Wei; Jeong, Yoonchan; Picqué, Nathalie; Tong, Limin; Reinhard, Björn M; Pellegrino, Paul M; Méndez, Alexis; Diem, Max; Vollmer, Frank; Quan, Qimin

2017-08-01

Sensors are devices or systems able to detect, measure and convert magnitudes from any domain to an electrical one. Using light as a probe for optical sensing is one of the most efficient approaches for this purpose. The history of optical sensing using some methods based on absorbance, emissive and florescence properties date back to the 16th century. The field of optical sensors evolved during the following centuries, but it did not achieve maturity until the demonstration of the first laser in 1960. The unique properties of laser light become particularly important in the case of laser-based sensors, whose operation is entirely based upon the direct detection of laser light itself, without relying on any additional mediating device. However, compared with freely propagating light beams, artificially engineered optical fields are in increasing demand for probing samples with very small sizes and/or weak light-matter interaction. Optical fiber sensors constitute a subarea of optical sensors in which fiber technologies are employed. Different types of specialty and photonic crystal fibers provide improved performance and novel sensing concepts. Actually, structurization with wavelength or subwavelength feature size appears as the most efficient way to enhance sensor sensitivity and its detection limit. This leads to the area of micro- and nano-engineered optical sensors. It is expected that the combination of better fabrication techniques and new physical effects may open new and fascinating opportunities in this area. This roadmap on optical sensors addresses different technologies and application areas of the field. Fourteen contributions authored by experts from both industry and academia provide insights into the current state-of-the-art and the challenges faced by researchers currently. Two sections of this paper provide an overview of laser-based and frequency comb-based sensors. Three sections address the area of optical fiber sensors, encompassing both

Quantitative photoacoustic microscopy of optical absorption coefficients from acoustic spectra in the optical diffusive regime.

Science.gov (United States)

Guo, Zijian; Favazza, Christopher; Garcia-Uribe, Alejandro; Wang, Lihong V

2012-06-01

Photoacoustic (PA) microscopy (PAM) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Conventionally, accurate quantification in PAM requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560, 565, 570, and 575 nm were quantified with errors of <3%. We also quantified the total hemoglobin concentration and hemoglobin oxygen saturation in a live mouse. Compared with the conventional amplitude method, the acoustic spectral method provides greater quantification accuracy in the optical diffusive regime. The limitations of the acoustic spectral method was also discussed.

Accessing High Spatial Resolution in Astronomy Using Interference Methods

Science.gov (United States)

Carbonel, Cyril; Grasset, Sébastien; Maysonnave, Jean

2018-04-01

In astronomy, methods such as direct imaging or interferometry-based techniques (Michelson stellar interferometry for example) are used for observations. A particular advantage of interferometry is that it permits greater spatial resolution compared to direct imaging with a single telescope, which is limited by diffraction owing to the aperture of the instrument as shown by Rueckner et al. in a lecture demonstration. The focus of this paper, addressed to teachers and/or students in high schools and universities, is to easily underline both an application of interferometry in astronomy and stress its interest for resolution. To this end very simple optical experiments are presented to explain all the concepts. We show how an interference pattern resulting from the combined signals of two telescopes allows us to measure the distance between two stars with a resolution beyond the diffraction limit. Finally this work emphasizes the breathtaking resolution obtained in state-of-the-art instruments such as the VLTi (Very Large Telescope interferometer).

Beyond MOS and fibers: Optical Fourier-transform Imaging Unit for Cananea Observatory (OFIUCO)

Science.gov (United States)

Nieto-Suárez, M. A.; Rosales-Ortega, F. F.; Castillo, E.; García, P.; Escobedo, G.; Sánchez, S. F.; González, J.; Iglesias-Páramo, J.; Mollá, M.; Chávez, M.; Bertone, E.; et al.

2017-11-01

Many physical processes in astronomy are still hampered by the lack of spatial and spectral resolution, and also restricted to the field-of-view (FoV) of current 2D spectroscopy instruments available worldwide. It is due to that, many of the ongoing or proposed studies are based on large-scale imaging and/or spectroscopic surveys. Under this philosophy, large aperture telescopes are dedicated to the study of intrinsically faint and/or distance objects, covering small FoVs, with high spatial resolution, while smaller telescopes are devoted to wide-field explorations. However, future astronomical surveys, should be addressed by acquiring un-biases, spatially resolved, high-quality spectroscopic information for a wide FoV. Therefore, and in order to improve the current instrumental offer in the Observatorio Astrofísico Guillermo Haro (OAGH) in Cananea, Mexico (INAOE); and to explore a possible instrument for the future Telescopio San Pedro Mártir (6.5m), we are currently integrating at INAOE an instrument prototype that will provide us with un-biased wide-field (few arcmin) spectroscopic information, and with the flexibility of operating at different spectral resolutions (R 1-20000), with a spatial resolution limited by seeing, and therefore, to be used in a wide range of astronomical problems. This instrument called OFIUCO: Optical Fourier-transform Imaging Unit for Cananea Observatory, will make use of the Fourier Transform Spectroscopic technique, which has been proved to be feasible in the optical wavelength range (350-1000 nm) with designs such as SITELLE (CFHT). We describe here the basic technical description of a Fourier transform spectrograph with important modifications from previous astronomical versions, as well as the technical advantages and weakness, and the science cases in which this instrument can be implemented.

Enhanced Interferometry with Programmable Spatial Light Modulator

Science.gov (United States)

2010-06-07

Interferometry, Spatial Light Modulator, Surface Accuracy, Optics, Mirror, Zernike , Freeform Optics, Null Testing, Hartman, Wavefront 16. SECURITY...S L M P ix e l- c a m Tilted Flat Mirror L a s e r PV. ± 3.4 λ -Tilt by the flat mirror, ~7 waves ~ 14 fringes Interferogram 3D view (Various...Interferogram ( 3D view) x- profile y- profile (Various waveplates and telescopes not shown) SLM can compensate tilted wavefronts with an accuracy of

Spatial modulation of the Fermi level by coherent illumination of undoped GaAs

Science.gov (United States)

Nolte, D. D.; Olson, D. H.; Glass, A. M.

1989-11-01

The Fermi level in undoped GaAs has been modulated spatially by optically quenching EL2 defects. The spatial gradient of the Fermi level produces internal electric fields that are much larger than fields generated by thermal diffusion alone. The resulting band structure is equivalent to a periodic modulation-doped p-i-p structure of alternating insulating and p-type layers. The internal fields are detected via the electro-optic effect by the diffraction of a probe laser in a four-wave mixing geometry. The direct control of the Fermi level distinguishes this phenomenon from normal photorefractive behavior and introduces a novel nonlinear optical process.

Using imputation to provide location information for nongeocoded addresses.

Directory of Open Access Journals (Sweden)

Frank C Curriero

2010-02-01

Full Text Available The importance of geography as a source of variation in health research continues to receive sustained attention in the literature. The inclusion of geographic information in such research often begins by adding data to a map which is predicated by some knowledge of location. A precise level of spatial information is conventionally achieved through geocoding, the geographic information system (GIS process of translating mailing address information to coordinates on a map. The geocoding process is not without its limitations, though, since there is always a percentage of addresses which cannot be converted successfully (nongeocodable. This raises concerns regarding bias since traditionally the practice has been to exclude nongeocoded data records from analysis.In this manuscript we develop and evaluate a set of imputation strategies for dealing with missing spatial information from nongeocoded addresses. The strategies are developed assuming a known zip code with increasing use of collateral information, namely the spatial distribution of the population at risk. Strategies are evaluated using prostate cancer data obtained from the Maryland Cancer Registry. We consider total case enumerations at the Census county, tract, and block group level as the outcome of interest when applying and evaluating the methods. Multiple imputation is used to provide estimated total case counts based on complete data (geocodes plus imputed nongeocodes with a measure of uncertainty. Results indicate that the imputation strategy based on using available population-based age, gender, and race information performed the best overall at the county, tract, and block group levels.The procedure allows for the potentially biased and likely under reported outcome, case enumerations based on only the geocoded records, to be presented with a statistically adjusted count (imputed count with a measure of uncertainty that are based on all the case data, the geocodes and imputed

Shaping the spatial and spectral emissivity at the diffraction limit

International Nuclear Information System (INIS)

Makhsiyan, Mathilde; Bouchon, Patrick; Jaeck, Julien; Pelouard, Jean-Luc; Haïdar, Riad

2015-01-01

Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing

Shaping the spatial and spectral emissivity at the diffraction limit

Energy Technology Data Exchange (ETDEWEB)

Makhsiyan, Mathilde [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); MiNaO, Laboratoire de Photonique et de Nanostructures (LPN), CNRS, Université Paris-Saclay, route de Nozay, F-91460 Marcoussis (France); Bouchon, Patrick, E-mail: patrick.bouchon@onera.fr; Jaeck, Julien [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); Pelouard, Jean-Luc [MiNaO, Laboratoire de Photonique et de Nanostructures (LPN), CNRS, Université Paris-Saclay, route de Nozay, F-91460 Marcoussis (France); Haïdar, Riad [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); École Polytechnique, Département de Physique, 91128 Palaiseau (France)

2015-12-21

Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing.

Quantifying spatial heterogeneity from images

International Nuclear Information System (INIS)

Pomerantz, Andrew E; Song Yiqiao

2008-01-01

Visualization techniques are extremely useful for characterizing natural materials with complex spatial structure. Although many powerful imaging modalities exist, simple display of the images often does not convey the underlying spatial structure. Instead, quantitative image analysis can extract the most important features of the imaged object in a manner that is easier to comprehend and to compare from sample to sample. This paper describes the formulation of the heterogeneity spectrum to show the extent of spatial heterogeneity as a function of length scale for all length scales to which a particular measurement is sensitive. This technique is especially relevant for describing materials that simultaneously present spatial heterogeneity at multiple length scales. In this paper, the heterogeneity spectrum is applied for the first time to images from optical microscopy. The spectrum is measured for thin section images of complex carbonate rock cores showing heterogeneity at several length scales in the range 10-10 000 μm.

Phase-only SLM Generating Variable Patterns Applied in Optical Connection

International Nuclear Information System (INIS)

Liu, B H; Wu, L Y; Zhang, J

2006-01-01

An adaptive optical communication system is proposed. The system sends spatial information by emitting multiple variable laser beams generated from a programmable diffractive optical element (DOE): phase-only liquid crystal Spatial Light Modulator (SLM). Laser beams carrying signals are programmable by an optimal algorithm based on an iterative Fourier transformation algorithm. The system has the advantage in redundancy of signal by the means of broadcast. It can adaptively seek position and transmit information in parallel

An adaptive optics imaging system designed for clinical use

Science.gov (United States)

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

2015-01-01

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

Electrically actuatable doped polymer flakes and electrically addressable optical devices using suspensions of doped polymer flakes in a fluid host

Science.gov (United States)

Trajkovska-Petkoska, Anka; Jacobs, Stephen D.; Marshall, Kenneth L.; Kosc, Tanya Z.

2010-05-11

Doped electrically actuatable (electrically addressable or switchable) polymer flakes have enhanced and controllable electric field induced motion by virtue of doping a polymer material that functions as the base flake matrix with either a distribution of insoluble dopant particles or a dopant material that is completely soluble in the base flake matrix. The base flake matrix may be a polymer liquid crystal material, and the dopants generally have higher dielectric permittivity and/or conductivity than the electrically actuatable polymer base flake matrix. The dopant distribution within the base flake matrix may be either homogeneous or non-homogeneous. In the latter case, the non-homogeneous distribution of dopant provides a dielectric permittivity and/or conductivity gradient within the body of the flakes. The dopant can also be a carbon-containing material (either soluble or insoluble in the base flake matrix) that absorbs light so as to reduce the unpolarized scattered light component reflected from the flakes, thereby enhancing the effective intensity of circularly polarized light reflected from the flakes when the flakes are oriented into a light reflecting state. Electro-optic devices contain these doped flakes suspended in a host fluid can be addressed with an applied electric field, thus controlling the orientation of the flakes between a bright reflecting state and a non-reflecting dark state.

Differential Deposition for Surface Figure Corrections in Grazing Incidence X-Ray Optics

Science.gov (United States)

Ramsey, Brian D.; Kilaru, Kiranmayee; Atkins, Carolyn; Gubarev, Mikhail V.; Broadway, David M.

2015-01-01

Differential deposition corrects the low- and mid- spatial-frequency deviations in the axial figure of Wolter-type grazing incidence X-ray optics. Figure deviations is one of the major contributors to the achievable angular resolution. Minimizing figure errors can significantly improve the imaging quality of X-ray optics. Material of varying thickness is selectively deposited, using DC magnetron sputtering, along the length of optic to minimize figure deviations. Custom vacuum chambers are built that can incorporate full-shell and segmented Xray optics. Metrology data of preliminary corrections on a single meridian of full-shell x-ray optics show an improvement of mid-spatial frequencies from 6.7 to 1.8 arc secs HPD. Efforts are in progress to correct a full-shell and segmented optics and to verify angular-resolution improvement with X-ray testing.

Pulse shaping using a spatial light modulator

CSIR Research Space (South Africa)

Botha, N

2009-07-01

Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

Active Full-Shell Grazing-Incidence Optics

Science.gov (United States)

Davis, Jacqueline M.; Elsner, Ronald F.; Ramsey, Brian D.; O'Dell, Stephen L.; Kolodziejczak, Jeffery; Weisskopf, Martin C.; Gubarev, Mikhail V.

2016-01-01

MSFC has a long history of developing full-shell grazing-incidence x-ray optics for both narrow (pointed) and wide field (surveying) applications. The concept presented in this paper shows the potential to use active optics to switch between narrow and wide-field geometries, while maintaining large effective area and high angular resolution. In addition, active optics has the potential to reduce errors due to mounting and manufacturing lightweight optics. The design presented corrects low spatial frequency error and has significantly fewer actuators than other concepts presented thus far in the field of active x-ray optics. Using a finite element model, influence functions are calculated using active components on a full-shell grazing-incidence optic. Next, the ability of the active optic to effect a change of optical prescription and to correct for errors due to manufacturing and mounting is modeled.

Spatially Resolved Analysis of Bragg Selectivity

Directory of Open Access Journals (Sweden)

Tina Sabel

2015-11-01

Full Text Available This paper targets an inherent control of optical shrinkage in photosensitive polymers, contributing by means of spatially resolved analysis of volume holographic phase gratings. Point by point scanning of the local material response to the Gaussian intensity distribution of the recording beams is accomplished. Derived information on the local grating period and grating slant is evaluated by mapping of optical shrinkage in the lateral plane as well as through the depth of the layer. The influence of recording intensity, exposure duration and the material viscosity on the Bragg selectivity is investigated.

Creating a three level building classification using topographic and address-based data for Manchester

Science.gov (United States)

Hussain, M.; Chen, D.

2014-11-01

Buildings, the basic unit of an urban landscape, host most of its socio-economic activities and play an important role in the creation of urban land-use patterns. The spatial arrangement of different building types creates varied urban land-use clusters which can provide an insight to understand the relationships between social, economic, and living spaces. The classification of such urban clusters can help in policy-making and resource management. In many countries including the UK no national-level cadastral database containing information on individual building types exists in public domain. In this paper, we present a framework for inferring functional types of buildings based on the analysis of their form (e.g. geometrical properties, such as area and perimeter, layout) and spatial relationship from large topographic and address-based GIS database. Machine learning algorithms along with exploratory spatial analysis techniques are used to create the classification rules. The classification is extended to two further levels based on the functions (use) of buildings derived from address-based data. The developed methodology was applied to the Manchester metropolitan area using the Ordnance Survey's MasterMap®, a large-scale topographic and address-based data available for the UK.

Spatial-Frequency Azimuthally Stable Cartography of Biological Polycrystalline Networks

Directory of Open Access Journals (Sweden)

V. A. Ushenko

2013-01-01

Full Text Available A new azimuthally stable polarimetric technique processing microscopic images of optically anisotropic structures of biological tissues histological sections is proposed. It has been used as a generalized model of phase anisotropy definition of biological tissues by using superposition of Mueller matrices of linear birefringence and optical activity. The matrix element M44 has been chosen as the main information parameter, whose value is independent of the rotation angle of both sample and probing beam polarization plane. For the first time, the technique of concerted spatial-frequency filtration has been used in order to separate the manifestation of linear birefringence and optical activity. Thereupon, the method of azimuthally stable spatial-frequency cartography of biological tissues histological sections has been elaborated. As the analyzing tool, complex statistic, correlation, and fractal analysis of coordinate distributions of M44 element has been performed. The possibility of using the biopsy of the uterine wall tissue in order to differentiate benign (fibromyoma and malignant (adenocarcinoma conditions has been estimated.

High numerical aperture imaging by using multimode fibers with micro-fabricated optics

KAUST Repository

Bianchi, Silvio; Rajamanickam, V.; Ferrara, Lorenzo; Di Fabrizio, Enzo M.; Di Leonardo, Roberto; Liberale, Carlo

2014-01-01

Controlling light propagation into multimode optical fibers through spatial light modulators provides highly miniaturized endoscopes and optical micromanipulation probes. We increase the numerical aperture up to nearly 1 by micro-optics fabricated on the fiber-end.

Linear rotary optical delay lines

Science.gov (United States)

Guerboukha, Hichem; Qu, Hang; Skorobogatiy, Maksim

2016-03-01

We present a semi-analytical solution for the design of a high-speed rotary optical delay line that use a combination of two rotating curvilinear reflectors. We demonstrate that it is possible to design an infinite variety of the optical delay lines featuring linear dependence of the optical delay on the rotation angle. This is achieved via shape optimization of the rotating reflector surfaces. Moreover, a convenient spatial separation of the incoming and outgoing beams is possible. For the sake of example, we present blades that fit into a circle of 10cm diameter. Finally, a prototype of a rotary delay line is fabricated using CNC machining, and its optical properties are characterized.

An alternative to the standard spatial econometric approaches in hedonic house price models

DEFF Research Database (Denmark)

von Graevenitz, Kathrine; Panduro, Toke Emil

2015-01-01

Omitted, misspecified, or mismeasured spatially varying characteristics are a cause for concern in hedonic house price models. Spatial econometrics or spatial fixed effects have become popular ways of addressing these concerns. We discuss the limitations of standard spatial approaches to hedonic...

Resonator memories and optical novelty filters

Science.gov (United States)

Anderson, Dana Z.; Erle, Marie C.

Optical resonators having holographic elements are potential candidates for storing information that can be accessed through content addressable or associative recall. Closely related to the resonator memory is the optical novelty filter, which can detect the differences between a test object and a set of reference objects. We discuss implementations of these devices using continuous optical media such as photorefractive materials. The discussion is framed in the context of neural network models. There are both formal and qualitative similarities between the resonator memory and optical novelty filter and network models. Mode competition arises in the theory of the resonator memory, much as it does in some network models. We show that the role of the phenomena of "daydreaming" in the real-time programmable optical resonator is very much akin to the role of "unlearning" in neural network memories. The theory of programming the real-time memory for a single mode is given in detail. This leads to a discussion of the optical novelty filter. Experimental results for the resonator memory, the real-time programmable memory, and the optical tracking novelty filter are reviewed. We also point to several issues that need to be addressed in order to implement more formal models of neural networks.

A review of snapshot multidimensional optical imaging: Measuring photon tags in parallel

Energy Technology Data Exchange (ETDEWEB)

Gao, Liang, E-mail: gaol@illinois.edu [Department of Electrical and Computer Engineering, University of Illinois at Urbana–Champaign, 306 N. Wright St., Urbana, IL 61801 (United States); Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, 405 North Mathews Avenue, Urbana, IL 61801 (United States); Wang, Lihong V., E-mail: lhwang@wustl.edu [Optical imaging laboratory, Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., MO, 63130 (United States)

2016-02-29

Multidimensional optical imaging has seen remarkable growth in the past decade. Rather than measuring only the two-dimensional spatial distribution of light, as in conventional photography, multidimensional optical imaging captures light in up to nine dimensions, providing unprecedented information about incident photons’ spatial coordinates, emittance angles, wavelength, time, and polarization. Multidimensional optical imaging can be accomplished either by scanning or parallel acquisition. Compared with scanning-based imagers, parallel acquisition–also dubbed snapshot imaging–has a prominent advantage in maximizing optical throughput, particularly when measuring a datacube of high dimensions. Here, we first categorize snapshot multidimensional imagers based on their acquisition and image reconstruction strategies, then highlight the snapshot advantage in the context of optical throughput, and finally we discuss their state-of-the-art implementations and applications.

Optical network democratization.

Science.gov (United States)

Nejabati, Reza; Peng, Shuping; Simeonidou, Dimitra

2016-03-06

The current Internet infrastructure is not able to support independent evolution and innovation at physical and network layer functionalities, protocols and services, while at same time supporting the increasing bandwidth demands of evolving and heterogeneous applications. This paper addresses this problem by proposing a completely democratized optical network infrastructure. It introduces the novel concepts of the optical white box and bare metal optical switch as key technology enablers for democratizing optical networks. These are programmable optical switches whose hardware is loosely connected internally and is completely separated from their control software. To alleviate their complexity, a multi-dimensional abstraction mechanism using software-defined network technology is proposed. It creates a universal model of the proposed switches without exposing their technological details. It also enables a conventional network programmer to develop network applications for control of the optical network without specific technical knowledge of the physical layer. Furthermore, a novel optical network virtualization mechanism is proposed, enabling the composition and operation of multiple coexisting and application-specific virtual optical networks sharing the same physical infrastructure. Finally, the optical white box and the abstraction mechanism are experimentally evaluated, while the virtualization mechanism is evaluated with simulation. © 2016 The Author(s).

Frontiers in optical imaging of cerebral blood flow and metabolism.

Science.gov (United States)

Devor, Anna; Sakadžić, Sava; Srinivasan, Vivek J; Yaseen, Mohammad A; Nizar, Krystal; Saisan, Payam A; Tian, Peifang; Dale, Anders M; Vinogradov, Sergei A; Franceschini, Maria Angela; Boas, David A

2012-07-01

In vivo optical imaging of cerebral blood flow (CBF) and metabolism did not exist 50 years ago. While point optical fluorescence and absorption measurements of cellular metabolism and hemoglobin concentrations had already been introduced by then, point blood flow measurements appeared only 40 years ago. The advent of digital cameras has significantly advanced two-dimensional optical imaging of neuronal, metabolic, vascular, and hemodynamic signals. More recently, advanced laser sources have enabled a variety of novel three-dimensional high-spatial-resolution imaging approaches. Combined, as we discuss here, these methods are permitting a multifaceted investigation of the local regulation of CBF and metabolism with unprecedented spatial and temporal resolution. Through multimodal combination of these optical techniques with genetic methods of encoding optical reporter and actuator proteins, the future is bright for solving the mysteries of neurometabolic and neurovascular coupling and translating them to clinical utility.

System performances of optical space code-division multiple-access-based fiber-optic two-dimensional parallel data link.

Science.gov (United States)

Nakamura, M; Kitayama, K

1998-05-10

Optical space code-division multiple access is a scheme to multiplex and link data between two-dimensional processors such as smart pixels and spatial light modulators or arrays of optical sources like vertical-cavity surface-emitting lasers. We examine the multiplexing characteristics of optical space code-division multiple access by using optical orthogonal signature patterns. The probability density function of interference noise in interfering optical orthogonal signature patterns is calculated. The bit-error rate is derived from the result and plotted as a function of receiver threshold, code length, code weight, and number of users. Furthermore, we propose a prethresholding method to suppress the interference noise, and we experimentally verify that the method works effectively in improving system performance.

Optical identification using imperfections in 2D materials

Science.gov (United States)

Cao, Yameng; Robson, Alexander J.; Alharbi, Abdullah; Roberts, Jonathan; Woodhead, Christopher S.; Noori, Yasir J.; Bernardo-Gavito, Ramón; Shahrjerdi, Davood; Roedig, Utz; Fal'ko, Vladimir I.; Young, Robert J.

2017-12-01

The ability to uniquely identify an object or device is important for authentication. Imperfections, locked into structures during fabrication, can be used to provide a fingerprint that is challenging to reproduce. In this paper, we propose a simple optical technique to read unique information from nanometer-scale defects in 2D materials. Imperfections created during crystal growth or fabrication lead to spatial variations in the bandgap of 2D materials that can be characterized through photoluminescence measurements. We show a simple setup involving an angle-adjustable transmission filter, simple optics and a CCD camera can capture spatially-dependent photoluminescence to produce complex maps of unique information from 2D monolayers. Atomic force microscopy is used to verify the origin of the optical signature measured, demonstrating that it results from nanometer-scale imperfections. This solution to optical identification with 2D materials could be employed as a robust security measure to prevent counterfeiting.

The optic nerve head in glaucoma

Directory of Open Access Journals (Sweden)

Rupert RA Bourne

2006-09-01

Full Text Available ll types of glaucoma involve glaucomatous optic neuropathy. The key to detection and management of glaucoma is understanding how to examine the optic nerve head (ONH. This pictorial glossary addresses the following issues: how to examine the ONH; normal characteristics of the ONH; characteristics of a glaucomatous ONH; how to tell if the glaucomatous optic neuropathy is getting worse;‘pitfalls and pearls’.

Localization of optical excitations on random surfaces: SNOM studies

DEFF Research Database (Denmark)

Bozhevolnyi, Sergey I.

1999-01-01

Localization of optical excitations on nanostructured metal surfaces and fractal colloid silver aggregates are studied by using a scanning near-field optical microscope (SNOM). The SNOM images obtained in both configurations exhibit spatially localized (within 150 to 250 nm) light intensity...

Linear optics and quantum maps

International Nuclear Information System (INIS)

Aiello, A.; Puentes, G.; Woerdman, J. P.

2007-01-01

We present a theoretical analysis of the connection between classical polarization optics and quantum mechanics of two-level systems. First, we review the matrix formalism of classical polarization optics from a quantum information perspective. In this manner the passage from the Stokes-Jones-Mueller description of classical optical processes to the representation of one- and two-qubit quantum operations, becomes straightforward. Second, as a practical application of our classical-vs-quantum formalism, we show how two-qubit maximally entangled mixed states can be generated by using polarization and spatial modes of photons generated via spontaneous parametric down conversion

Integration of LCoS-SLM and LabVIEW based software to simulate fundamental optics, wave optics, and Fourier optics

Science.gov (United States)

Lyu, Bo-Han; Wang, Chen; Tsai, Chun-Wei

2017-08-01

Jasper Display Corp. (JDC) offer high reflectivity, high resolution Liquid Crystal on Silicon - Spatial Light Modulator (LCoS-SLM) which include an associated controller ASIC and LabVIEW based modulation software. Based on this LCoS-SLM, also called Education Kit (EDK), we provide a training platform which includes a series of optical theory and experiments to university students. This EDK not only provides a LabVIEW based operation software to produce Computer Generated Holograms (CGH) to generate some basic diffraction image or holographic image, but also provides simulation software to verity the experiment results simultaneously. However, we believe that a robust LCoSSLM, operation software, simulation software, training system, and training course can help students to study the fundamental optics, wave optics, and Fourier optics more easily. Based on these fundamental knowledges, they could develop their unique skills and create their new innovations on the optoelectronic application in the future.

Applications of Spatial Data Using Business Analytics Tools

Directory of Open Access Journals (Sweden)

Anca Ioana ANDREESCU

2011-12-01

Full Text Available This paper addresses the possibilities of using spatial data in business analytics tools, with emphasis on SAS software. Various kinds of map data sets containing spatial data are presented and discussed. Examples of map charts illustrating macroeconomic parameters demonstrate the application of spatial data for the creation of map charts in SAS Enterprise Guise. Extended features of map charts are being exemplified by producing charts via SAS programming procedures.

RADIANCE AND PHOTON NOISE: Imaging in geometrical optics, physical optics, quantum optics and radiology.

Science.gov (United States)

Barrett, Harrison H; Myers, Kyle J; Caucci, Luca

2014-08-17

A fundamental way of describing a photon-limited imaging system is in terms of a Poisson random process in spatial, angular and wavelength variables. The mean of this random process is the spectral radiance. The principle of conservation of radiance then allows a full characterization of the noise in the image (conditional on viewing a specified object). To elucidate these connections, we first review the definitions and basic properties of radiance as defined in terms of geometrical optics, radiology, physical optics and quantum optics. The propagation and conservation laws for radiance in each of these domains are reviewed. Then we distinguish four categories of imaging detectors that all respond in some way to the incident radiance, including the new category of photon-processing detectors. The relation between the radiance and the statistical properties of the detector output is discussed and related to task-based measures of image quality and the information content of a single detected photon.

Application of Fourier analysis to multispectral/spatial recognition

Science.gov (United States)

Hornung, R. J.; Smith, J. A.

1973-01-01

One approach for investigating spectral response from materials is to consider spatial features of the response. This might be accomplished by considering the Fourier spectrum of the spatial response. The Fourier Transform may be used in a one-dimensional to multidimensional analysis of more than one channel of data. The two-dimensional transform represents the Fraunhofer diffraction pattern of the image in optics and has certain invariant features. Physically the diffraction pattern contains spatial features which are possibly unique to a given configuration or classification type. Different sampling strategies may be used to either enhance geometrical differences or extract additional features.

2D Spatial Frequency Considerations in Comparing 1D Power Spectral Density Measurements

International Nuclear Information System (INIS)

Takacs, P.Z.; Barber, S.; Church, E.L.; Kaznatcheev, K.; McKinney, W.R.; Yashchuk, V.Y.

2010-01-01

The frequency footprint of ID and 2D profiling instruments needs to be carefully considered in comparing ID surface roughness spectrum measurements made by different instruments. Contributions from orthogonal direction frequency components can not be neglected. The use of optical profiling instruments is ubiquitous in the measurement of the roughness of optical surfaces. Their ease-of-use and non-contact measurement method found widespread use in the optics industry for measuring the quality of delicate optical surfaces. Computerized digital data acquisition with these instruments allowed for quick and easy calculation of surface roughness statistics, such as root-mean-square (RMS) roughness. The computing power of the desktop computer allowed for the rapid conversion of spatial domain data into the frequency domain, enabling the application of sophisticated signal processing techniques to be applied to the analysis of surface roughness, the most powerful of which is the power spectral density (PSP) function. Application of the PSD function to surface statistics introduced the concept of 'bandwidth-limited' roughness, where the value of the RMS roughness depends critically upon the spatial frequency response of the instrument. Different instruments with different spatial frequency response characteristics give different answers when measuring the same surface.

KEYNOTE ADDRESS: The role of standards in the emerging optical digital data disk storage systems market

Science.gov (United States)

Bainbridge, Ross C.

1984-09-01

The Institute for Computer Sciences and Technology at the National Bureau of Standards is pleased to cooperate with the International Society for Optical Engineering and to join with the other distinguished organizations in cosponsoring this conference on applications of optical digital data disk storage systems.

Fiber-optic dosimeters for radiation therapy

Science.gov (United States)

Li, Enbang; Archer, James

2017-10-01

According to the figures provided by the World Health Organization, cancer is a leading cause of death worldwide, accounting for 8.8 million deaths in 2015. Radiation therapy, which uses x-rays to destroy or injure cancer cells, has become one of the most important modalities to treat the primary cancer or advanced cancer. The newly developed microbeam radiation therapy (MRT), which uses highly collimated, quasi-parallel arrays of x-ray microbeams (typically 50 μm wide and separated by 400 μm) produced by synchrotron sources, represents a new paradigm in radiotherapy and has shown great promise in pre-clinical studies on different animal models. Measurements of the absorbed dose distribution of microbeams are vitally important for clinical acceptance of MRT and for developing quality assurance systems for MRT, hence are a challenging and important task for radiation dosimetry. On the other hand, during the traditional LINAC based radiotherapy and breast cancer brachytherapy, skin dose measurements and treatment planning also require a high spatial resolution, tissue equivalent, on-line dosimeter that is both economical and highly reliable. Such a dosimeter currently does not exist and remains a challenge in the development of radiation dosimetry. High resolution, water equivalent, optical and passive x-ray dosimeters have been developed and constructed by using plastic scintillators and optical fibers. The dosimeters have peak edge-on spatial resolutions ranging from 50 to 500 microns in one dimension, with a 10 micron resolution dosimeter under development. The developed fiber-optic dosimeters have been test with both LINAC and synchrotron x-ray beams. This work demonstrates that water-equivalent and high spatial resolution radiation detection can be achieved with scintillators and optical fiber systems. Among other advantages, the developed fiber-optic probes are also passive, energy independent, and radiation hard.

Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography.

Science.gov (United States)

Liu, Chih-Hao; Du, Yong; Singh, Manmohan; Wu, Chen; Han, Zhaolong; Li, Jiasong; Chang, Anthony; Mohan, Chandra; Larin, Kirill V

2016-08-01

Acute glomerulonephritis caused by antiglomerular basement membrane marked by high mortality. The primary reason for this is delayed diagnosis via blood examination, urine analysis, tissue biopsy, or ultrasound and X-ray computed tomography imaging. Blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution, with reduced sensitivity. Optical coherence tomography is a noninvasive and high-resolution imaging technique that provides superior spatial resolution (micrometer scale) as compared to ultrasound and CT. Changes in tissue properties can be detected based on the optical metrics analyzed from the OCT signals, such as optical attenuation and speckle variance. Furthermore, OCT does not rely on ionizing radiation as with CT imaging. In addition to structural changes, the elasticity of the kidney can significantly change due to nephritis. In this work, OCT has been utilized to quantify the difference in tissue properties between healthy and nephritic murine kidneys. Although OCT imaging could identify the diseased tissue, its classification accuracy is clinically inadequate. By combining optical metrics with elasticity, the classification accuracy improves from 76% to 95%. These results show that OCT combined with OCE can be a powerful tool for identifying and classifying nephritis. Therefore, the OCT/OCE method could potentially be used as a minimally invasive tool for longitudinal studies during the progression and therapy of glomerulonephritis as well as complement and, perhaps, substitute highly invasive tissue biopsies. Elastic-wave propagation in mouse healthy and nephritic kidneys. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-Mechanical Beam Steering in Free-Space Optical Communication Transceivers

Science.gov (United States)

Shortt, Kevin

Free-space optical communications systems are a rapidly growing field as they carry many of the advantages of traditional fibre-based communications systems without the added investment of installing complex infrastructure. Moreover, these systems are finding key niches in mobile platforms in order to take advantage of the increased bandwidth over traditional RF systems. Of course, the inevitable problem of tracking arises when dealing with mobile stations. To compound the problem in the case of communications to low Earth or geosynchronous orbits, FSOC systems typically operate with tightly confined beams over great distances often requiring pointing accuracies on the order of micro-radians or smaller. Mechanisms such as gimbal mounts and fine-steering mirrors are the usual candidates for platform stabilization, however, these clearly have substantial power requirements and inflate the mass of the system. Spatial light modulators (also known as optical phased arrays), on the other hand, offer a suitable alternative for beam-pointing stabilization. Some of the advantages of spatial light modulators over fine-steering mirrors include programmable multiple simultaneous beams, dynamic focus/defocus and moderate to excellent optical power handling capability. This thesis serves as an investigation into the implementation of spatial light modulators as a replacement for traditional fine-steering mirrors in the fine-pointing subsystem. In particular, pointing accuracy and scanning ability will be highlighted as performance metrics in the context of a variety of communication scenarios. Keywords: Free-space optical communications, beam steering, fine-steering mirror, spatial light modulator, optical phased array.

Fabry-Perot confocal resonator optical associative memory

Science.gov (United States)

Burns, Thomas J.; Rogers, Steven K.; Vogel, George A.

1993-03-01

A unique optical associative memory architecture is presented that combines the optical processing environment of a Fabry-Perot confocal resonator with the dynamic storage and recall properties of volume holograms. The confocal resonator reduces the size and complexity of previous associative memory architectures by folding a large number of discrete optical components into an integrated, compact optical processing environment. Experimental results demonstrate the system is capable of recalling a complete object from memory when presented with partial information about the object. A Fourier optics model of the system's operation shows it implements a spatially continuous version of a discrete, binary Hopfield neural network associative memory.

Optically intraconnected computer employing dynamically reconfigurable holographic optical element

Science.gov (United States)

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.

Current developments in optical engineering and commercial optics; Proceedings of the Meeting, San Diego, CA, Aug. 7-11, 1989

Science.gov (United States)

Fischer, Robert E. (Editor); Pollicove, Harvey M. (Editor); Smith, Warren J. (Editor)

1989-01-01

Various papers on current developments in optical engineering and commercial optics are presented. Individual topics addressed include: large optics fabrication technology drivers and new manufacturing techniques, new technology for beryllium mirror production, design examples of hybrid refractive-diffractive lenses, optical sensor designs for detecting cracks in optical materials, retroreflector field-of-view properties for open and solid cube corners, correction of misalignment-dependent aberrations of the HST via phase retrieval, basic radiometry review for seeker test set, radiation effects on visible optical elements, and nonlinear simulation of efficiency for large-orbit nonwiggler FELs.

Observation of three dimensional optical rogue waves through obstacles

International Nuclear Information System (INIS)

Leonetti, Marco; Conti, Claudio

2015-01-01

We observe three-dimensional rogue waves in the speckle distribution of a spatially modulated optical beam. Light is transmitted beyond a partially reflecting obstacle generating optical rogue waves at a controlled position in the shadow of the barrier. When the barrier transmits only 0.07% of the input laser power, we observe the mostly localized event. These results demonstrate that an optimum amount of spatial non-homogeneity maximizes the probability of a gigantic event while the technique we exploit enables to control light behind a fully reflective wall

Status of optics on the OMEGA laser after 18 months of operation

International Nuclear Information System (INIS)

Rigatti, A.L.; Smith, D.J.

1997-01-01

The 60-beam OMEGA laser has sustained approximately 1000 target shots without significant damage to the optics. Approximately 3000 optics on the OMEGA laser system were closely monitored during their installation, and inspections continue throughout the operation of the system. A review of the condition of these optics at each stage of the laser and a summary of the peak incident fluences are presented. The most severe damage on OMEGA is seen on the input, fused-silica, spatial filter lenses. Since these optics are under vacuum, inspection of damaged lenses occurs on a more frequent cycle to track the growth of the defect and to maintain the system's safety. An optic is replaced well before massive failure is expected to occur. Other optics on the system that exhibit different types of damage are BK-7 spatial filter lenses, focus lenses, and target mirrors. The majority of OMEGA optics are not damaging. These include the polarizers, frequency-conversion crystals, primary pickoff lenses, calorimeters, and liquid-crystal optics. Laser glass and development optics such as distributed phase plates are not covered in this review

Spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources. Experimental results

International Nuclear Information System (INIS)

Panitzsch, Lauri

2013-01-01

The experimental determination of the spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources (ECRIS) defines the focus of this thesis. The spatial distributions of different ion species were obtained in the object plane of the bending magnet (∼45 cm downstream from the plasma electrode) and in the plane of the plasma electrode itself, both in high spatial resolution. The results show that each of the different ion species forms a bloated, triangular structure in the aperture of the plasma electrode. The geometry and the orientation of these structures are defined by the superposition of the radial and axial magnetic fields. The radial extent of each structure is defined by the charge of the ion. Higher charge states occupy smaller, more concentrated structures. The total current density increases towards the center of the plasma electrode. The circular and star-like structures that can be observed in the beam profiles of strongly focused, extracted ion beams are each dominated by ions of a single charge state. In addition, the spatially resolved current density distribution of charged particles in the plasma chamber that impinge on the plasma electrode was determined, differentiating between ions and electrons. The experimental results of this work show that the electrons of the plasma are strongly connected to the magnetic field lines in the source and thus spatially well confined in a triangular-like structure. The intensity of the electrons increases towards the center of the plasma electrode and the plasma chamber, as well. These electrons are surrounded by a spatially far less confined and less intense ion population. All the findings mentioned above were already predicted in parts by simulations of different groups. However, the results presented within this thesis represent the first (and by now only) direct experimental verification of those predictions and are qualitatively transferable to other

Spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources. Experimental results

Energy Technology Data Exchange (ETDEWEB)

Panitzsch, Lauri

2013-02-08

The experimental determination of the spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources (ECRIS) defines the focus of this thesis. The spatial distributions of different ion species were obtained in the object plane of the bending magnet ({approx}45 cm downstream from the plasma electrode) and in the plane of the plasma electrode itself, both in high spatial resolution. The results show that each of the different ion species forms a bloated, triangular structure in the aperture of the plasma electrode. The geometry and the orientation of these structures are defined by the superposition of the radial and axial magnetic fields. The radial extent of each structure is defined by the charge of the ion. Higher charge states occupy smaller, more concentrated structures. The total current density increases towards the center of the plasma electrode. The circular and star-like structures that can be observed in the beam profiles of strongly focused, extracted ion beams are each dominated by ions of a single charge state. In addition, the spatially resolved current density distribution of charged particles in the plasma chamber that impinge on the plasma electrode was determined, differentiating between ions and electrons. The experimental results of this work show that the electrons of the plasma are strongly connected to the magnetic field lines in the source and thus spatially well confined in a triangular-like structure. The intensity of the electrons increases towards the center of the plasma electrode and the plasma chamber, as well. These electrons are surrounded by a spatially far less confined and less intense ion population. All the findings mentioned above were already predicted in parts by simulations of different groups. However, the results presented within this thesis represent the first (and by now only) direct experimental verification of those predictions and are qualitatively transferable to

Azimuthal decomposition of optical modes

CSIR Research Space (South Africa)

Dudley, Angela L

2012-07-01

Full Text Available This presentation analyses the azimuthal decomposition of optical modes. Decomposition of azimuthal modes need two steps, namely generation and decomposition. An azimuthally-varying phase (bounded by a ring-slit) placed in the spatial frequency...

Spatial and temporal variability in bio-optical properties of the Wadden Sea

NARCIS (Netherlands)

Hommersom, A.; Peters, S.W.M.; Wernand, M.; de Boer, J.

2009-01-01

The Wadden Sea, a shallow coastal area bordering the North Sea, is optically a complex area due to its shallowness, high turbidity and fast changes in concentrations of optically active substances. This study gathers information from the area on concentrations of suspended particulate matter (SPM),

TV-acquired optical diagnostics systems on ATA

International Nuclear Information System (INIS)

Kalibjian, R.; Chong, Y.P.; Cornish, J.P.; Jackson, C.H.; Fessenden, T.J.

1984-06-01

The purpose of this paper is to report on optical system developments on the ATA and their applications to ATA beam characterization. Television (TV)-acquired optical diagnostics data provide spatial and temporal properties of the ATA beam that complements recorded information from other types of sensors, such as, beam-wall current monitors, x-ray probes, and rf probes. The ATA beam operates: (1) in the normal mode at 50-MeV, 10-kA at a 1-Hz rate; and (2) in the 1-KHz burst mode (for 10-pulses) at a 0.5 Hz rate. The beam has a 70-ns pulse width in vacuum propagation; however, beam-head erosion will occur in atmospheric propagation, thus limiting the pulse width to less than 50-ns. Various optical systems are used for ATA diagnostics. Optical-imaging provides a convenient measurement in a single pulse of the 2-dimensional profile of the beam intensity. It can also provide multiple 2-D framing in a single pulse. In some studies it may be desirable to study optical events with temporal resolution less than 100-ps with 1-dimensional streak cameras. Spatially integrated data from phototube cameras can also be used for background measurement applications as well as for single pixel monitoring. The optical line-of-sight (LOS) configurations have been made versatile to accommodate a large number of options for the various optical systems

Single spin stochastic optical reconstruction microscopy

OpenAIRE

Pfender, Matthias; Aslam, Nabeel; Waldherr, Gerald; Wrachtrup, Jörg

2014-01-01

We experimentally demonstrate precision addressing of single quantum emitters by combined optical microscopy and spin resonance techniques. To this end we utilize nitrogen-vacancy (NV) color centers in diamond confined within a few ten nanometers as individually resolvable quantum systems. By developing a stochastic optical reconstruction microscopy (STORM) technique for NV centers we are able to simultaneously perform sub diffraction-limit imaging and optically detected spin resonance (ODMR)...

Performance analysis of decode-and-forward dual-hop optical spatial modulation with diversity combiner over atmospheric turbulence

Science.gov (United States)

Odeyemi, Kehinde O.; Owolawi, Pius A.; Srivastava, Viranjay M.

2017-11-01

Dual-hops transmission is a growing interest technique that can be used to mitigate against atmospheric turbulence along the Free Space Optical (FSO) communication links. This paper analyzes the performance of Decode-and-Forward (DF) dual-hops FSO systems in-conjunction with spatial modulation and diversity combiners over a Gamma-Gamma atmospheric turbulence channel using heterodyne detection. Maximum Ratio Combiner (MRC), Equal Gain Combiner (EGC) and Selection Combiner (SC) are considered at the relay and destination as mitigation tools to improve the system error performance. Power series expansion of modified Bessel function is used to derive the closed form expression for the end-to-end Average Pairwise Error Probability (APEP) expressions for each of the combiners under study and a tight upper bound on the Average Bit Error Rate (ABER) per hop is given. Thus, the overall end-to-end ABER for the dual-hops FSO system is then evaluated. The numerical results depicted that dual-hops transmission systems outperformed the direct link systems. Moreover, the impact of having the same and different combiners at the relay and destination are also presented. The results also confirm that the combination of dual hops transmission with spatial modulation and diversity combiner significantly improves the systems error rate with the MRC combiner offering an optimal performance with respect to variation in atmospheric turbulence, change in links average received SNR and link range of the system.

Machine learning concepts in coherent optical communication systems

DEFF Research Database (Denmark)

Zibar, Darko; Schäffer, Christian G.

2014-01-01

Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA.......Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA....

Causality and analyticity in optics

International Nuclear Information System (INIS)

Nussenzveig, H.M.

In order to provide an overall picture of the broad range of optical phenomena that are directly linked with the concepts of causality and analyticity, the following topics are briefly reviewed, emphasizing recent developments: 1) Derivation of dispersion relations for the optical constants of general linear media from causality. Application to the theory of natural optical activity. 2) Derivation of sum rules for the optical constants from causality and from the short-time response function (asymptotic high-frequency behavior). Average spectral behavior of optical media. Applications. 3) Role of spectral conditions. Analytic properties of coherence functions in quantum optics. Reconstruction theorem.4) Phase retrieval problems. 5) Inverse scattering problems. 6) Solution of nonlinear evolution equations in optics by inverse scattering methods. Application to self-induced transparency. Causality in nonlinear wave propagation. 7) Analytic continuation in frequency and angular momentum. Complex singularities. Resonances and natural-mode expansions. Regge poles. 8) Wigner's causal inequality. Time delay. Spatial displacements in total reflection. 9) Analyticity in diffraction theory. Complex angular momentum theory of Mie scattering. Diffraction as a barrier tunnelling effect. Complex trajectories in optics. (Author) [pt

Characterisation of optical filters for broadband UVA radiometer

Science.gov (United States)

Alves, Luciana C.; Coelho, Carla T.; Corrêa, Jaqueline S. P. M.; Menegotto, Thiago; Ferreira da Silva, Thiago; Aparecida de Souza, Muriel; Melo da Silva, Elisama; Simões de Lima, Maurício; Dornelles de Alvarenga, Ana Paula

2016-07-01

Optical filters were characterized in order to know its suitability for use in broadband UVA radiometer head for spectral irradiance measurements. The spectral transmittance, the angular dependence and the spatial uniformity of the spectral transmittance of the UVA optical filters were investigated. The temperature dependence of the transmittance was also studied.

Distributed fiber?optic temperature sensing for hydrologic systems

NARCIS (Netherlands)

Selker, J.S.; Thévenaz, L.; Huwald, H.; Mallet, A.; Luxemburg, W.M.J.; Van de Giesen, N.; Stejskal, M.; Zeman, J.; Westhoff, M.; Parlange, M.B.

2006-01-01

Instruments for distributed fiber-optic measurement of temperature are now available with temperature resolution of 0.01°C and spatial resolution of 1 m with temporal resolution of fractions of a minute along standard fiber-optic cables used for communication with lengths of up to 30,000 m. We

Distributed fiber-optic temperature sensing for hydrologic systems

NARCIS (Netherlands)

Selker, John S.; Thévenaz, Luc; Huwald, Hendrik; Mallet, Alfred; Luxemburg, Wim; van de Giesen, Nick C.; Stejskal, Martin; Zeman, Josef; Westhoff, Martijn; Parlange, Marc B.

2006-01-01

Instruments for distributed fiber-optic measurement of temperature are now available with temperature resolution of 0.01°C and spatial resolution of 1 m with temporal resolution of fractions of a minute along standard fiber-optic cables used for communication with lengths of up to 30,000 m. We

Atomic molecular and optical physics

International Nuclear Information System (INIS)

Anon.

1986-01-01

Laser-assisted manufacturing and fiber-optics communications are but two of the products of atomic, molecular, and optical physics, (AMO) research. AMO physics provides theoretical and experimental methods and essential data to neighboring areas of science such as chemistry, astrophysics, condensed-matter physics, plasma physics, surface science, biology, and medicine. This book addresses advances in atomic, molecular, and optical fields and provides recommendations for further research. It also looks at scientific applications in national security, manufacturing, medicine, and other fields

Hierarchical modeling and analysis for spatial data

CERN Document Server

Banerjee, Sudipto; Gelfand, Alan E

2003-01-01

Among the many uses of hierarchical modeling, their application to the statistical analysis of spatial and spatio-temporal data from areas such as epidemiology And environmental science has proven particularly fruitful. Yet to date, the few books that address the subject have been either too narrowly focused on specific aspects of spatial analysis, or written at a level often inaccessible to those lacking a strong background in mathematical statistics.Hierarchical Modeling and Analysis for Spatial Data is the first accessible, self-contained treatment of hierarchical methods, modeling, and dat

Quantum optical effective-medium theory and transformation quantum optics for metamaterials

DEFF Research Database (Denmark)

Wubs, Martijn; Amooghorban, Ehsan; Zhang, Jingjing

2016-01-01

electrodynamics of media with both loss and gain. In the second part of this paper, we present a new application of transformation optics whereby local spontaneous-emission rates of quantum emitters can be designed. This follows from an analysis how electromagnetic Green functions transform under coordinate......While typically designed to manipulate classical light, metamaterials have many potential applications for quantum optics as well. We argue why a quantum optical effective-medium theory is needed. We present such a theory for layered metamaterials that is valid for light propagation in all spatial...... directions, thereby generalizing earlier work for one-dimensional propagation. In contrast to classical effective-medium theory there is an additional effective parameter that describes quantum noise. Our results for metamaterials are based on a rather general Lagrangian theory for the quantum...

Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

Science.gov (United States)

Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

2015-02-01

We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz.

Accounting for spatial effects in land use regression for urban air pollution modeling.

Science.gov (United States)

Bertazzon, Stefania; Johnson, Markey; Eccles, Kristin; Kaplan, Gilaad G

2015-01-01

In order to accurately assess air pollution risks, health studies require spatially resolved pollution concentrations. Land-use regression (LUR) models estimate ambient concentrations at a fine spatial scale. However, spatial effects such as spatial non-stationarity and spatial autocorrelation can reduce the accuracy of LUR estimates by increasing regression errors and uncertainty; and statistical methods for resolving these effects--e.g., spatially autoregressive (SAR) and geographically weighted regression (GWR) models--may be difficult to apply simultaneously. We used an alternate approach to address spatial non-stationarity and spatial autocorrelation in LUR models for nitrogen dioxide. Traditional models were re-specified to include a variable capturing wind speed and direction, and re-fit as GWR models. Mean R(2) values for the resulting GWR-wind models (summer: 0.86, winter: 0.73) showed a 10-20% improvement over traditional LUR models. GWR-wind models effectively addressed both spatial effects and produced meaningful predictive models. These results suggest a useful method for improving spatially explicit models. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Structured caustic vector vortex optical field: manipulating optical angular momentum flux and polarization rotation.

Science.gov (United States)

Chen, Rui-Pin; Chen, Zhaozhong; Chew, Khian-Hooi; Li, Pei-Gang; Yu, Zhongliang; Ding, Jianping; He, Sailing

2015-05-29

A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-based approach. The desired caustic with arbitrary acceleration trajectories, as well as the structured states of polarization (SoP) and vortex orders located in different positions in the field cross-section, is generated by imposing the corresponding spatial phase function in a vector vortex optical field. Our study reveals that different spin and orbital angular momentum flux distributions (including opposite directions) in different positions in the cross-section of a caustic vector vortex optical field can be dynamically managed during propagation by intentionally choosing the initial polarization and vortex topological charges, as a result of the modulation of the caustic phase. We find that the SoP in the field cross-section rotates during propagation due to the existence of the vortex. The unique structured feature of the caustic vector vortex optical field opens the possibility of multi-manipulation of optical angular momentum fluxes and SoP, leading to more complex manipulation of the optical field scenarios. Thus this approach further expands the functionality of an optical system.

Wavefront measurement using computational adaptive optics.

Science.gov (United States)

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

2018-03-01

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

Spatial Culture

DEFF Research Database (Denmark)

Reeh, Henrik

2012-01-01

Spatial Culture – A Humanities Perspective Abstract of introductory essay by Henrik Reeh Secured by alliances between socio-political development and cultural practices, a new field of humanistic studies in spatial culture has developed since the 1990s. To focus on links between urban culture...... and modern society is, however, an intellectual practice which has a much longer history. Already in the 1980s, the debate on the modern and the postmodern cited Paris and Los Angeles as spatio-cultural illustrations of these major philosophical concepts. Earlier, in the history of critical studies, the work...... Foucault considered a constitutive feature of 20th-century thinking and one that continues to occupy intellectual and cultural debates in the third millennium. A conceptual framework is, nevertheless, necessary, if the humanities are to adequa-tely address city and space – themes that have long been...

Theoretical description and design of nanomaterial slab waveguides: application to compensation of optical diffraction.

Science.gov (United States)

Kivijärvi, Ville; Nyman, Markus; Shevchenko, Andriy; Kaivola, Matti

2018-04-02

Planar optical waveguides made of designable spatially dispersive nanomaterials can offer new capabilities for nanophotonic components. As an example, a thin slab waveguide can be designed to compensate for optical diffraction and provide divergence-free propagation for strongly focused optical beams. Optical signals in such waveguides can be transferred in narrow channels formed by the light itself. We introduce here a theoretical method for characterization and design of nanostructured waveguides taking into account their inherent spatial dispersion and anisotropy. Using the method, we design a diffraction-compensating slab waveguide that contains only a single layer of silver nanorods. The waveguide shows low propagation loss and broadband diffraction compensation, potentially allowing transfer of optical information at a THz rate.

Atlas-based head modeling and spatial normalization for high-density diffuse optical tomography: in vivo validation against fMRI.

Science.gov (United States)

Ferradal, Silvina L; Eggebrecht, Adam T; Hassanpour, Mahlega; Snyder, Abraham Z; Culver, Joseph P

2014-01-15

Diffuse optical imaging (DOI) is increasingly becoming a valuable neuroimaging tool when fMRI is precluded. Recent developments in high-density diffuse optical tomography (HD-DOT) overcome previous limitations of sparse DOI systems, providing improved image quality and brain specificity. These improvements in instrumentation prompt the need for advancements in both i) realistic forward light modeling for accurate HD-DOT image reconstruction, and ii) spatial normalization for voxel-wise comparisons across subjects. Individualized forward light models derived from subject-specific anatomical images provide the optimal inverse solutions, but such modeling may not be feasible in all situations. In the absence of subject-specific anatomical images, atlas-based head models registered to the subject's head using cranial fiducials provide an alternative solution. In addition, a standard atlas is attractive because it defines a common coordinate space in which to compare results across subjects. The question therefore arises as to whether atlas-based forward light modeling ensures adequate HD-DOT image quality at the individual and group level. Herein, we demonstrate the feasibility of using atlas-based forward light modeling and spatial normalization methods. Both techniques are validated using subject-matched HD-DOT and fMRI data sets for visual evoked responses measured in five healthy adult subjects. HD-DOT reconstructions obtained with the registered atlas anatomy (i.e. atlas DOT) had an average localization error of 2.7mm relative to reconstructions obtained with the subject-specific anatomical images (i.e. subject-MRI DOT), and 6.6mm relative to fMRI data. At the group level, the localization error of atlas DOT reconstruction was 4.2mm relative to subject-MRI DOT reconstruction, and 6.1mm relative to fMRI. These results show that atlas-based image reconstruction provides a viable approach to individual head modeling for HD-DOT when anatomical imaging is not available

Improving the surface metrology accuracy of optical profilers by using multiple measurements

Science.gov (United States)

Xu, Xudong; Huang, Qiushi; Shen, Zhengxiang; Wang, Zhanshan

2016-10-01

The performance of high-resolution optical systems is affected by small angle scattering at the mid-spatial-frequency irregularities of the optical surface. Characterizing these irregularities is, therefore, important. However, surface measurements obtained with optical profilers are influenced by additive white noise, as indicated by the heavy-tail effect observable on their power spectral density (PSD). A multiple-measurement method is used to reduce the effects of white noise by averaging individual measurements. The intensity of white noise is determined using a model based on the theoretical PSD of fractal surface measurements with additive white noise. The intensity of white noise decreases as the number of times of multiple measurements increases. Using multiple measurements also increases the highest observed spatial frequency; this increase is derived and calculated. Additionally, the accuracy obtained using multiple measurements is carefully studied, with the analysis of both the residual reference error after calibration, and the random errors appearing in the range of measured spatial frequencies. The resulting insights on the effects of white noise in optical profiler measurements and the methods to mitigate them may prove invaluable to improve the quality of surface metrology with optical profilers.

Progress in Nano-Electro-Optics III Industrial Applications and Dynamics of the Nano-Optical System

CERN Document Server

Ohtsu, Motoichi

2005-01-01

This unique monograph series "Progress in Nano-Electro Optics" reviews the results of advanced studies of electro-optics on the nanometric scale. This third volume covers the most recent topics of theoretical and experimental interest including classical and quantum optics, organic and inorganic material science and technology, surface science, spectroscopy, atom manipulation, photonics, and electronics. Each chapter is written by one or more leading scientists from the relevant field. Thus, high-quality scientific and technical information is provided to scientists, engineers, and students engaged in nano-electro optics and nanophotonics research. The first two volumes addressed the "Basics and Theory of Near Field Optics" (2002) and "Novel Devices and Atom Manipulation" (2003).

Optical wireless communications: Theory and applications

Science.gov (United States)

Aminikashani, Mohammadreza

on the potentials of currently used FSO systems. Furthermore, utilizing this new statistical channel model, closed-form expressions for the diversity gain and the error rate performance of FSO links with spatial diversity are derived. In addition to addressing ways to improve outdoor FSO communication sys- tems, this dissertation addresses some major challenges in indoor visible light communication (VLC). VLC is an advantageous technique that is proposed for wireless indoor communications. In VLC systems, the existence of multiple paths between the transmitter and receiver causes multipath distortion, particularly in links using non-directional transmitters and receivers, or in links relying upon non-line of-sight propagation. This multipath distortion can lead to intersymbol interference (ISI) at high bit rates. Multicarrier modulation usually implemented by orthogonal frequency division multiplexing (OFDM) can be used to mitigate ISI and multipath dispersion. Nevertheless, the performance of VLC systems employing OFDM modulation is significantly affected by nonlinear characteristic of light-emitting diode (LED) due to the large peak-to-average power ratio (PAPR) of OFDM signal. In other words, signal amplitudes below the LED turn-on-voltage and above the LED saturation point are clipped. This dissertation targets these important issues and successfully addresses them by developing some techniques to reduce high PAPR of optical OFDM signal and determining the optimum operating characteristics of LEDs for combined lighting and communications applications. VLC can also provide a practical solution for indoor positioning as global po- sitioning system (GPS) does not provide an accurate and rapid indoor positioning since GPS radio signals are attenuated and scattered by walls of large buildings and other objects. A practical VLC system would be likely to deploy the same configuration for both positioning and communication purposes where high speed data rates are desired

Binary optics: Trends and limitations

Science.gov (United States)

Farn, Michael W.; Veldkamp, Wilfrid B.

1993-01-01

We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

Expansions of general stationary stochastic optical fields: general formalism

International Nuclear Information System (INIS)

Martinez-Herrero, R.; Mejias, P.M.

1985-01-01

A new expansion of a general stationary stochastic optical field is derived. Each term of the series is seen to represent a recently defined new class of optical fields, the so-called spectrally quasi-factorizable fields. Alternative expansion in terms of nonstationary fields that obey the wave equation is also shown. A relationship between temporal and spatial features of stationary free optical fields is discussed

Elliptic-symmetry vector optical fields.

Science.gov (United States)

Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian

2014-08-11

We present in principle and demonstrate experimentally a new kind of vector fields: elliptic-symmetry vector optical fields. This is a significant development in vector fields, as this breaks the cylindrical symmetry and enriches the family of vector fields. Due to the presence of an additional degrees of freedom, which is the interval between the foci in the elliptic coordinate system, the elliptic-symmetry vector fields are more flexible than the cylindrical vector fields for controlling the spatial structure of polarization and for engineering the focusing fields. The elliptic-symmetry vector fields can find many specific applications from optical trapping to optical machining and so on.

Geometrical optics in correlated imaging systems

International Nuclear Information System (INIS)

Cao Dezhong; Xiong Jun; Wang Kaige

2005-01-01

We discuss the geometrical optics of correlated imaging for two kinds of spatial correlations corresponding, respectively, to a classical thermal light source and a quantum two-photon entangled source. Due to the different features in the second-order spatial correlation, the two sources obey different imaging equations. The quantum entangled source behaves as a mirror, whereas the classical thermal source looks like a phase-conjugate mirror in the correlated imaging

The Standardization Method of Address Information for POIs from Internet Based on Positional Relation

Directory of Open Access Journals (Sweden)

WANG Yong

2016-05-01

Full Text Available As points of interest (POIon the internet, exists widely incomplete addresses and inconsistent literal expressions, a fast standardization processing method of network POIs address information based on spatial constraints was proposed. Based on the model of the extensible address expression, first of all, address information of POI was segmented and extracted. Address elements are updated by means of matching with the address tree layer by layer. Then, by defining four types of positional relations, corresponding set are selected from standard POI library as candidate for enrichment and amendment of non-standard address. At last, the fast standardized processing of POI address information was achieved with the help of backtracking address elements with minimum granularity. Experiments in this paper proved that the standardization processing of an address can be realized by means of this method with higher accuracy in order to build the address database.

Optical coherence tomography for blood glucose monitoring in vitro through spatial and temporal approaches

Science.gov (United States)

De Pretto, Lucas Ramos; Yoshimura, Tania Mateus; Ribeiro, Martha Simões; Zanardi de Freitas, Anderson

2016-08-01

As diabetes causes millions of deaths worldwide every year, new methods for blood glucose monitoring are in demand. Noninvasive approaches may increase patient adherence to treatment while reducing costs, and optical coherence tomography (OCT) may be a feasible alternative to current invasive diagnostics. This study presents two methods for blood sugar monitoring with OCT in vitro. The first, based on spatial statistics, exploits changes in the light total attenuation coefficient caused by different concentrations of glucose in the sample using a 930-nm commercial OCT system. The second, based on temporal analysis, calculates differences in the decorrelation time of the speckle pattern in the OCT signal due to blood viscosity variations with the addition of glucose with data acquired by a custom built Swept Source 1325-nm OCT system. Samples consisted of heparinized mouse blood, phosphate buffer saline, and glucose. Additionally, further samples were prepared by diluting mouse blood with isotonic saline solution to verify the effect of higher multiple scattering components on the ability of the methods to differentiate glucose levels. Our results suggest a direct relationship between glucose concentration and both decorrelation rate and attenuation coefficient, with our systems being able to detect changes of 65 mg/dL in glucose concentration.

Optical trapping of carbon nanotubes and graphene

Directory of Open Access Journals (Sweden)

S. Vasi

2011-09-01

Full Text Available We study optical trapping of nanotubes and graphene. We extract the distribution of both centre-of-mass and angular fluctuations from three-dimensional tracking of these optically trapped carbon nanostructures. The optical force and torque constants are measured from auto and cross-correlation of the tracking signals. We demonstrate that nanotubes enable nanometer spatial, and femto-Newton force resolution in photonic force microscopy by accurately measuring the radiation pressure in a double frequency optical tweezers. Finally, we integrate optical trapping with Raman and photoluminescence spectroscopy demonstrating the use of a Raman and photoluminescence tweezers by investigating the spectroscopy of nanotubes and graphene flakes in solution. Experimental results are compared with calculations based on electromagnetic scattering theory.

Optical detection of ultrasound using an apertureless near-field scanning optical microscopy system

Science.gov (United States)

Ahn, Phillip; Zhang, Zhen; Sun, Cheng; Balogun, Oluwaseyi

2013-01-01

Laser ultrasonics techniques are power approaches for non-contact generation and detection of high frequency ultrasound on a local scale. In these techniques, optical diffraction limits the spatial information that can be accessed from a measurement. In order to improve the lateral spatial resolution, we incorporate an apertureless near-field scanning optical microscope (aNSOM) into laser ultrasonics setup for local detection of laser generated ultrasound. The aNSOM technique relies on the measurement of a weak backscattered near-field light intensity resulting from the oblique illumination of a nanoscale probe-tip positioned close to a sample surface. We enhance the optical near-field intensity by coupling light to surface plasmon polaritons (SPPs) on the shaft of an atomic force microscopy (AFM) cantilever. The SPPs propagate down the AFM shaft, localize at the tip apex, and are backscattered to the far-field when the separation distance between the probe tip and the sample surface is comparable to the probe-tip radius. The backscattered near-field intensity is dynamically modulated when an ultrasonic wave arrives at the sample surface leading to a transient change in the tip-sample separation distance. We present experimental results detailing measurement of broadband and narrowband laser generated ultrasound in solids with frequencies reaching up to 180 MHz range.

CDPOP: A spatially explicit cost distance population genetics program

Science.gov (United States)

Erin L. Landguth; S. A. Cushman

2010-01-01

Spatially explicit simulation of gene flow in complex landscapes is essential to explain observed population responses and provide a foundation for landscape genetics. To address this need, we wrote a spatially explicit, individual-based population genetics model (CDPOP). The model implements individual-based population modelling with Mendelian inheritance and k-allele...

Optical encryption using pseudorandom complex spatial modulation.

Science.gov (United States)

Sarkadi, Tamás; Koppa, Pál

2012-12-01

In this paper we propose a new (to our knowledge) complex spatial modulation method to encode data pages applicable in double random phase encryption (DRPE) to make the system more resistant to brute-force attack. The proposed modulation method uses data page pixels with random phase and amplitude values with the condition that the intensity of the interference of light from two adjacent pixels should correspond to the encoded information. A differential phase contrast technique is applied to recover the data page at the output of the system. We show that the proposed modulation method can enhance the robustness of the DRPE technique using point spread function analysis. Key space expansion is determined by numeric model calculations.

Spatial Learning: Conditions and Basic Effects

Directory of Open Access Journals (Sweden)

Victoria D. Chamizo

2002-01-01

Full Text Available A growing body of evidence suggests that the spatial and the temporal domains seem to share the same or similar conditions, basic effects, and mechanisms. The blocking, unblocking and overshadowing experiments (and also those of latent inhibition and perceptual learning reviewed by Prados and Redhead in this issue show that to exclude associative learning as a basic mechanism responsible for spatial learning is quite inappropriate. All these results, especially those obtained with strictly spatial tasks, seem inconsistent with O’Keefe and Nadel’s account of true spatial learning or locale learning. Their theory claims that this kind of learning is fundamentally different and develops with total independence from other ways of learning (like classical and instrumental conditioning -taxon learning. In fact, the results reviewed can be explained appealing on to a sophisticated guidance system, like for example the one proposed by Leonard and McNaughton (1990; see also McNaughton and cols, 1996. Such a system would allow that an animal generates new space information: given the distance and address from of A to B and from A to C, being able to infer the distance and the address from B to C, even when C is invisible from B (see Chapuis and Varlet, 1987 -the contribution by McLaren in this issue constitutes a good example of a sophisticated guidance system.

Geometrical optics modeling of the grating-slit test.

Science.gov (United States)

Liang, Chao-Wen; Sasian, Jose

2007-02-19

A novel optical testing method termed the grating-slit test is discussed. This test uses a grating and a slit, as in the Ronchi test, but the grating-slit test is different in that the grating is used as the incoherent illuminating object instead of the spatial filter. The slit is located at the plane of the image of a sinusoidal intensity grating. An insightful geometrical-optics model for the grating-slit test is presented and the fringe contrast ratio with respect to the slit width and object-grating period is obtained. The concept of spatial bucket integration is used to obtain the fringe contrast ratio.

Neural mechanisms underlying spatial realignment during adaptation to optical wedge prisms.

Science.gov (United States)

Chapman, Heidi L; Eramudugolla, Ranmalee; Gavrilescu, Maria; Strudwick, Mark W; Loftus, Andrea; Cunnington, Ross; Mattingley, Jason B

2010-07-01

Visuomotor adaptation to a shift in visual input produced by prismatic lenses is an example of dynamic sensory-motor plasticity within the brain. Prism adaptation is readily induced in healthy individuals, and is thought to reflect the brain's ability to compensate for drifts in spatial calibration between different sensory systems. The neural correlate of this form of functional plasticity is largely unknown, although current models predict the involvement of parieto-cerebellar circuits. Recent studies that have employed event-related functional magnetic resonance imaging (fMRI) to identify brain regions associated with prism adaptation have discovered patterns of parietal and cerebellar modulation as participants corrected their visuomotor errors during the early part of adaptation. However, the role of these regions in the later stage of adaptation, when 'spatial realignment' or true adaptation is predicted to occur, remains unclear. Here, we used fMRI to quantify the distinctive patterns of parieto-cerebellar activity as visuomotor adaptation develops. We directly contrasted activation patterns during the initial error correction phase of visuomotor adaptation with that during the later spatial realignment phase, and found significant recruitment of the parieto-cerebellar network--with activations in the right inferior parietal lobe and the right posterior cerebellum. These findings provide the first evidence of both cerebellar and parietal involvement during the spatial realignment phase of prism adaptation. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Fluorescence imaging spectrometer optical design

Science.gov (United States)

Taiti, A.; Coppo, P.; Battistelli, E.

2015-09-01

The optical design of the FLuORescence Imaging Spectrometer (FLORIS) studied for the Fluorescence Explorer (FLEX) mission is discussed. FLEX is a candidate for the ESA's 8th Earth Explorer opportunity mission. FLORIS is a pushbroom hyperspectral imager foreseen to be embarked on board of a medium size satellite, flying in tandem with Sentinel-3 in a Sun synchronous orbit at a height of about 815 km. FLORIS will observe the vegetation fluorescence and reflectance within a spectral range between 500 and 780 nm. Multi-frames acquisitions on matrix detectors during the satellite movement will allow the production of 2D Earth scene images in two different spectral channels, called HR and LR with spectral resolution of 0.3 and 2 nm respectively. A common fore optics is foreseen to enhance by design the spatial co-registration between the two spectral channels, which have the same ground spatial sampling (300 m) and swath (150 km). An overlapped spectral range between the two channels is also introduced to simplify the spectral coregistration. A compact opto-mechanical solution with all spherical and plane optical elements is proposed, and the most significant design rationales are described. The instrument optical architecture foresees a dual Babinet scrambler, a dioptric telescope and two grating spectrometers (HR and LR), each consisting of a modified Offner configuration. The developed design is robust, stable vs temperature, easy to align, showing very high optical quality along the whole field of view. The system gives also excellent correction for transverse chromatic aberration and distortions (keystone and smile).

Near-to-eye electroholography via guided-wave acousto-optics for augmented reality

Science.gov (United States)

Jolly, Sundeep; Savidis, Nickolaos; Datta, Bianca; Smalley, Daniel; Bove, V. Michael

2017-03-01

Near-to-eye holographic displays act to directly project wavefronts into a viewer's eye in order to recreate 3-D scenes for augmented or virtual reality applications. Recently, several solutions for near-to-eye electroholography have been proposed based on digital spatial light modulators in conjunction with supporting optics, such as holographic waveguides for light delivery; however, such schemes are limited by the inherent low space-bandwidth product available with current digital SLMs. In this paper, we depict a fully monolithic, integrated optical platform for transparent near-to-eye holographic display requiring no supporting optics. Our solution employs a guided-wave acousto-optic spatial light modulator implemented in lithium niobate in conjunction with an integrated Bragg-regime reflection volume hologram.

X-ray Optics for BES Light Source Facilities

Energy Technology Data Exchange (ETDEWEB)

Mills, Dennis [Argonne National Lab. (ANL), Argonne, IL (United States); Padmore, Howard [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lessner, Eliane [Dept. of Energy (DOE), Washington DC (United States). Office of Science

2013-03-27

nanolithographic techniques for improved spatial resolution and efficiency of zone plates. Development of large, perfect single crystals of materials other than silicon for use as beam splitters, seeding monochromators, and high-resolution analyzers. Development of improved thin-film deposition methods for fabrication of multilayer Laue lenses and high-spectral-resolution multilayer gratings. Development of supports, actuator technologies, algorithms, and controls to provide fully integrated and robust adaptive X-ray optic systems. Development of fabrication processes for refractive lenses in materials other than silicon. The workshop participants also addressed two important nontechnical areas: our relationship with industry and organization of optics within the light source facilities. Optimization of activities within these two areas could have an important effect on the effectiveness and efficiency of our overall endeavor. These are crosscutting managerial issues that we identified as areas that needed further in-depth study, but they need to be coordinated above the individual facilities. Finally, an issue that cuts across many of the optics improvements listed above is routine access to beamlines that ideally are fully dedicated to optics research and/or development. The success of the BES X-ray user facilities in serving a rapidly increasing user community has led to a squeezing of beam time for vital instrumentation activities. Dedicated development beamlines could be shared with other R&D activities, such as detector programs and novel instrument development. In summary, to meet the challenges of providing the highest-quality X-ray beams for users and to fully utilize the high-brightness sources of today and those that are on the horizon, it will be critical to make strategic investments in X-ray optics R&D. This report can provide guidance and direction for effective use of investments in the field of X-ray optics and potential approaches to develop a better

X-ray Optics for BES Light Source Facilities

International Nuclear Information System (INIS)

Mills, Dennis; Padmore, Howard; Lessner, Eliane

2013-01-01

nanolithographic techniques for improved spatial resolution and efficiency of zone plates. Development of large, perfect single crystals of materials other than silicon for use as beam splitters, seeding monochromators, and high-resolution analyzers. Development of improved thin-film deposition methods for fabrication of multilayer Laue lenses and high-spectral-resolution multilayer gratings. Development of supports, actuator technologies, algorithms, and controls to provide fully integrated and robust adaptive X-ray optic systems. Development of fabrication processes for refractive lenses in materials other than silicon. The workshop participants also addressed two important nontechnical areas: our relationship with industry and organization of optics within the light source facilities. Optimization of activities within these two areas could have an important effect on the effectiveness and efficiency of our overall endeavor. These are crosscutting managerial issues that we identified as areas that needed further in-depth study, but they need to be coordinated above the individual facilities. Finally, an issue that cuts across many of the optics improvements listed above is routine access to beamlines that ideally are fully dedicated to optics research and/or development. The success of the BES X-ray user facilities in serving a rapidly increasing user community has led to a squeezing of beam time for vital instrumentation activities. Dedicated development beamlines could be shared with other R&D activities, such as detector programs and novel instrument development. In summary, to meet the challenges of providing the highest-quality X-ray beams for users and to fully utilize the high-brightness sources of today and those that are on the horizon, it will be critical to make strategic investments in X-ray optics R&D. This report can provide guidance and direction for effective use of investments in the field of X-ray optics and potential approaches to develop a better

Use of an optical trap for study of host-pathogen interactions for dynamic live cell imaging.

Science.gov (United States)

Tam, Jenny M; Castro, Carlos E; Heath, Robert J W; Mansour, Michael K; Cardenas, Michael L; Xavier, Ramnik J; Lang, Matthew J; Vyas, Jatin M

2011-07-28

Dynamic live cell imaging allows direct visualization of real-time interactions between cells of the immune system(1, 2); however, the lack of spatial and temporal control between the phagocytic cell and microbe has rendered focused observations into the initial interactions of host response to pathogens difficult. Historically, intercellular contact events such as phagocytosis(3) have been imaged by mixing two cell types, and then continuously scanning the field-of-view to find serendipitous intercellular contacts at the appropriate stage of interaction. The stochastic nature of these events renders this process tedious, and it is difficult to observe early or fleeting events in cell-cell contact by this approach. This method requires finding cell pairs that are on the verge of contact, and observing them until they consummate their contact, or do not. To address these limitations, we use optical trapping as a non-invasive, non-destructive, but fast and effective method to position cells in culture. Optical traps, or optical tweezers, are increasingly utilized in biological research to capture and physically manipulate cells and other micron-sized particles in three dimensions(4). Radiation pressure was first observed and applied to optical tweezer systems in 1970(5, 6), and was first used to control biological specimens in 1987(7). Since then, optical tweezers have matured into a technology to probe a variety of biological phenomena(8-13). We describe a method(14) that advances live cell imaging by integrating an optical trap with spinning disk confocal microscopy with temperature and humidity control to provide exquisite spatial and temporal control of pathogenic organisms in a physiological environment to facilitate interactions with host cells, as determined by the operator. Live, pathogenic organisms like Candida albicans and Aspergillus fumigatus, which can cause potentially lethal, invasive infections in immunocompromised individuals(15, 16) (e.g. AIDS

Spatial filtering velocimetry for real-time out-of-plane displacement measurements

DEFF Research Database (Denmark)

Olesen, Anders Sig; Yura, H.T.; Jakobsen, Michael Linde

2016-01-01

power spectrum of the photocurrent produced by this filter. This main contribution of this paper is a model, which describe the selectivity of the sensor, applied to speckle dynamics generated by an object moving out-of-plane. To motivate our interest in these filters we also present an all optical......We probe the dynamics of objective laser speckles as the axial distance between the object and the observation plane changes. With the purpose of measuring out-of-plane motion in real time, we apply optical spatial filtering velocimetry to the speckle dynamics. To achieve this, a rotationally...... symmetric spatial filter is designed. The spatial filter converts the speckle dynamics into a photocurrent with a quasi-sinusoidal response to the out-of-plane motion. The selectivity of the sensor relates directly to the uncertainty on sensor measurements. The selectivity most be derived from a temporal...

Second law of thermodynamics and urban green infrastructure - A knowledge synthesis to address spatial planning strategies

Directory of Open Access Journals (Sweden)

Raffaele Pelorosso

2018-04-01

Full Text Available Planning of ecosystem services provided by the Urban Green Infrastructure (UGI is a key issue for urban sustainability. Planning strategies driven by the second law of thermodynamics (SLT are innovative approaches to sustainability but they are still in seminal phase. In this article, a coupled review of SLT within spatial planning is accomplished looking at the main applications in urban green infrastructure (UGI planning. The work has supported the definition of a preliminary low-entropy UGI planning strategy (Pelorosso, Gobattoni, & Leone, 2017 but it also aims to contribute to the improvement and/or development of even more solid planning strategies based on SLT. In particular, a systemic review of UGI planning and thermodynamics has been carried out to identify all the occurrences to date in the scientific literature. Secondly, a scoping review of SLT-related concepts of exergy, entropy and urban metabolism is presented in order to investigate the main applications of, and gaps in, urban spatial planning. Results indicate that UGI and ecosystem service planning based on SLT is a relatively new field of research. Moreover, some general indications are derived for the development of spatial UGI planning strategies based on SLT.

PREVAIL: latest electron optics results

Science.gov (United States)

Pfeiffer, Hans C.; Golladay, Steven D.; Gordon, Michael S.; Kendall, Rodney A.; Lieberman, Jon E.; Rockrohr, James D.; Stickel, Werner; Yamaguchi, Takeshi; Okamoto, Kazuya; Umemoto, Takaaki; Shimizu, Hiroyasu; Kojima, Shinichi; Hamashima, Muneki

2002-07-01

The PREVAIL electron optics subsystem developed by IBM has been installed at Nikon's facility in Kumagaya, Japan, for integration into the Nikon commercial EPL stepper. The cornerstone of the electron optics design is the Curvilinear Variable Axis Lens (CVAL) technique originally demonstrated with a proof of concept system. This paper presents the latest experimental results obtained with the electron optical subsystem at Nikon's facility. The results include micrographs illustrating proper CVAL operation through the spatial resolution achieved over the entire optical field of view. They also include data on the most critical issue of the EPL exposure approach: subfield stitching. The methodology of distortion correction will be described and both micrographs and metrology data of stitched subfields will be presented. This paper represents a progress report of the IBM/Nikon alliance activity on EPL.

Spatially Resolved Gas Temperature Measurements in an Atmospheric Pressure DC Glow Microdischarge with Raman Scattering

Science.gov (United States)

Belostotskiy, S.; Wang, Q.; Donnelly, V.; Economou, D.; Sadeghi, N.

2006-10-01

Spatially resolved rotational Raman spectroscopy of ground state nitrogen N2(X^1σg^+) was used to measure the gas temperature (Tg) in a nitrogen dc glow microdischarge (gap between electrodes d˜500 μm). An original backscattering, confocal optical system was developed for collecting Raman spectra. Stray laser light and Raleigh scattering were blocked by using a triple grating monochromator and spatial filters, designed specifically for these experiments. The optical system provided a spatial resolution of electrodes, Tg increased linearly with jd, reaching 500 K at 1000 mA/cm^2 jd for a pressure of 720 Torr. Spatially resolved gas temperature measurements will also be presented and discussed in combination with a mathematical model for gas heating in the microplasma. This work is supported by DoE/NSF.

Miniaturised optical sensors for industrial applications

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Hanson, Steen Grüner

2010-01-01

. The technology is based on compact and low-cost laser sources such as Vertical Cavity Surface Emitting Lasers (VCSELs). The methods characterise the object motion by speckle translation in the near field (imaging) or far field (optical Fourier transform) by optical spatial filtering velocimetry. The volume...... of the two optical solutions is less than 1 cm3, including the application specific integrated circuit (ASIC), which processes the data and interfaces a PC/Laptop directly via a USB driver. The sensors are designed for working distances of 2 and 12 mm for near field and far field, respectively. We...

Web-Based Spatial Training Using Handheld Touch Screen Devices

Science.gov (United States)

Martin-Dorta, Norena; Saorin, Jose Luis; Contero, Manuel

2011-01-01

This paper attempts to harness the opportunities for mobility and the new user interfaces that handheld touch screen devices offer, in a non-formal learning context, with a view to developing spatial ability. This research has addressed two objectives: first, analyzing the effects that training can have on spatial visualisation using the…

Evaluations of fiber optic sensors for interior applications

Energy Technology Data Exchange (ETDEWEB)

Sandoval, M.W.; Malone, T.P.

1996-02-01

This report addresses the testing and evaluation of commercial fiber optic intrusion detection systems in interior applications. The applications include laying optical fiber cable above suspended ceilings to detect removal of ceiling tiles, embedding optical fibers inside a tamper or item monitoring blanket that could be placed over an asset, and installing optical fibers on a door to detect movement or penetration. Detection capability of the fiber optic sensors as well as nuisance and false alarm information were focused on during the evaluation. Fiber optic sensor processing, system components, and system setup are described.

The neural bases of spatial frequency processing during scene perception

Science.gov (United States)

Kauffmann, Louise; Ramanoël, Stephen; Peyrin, Carole

2014-01-01

Theories on visual perception agree that scenes are processed in terms of spatial frequencies. Low spatial frequencies (LSF) carry coarse information whereas high spatial frequencies (HSF) carry fine details of the scene. However, how and where spatial frequencies are processed within the brain remain unresolved questions. The present review addresses these issues and aims to identify the cerebral regions differentially involved in low and high spatial frequency processing, and to clarify their attributes during scene perception. Results from a number of behavioral and neuroimaging studies suggest that spatial frequency processing is lateralized in both hemispheres, with the right and left hemispheres predominantly involved in the categorization of LSF and HSF scenes, respectively. There is also evidence that spatial frequency processing is retinotopically mapped in the visual cortex. HSF scenes (as opposed to LSF) activate occipital areas in relation to foveal representations, while categorization of LSF scenes (as opposed to HSF) activates occipital areas in relation to more peripheral representations. Concomitantly, a number of studies have demonstrated that LSF information may reach high-order areas rapidly, allowing an initial coarse parsing of the visual scene, which could then be sent back through feedback into the occipito-temporal cortex to guide finer HSF-based analysis. Finally, the review addresses spatial frequency processing within scene-selective regions areas of the occipito-temporal cortex. PMID:24847226

NIF optical specifications - the importance of the RMS gradient specification

International Nuclear Information System (INIS)

Auerbach, J. M.; Cotton, C. T.; English, R. E.; Henesian, M. A.; Hunt, J. T.; Kelly, J. H.; Lawson, J. K.; Sacks, J. B.; Shoup, M. J.; Trenholme, W. H.

1998-01-01

The performance of the National Ignition Facility (NIF), especially in terms of laser focusability, will be determined by several key factors. One of these key factors is the optical specification for the thousands of large aperture optics that will comprise the 192 beamlines. We have previously reported on the importance of the specification of the power spectral density (PSD) on NIF performance. Recently, we have been studying the importance of long spatial wavelength (>33 mm) phase errors on focusability. We have concluded that the preferred metric for determining the impact of these long spatial wavelength phase errors is the rms phase gradient. In this paper, we outline the overall approach to NIF optical specifications, detail the impact of the rms phase gradient on NIF focusability, discuss its trade-off with the PSD in determining the spot size and review measurements of optics similar to those to be manufactured for NIF

A reconstruction algorithm for three-dimensional object-space data using spatial-spectral multiplexing

Science.gov (United States)

Wu, Zhejun; Kudenov, Michael W.

2017-05-01

This paper presents a reconstruction algorithm for the Spatial-Spectral Multiplexing (SSM) optical system. The goal of this algorithm is to recover the three-dimensional spatial and spectral information of a scene, given that a one-dimensional spectrometer array is used to sample the pupil of the spatial-spectral modulator. The challenge of the reconstruction is that the non-parametric representation of the three-dimensional spatial and spectral object requires a large number of variables, thus leading to an underdetermined linear system that is hard to uniquely recover. We propose to reparameterize the spectrum using B-spline functions to reduce the number of unknown variables. Our reconstruction algorithm then solves the improved linear system via a least- square optimization of such B-spline coefficients with additional spatial smoothness regularization. The ground truth object and the optical model for the measurement matrix are simulated with both spatial and spectral assumptions according to a realistic field of view. In order to test the robustness of the algorithm, we add Poisson noise to the measurement and test on both two-dimensional and three-dimensional spatial and spectral scenes. Our analysis shows that the root mean square error of the recovered results can be achieved within 5.15%.

Long-distance fiber optic sensing solutions for pipeline leakage, intrusion, and ground movement detection

Science.gov (United States)

Nikles, Marc

2009-05-01

An increasing number of pipelines are constructed in remote regions affected by harsh environmental conditions where pipeline routes often cross mountain areas which are characterized by unstable grounds and where soil texture changes between winter and summer increase the probability of hazards. Third party intentional interference or accidental intrusions are a major cause of pipeline failures leading to large leaks or even explosions. Due to the long distances to be monitored and the linear nature of pipelines, distributed fiber optic sensing techniques offer significant advantages and the capability to detect and localize pipeline disturbance with great precision. Furthermore pipeline owner/operators lay fiber optic cable parallel to transmission pipelines for telecommunication purposes and at minimum additional cost monitoring capabilities can be added to the communication system. The Brillouin-based Omnisens DITEST monitoring system has been used in several long distance pipeline projects. The technique is capable of measuring strain and temperature over 100's kilometers with meter spatial resolution. Dedicated fiber optic cables have been developed for continuous strain and temperature monitoring and their deployment along the pipeline has enabled permanent and continuous pipeline ground movement, intrusion and leak detection. This paper presents a description of the fiber optic Brillouin-based DITEST sensing technique, its measurement performance and limits, while addressing future perspectives for pipeline monitoring. The description is supported by case studies and illustrated by field data.

Sub–100-nm metafluorophores with digitally tunable optical properties self-assembled from DNA

Science.gov (United States)

Woehrstein, Johannes B.; Strauss, Maximilian T.; Ong, Luvena L.; Wei, Bryan; Zhang, David Y.; Jungmann, Ralf; Yin, Peng

2017-01-01

Fluorescence microscopy allows specific target detection down to the level of single molecules and has become an enabling tool in biological research. To transduce the biological information to an imageable signal, we have developed a variety of fluorescent probes, such as organic dyes or fluorescent proteins with different colors. Despite their success, a limitation on constructing small fluorescent probes is the lack of a general framework to achieve precise and programmable control of critical optical properties, such as color and brightness. To address this challenge, we introduce metafluorophores, which are constructed as DNA nanostructure–based fluorescent probes with digitally tunable optical properties. Each metafluorophore is composed of multiple organic fluorophores, organized in a spatially controlled fashion in a compact sub–100-nm architecture using a DNA nanostructure scaffold. Using DNA origami with a size of 90 × 60 nm2, substantially smaller than the optical diffraction limit, we constructed small fluorescent probes with digitally tunable brightness, color, and photostability and demonstrated a palette of 124 virtual colors. Using these probes as fluorescent barcodes, we implemented an assay for multiplexed quantification of nucleic acids. Additionally, we demonstrated the triggered in situ self-assembly of fluorescent DNA nanostructures with prescribed brightness upon initial hybridization to a nucleic acid target. PMID:28691083

Action Recognition by Joint Spatial-Temporal Motion Feature

Directory of Open Access Journals (Sweden)

Weihua Zhang

2013-01-01

Full Text Available This paper introduces a method for human action recognition based on optical flow motion features extraction. Automatic spatial and temporal alignments are combined together in order to encourage the temporal consistence on each action by an enhanced dynamic time warping (DTW algorithm. At the same time, a fast method based on coarse-to-fine DTW constraint to improve computational performance without reducing accuracy is induced. The main contributions of this study include (1 a joint spatial-temporal multiresolution optical flow computation method which can keep encoding more informative motion information than recent proposed methods, (2 an enhanced DTW method to improve temporal consistence of motion in action recognition, and (3 coarse-to-fine DTW constraint on motion features pyramids to speed up recognition performance. Using this method, high recognition accuracy is achieved on different action databases like Weizmann database and KTH database.

Cryo-optical testing of large aspheric reflectors operating in the sub mm range

Science.gov (United States)

Roose, S.; Houbrechts, Y.; Mazzoli, A.; Ninane, N.; Stockman, Y.; Daddato, R.; Kirschner, V.; Venacio, L.; de Chambure, D.

2006-02-01

The cryo-optical testing of the PLANCK primary reflector (elliptical off-axis CFRP reflector of 1550 mm x 1890 mm) is one of the major issue in the payload development program. It is requested to measure the changes of the Surface Figure Error (SFE) with respect to the best ellipsoid, between 293 K and 50 K, with a 1 μm RMS accuracy. To achieve this, Infra Red interferometry has been used and a dedicated thermo mechanical set-up has been constructed. This paper summarises the test activities, the test methods and results on the PLANCK Primary Reflector - Flight Model (PRFM) achieved in FOCAL 6.5 at Centre Spatial de Liege (CSL). Here, the Wave Front Error (WFE) will be considered, the SFE can be derived from the WFE measurement. After a brief introduction, the first part deals with the general test description. The thermo-elastic deformations will be addressed: the surface deformation in the medium frequency range (spatial wavelength down to 60 mm) and core-cell dimpling.

Isometric multimodal photoacoustic microscopy based on optically transparent micro-ring ultrasonic detection.

Science.gov (United States)

Dong, Biqin; Li, Hao; Zhang, Zhen; Zhang, Kevin; Chen, Siyu; Sun, Cheng; Zhang, Hao F

2015-01-01

Photoacoustic microscopy (PAM) is an attractive imaging tool complementary to established optical microscopic modalities by providing additional molecular specificities through imaging optical absorption contrast. While the development of optical resolution photoacoustic microscopy (ORPAM) offers high lateral resolution, the acoustically-determined axial resolution is limited due to the constraint in ultrasonic detection bandwidth. ORPAM with isometric spatial resolution along both axial and lateral direction is yet to be developed. Although recently developed sophisticated optical illumination and reconstruction methods offer improved axial resolution in ORPAM, the image acquisition procedures are rather complicated, limiting their capabilities for high-speed imaging and being easily integrated with established optical microscopic modalities. Here we report an isometric ORPAM based on an optically transparent micro-ring resonator ultrasonic detector and a commercial inverted microscope platform. Owing to the superior spatial resolution and the ease of integrating our ORPAM with established microscopic modalities, single cell imaging with extrinsic fluorescence staining, intrinsic autofluorescence, and optical absorption can be achieved simultaneously. This technique holds promise to greatly improve the accessibility of PAM to the broader biomedical researchers.

Flat-field response and geometric distortion measurements of optical streak cameras

International Nuclear Information System (INIS)

Montgomery, D.S.; Drake, R.P.; Jones, B.A.; Wiedwald, J.D.

1987-08-01

To accurately measure pulse amplitude, shape, and relative time histories of optical signals with an optical streak camera, it is necessary to correct each recorded image for spatially-dependent gain nonuniformity and geometric distortion. Gain nonuniformities arise from sensitivity variations in the streak-tube photocathode, phosphor screen, image-intensifier tube, and image recording system. These nonuniformities may be severe, and have been observed to be on the order of 100% for some LLNL optical streak cameras. Geometric distortion due to optical couplings, electron-optics, and sweep nonlinearity not only affects pulse position and timing measurements, but affects pulse amplitude and shape measurements as well. By using a 1.053-μm, long-pulse, high-power laser to generate a spatially and temporally uniform source as input to the streak camera, the combined effects of flat-field response and geometric distortion can be measured under the normal dynamic operation of cameras with S-1 photocathodes. Additionally, by using the same laser system to generate a train of short pulses that can be spatially modulated at the input of the streak camera, we can effectively create a two-dimensional grid of equally-spaced pulses. This allows a dynamic measurement of the geometric distortion of the streak camera. We will discuss the techniques involved in performing these calibrations, will present some of the measured results for LLNL optical streak cameras, and will discuss software methods to correct for these effects. 6 refs., 6 figs

Beam profile measurements on the advanced test accelerator using optical techniques

International Nuclear Information System (INIS)

Chong, Y.P.; Kalibjian, R.; Cornish, J.P.; Kallman, J.S.; Donnelly, D.

1986-01-01

Beam current density profiles of ATA have been measured both spatially and temporally using a number of diagnostics. An extremely important technique involves measuring optical emissions from either a target foil inserted into the beam path or gas atoms and molecules excited by beam electrons. This paper describes the detection of the optical emission. A 2-D gated television camera with a single or dual micro-channel-plate (MCP) detector for high gain provides excellent spatial and temporal resolution. Measurements are routinely made with resolutions of 1 mm and 5 ns respectively. The optical line of sight allows splitting part of the signal to a streak camera or photometer for even higher time resolution

Spatial and temporal interpolation of satellite-based aerosol optical depth measurements over North America using B-splines

Science.gov (United States)

Pfister, Nicolas; O'Neill, Norman T.; Aube, Martin; Nguyen, Minh-Nghia; Bechamp-Laganiere, Xavier; Besnier, Albert; Corriveau, Louis; Gasse, Geremie; Levert, Etienne; Plante, Danick

2005-08-01

Satellite-based measurements of aerosol optical depth (AOD) over land are obtained from an inversion procedure applied to dense dark vegetation pixels of remotely sensed images. The limited number of pixels over which the inversion procedure can be applied leaves many areas with little or no AOD data. Moreover, satellite coverage by sensors such as MODIS yields only daily images of a given region with four sequential overpasses required to straddle mid-latitude North America. Ground based AOD data from AERONET sun photometers are available on a more continuous basis but only at approximately fifty locations throughout North America. The object of this work is to produce a complete and coherent mapping of AOD over North America with a spatial resolution of 0.1 degree and a frequency of three hours by interpolating MODIS satellite-based data together with available AERONET ground based measurements. Before being interpolated, the MODIS AOD data extracted from different passes are synchronized to the mapping time using analyzed wind fields from the Global Multiscale Model (Meteorological Service of Canada). This approach amounts to a trajectory type of simplified atmospheric dynamics correction method. The spatial interpolation is performed using a weighted least squares method applied to bicubic B-spline functions defined on a rectangular grid. The least squares method enables one to weight the data accordingly to the measurement errors while the B-splines properties of local support and C2 continuity offer a good approximation of AOD behaviour viewed as a function of time and space.

Spatial hole burning and spectral stability of a quantum-dot laser

International Nuclear Information System (INIS)

Savelyev, A. V.; Korenev, V. V.; Maximov, M. V.; Zhukov, A. E.

2015-01-01

The inhomogeneous intensity distribution of the optical model along the axis of a semiconductor quantum-dot laser results in spatial hole burning. The influence of this phenomenon on the stability of the multifrequency emission spectrum is studied when the optical transition of the quantum dots is characterized by considerable homogeneous broadening. The results of two models—in which inhomogeneous broadening is disregarded and taken into account—regarding the stability of the radiation spectrum under the influence of slight variation of the spectral loss dependence in the resonator are compared. Inhomogeneous distribution of the charge carriers (spatial hole burning) is found to be a critical factor in determining the form and stability of the spectrum

Spatial hole burning and spectral stability of a quantum-dot laser

Energy Technology Data Exchange (ETDEWEB)

Savelyev, A. V., E-mail: savelev@mail.ioffe.ru; Korenev, V. V.; Maximov, M. V.; Zhukov, A. E. [Russian Academy of Sciences, Nanotechnology Center, St. Petersburg Academic University (Russian Federation)

2015-11-15

The inhomogeneous intensity distribution of the optical model along the axis of a semiconductor quantum-dot laser results in spatial hole burning. The influence of this phenomenon on the stability of the multifrequency emission spectrum is studied when the optical transition of the quantum dots is characterized by considerable homogeneous broadening. The results of two models—in which inhomogeneous broadening is disregarded and taken into account—regarding the stability of the radiation spectrum under the influence of slight variation of the spectral loss dependence in the resonator are compared. Inhomogeneous distribution of the charge carriers (spatial hole burning) is found to be a critical factor in determining the form and stability of the spectrum.

Partially coherent imaging and spatial coherence wavelets

International Nuclear Information System (INIS)

Castaneda, Roman

2003-03-01

A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function. (author)

Biobeam—Multiplexed wave-optical simulations of light-sheet microscopy

Science.gov (United States)

Weigert, Martin; Bundschuh, Sebastian T.

2018-01-01

Sample-induced image-degradation remains an intricate wave-optical problem in light-sheet microscopy. Here we present biobeam, an open-source software package that enables simulation of operational light-sheet microscopes by combining data from 105–106 multiplexed and GPU-accelerated point-spread-function calculations. The wave-optical nature of these simulations leads to the faithful reproduction of spatially varying aberrations, diffraction artifacts, geometric image distortions, adaptive optics, and emergent wave-optical phenomena, and renders image-formation in light-sheet microscopy computationally tractable. PMID:29652879

Applications of optical fibers in nuclear test diagnostics

International Nuclear Information System (INIS)

Lyons, P.B.; Hodson, E.K.; Looney, L.D.

1980-01-01

Two new plasma diagnostic experiments have been successfully fielded on nuclear device tests at NTS. Both systems rely on the unique advantages provided by optical fiber technology and both systems provide new diagnostic capabilities that previously were beyond the state-of-the-art in coaxial cable systems. One system addresses the need to record e wide bandwidth data on gamma-ray sources. Over the long (< 1 km) distances that characterize NTS testing, the bandwidth of coaxial cable systems is usually limited to < 200 to 400 MHz even with extensive equalization. The new system uses the Cerenkov process to generate light in a converter material. High bandwidth fibers and detectors are used to approach a 1-GHz bandwidth. In this case fibers provided the bandwidth capability. The second system provides time and space resolution of a neutron source on a fast (ns) time scale. Previous systems have utilized either an array of neutron detectors with individual coaxial cables or a fast scintillator viewed by a gated image intensifier. For a large number of channels, the coaxial system becomes very costly and is subject to potentially severe EMI concerns. The gated intensifier system requires complex electronics and accurate timing and can be affected by EMI. An alternative system is described which provides continuous time coverage with limited spatial resolution. Complete freedom from EMI is achieved through the use of optical data collection and transmission. The optical fibers offered a major (2 to 3 times) cost savings and a large weight savings relative to the coax system. Each system is discussed

Evaluation of device-independent internet spatial location

OpenAIRE

Komosný, Dan; Pang, Paul; Mehic, Miralem; Vozňák, Miroslav

2017-01-01

Device-independent Internet spatial location is needed for many purposes, such as data personalisation and social behaviour analysis. Internet spatial databases provide such locations based the IP address of a device. The free to use databases are natively included into many UNIX and Linux operating systems. These systems are predominantly used for e-shops, social networks, and cloud data storage. Using a constructed ground truth dataset, we comprehensively evaluate these databases for null r...

Aberration compensation using a spatial light modulator LCD

International Nuclear Information System (INIS)

Amezquita, R; Rincon, O; Torres, Y M

2011-01-01

The dynamic correction of aberrations introduced in optical systems have been a widely discussed topic in the past 10 years. Adaptive optics is the most important developed field where the Shack-Hartmann sensors and deformable mirrors are used for the measurement and correction of wavefronts. In this paper, an interferometric set-up which uses a Spatial Light Modulator (SLM) as an active element is proposed. Using this SLM a procedure for the compensation of all phase aberrations present in the experimental setup is shown.

Monitoring spatial-temporal variability of aerosol over Kenya ...

African Journals Online (AJOL)

This study sought to investigate the spatial and temporal variations of aerosols over Kenya based on Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor Aerosol Optical Depth (AOD) data for the period between 2001 and 2012. A Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) ...

Autoresonant four-wave mixing in optical fibers

International Nuclear Information System (INIS)

Yaakobi, O.; Friedland, L.

2010-01-01

A theory of autoresonant four-wave mixing in tapered fibers is developed in application to optical parametric amplification (OPA). In autoresonance, the interacting waves (two pump waves, a signal, and an idler) stay phase-locked continuously despite variation of system parameters (spatial tapering). This spatially extended phase-locking allows complete pump depletion in the system and uniform amplification spectrum in a wide frequency band. Different aspects of autoresonant OPA are described including the automatic initial phase-locking, conditions for autoresonant transition, stability, and spatial range of the autoresonant interaction.

Spatial filtering velocimetry of objective speckles for measuring out-of-plane motion

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Yura, H. T.; Hanson, Steen Grüner

2012-01-01

This paper analyzes the dynamics of objective laser speckles as the distance between the object and the observation plane continuously changes. With the purpose of applying optical spatial filtering velocimetry to the speckle dynamics, in order to measure out-of-plane motion in real time......, a rotational symmetric spatial filter is designed. The spatial filter converts the speckle dynamics into a photocurrent with a quasi-sinusoidal response to the out-of-plane motion. The spatial filter is here emulated with a CCD camera, and is tested on speckles arising from a real application. The analysis...

Fiber-optic fluorometer for microscale mapping of photosynthetic pigments in microbial communities

DEFF Research Database (Denmark)

Thar, Roland Matthias; Kühl, Michael; Holst, Gerhard

2001-01-01

Microscale fluorescence measurements were performed in photosynthetic biofilms at a spatial resolution of 100 to 200 µm with a new fiber-optic fluorometer which allowed four different excitation and emission wavelengths and was configured for measuring phycobiliproteins, chlorophylls, and bacteri......Microscale fluorescence measurements were performed in photosynthetic biofilms at a spatial resolution of 100 to 200 µm with a new fiber-optic fluorometer which allowed four different excitation and emission wavelengths and was configured for measuring phycobiliproteins, chlorophylls...

Fourier optical cryptosystem using complex spatial modulation

International Nuclear Information System (INIS)

Sarkadi, T; Koppa, P

2014-01-01

Our goal is to enhance the security level of a Fourier optical encryption system. Therefore we propose a Mach–Zehnder interferometer based encryption setup. The input data is organized in a binary array, and it is encoded in the two wave fronts propagated in the arms of the interferometer. Both input wave fronts are independently encrypted by Fourier systems, hence the proposed method has two encryption keys. During decryption, the encrypted wave fronts are propagated through the interferometer setup. The interference pattern of the output shows the reconstructed data in cases where the correct decryption Fourier keys are used. We propose a novel input image modulation method with a user defined phase parameter. We show that the security level of the proposed cryptosystem can be enhanced by an optimally chosen phase parameter. (paper)

Effects of acoustic radiation force and shear waves for absorption and stiffness sensing in ultrasound modulated optical tomography.

Science.gov (United States)

Li, Rui; Elson, Daniel S; Dunsby, Chris; Eckersley, Robert; Tang, Meng-Xing

2011-04-11

Ultrasound-modulated optical tomography (UOT) combines optical contrast with ultrasound spatial resolution and has great potential for soft tissue functional imaging. One current problem with this technique is the weak optical modulation signal, primarily due to strong optical scattering in diffuse media and minimal acoustically induced modulation. The acoustic radiation force (ARF) can create large particle displacements in tissue and has been shown to be able to improve optical modulation signals. However, shear wave propagation induced by the ARF can be a significant source of nonlocal optical modulation which may reduce UOT spatial resolution and contrast. In this paper, the time evolution of shear waves was examined on tissue mimicking-phantoms exposed to 5 MHz ultrasound and 532 nm optical radiation and measured with a CCD camera. It has been demonstrated that by generating an ARF with an acoustic burst and adjusting both the timing and the exposure time of the CCD measurement, optical contrast and spatial resolution can be improved by ~110% and ~40% respectively when using the ARF rather than 5 MHz ultrasound alone. Furthermore, it has been demonstrated that this technique simultaneously detects both optical and mechanical contrast in the medium and the optical and mechanical contrast can be distinguished by adjusting the CCD exposure time. © 2011 Optical Society of America

Electro-optic transceivers for terahertz-wave applications

International Nuclear Information System (INIS)

Chen, Q.; Tani, M.; Jiang, Zhiping; Zhang, X.-C.

2001-01-01

Because of the reciprocal behavior of the optical rectification and the electro-optic effect in a nonlinear optical crystal, an electro-optic transceiver can alternately transmit pulsed electromagnetic radiation (optical rectification) and detect the return signal (electro-optic effect) in the same crystal. However, the optimal condition of the electro-optic transceiver may be very different from that of the spatially separated emitter and receiver. We present a detailed description of the crystal-orientation dependence of the electro-optic terahertz devices (transmitter, receiver, and transceiver). It is found that for a (110) zinc-blende electro-optical crystal, the efficiency of the electro-optic transceiver will be optimized when the angle between the polarization of the optical pump beam and the crystallographic z axis [0,0,1] is 26 degree. Meanwhile, for a (111) crystal, the angle between the optical beam and the crystallographic direction [-1,-1,2] should be 23 degree. The experimental results from a (110) ZnTe transceiver verify theoretical calculations and demonstrate a direct way to optimize the working efficiency of an electro-optic terahertz transceiver. [copyright] 2001 Optical Society of America

Spectro-spatial analysis of wave packet propagation in nonlinear acoustic metamaterials

Science.gov (United States)

Zhou, W. J.; Li, X. P.; Wang, Y. S.; Chen, W. Q.; Huang, G. L.

2018-01-01

The objective of this work is to analyze wave packet propagation in weakly nonlinear acoustic metamaterials and reveal the interior nonlinear wave mechanism through spectro-spatial analysis. The spectro-spatial analysis is based on full-scale transient analysis of the finite system, by which dispersion curves are generated from the transmitted waves and also verified by the perturbation method (the L-P method). We found that the spectro-spatial analysis can provide detailed information about the solitary wave in short-wavelength region which cannot be captured by the L-P method. It is also found that the optical wave modes in the nonlinear metamaterial are sensitive to the parameters of the nonlinear constitutive relation. Specifically, a significant frequency shift phenomenon is found in the middle-wavelength region of the optical wave branch, which makes this frequency region behave like a band gap for transient waves. This special frequency shift is then used to design a direction-biased waveguide device, and its efficiency is shown by numerical simulations.

Reconstructions in ultrasound modulated optical tomography

KAUST Repository

Allmaras, Moritz; Bangerth, Wolfgang

2011-01-01

We introduce a mathematical model for ultrasound modulated optical tomography and present a simple reconstruction scheme for recovering the spatially varying optical absorption coefficient from scanning measurements with narrowly focused ultrasound signals. Computational results for this model show that the reconstruction of sharp features of the absorption coefficient is possible. A formal linearization of the model leads to an equation with a Fredholm operator, which explains the stability observed in our numerical experiments. © de Gruyter 2011.

Geometrical superresolved imaging using nonperiodic spatial masking.

Science.gov (United States)

Borkowski, Amikam; Zalevsky, Zeev; Javidi, Bahram

2009-03-01

The resolution of every imaging system is limited either by the F-number of its optics or by the geometry of its detection array. The geometrical limitation is caused by lack of spatial sampling points as well as by the shape of every sampling pixel that generates spectral low-pass filtering. We present a novel approach to overcome the low-pass filtering that is due to the shape of the sampling pixels. The approach combines special algorithms together with spatial masking placed in the intermediate image plane and eventually allows geometrical superresolved imaging without relation to the actual shape of the pixels.

Hanle Detection for Optical Clocks

Directory of Open Access Journals (Sweden)

Xiaogang Zhang

2015-01-01

Full Text Available Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard.

Low-intensity focused ultrasound alters the latency and spatial patterns of sensory-evoked cortical responses in vivo

Science.gov (United States)

Fisher, Jonathan A. N.; Gumenchuk, Iryna

2018-06-01

Objective. The use of transcranial, low intensity focused ultrasound (FUS) is an emerging neuromodulation technology that shows promise for both therapeutic and research applications. Among many, one of the most exciting applications is the use of FUS to rehabilitate or augment human sensory capabilities. While there is compelling empirical evidence demonstrating this capability, basic questions regarding the spatiotemporal extent of the modulatory effects remain. Our objective was to assess the basic, yet often overlooked hypothesis that FUS in fact alters sensory-evoked neural activity within the region of the cerebral cortex at the beam’s focus. Approach. To address this knowledge gap, we developed an approach to optically interrogate patterns of neural activity in the cortex directly at the acoustic focus, in vivo. Implementing simultaneous wide-field optical imaging and FUS stimulation in mice, our experiments probed somatosensory-evoked electrical activity through the use of voltage sensitive dyes (VSDs) and, in transgenic mice expressing GCaMP6f, monitored associated Ca2+ responses. Main results. Our results demonstrate that low-intensity FUS alters both the kinetics and spatial patterns of neural activity in primary somatosensory cortex at the acoustic focus. When preceded by 1 s of pulsed ultrasound at intensities below 1 W cm‑2 (I sppa), the onset of sensory-evoked cortical responses occurred 3.0  ±  0.7 ms earlier and altered the surface spatial morphology of Ca2+ responses. Significance. These findings support the heretofore unconfirmed assumption that FUS-induced sensory modulation reflects, at least in part, altered reactivity in primary sensory cortex at the site of sonication. The findings are significant given the interest in using FUS to target and alter spatial aspects of sensory receptive fields on the cerebral cortex.

Low-intensity focused ultrasound alters the latency and spatial patterns of sensory-evoked cortical responses in vivo.

Science.gov (United States)

Fisher, Jonathan A N; Gumenchuk, Iryna

2018-02-13

The use of transcranial, low intensity focused ultrasound (FUS) is an emerging neuromodulation technology that shows promise for both therapeutic and research applications. Among many, one of the most exciting applications is the use of FUS to rehabilitate or augment human sensory capabilities. While there is compelling empirical evidence demonstrating this capability, basic questions regarding the spatiotemporal extent of the modulatory effects remain. Our objective was to assess the basic, yet often overlooked hypothesis that FUS in fact alters sensory-evoked neural activity within the region of the cerebral cortex at the beam's focus. To address this knowledge gap, we developed an approach to optically interrogate patterns of neural activity in the cortex directly at the acoustic focus, in vivo. Implementing simultaneous wide-field optical imaging and FUS stimulation in mice, our experiments probed somatosensory-evoked electrical activity through the use of voltage sensitive dyes (VSDs) and, in transgenic mice expressing GCaMP6f, monitored associated Ca 2+ responses. Our results demonstrate that low-intensity FUS alters both the kinetics and spatial patterns of neural activity in primary somatosensory cortex at the acoustic focus. When preceded by 1 s of pulsed ultrasound at intensities below 1 W cm -2 (I sppa ), the onset of sensory-evoked cortical responses occurred 3.0  ±  0.7 ms earlier and altered the surface spatial morphology of Ca 2+ responses. These findings support the heretofore unconfirmed assumption that FUS-induced sensory modulation reflects, at least in part, altered reactivity in primary sensory cortex at the site of sonication. The findings are significant given the interest in using FUS to target and alter spatial aspects of sensory receptive fields on the cerebral cortex.

Optical Effects Induced by Bloch Surface Waves in One-Dimensional Photonic Crystals

Directory of Open Access Journals (Sweden)

Irina V. Soboleva

2018-01-01

Full Text Available The review considers the influence of Bloch surface waves on the optical and magneto-optical effects observed in photonic crystals; for example, the Goos–Hänchen effect, the Faraday effect, optical trapping and so on. Prospects for using Bloch surface waves for spatial light modulation, for controlling the polarization of light, for optical trapping and control of micro-objects are discussed.

Fourier phase in Fourier-domain optical coherence tomography

Science.gov (United States)

Uttam, Shikhar; Liu, Yang

2015-01-01

Phase of an electromagnetic wave propagating through a sample-of-interest is well understood in the context of quantitative phase imaging in transmission-mode microscopy. In the past decade, Fourier-domain optical coherence tomography has been used to extend quantitative phase imaging to the reflection-mode. Unlike transmission-mode electromagnetic phase, however, the origin and characteristics of reflection-mode Fourier phase are poorly understood, especially in samples with a slowly varying refractive index. In this paper, the general theory of Fourier phase from first principles is presented, and it is shown that Fourier phase is a joint estimate of subresolution offset and mean spatial frequency of the coherence-gated sample refractive index. It is also shown that both spectral-domain phase microscopy and depth-resolved spatial-domain low-coherence quantitative phase microscopy are special cases of this general theory. Analytical expressions are provided for both, and simulations are presented to explain and support the theoretical results. These results are further used to show how Fourier phase allows the estimation of an axial mean spatial frequency profile of the sample, along with depth-resolved characterization of localized optical density change and sample heterogeneity. Finally, a Fourier phase-based explanation of Doppler optical coherence tomography is also provided. PMID:26831383

Fourier phase in Fourier-domain optical coherence tomography.

Science.gov (United States)

Uttam, Shikhar; Liu, Yang

2015-12-01

Phase of an electromagnetic wave propagating through a sample-of-interest is well understood in the context of quantitative phase imaging in transmission-mode microscopy. In the past decade, Fourier-domain optical coherence tomography has been used to extend quantitative phase imaging to the reflection-mode. Unlike transmission-mode electromagnetic phase, however, the origin and characteristics of reflection-mode Fourier phase are poorly understood, especially in samples with a slowly varying refractive index. In this paper, the general theory of Fourier phase from first principles is presented, and it is shown that Fourier phase is a joint estimate of subresolution offset and mean spatial frequency of the coherence-gated sample refractive index. It is also shown that both spectral-domain phase microscopy and depth-resolved spatial-domain low-coherence quantitative phase microscopy are special cases of this general theory. Analytical expressions are provided for both, and simulations are presented to explain and support the theoretical results. These results are further used to show how Fourier phase allows the estimation of an axial mean spatial frequency profile of the sample, along with depth-resolved characterization of localized optical density change and sample heterogeneity. Finally, a Fourier phase-based explanation of Doppler optical coherence tomography is also provided.

Radiation-induced refraction artifacts in the optical CT readout of polymer gel dosimeters

International Nuclear Information System (INIS)

Campbell, Warren G.; Jirasek, Andrew; Wells, Derek M.

2014-01-01

data, 10 Gy for AM, and 3.1 Gy for ISG. The ISG routine also addressed unrelated artifacts that previously needed to be manually removed in sinogram space. However, the ISG routine blurred reconstructions, causing losses in spatial resolution of ∼5 mm in the plane of the fan-beam and ∼8 mm perpendicular to the fan-beam. Conclusions: This paper reveals a new category of imaging artifacts that can affect the optical CT readout of polyacrylamide gel dosimeters. Investigative scans show that radiation-induced RI changes can cause significant rayline errors when rays confront a prolonged dose gradient that runs perpendicular to their trajectory. In fan-beam optical CT, these errors manifested in two ways: (1) distinct streaking artifacts caused by in-plane rayline bending and (2) severe overestimations of opacity caused by rays bending out of the fan-beam plane and missing the detector array. Although the ISG filtering routine mitigated these errors better than an adaptive-mean filtering routine, it caused unacceptable losses in spatial resolution

Secchi depth analysis using bio-optical parameters measured in the Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Suresh, T.; Naik, P.; Bandishte, M.; Desa, E.; Mascarenhas, A.A.M.Q.; Matondkar, S.G.P.

spatial and temporal variability of Secchi depth and their dependence on the optical properties beam attenuation and diffuse attenuation the biological parameter of Chlorophyll. The in-situ measured inherent and apparent optical properties have been used...

A spatio-temporally compensated acousto-optic scanner for two-photon microscopy providing large field of view.

Science.gov (United States)

Kremer, Y; Léger, J-F; Lapole, R; Honnorat, N; Candela, Y; Dieudonné, S; Bourdieu, L

2008-07-07

Acousto-optic deflectors (AOD) are promising ultrafast scanners for non-linear microscopy. Their use has been limited until now by their small scanning range and by the spatial and temporal dispersions of the laser beam going through the deflectors. We show that the use of AOD of large aperture (13mm) compared to standard deflectors allows accessing much larger field of view while minimizing spatio-temporal distortions. An acousto-optic modulator (AOM) placed at distance of the AOD is used to compensate spatial and temporal dispersions. Fine tuning of the AOM-AOD setup using a frequency-resolved optical gating (GRENOUILLE) allows elimination of pulse front tilt whereas spatial chirp is minimized thanks to the large aperture AOD.

Interference electron microscopy of one-dimensional electron-optical phase objects

International Nuclear Information System (INIS)

Fazzini, P.F.; Ortolani, L.; Pozzi, G.; Ubaldi, F.

2006-01-01

The application of interference electron microscopy to the investigation of electron optical one-dimensional phase objects like reverse biased p-n junctions and ferromagnetic domain walls is considered. In particular the influence of diffraction from the biprism edges on the interference images is analyzed and the range of applicability of the geometric optical equation for the interpretation of the interference fringe shifts assessed by comparing geometric optical images with full wave-optical simulations. Finally, the inclusion of partial spatial coherence effects are discussed

Dynamic array of dark optical traps

DEFF Research Database (Denmark)

Daria, V.R.; Rodrigo, P.J.; Glückstad, J.

2004-01-01

A dynamic array of dark optical traps is generated for simultaneous trapping and arbitrary manipulation of multiple low-index microstructures. The dynamic intensity patterns forming the dark optical trap arrays are generated using a nearly loss-less phase-to-intensity conversion of a phase......-encoded coherent light source. Two-dimensional input phase distributions corresponding to the trapping patterns are encoded using a computer-programmable spatial light modulator, enabling each trap to be shaped and moved arbitrarily within the plane of observation. We demonstrate the generation of multiple dark...... optical traps for simultaneous manipulation of hollow "air-filled" glass microspheres suspended in an aqueous medium. (C) 2004 American Institute of Physics....

Optical Beams in Nonlocal Nonlinear Media

DEFF Research Database (Denmark)

Królikowski, W.; Bang, Ole; Wyller, J.

2003-01-01

We discuss propagation of optical beams in nonlocal Kerr-like media with the nonlocality of general form. We study the effect of nonlocality on modulational instability of the plane wave fronts, collapse of finite beams and formation of spatial solitons....

Adapting an optical nanoantenna for high E-field probing applications to a waveguided optical waveguide (WOW)

DEFF Research Database (Denmark)

Rindorf, Lars Henning; Glückstad, Jesper

2013-01-01

In the current work we intend to use the optical nano-antenna to include various functionalities for the recently demonstrated waveguided optical waveguide (WOW) by Palima et al. (Optics Express 2012). Specifically, we intend to study a WOW with an optical nano-antenna which can block the guiding......-stop characteristic. We give geometrical parameters necessary for realizing functioning nanoantennas. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.......In the current work we intend to use the optical nano-antenna to include various functionalities for the recently demonstrated waveguided optical waveguide (WOW) by Palima et al. (Optics Express 2012). Specifically, we intend to study a WOW with an optical nano-antenna which can block the guiding...... light wavelength while admitting other wavelengths of light which address certain functionalities, e.g. drug release, in the WOW. In particular, we study a bow-tie optical nano-antenna to circular dielectric waveguides in aqueous environments. It is shown with finite element computer simulations...

Optical and mechanical design of the fore-optics of HARMONI

Science.gov (United States)

Sánchez-Capuchino, J.; Hernández, E.; Bueno, A.; Herreros, J. M.; Thatte, N.; Bryson, I.; Clarke, F.; Tecza, M.

2014-07-01

HARMONI is a visible and near-infrared (0.47μm to 2.5μm) integral field spectrometer providing the E-ELT's core spectroscopic capability. It will provide ~32000 simultaneous spectra of a rectangular field of view at four foreseen different spatial sample (spaxel) scales. The HARMONI fore-optics re-formats the native telescope plate scale to suitable values for the downstream instrument optics. This telecentric adaptation includes anamorphic magnification of the plate scale to optimize the performance of the IFU, which contains the image slicer, and their four spectrographs. In addition, it provides an image of the telescope pupil to assemble a cold stop shared among all the scales allowing efficient suppression of the thermal background. A pupil imaging unit also re-images the pupil cold stop onto the image slicer to check the relative alignment between the E-ELT and HARMONI pupils. The scale changer will also host the filter wheel with the long-pass filters to select the wavelength range. The main reasoning specifying the importance of the HARMONI fore-optics and its current optical and mechanical design is described in this contribution.

Fourier synthesis of asymmetrical optical potentials for atoms; Fourier-Synthese von asymmetrischen optischen Potentialen fuer Atome