Recent advances in head-mounted light field displays for virtual and augmented reality (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hua, Hong

2017-02-01

Head-mounted light field displays render a true 3D scene by sampling either the projections of the 3D scene at different depths or the directions of the light rays apparently emitted by the 3D scene and viewed from different eye positions. They are capable of rendering correct or nearly correct focus cues and addressing the very well-known vergence-accommodation mismatch problem in conventional virtual and augmented reality displays. In this talk, I will focus on reviewing recent advancements of head-mounted light field displays for VR and AR applications. I will demonstrate examples of HMD systems developed in my group.

The potential of ill-nitride laser diodes for solid-state lighting [Advantages of III-Nitride Laser Diodes in Solid-State Lighting

DOE PAGES

Wierer, Jonathan; Tsao, Jeffrey Y.

2014-09-01

III-nitride laser diodes (LDs) are an interesting light source for solid-state lighting (SSL). Modelling of LDs is performed to reveal the potential advantages over traditionally used light-emitting diodes (LEDs). The first, and most notable, advantage is LDs have higher efficiency at higher currents when compared to LEDs. This is because Auger recombination that causes efficiency droop can no longer grow after laser threshold. Second, the same phosphor-converted methods used with LEDs can also be used with LDs to produce white light with similar color rendering and color temperature. Third, producing white light from direct emitters is equally challenging for bothmore » LEDs and LDs, with neither source having a direct advantage. Lastly, the LD emission is directional and can be more readily captured and focused, leading to the possibility of novel and more compact luminaires. These advantages make LDs a compelling source for future SSL.« less

Optical trapping and rotation of airborne absorbing particles with a single focused laser beam

NASA Astrophysics Data System (ADS)

Lin, Jinda; Li, Yong-qing

2014-03-01

We measure the periodic circular motion of single absorbing aerosol particles that are optically trapped with a single focused Gaussian beam and rotate around the laser propagation direction. The scattered light from the trapped particle is observed to be directional and change periodically at 0.4-20 kHz. The instantaneous positions of the moving particle within a rotation period are measured by a high-speed imaging technique using a charge coupled device camera and a repetitively pulsed light-emitting diode illumination. The centripetal acceleration of the trapped particle as high as ˜20 times the gravitational acceleration is observed and is attributed to the photophoretic forces.

Beam shaping with vortex beam generated by liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Gao, Yue; Liu, Ke; Sun, Zeng-yu; Guo, Lei; Gan, Yu

2015-02-01

An optical vortex is a beam of light with phase varying in a corkscrew-like manner along its direction of propagation and so has a helical wavefront. When such a vectorial vortex beam and the Gaussian beam with orthogonal polarization are focused by low NA lens, the Gaussian component causes a focal intensity distribution with a solid center and the vortex component causes a donut distribution with hollow dark center. The shape of the focus can be continuously varied by continuously adjusting the relative weight of the two components. Flat top focusing can be obtained under appropriate conditions. It is demonstrated through experiments with a liquid crystal spatial light modulator in such a beam, that flattop focus can be obtained by vectorial vortex beams with topological charge of +1 to achieve beam shaping vortex.

Plate-Focusing Based on a Meta-Molecule of Dendritic Structure in the Visible Frequency.

PubMed

Cheng, Suna; An, Di; Chen, Huan; Zhao, Xiaopeng

2018-05-31

To study the potential application of metasurfaces in lens technology, we propose a dendritic meta-molecule surface (also referred to as a dendritic metasurface) and realize the focusing effect in the visible spectrum through simulations and experiments. Using asymmetric dendritic structures, this metasurface can achieve distinct broadband anomalous reflection and refraction. When the metasurface is rotated by 180° around the z axis, anomalous reflection and refraction in vertically incident optical waves are in opposite directions. Considering this feature, a metasurface is designed to achieve a prominent plate-focusing effect. Samples with a transmission peak of green light at 555 nm, yellow light at 580 nm, and red light at 650 nm were prepared using bottom-up electrochemical deposition, and the focus intensity of approximately 10% and focal length of almost 600 µm were experimentally demonstrated.

Imaging Spectrometer Designs Utilizing Immersed Gratings With Accessible Entrance Slit

DOEpatents

Chrisp, Michael P.; Lerner, Scott A.

2006-03-21

A compact imaging spectrometer comprises an entrance slit, a catadioptric lens with a mirrored surface, a grating, and a detector array. The entrance slit directs light to the mirrored surface of the catadioptric lens; the mirrored surface reflects the light back through the lens to the grating. The grating receives the light from the catadioptric lens and diffracts the light to the lens away from the mirrored surface. The lens transmits the light and focuses it onto the detector array.

Tunable Liquid Gradient Refractive Index (L-GRIN) lens with two degrees of freedom.

PubMed

Mao, Xiaole; Lin, Sz-Chin Steven; Lapsley, Michael Ian; Shi, Jinjie; Juluri, Bala Krishna; Huang, Tony Jun

2009-07-21

We report a tunable optofluidic microlens configuration named the Liquid Gradient Refractive Index (L-GRIN) lens for focusing light within a microfluidic device. The focusing of light was achieved through the gradient refractive index (GRIN) within the liquid medium, rather than via curved refractive lens surfaces. The diffusion of solute (CaCl(2)) between side-by-side co-injected microfluidic laminar flows was utilized to establish a hyperbolic secant (HS) refractive index profile to focus light. Tailoring the refractive index profile by adjusting the flow conditions enables not only tuning of the focal distance (translation mode), but also shifting of the output light direction (swing mode), a second degree of freedom that to our knowledge has yet to be accomplished for in-plane tunable microlenses. Advantages of the L-GRIN lens also include a low fluid consumption rate, competitive focusing performance, and high compatibility with existing microfluidic devices. This work provides a new strategy for developing integrative tunable microlenses for a variety of lab-on-a-chip applications.

Incident light adjustable solar cell by periodic nanolens architecture

PubMed Central

Yun, Ju-Hyung; Lee, Eunsongyi; Park, Hyeong-Ho; Kim, Dong-Wook; Anderson, Wayne A.; Kim, Joondong; Litchinitser, Natalia M.; Zeng, Jinwei; Yi, Junsin; Kumar, M. Melvin David; Sun, Jingbo

2014-01-01

Could nanostructures act as lenses to focus incident light for efficient utilization of photovoltaics? Is it possible, in order to avoid serious recombination loss, to realize periodic nanostructures in solar cells without direct etching in a light absorbing semiconductor? Here we propose and demonstrate a promising architecture to shape nanolenses on a planar semiconductor. Optically transparent and electrically conductive nanolenses simultaneously provide the optical benefit of modulating the incident light and the electrical advantage of supporting carrier transportation. A transparent indium-tin-oxide (ITO) nanolens was designed to focus the incident light-spectrum in focal lengths overlapping to a strong electric field region for high carrier collection efficiency. The ITO nanolens effectively broadens near-zero reflection and provides high tolerance to the incident light angles. We present a record high light-conversion efficiency of 16.0% for a periodic nanostructured Si solar cell. PMID:25371099

Solar internal lighting using optical collectors and fibers

NASA Astrophysics Data System (ADS)

Francini, F.; Fontani, D.; Jafrancesco, D.; Mercatelli, L.; Sansoni, P.

2006-08-01

A system exploiting solar energy, by means of optical collectors and fibres, has been applied for indoor illumination. The project has been called "The Sunflowers" for the property of solar collectors to track solar position during the day. Every "sunflower" contains several solar collectors, each of which is coupled to an optical fibre. The "Sunflower" is provided of mechanical systems and electric accessories for solar tracking. The light focused by the solar collector can be used in two possible ways: for internal illumination with direct solar light; otherwise it can be accumulated for lighting when the sun is not present. The first function is obtained coupling the optical collector to an optical fibre, which transports the solar light in selected points within the showcases. The second one consists in focusing solar light on a photovoltaic cell of the last generation type with high efficiency. In this configuration the photovoltaic cell converts the focused light into electric energy to be used for illumination in case of sun absence. A demonstrative installation has been realised applying this solar illumination system to museum lighting: a prototype has been tested in a prestigious museum in Florence.

Device for translating negative film image to a line scan

DOEpatents

Dutton, G.W.

1998-05-19

A negative film reader records high-resolution optical density changes across negative film radiographic images to allow precise image dimensions to be determined. A laser light source capable of high-resolution focusing is passed through an intensity control filter, focused by a lens, and reflected off a mirror to focus in the plane of the negative film. The light transmitted through the film is collected by a second lens and directed to a photo diode detector which senses the transmitted intensity. The output of the photo diode signal amplifier is sent to the Y-axis input of an X-Y recorder. The film sample is transported in a plane perpendicular to the beam axis by means of a slide. The film position is monitored, with the signal amplified and recorded as the X-axis on the X-Y recorder. The linear dimensions and positions of image components can be determined by direct measurement of the amplified recording.

Light intensity modulation by coccoliths of Emiliania huxleyi as a micro-photo-regulator.

PubMed

Mizukawa, Yuri; Miyashita, Yuito; Satoh, Manami; Shiraiwa, Yoshihiro; Iwasaka, Masakazu

2015-09-01

In this study, we present experimental evidence showing that coccoliths have light-scattering anisotropy that contributes to a possible control of solar light exposure in the ocean. Changing the angle between the incident light and an applied magnetic field causes differences in the light-scattering intensities of a suspension of coccoliths isolated from Emiliania huxleyi. The magnetic field effect is induced by the diamagnetic torque force directing the coccolith radial plane perpendicular to the applied magnetic fields at 400 to 500 mT. The developed technique reveals the light-scattering anisotropies in the 3-μm-diameter floating coccoliths by orienting themselves in response to the magnetic fields. The detached coccolith scatters radially the light incident to its radial plane. The experimental results on magnetically oriented coccoliths show that an individual coccolith has a specific direction of light scattering, although the possible physiological effect of the coccolith remains for further study, focusing on the light-scattering anisotropies of coccoliths on living cells.

Light intensity modulation by coccoliths of Emiliania huxleyi as a micro-photo-regulator

NASA Astrophysics Data System (ADS)

Mizukawa, Yuri; Miyashita, Yuito; Satoh, Manami; Shiraiwa, Yoshihiro; Iwasaka, Masakazu

2015-09-01

In this study, we present experimental evidence showing that coccoliths have light-scattering anisotropy that contributes to a possible control of solar light exposure in the ocean. Changing the angle between the incident light and an applied magnetic field causes differences in the light-scattering intensities of a suspension of coccoliths isolated from Emiliania huxleyi. The magnetic field effect is induced by the diamagnetic torque force directing the coccolith radial plane perpendicular to the applied magnetic fields at 400 to 500 mT. The developed technique reveals the light-scattering anisotropies in the 3-μm-diameter floating coccoliths by orienting themselves in response to the magnetic fields. The detached coccolith scatters radially the light incident to its radial plane. The experimental results on magnetically oriented coccoliths show that an individual coccolith has a specific direction of light scattering, although the possible physiological effect of the coccolith remains for further study, focusing on the light-scattering anisotropies of coccoliths on living cells.

Optical system

NASA Technical Reports Server (NTRS)

Breckinridge, J. B.; Page, N. A.; Shack, R. V.; Shannon, R. R. (Inventor)

1985-01-01

Disclosed is an otpical system used in a spacecraft to observe a remote surface and provide a spatial and spectral image of this surface. The optical system includes aspheric and spherical mirrors aligned to focus at a first focal plane an image of the surface, and a mirror at this first focal plane which reflects light back on to the spherical mirror. This spherical mirror collimates the light and directs it through a prism which disperses it. The dispersed light is then focused on an array of light responsive elements disposed at a second focal plane. The prism is designed such that it disperses light into components of different wavelengths, with the components of shorter wavelengths being dispersed more than the components of longer wavelengths to present at the second focal plane a distribution pattern in which preselected groupings of the components are dispersed over essentially equal spacing intervals.

Plasmonic nanofocusing of light in an integrated silicon photonics platform.

PubMed

Desiatov, Boris; Goykhman, Ilya; Levy, Uriel

2011-07-04

The capability to focus electromagnetic energy at the nanoscale plays an important role in nanoscinece and nanotechnology. It allows enhancing light matter interactions at the nanoscale with applications related to nonlinear optics, light emission and light detection. It may also be used for enhancing resolution in microscopy, lithography and optical storage systems. Hereby we propose and experimentally demonstrate the nanoscale focusing of surface plasmons by constructing an integrated plasmonic/photonic on chip nanofocusing device in silicon platform. The device was tested directly by measuring the optical intensity along it using a near-field microscope. We found an order of magnitude enhancement of the intensity at the tip's apex. The spot size is estimated to be 50 nm. The demonstrated device may be used as a building block for "lab on a chip" systems and for enhancing light matter interactions at the apex of the tip.

Enhancement of second harmonic generation in NaNO{sub 2}-infiltrated opal photonic crystal using structural light focusing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaytsev, Kirill I., E-mail: kirzay@gmail.com; Yurchenko, Stanislav O., E-mail: st.yurchenko@mail.ru

Experimental and numerical results for second harmonic generation (SHG) in photonic crystal (PC) based on NaNO{sub 2}-infiltrated opal matrix are presented. SHG is performed in reflection mode; thus, the direction of the SHG maximum is equal to the angle of mirror reflection. The PC was pumped with femtosecond optical pulses at different angles of incidence, allowing the dependence of the SHG efficiency on the location of the fundamental wavelength toward the PC band gap (BG) to be examined. The most efficient SHG was observed when pumping the BG of the PC. To interpret the experimental results, finite-difference time-domain numerical simulationsmore » of the light interaction with the PC were conducted. The observed effect of highly efficient SHG is associated with structural light focusing, and, as a consequence, with strong optical field localization within certain near-surface PC regions. Thus, SHG enhancement based on structural light focusing in PC was demonstrated.« less

Injection moulding of plastic parts with laser textured surfaces with optical applications

NASA Astrophysics Data System (ADS)

Pina-Estany, J.; García-Granada, A. A.; Corull-Massana, E.

2018-05-01

The purpose of this work is to manufacture micro and nanotextured surfaces on plastic injection moulds with the aim of replicating them and obtaining plastic parts with optical applications. Different patterns are manufactured with nanosecond and femtosecond lasers in order to obtain three different optical applications: (i) homogeneous light diffusion (ii) 1D light directionality and (iii) 2D light directionality. Induction heating is used in the injections in order to improve the textures degree of replication. The steel mould and the plastic parts are analyzed with a confocal/focus variation microscope and with a surface roughness tester. A mock-up and a luminance camera are used to evaluate the homogeneity and luminance of the homogeneous light diffusion application in comparison with the current industrial solutions.

And There Was Light: Prospects for the Creation of Micro- and Nanostructures through Maskless Photolithography.

PubMed

Rühe, J

2017-09-26

In photolithographic processes, the light inducing the photochemical reactions is confined to a small volume, which enables direct writing of micro- and nanoscale features onto solid surfaces without the need of a predefined photomask. The direct writing process can be used to generate topographic patterns through photopolymerization or photo-cross-linking or can be employed to use light to generate chemical patterns on the surface with high spatial control, which would make such processes attractive for bioapplications. The prospects of maskless photolithography technologies with a focus on two-photon lithography and scanning-probe-based photochemical processes based on scanning near-field optical microscopy or beam pen lithography are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yichen, E-mail: ycshen@mit.edu; Joannopoulos, John D.; Soljačić, Marin

Humankind has long endeavored to control the propagation direction of light. Since time immemorial, shades, lenses, and mirrors have been used to control the flow of light. In modern society, with the rapid development of nanotechnology, the control of light is moving toward devices at micrometer and even nanometer scales. At such scales, traditional devices based on geometrical optics reach their fundamental diffraction limits and cease to work. Nano-photonics, on the other hand, has attracted wide attention from researchers, especially in the last decade, due to its ability to manipulate light at the nanoscale. This review focuses on the nano-photonicsmore » systems that aim to select light based on its propagation direction. In the first half of this review, we survey the literature and the current state of the art focused on enabling optical broadband angular selectivity. The mechanisms we review can be classified into three main categories: (i) microscale geometrical optics, (ii) multilayer birefringent materials, and (iii) Brewster modes in plasmonic systems, photonic crystals, and metamaterials. In the second half, we present two categories of potential applications for broadband angularly selective systems. The first category aims at enhancing the efficiency of solar energy harvesting, through photovoltaic process or solar thermal process. The second category aims at enhancing light extracting efficiency and detection sensitivity. Finally, we discuss the most prominent challenges in broadband angular selectivity and some prospects on how to solve these challenges.« less

How to harvest efficient laser from solar light

NASA Astrophysics Data System (ADS)

Zhao, Changming; Guan, Zhe; Zhang, Haiyang

2018-02-01

Solar Pumped Solid State Lasers (SPSSL) is a kind of solid state lasers that can transform solar light into laser directly, with the advantages of least energy transform procedure, higher energy transform efficiency, simpler structure, higher reliability, and longer lifetime, which is suitable for use in unmanned space system, for solar light is the only form of energy source in space. In order to increase the output power and improve the efficiency of SPSSL, we conducted intensive studies on the suitable laser material selection for solar pump, high efficiency/large aperture focusing optical system, the optimization of concave cavity as the second focusing system, laser material bonding and surface processing. Using bonded and grooved Nd:YAG rod as laser material, large aperture Fresnel lens as the first stage focusing element, concave cavity as the second stage focusing element, we finally got 32.1W/m2 collection efficiency, which is the highest collection efficiency in the world up to now.

A new linear structured light module based on the MEMS micromirror

NASA Astrophysics Data System (ADS)

Zhou, Peng; Shen, Wenjiang; Yu, Huijun

2017-10-01

A new linear structured light module based on the Micro-Electro-Mechanical System (MEMS) two-dimensional scanning micromirror was designed and created. This module consists of a laser diode, a convex lens, and the MEMS micromirror. The laser diode generates the light and the convex lens control the laser beam to converge on a single point with large depth of focus. The fast scan in horizontal direction of the micromirror will turn the laser spot into a homogenous laser line. Meanwhile, the slow scan in vertical direction of the micromirror will move the laser line in the vertical direction. The width of the line generated by this module is 300μm and the length is 120mm and the moving distance is 100mm at 30cm away from the module. It will promote the development of industrial detection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeylikovich, I.; Xu, M., E-mail: mxu@fairfield.edu

The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyzemore » theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.« less

Dynamic coherent backscattering mirror

NASA Astrophysics Data System (ADS)

Zeylikovich, I.; Xu, M.

2016-02-01

The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.

Lighting Control Systems

DTIC Science & Technology

2004-02-26

Shorter payback periods After 19 Cost Benefit of Powerlink Rule of Thumb for Powerlink: Powerlink becomes more cost effective beyond 16 controlled...web enabled control (and management software) Increase in level of integration between building systems Increase in new features, functions, benefits ...focus on reducing run-time via Scheduling, Sensing, Switching Growing focus on payback Direct energy cost (with demand) Additional maintenance benefits

Light directs zebrafish period2 expression via conserved D and E boxes.

PubMed

Vatine, Gad; Vallone, Daniela; Appelbaum, Lior; Mracek, Philipp; Ben-Moshe, Zohar; Lahiri, Kajori; Gothilf, Yoav; Foulkes, Nicholas S

2009-10-01

For most species, light represents the principal environmental signal for entraining the endogenous circadian clock. The zebrafish is a fascinating vertebrate model for studying this process since unlike mammals, direct exposure of most of its tissues to light leads to local clock entrainment. Importantly, light induces the expression of a set of genes including certain clock genes in most zebrafish cell types in vivo and in vitro. However, the mechanism linking light to gene expression remains poorly understood. To elucidate this key mechanism, here we focus on how light regulates transcription of the zebrafish period2 (per2) gene. Using transgenic fish and stably transfected cell line-based assays, we define a Light Responsive Module (LRM) within the per2 promoter. The LRM lies proximal to the transcription start site and is both necessary and sufficient for light-driven gene expression and also for a light-dependent circadian clock regulation. Curiously, the LRM sequence is strongly conserved in other vertebrate per2 genes, even in species lacking directly light-sensitive peripheral clocks. Furthermore, we reveal that the human LRM can substitute for the zebrafish LRM to confer light-regulated transcription in zebrafish cells. The LRM contains E- and D-box elements that are critical for its function. While the E-box directs circadian clock regulation by mediating BMAL/CLOCK activity, the D-box confers light-driven expression. The zebrafish homolog of the thyrotroph embryonic factor binds efficiently to the LRM D-box and transactivates expression. We demonstrate that tef mRNA levels are light inducible and that knock-down of tef expression attenuates light-driven transcription from the per2 promoter in vivo. Together, our results support a model where a light-dependent crosstalk between E- and D-box binding factors is a central determinant of per2 expression. These findings extend the general understanding of the mechanism whereby the clock is entrained by light and how the regulation of clock gene expression by light has evolved in vertebrates.

Tuning subwavelength-structured focus in the hyperbolic metamaterials

NASA Astrophysics Data System (ADS)

Pan, Rong; Tang, Zhixiang; Pan, Jin; Peng, Runwu

2016-10-01

In this paper, we have systematically investigated light propagating in the hyperbolic metamaterials (HMMs) covered by a subwavelength grating. Based on the equal-frequency contour analyses, light in the HMM is predicted to propagate along a defined direction because of its hyperbolic dispersion, which is similar to the self-collimating effects in photonic crystals. By using the finite-difference time-domain, numerical simulations demonstrate a subwavelength bright spot at the intersection of the adjacent directional beams. Different from the images in homogeneous media, the magnetic fields and electric fields at the spot are layered, especially for the electric fields Ez that is polarized to the propagating direction, i.e., the layer normal direction. Moreover, the Ez is hollow in the layer plane and is stronger than the other electric field component Ex. Therefore, the whole electric field is structured and its pattern can be tuned by the HMM's effective anisotropic electromagnetic parameters. Our results may be useful for generating subwavelength structured light.

A programmable light engine for quantitative single molecule TIRF and HILO imaging.

PubMed

van 't Hoff, Marcel; de Sars, Vincent; Oheim, Martin

2008-10-27

We report on a simple yet powerful implementation of objective-type total internal reflection fluorescence (TIRF) and highly inclined and laminated optical sheet (HILO, a type of dark-field) illumination. Instead of focusing the illuminating laser beam to a single spot close to the edge of the microscope objective, we are scanning during the acquisition of a fluorescence image the focused spot in a circular orbit, thereby illuminating the sample from various directions. We measure parameters relevant for quantitative image analysis during fluorescence image acquisition by capturing an image of the excitation light distribution in an equivalent objective backfocal plane (BFP). Operating at scan rates above 1 MHz, our programmable light engine allows directional averaging by circular spinning the spot even for sub-millisecond exposure times. We show that restoring the symmetry of TIRF/HILO illumination reduces scattering and produces an evenly lit field-of-view that affords on-line analysis of evanescnt-field excited fluorescence without pre-processing. Utilizing crossed acousto-optical deflectors, our device generates arbitrary intensity profiles in BFP, permitting variable-angle, multi-color illumination, or objective lenses to be rapidly exchanged.

Time-reversed ultrasonically encoded (TRUE) focusing for deep-tissue optogenetic modulation

NASA Astrophysics Data System (ADS)

Brake, Joshua; Ruan, Haowen; Robinson, J. Elliott; Liu, Yan; Gradinaru, Viviana; Yang, Changhuei

2018-02-01

The problem of optical scattering was long thought to fundamentally limit the depth at which light could be focused through turbid media such as fog or biological tissue. However, recent work in the field of wavefront shaping has demonstrated that by properly shaping the input light field, light can be noninvasively focused to desired locations deep inside scattering media. This has led to the development of several new techniques which have the potential to enhance the capabilities of existing optical tools in biomedicine. Unfortunately, extending these methods to living tissue has a number of challenges related to the requirements for noninvasive guidestar operation, speed, and focusing fidelity. Of existing wavefront shaping methods, time-reversed ultrasonically encoded (TRUE) focusing is well suited for applications in living tissue since it uses ultrasound as a guidestar which enables noninvasive operation and provides compatibility with optical phase conjugation for high-speed operation. In this paper, we will discuss the results of our recent work to apply TRUE focusing for optogenetic modulation, which enables enhanced optogenetic stimulation deep in tissue with a 4-fold spatial resolution improvement in 800-micron thick acute brain slices compared to conventional focusing, and summarize future directions to further extend the impact of wavefront shaping technologies in biomedicine.

Energy and daylighting: A correlation between quality of light and energy consciousness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krug, N.

1997-12-31

Energy and Daylighting, an advanced topics graduate/professional elective has been established to help the student develop a deeper understanding of Architectural Daylighting, Energy Conserving Design, and Material/Construction/Methods through direct application. After a brief survey of the principles and applications of current and developing attitudes and techniques in energy conservation and natural lighting strategies is conducted (in order to build upon previous courses), an extensive exercise follows which allows the student the opportunity for direct applications. Both computer modeling/analysis and physical modeling (light box simulation with photographic documentation) are employed to focus attention on the interrelationships between natural lighting and passivemore » energy conserving design--all within the context of establishing environmental (interior) quality and (exterior) design direction. As a result, students broaden their understanding of natural light and energy conservation as design tools; the importance of environmental responsibility, both built and natural environments; and using computer analysis as a design tool. This presentation centers around the activities and results obtained from explorations into Energy and Daylighting. Discussion will highlight the course objectives, the methodology involved in the studies, specific requirements and means of evaluation, a slide show of befores and afters (results), and a retrospective look at the course`s value, as well as future directions and implications.« less

Enhanced light trapping by focused ion beam (FIB) induced self-organized nanoripples on germanium (100) surface

NASA Astrophysics Data System (ADS)

Kamaliya, Bhaveshkumar; Mote, Rakesh G.; Aslam, Mohammed; Fu, Jing

2018-03-01

In this paper, we demonstrate enhanced light trapping by self-organized nanoripples on the germanium surface. The enhanced light trapping leading to high absorption of light is confirmed by the experimental studies as well as the numerical simulations using the finite-difference time-domain method. We used gallium ion (Ga+) focused ion beam to enable the formation of the self-organized nanoripples on the germanium (100) surface. During the fabrication, the overlap of the scanning beam is varied from zero to negative value and found to influence the orientation of the nanoripples. Evolution of nanostructures with the variation of beam overlap is investigated. Parallel, perpendicular, and randomly aligned nanoripples with respect to the scanning direction are obtained via manipulation of the scanning beam overlap. 95% broadband absorptance is measured in the visible electromagnetic region for the nanorippled germanium surface. The reported light absorption enhancement can significantly improve the efficiency of germanium-silicon based photovoltaic systems.

Advantages of III-nitride laser diodes in solid-state lighting: Advantages of III-nitride laser diodes in solid-state lighting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wierer, Jonathan J.; Tsao, Jeffrey Y.

2015-01-14

III-nitride laser diodes (LDs) are an interesting light source for solid-state lighting (SSL). Modelling of LDs is performed to reveal the potential advantages over traditionally used light-emitting diodes (LEDs). The first, and most notable, advantage is LDs have higher efficiency at higher currents when compared to LEDs. This is because Auger recombination that causes efficiency droop can no longer grow after laser threshold. Second, the same phosphor-converted methods used with LEDs can also be used with LDs to produce white light with similar color rendering and color temperature. Third, producing white light from color mixed emitters is equally challenging formore » both LEDs and LDs, with neither source having a direct advantage. Fourth, the LD emission is directional and can be more readily captured and focused, leading to the possibility of novel and more compact luminaires. Finally, the smaller area and higher current density operation of LDs provides them with a potential cost advantage over LEDs. These advantages make LDs a compelling source for future SSL.« less

Vacuum aperture isolator for retroreflection from laser-irradiated target

DOEpatents

Benjamin, Robert F.; Mitchell, Kenneth B.

1980-01-01

The disclosure is directed to a vacuum aperture isolator for retroreflection of a laser-irradiated target. Within a vacuum chamber are disposed a beam focusing element, a disc having an aperture and a recollimating element. The edge of the focused beam impinges on the edge of the aperture to produce a plasma which refracts any retroreflected light from the laser's target.

Impact of multi-focused images on recognition of soft biometric traits

NASA Astrophysics Data System (ADS)

Chiesa, V.; Dugelay, J. L.

2016-09-01

In video surveillance semantic traits estimation as gender and age has always been debated topic because of the uncontrolled environment: while light or pose variations have been largely studied, defocused images are still rarely investigated. Recently the emergence of new technologies, as plenoptic cameras, yields to deal with these problems analyzing multi-focus images. Thanks to a microlens array arranged between the sensor and the main lens, light field cameras are able to record not only the RGB values but also the information related to the direction of light rays: the additional data make possible rendering the image with different focal plane after the acquisition. For our experiments, we use the GUC Light Field Face Database that includes pictures from the First Generation Lytro camera. Taking advantage of light field images, we explore the influence of defocusing on gender recognition and age estimation problems. Evaluations are computed on up-to-date and competitive technologies based on deep learning algorithms. After studying the relationship between focus and gender recognition and focus and age estimation, we compare the results obtained by images defocused by Lytro software with images blurred by more standard filters in order to explore the difference between defocusing and blurring effects. In addition we investigate the impact of deblurring on defocused images with the goal to better understand the different impacts of defocusing and standard blurring on gender and age estimation.

The high-energy x-ray diffraction and scattering beamline at the Canadian Light Source

NASA Astrophysics Data System (ADS)

Gomez, A.; Dina, G.; Kycia, S.

2018-06-01

The optical design for the high-energy x-ray diffraction and scattering beamline of the Brockhouse sector at the Canadian Light Source is described. The design is based on a single side-bounce silicon focusing monochromator that steers the central part of a high-field permanent magnet wiggler beam into the experimental station. Two different configurations are proposed: a higher energy resolution with vertical focusing and a lower energy resolution with horizontal and vertical focusing. The monochromator will have the possibility of mounting three crystals: one crystal optimized for 35 keV that focuses in the horizontal and vertical directions using reflection (1,1,1) and two other crystals both covering the energies above 40 keV: one with only vertical focusing and another one with horizontal and vertical focusing. The geometry of the last two monochromator crystals was optimized to use reflections (4,2,2) and (5,3,3) to cover the broad energy range from 40 to 95 keV.

Achromatic illumination system for small targets

DOEpatents

Sigler, Robert D.

1979-01-01

A pair of light beams is directed to provide illumination that is substantially uniform from all directions on a small target by a system comprising a pair of corrector windows, a pair of planar reflecting surfaces, a pair of paraboloidal mirrors and a reflecting mirror cavity. The components are arranged so that each of the beams passes through a corrector and is reflected from the planar surface to the paraboloidal mirror, from which it is focused through a hole in the planar surface to the interior of the cavity. The surface of the interior portion of the cavity is shaped to reflect the focused beam three times before the focused reflected beam strikes the target.

Light-driven liquid microlenses

NASA Astrophysics Data System (ADS)

Angelini, A.; Pirani, F.; Frascella, F.; Ricciardi, S.; Descrovi, E.

2017-02-01

We propose a liquid polymeric compound based on photo-responsive azo-polymers to be used as light-activated optical element with tunable and reversible functionalities. The interaction of a laser beam locally modifies the liquid density thus producing a refractive index gradient. The laser induced refractive index profiles are observed along the optical axis of the microscope to evaluate the total phase shift induced and along the orthogonal direction to provide the axial distribution of the refractive index variation. The focusing and imaging properties of the liquid lenses as functions of the light intensity are illustrated.

Optical switch

DOEpatents

Reedy, R.P.

1985-01-18

An optical switching device is provided whereby light from a first glass fiber or a second glass fiber may be selectively transmitted into a third glass fiber. Each glass fiber is provided with a focusing and collimating lens system. In one mode of operation, light from the first glass fiber is reflected by a planar mirror into the third glass fiber. In another mode of operation, light from the second glass fiber passes directly into the third glass fiber. The planar mirror is attached to a rotatable table which is rotated to provide the optical switching.

Optical switch

DOEpatents

Reedy, R.P.

1987-11-10

An optical switching device is provided whereby light from a first glass fiber or a second glass fiber may be selectively transmitted into a third glass fiber. Each glass fiber is provided with a focusing and collimating lens system. In one mode of operation, light from the first glass fiber is reflected by a planar mirror into the third glass fiber. In another mode of operation, light from the second glass fiber passes directly into the third glass fiber. The planar mirror is attached to a rotatable table which is rotated to provide the optical switching. 3 figs.

Effect of gravitational focusing on annual modulation in dark-matter direct-detection experiments.

PubMed

Lee, Samuel K; Lisanti, Mariangela; Peter, Annika H G; Safdi, Benjamin R

2014-01-10

The scattering rate in dark-matter direct-detection experiments should modulate annually due to Earth's orbit around the Sun. The rate is typically thought to be extremized around June 1, when the relative velocity of Earth with respect to the dark-matter wind is maximal. We point out that gravitational focusing can alter this modulation phase. Unbound dark-matter particles are focused by the Sun's gravitational potential, affecting their phase-space density in the lab frame. Gravitational focusing can result in a significant overall shift in the annual-modulation phase, which is most relevant for dark matter with low scattering speeds. The induced phase shift for light O(10)  GeV dark matter may also be significant, depending on the threshold energy of the experiment.

Miniature photometric stereo system for textile surface structure reconstruction

NASA Astrophysics Data System (ADS)

Gorpas, Dimitris; Kampouris, Christos; Malassiotis, Sotiris

2013-04-01

In this work a miniature photometric stereo system is presented, targeting the three-dimensional structural reconstruction of various fabric types. This is a supportive module to a robot system, attempting to solve the well known "laundry problem". The miniature device has been designed for mounting onto the robot gripper. It is composed of a low-cost off-the-shelf camera, operating in macro mode, and eight light emitting diodes. The synchronization between image acquisition and lighting direction is controlled by an Arduino Nano board and software triggering. The ambient light has been addressed by a cylindrical enclosure. The direction of illumination is recovered by locating the reflection or the brightest point on a mirror sphere, while a flatfielding process compensates for the non-uniform illumination. For the evaluation of this prototype, the classical photometric stereo methodology has been used. The preliminary results on a large number of textiles are very promising for the successful integration of the miniature module to the robot system. The required interaction with the robot is implemented through the estimation of the Brenner's focus measure. This metric successfully assesses the focus quality with reduced time requirements in comparison to other well accepted focus metrics. Besides the targeting application, the small size of the developed system makes it a very promising candidate for applications with space restrictions, like the quality control in industrial production lines or object recognition based on structural information and in applications where easiness in operation and light-weight are required, like those in the Biomedical field, and especially in dermatology.

Tale of the atom tamers

NASA Astrophysics Data System (ADS)

Commissariat, Tushna

2018-03-01

Written and directed by film-maker Mila Aung-Thwin, Let There Be Light: the 100 Year Journey to Fusion tells the story of our ongoing quest for fusion here on Earth, with a prominent focus on the science and the scientists behind ITER.

Laser ignition

DOEpatents

Early, James W.; Lester, Charles S.

2004-01-13

Sequenced pulses of light from an excitation laser with at least two resonator cavities with separate output couplers are directed through a light modulator and a first polarzing analyzer. A portion of the light not rejected by the first polarizing analyzer is transported through a first optical fiber into a first ignitor laser rod in an ignitor laser. Another portion of the light is rejected by the first polarizing analyzer and directed through a halfwave plate into a second polarization analyzer. A first portion of the output of the second polarization analyzer passes through the second polarization analyzer to a second, oscillator, laser rod in the ignitor laser. A second portion of the output of the second polarization analyzer is redirected by the second polarization analyzer to a second optical fiber which delays the beam before the beam is combined with output of the first ignitor laser rod. Output of the second laser rod in the ignitor laser is directed into the first ignitor laser rod which was energized by light passing through the first polarizing analyzer. Combined output of the first ignitor laser rod and output of the second optical fiber is focused into a combustible fuel where the first short duration, high peak power pulse from the ignitor laser ignites the fuel and the second long duration, low peak power pulse directly from the excitation laser sustains the combustion.

Ultrasound-mediated Optical Imaging and Focusing in Scattering Media

NASA Astrophysics Data System (ADS)

Suzuki, Yuta

Because of its non-ionizing and molecular sensing nature, light has been an attractive tool in biomedicine. Scanning an optical focus allows not only high-resolution imaging but also manipulation and therapy. However, due to multiple photon scattering events, conventional optical focusing using an ordinary lens is limited to shallow depths of one transport mean free path (lt'), which corresponds to approximately 1 mm in human tissue. To overcome this limitation, ultrasonic modulation (or encoding ) of diffuse light inside scattering media has enabled us to develop both deep-tissue optical imaging and focusing techniques, namely, ultrasound-modulated optical tomography (UOT) and time-reversed ultrasonically encoded (TRUE) optical focusing. While UOT measures the power of the encoded light to obtain an image, TRUE focusing generates a time-reversed (or phase-conjugated) copy of the encoded light, using a phase-conjugate mirror to focus light inside scattering media beyond 1 lt'. However, despite extensive progress in both UOT and TRUE focusing, the low signal-to-noise ratio in encoded-light detection remains a challenge to meeting both the speed and depth requirements for in vivo applications. This dissertation describes technological advancements of both UOT and TRUE focusing, in terms of their signal detection sensitivities, operational depths, and operational speeds. The first part of this dissertation describes sensitivity improvements of encoded-light detection in UOT, achieved by using a large area (˜5 cm x 5 cm) photorefractive polymer. The photorefractive polymer allowed us to improve the detection etendue by more than 10 times that of previous detection schemes. It has enabled us to resolve absorbing objects embedded inside diffused media thicker than 80 lt', using moderate light power and short ultrasound pulses. The second part of this dissertation describes energy enhancement and fluorescent excitation using TRUE focusing in turbid media, using photorefractive materials as the phase-conjugate mirrors. By using a large-area photorefractive polymer as the phase-conjugate mirror, we boosted the focused optical energy by ~40 times over the output of a previously used photorefractive Bi 12SiO20 crystal. Furthermore, using both a photorefractive polymer and a Bi12SiO20 crystal as the phase-conjugate mirrors, we show direct visualization and dynamic control of TRUE focus, and demonstrate fluorescence imaging in a thick turbid medium. The last part of this dissertation describes improvements in the scanning speed of a TRUE focus, using digital phase-conjugate mirrors in both transmission and reflection modes. By employing a multiplex recording of ultrasonically encoded wavefronts in transmission mode, we have accelerated the generation of multiple TRUE foci, using frequency sweeping of both ultrasound and light. With this technique, we obtained a 2-D image of a fluorescent target centered inside a turbid sample having a thickness of 2.4 lt'. Also, by gradually moving the focal position in reflection mode, we show that the TRUE focal intensity is improved, and can be continuously scanned to image fluorescent targets in a shorter time.

Effects of light on direct and indirect defences against herbivores of young plants of Mallotus japonicus demonstrate a trade-off between two indirect defence traits

PubMed Central

Yamawo, Akira; Hada, Yoshio

2010-01-01

Background and Aims Although most studies on plant defence strategies have focused on a particular defence trait, some plant species develop multiple defence traits. To clarify the effects of light on the development of multiple defence traits, the production of direct and indirect defence traits of young plants of Mallotus japonicus were examined experimentally under different light conditions. Methods The young plants were cultivated under three light conditions in the experimental field for 3 months from May to July. Numbers of ants and pearl bodies on leaves in July were examined. After cultivation, the plants were collected and the developments of trichomes and pellucid dots, and extrafloral nectaries (EFNs) on the leaves were examined. On plants without nectar-collecting insects, the size of EFNs and the volume of extrafloral nectar secreted from the EFNs were examined. Key results Densities of trichomes and pellucid dots did not differ significantly among the plants under the different light conditions, suggesting that the chemical and physical defences function under both high and low light availability. The number of EFNs on the leaves did not differ significantly among the plants under the different light conditions, but there appeared to be a trade-off between the size of EFNs and the number of pearl bodies; the largest EFNs and the smallest number of pearl bodies were found under high light availability. EFN size was significantly correlated with the volume of extrafloral nectar secreted for 24 h. The number of ants on the plants was smaller under low light availability than under high and moderate light availability. Conclusions These results suggest that direct defence traits function regardless of light conditions, but light conditions affected the development of indirect defence traits. PMID:20472698

Nanoplasmon-enabled macroscopic thermal management

PubMed Central

Jonsson, Gustav Edman; Miljkovic, Vladimir; Dmitriev, Alexandre

2014-01-01

In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial. PMID:24870613

Microinterferometer transducer

DOEpatents

Corey, III, Harry S.

1979-01-01

An air-bearing microinterferometer transducer is provided for increased accuracy, range and linearity over conventional displacement transducers. A microinterferometer system is housed within a small compartment of an air-bearing displacement transducer housing. A movable cube corner reflector of the interferometer is mounted to move with the displacement gauging probe of the transducer. The probe is disposed for axial displacement by means of an air-bearing. Light from a single frequency laser is directed into an interferometer system within the transducer housing by means of a self-focusing fiber optic cable to maintain light coherency. Separate fringe patterns are monitored by a pair of fiber optic cables which transmit the patterns to a detecting system. The detecting system includes a bidirectional counter which counts the light pattern fringes according to the direction of movement of the probe during a displacement gauging operation.

Non-focusing optics spectrophotometer, and methods of use

DOEpatents

Kramer, David M.; Sacksteder, Colette A.

2004-11-02

In one aspect, the present invention provides kinetic spectrophotometers that each comprise: (a) a light source; and (b) a compound parabolic concentrator disposed to receive light from the light source and configured to (1) intensify and diffuse the light received from the light source, and (2) direct the intensified and diffused light onto a sample. In other aspects, the present invention provides methods for measuring a photosynthetic parameter, the methods comprising the steps of: (a) illuminating a plant leaf until steady-state photosynthesis is achieved; (b) subjecting the illuminated plant leaf to a period of darkness; (c) using a kinetic spectrophotometer of the invention to collect spectral data from the plant leaf treated in accordance with steps (a) and (b); and (d) determining a value for a photosynthetic parameter from the spectral data.

CELSS Program Meeting

NASA Technical Reports Server (NTRS)

Tremor, John W.; Macelroy, Robert D.

1987-01-01

A meeting on the potential contributions of plant science to the goals of Controlled Ecological Life Support System (CELSS) research produced discussions that helped to focus on a variety of topics. In the area of volatiles and soluble organics, microbial activity, disease, and productivity, participants emphasized the need to know more about the consequences of closure for the growth of plants. Under nutrient delivery systems, the problems focus on the need to maintain a stable, optimum nutrient system. Lighting systems discussions emphasized unique methods of direct lighting and development of improved irradiation sources. Flight experiment opportunities were outlined by one speaker. Documentation of the Plant Growth Module was discussed. The last day's discussion focused on the organization of the research group to be involved in the development and use of a two to three cubic meter sealed chamber and ancillary equipment.

Tunable two-dimensional liquid gradient refractive index (L-GRIN) lens for variable light focusing.

PubMed

Huang, Hua; Mao, Xiaole; Lin, Sz-Chin Steven; Kiraly, Brian; Huang, Yiping; Huang, Tony Jun

2010-09-21

We report a two-dimensional (2D) tunable liquid gradient refractive index (L-GRIN) lens for variable focusing of light in the out-of-plane direction. This lens focuses a light beam through a liquid medium with a 2D hyperbolic secant (HS) refractive index gradient. The refractive index gradient is established in a microfluidic chamber through the diffusion between two fluids with different refractive indices, i.e. CaCl(2) solution and deionized (DI) water. The 2D HS refractive index profile and subsequently the focal length of the L-GRIN lens can be tuned by changing the ratio of the flow rates of the CaCl(2) solution and DI water. The focusing effect is experimentally characterized through side-view and top-view image analysis, and the experimental data match well with the results from ray-tracing optical simulations. Advantages of the 2D L-GRIN lens include simple device fabrication procedure, low fluid consumption rate, convenient lens-tuning mechanism, and compatibility with existing microfluidic devices. We expect that with further optimizations, this 2D L-GRIN lens can be used in many optics-based lab-on-a-chip applications.

Manipulation of heat-diffusion channel in laser thermal lithography.

PubMed

Wei, Jingsong; Wang, Yang; Wu, Yiqun

2014-12-29

Laser thermal lithography is a good alternative method for forming small pattern feature size by taking advantage of the structural-change threshold effect of thermal lithography materials. In this work, the heat-diffusion channels of laser thermal lithography are first analyzed, and then we propose to manipulate the heat-diffusion channels by inserting thermal conduction layers in between channels. Heat-flow direction can be changed from the in-plane to the out-of-plane of the thermal lithography layer, which causes the size of the structural-change threshold region to become much smaller than the focused laser spot itself; thus, nanoscale marks can be obtained. Samples designated as "glass substrate/thermal conduction layer/thermal lithography layer (100 nm)/thermal conduction layer" are designed and prepared. Chalcogenide phase-change materials are used as thermal lithography layer, and Si is used as thermal conduction layer to manipulate heat-diffusion channels. Laser thermal lithography experiments are conducted on a home-made high-speed rotation direct laser writing setup with 488 nm laser wavelength and 0.90 numerical aperture of converging lens. The writing marks with 50-60 nm size are successfully obtained. The mark size is only about 1/13 of the focused laser spot, which is far smaller than that of the light diffraction limit spot of the direct laser writing setup. This work is useful for nanoscale fabrication and lithography by exploiting the far-field focusing light system.

Device for imaging scenes with very large ranges of intensity

DOEpatents

Deason, Vance Albert [Idaho Falls, ID

2011-11-15

A device for imaging scenes with a very large range of intensity having a pair of polarizers, a primary lens, an attenuating mask, and an imaging device optically connected along an optical axis. Preferably, a secondary lens, positioned between the attenuating mask and the imaging device is used to focus light on the imaging device. The angle between the first polarization direction and the second polarization direction is adjustable.

Deep-tissue focal fluorescence imaging with digitally time-reversed ultrasound-encoded light

PubMed Central

Wang, Ying Min; Judkewitz, Benjamin; DiMarzio, Charles A.; Yang, Changhuei

2012-01-01

Fluorescence imaging is one of the most important research tools in biomedical sciences. However, scattering of light severely impedes imaging of thick biological samples beyond the ballistic regime. Here we directly show focusing and high-resolution fluorescence imaging deep inside biological tissues by digitally time-reversing ultrasound-tagged light with high optical gain (~5×105). We confirm the presence of a time-reversed optical focus along with a diffuse background—a corollary of partial phase conjugation—and develop an approach for dynamic background cancellation. To illustrate the potential of our method, we image complex fluorescent objects and tumour microtissues at an unprecedented depth of 2.5 mm in biological tissues at a lateral resolution of 36 μm×52 μm and an axial resolution of 657 μm. Our results set the stage for a range of deep-tissue imaging applications in biomedical research and medical diagnostics. PMID:22735456

Two-way communication with neural networks in vivo using focused light

PubMed Central

Wilson, Nathan R.; Schummers, James; Runyan, Caroline A.; Yan, Sherry; Chen, Robert F.; Deng, Yuting; Sur, Mriganka

2014-01-01

Neuronal networks process information in a distributed, spatially heterogeneous fashion that transcends the layout of electrodes. In contrast, directed and steerable light offers the potential to engage specific cells on demand. We present a unified framework for adapting microscopes to use light for simultaneous in vivo stimulation and recording of cells at fine spatiotemporal resolutions. We utilize straightforward optics to lock onto networks in vivo, steer light to activate circuit elements, and simultaneously record from other cells. We then actualize this “free” augmentation on both an “open” two-photon microscope, and a leading commercial one. Following this protocol, setup of the system takes a few days and the result is a non-invasive interface to brain dynamics based on directed light, at a network resolution that was not previously possible and which will further improve with the rapid advance in development of optical reporters and effectors. This protocol is for physiologists who are competent with computers and wish to extend hardware and software to interface more fluidly with neuronal networks. PMID:23702834

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reininger, Ruben; Dhesi, Sarnjeet

The main requirement of the Nanoscience Beamline at Diamond is to deliver the highest possible flux at the sample position of a PEEM with a resolving power of about 5000 in the energy range 80-2000 eV. The source of the beamline is a couple of APPLE II helical undulators in tandem that can also be used separately to allow for faster switching of the circular polarization. Based on its versatility, a collimated plane grating monochromator using sagittally focusing elements was chosen to cover the required energy range with three gratings. The operation of this monochromator requires a collimated beam incidentmore » on the grating along the dispersion direction. This can be achieved either with a toroid, focusing with its major radius along the non-dispersive direction at the exit slit, or with a sagittal cylinder. The former option uses a sagittal cylinder after the grating to focus the collimated beam at the exit slit. In the latter case, a toroid after the grating is used to focus in both directions at the exit slit. The advantage of the toroid downstream the grating is the higher horizontal demagnification. This configuration fulfills the Nanoscience Beamline's required resolving power but cannot be used to achieve very high resolution due to the astigmatic coma aberration of the toroidal mirror. The focusing at the sample position is performed with a KB pair of plane elliptical mirrors. Assuming achievable values for the errors on all the optical surfaces, the expected spots FWHW in the horizontal and vertical directions are 10 {mu}m and 3 {mu}m, respectively. The calculated photon flux at this spot at 5000 resolving power is >1012 photons/sec between 80 and 1600 eV for linearly polarized light and between 106 and 1200 eV for circularly polarized light. The beamline is expected to be operational in January 2007.« less

Size-effect of oligomeric cholesteric liquid-crystal microlenses on the optical specifications.

PubMed

Bayon, Chloé; Agez, Gonzague; Mitov, Michel

2015-10-15

In cholesteric liquid-crystalline microlenses, we have studied the role of the microlens size on the focused light intensity and the focal length. We have found that the intensity is maximized by aiming a specific range for the diameter and the thickness of microlenses and that the focal length is adjusted by controlling the diameter and the annealing time of the optical film. Cholesteric microlenses may be used as wavelength-tunable directional light sources in organic soft-matter circuits.

Fiber optic laser-induced breakdown spectroscopy sensor for molten material analysis

DOEpatents

Zhang, Hansheng; Rai, Awadesh K.; Singh, Jagdish P.; Yueh, Fang-Yu

2004-07-13

A fiber optic laser-induced breakdown spectroscopy (LIBS) sensor, including a laser light source, a harmonic separator for directing the laser light, a dichroic mirror for reflecting the laser light, a coupling lens for coupling the laser light at an input of a multimode optical fiber, a connector for coupling the laser light from an output of the multimode optical fiber to an input of a high temperature holder, such as a holder made of stainless steel, and a detector portion for receiving emission signal and analyzing LIBS intensities. In one variation, the multimode optical fiber has silica core and silica cladding. The holder includes optical lenses for collimating and focusing the laser light in a molten alloy to produce a plasma, and for collecting and transmitting an emission signal to the multimode optical fiber.

Optical switch

DOEpatents

Reedy, Robert P.

1987-01-01

An optical switching device (10) is provided whereby light from a first glass fiber (16) or a second glass fiber (14) may be selectively transmitted into a third glass fiber (18). Each glass fiber is provided with a focusing and collimating lens system (26, 28, 30). In one mode of operation, light from the first glass fiber (16) is reflected by a planar mirror (36) into the third glass fiber (18). In another mode of operation, light from the second glass fiber (14) passes directly into the third glass fiber (18). The planar mirror (36) is attached to a rotatable table (32) which is rotated to provide the optical switching.

Bendable Focusing X-Ray Optics for the ALS and the LCLS/FEL: Design, Metrology, and Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yashchuk, V. V.; Yuan, S.; Baker, S.

2010-06-02

We review the recent development of bendable x-ray optics used for focusing of beams of soft and hard x-rays at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory and at the Linac Coherent Light Source (LCLS) x-ray free electron laser (FEL) at the Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory. For simultaneous focusing in the tangential and sagittal directions, two elliptically cylindrical reflecting elements, a Kirkpatrick-Baez (KB) pair, are used. Because fabrication of elliptical surfaces is complicated, the cost of directly fabricated tangential elliptical cylinders is often prohibitive. Moreover, such optics cannot be easily readjusted for usemore » in multiple, different experimental arrangements, e.g. at different focal distances. This is in contrast to flat optics that are simpler to manufacture and easier to measure by conventional interferometry. The tangential figure of a flat substrate is changed by placing torques (couples) at each end. Depending on the applied couples, one can tune the shape close to a desired tangential cylinder, ellipse or parabola. We review the nature of the bending, requirements and approaches to the mechanical design, describe original optical and at-wavelength techniques for optimal tuning of bendable optics and alignment on the beamline, and provide beamline performance of the bendable optics used for sub-micro and nano focusing of soft x-rays.« less

Demonstration of a memory for tightly guided light in an optical nanofiber.

PubMed

Gouraud, B; Maxein, D; Nicolas, A; Morin, O; Laurat, J

2015-05-08

We report the experimental observation of slow-light and coherent storage in a setting where light is tightly confined in the transverse directions. By interfacing a tapered optical nanofiber with a cold atomic ensemble, electromagnetically induced transparency is observed and light pulses at the single-photon level are stored in and retrieved from the atomic medium. The decay of efficiency with storage time is also measured and related to concurrent decoherence mechanisms. Collapses and revivals can be additionally controlled by an applied magnetic field. Our results based on subdiffraction-limited optical mode interacting with atoms via the strong evanescent field demonstrate an alternative to free-space focusing and a novel capability for information storage in an all-fibered quantum network.

Polarization of Light by Leaves and Plant Canopies

NASA Technical Reports Server (NTRS)

Vanderbilt, V. C.

2006-01-01

This talk will focus first on the information contained in the surface-scattered light from leaves, plant canopies and surface waters. This light is in general polarized and depends upon surface roughness. Thus, for example, - The surface reflection from shiny green leaves measured in the specular direction shows no chlorophyll absorption bands, no 'red edge.' - Conversely, the degree of linear polarization of such light displays marked variation with wavelength having local maxima in the chlorophyll absorption bands and an inverted red edge. - Plant canopies with shiny leaves distributed in angle like the area on a sphere, specularly reflect sunlight in the subsolar or specular direction- but also in every other view direction. - Canopies of green plants may appear white not green when viewed obliquely toward the sun. - In a light to moderate wind, the often blindingly bright glitter of sunlight off smooth water surfaces provides a strong, angularly narrow signature reflection characteristic of inundated vegetated areas that are big sources of atmospheric methane, a climatically important greenhouse gas. (Conversely, a blindingly bright glitter-type reflection is uncharacteristic of upland or wind ruffled open water areas that are poor sources of atmospheric methane.) Because some of these results may be 'head scratchers,' it's always important to properly calibrate ones instruments. Indeed, as the second portion of the talk will show, the characteristics of the light measuring instrument, particularly its entrance aperture, may affect the results and should be taken into account during across-instrument data comparisons.

Nanostructures and functional materials fabricated by interferometric lithography.

PubMed

Xia, Deying; Ku, Zahyun; Lee, S C; Brueck, S R J

2011-01-11

Interferometric lithography (IL) is a powerful technique for the definition of large-area, nanometer-scale, periodically patterned structures. Patterns are recorded in a light-sensitive medium, such as a photoresist, that responds nonlinearly to the intensity distribution associated with the interference of two or more coherent beams of light. The photoresist patterns produced with IL are a platform for further fabrication of nanostructures and growth of functional materials and are building blocks for devices. This article provides a brief review of IL technologies and focuses on various applications for nanostructures and functional materials based on IL including directed self-assembly of colloidal nanoparticles, nanophotonics, semiconductor materials growth, and nanofluidic devices. Perspectives on future directions for IL and emerging applications in other fields are presented.

Compact antenna for efficient and unidirectional launching and decoupling of surface plasmons.

PubMed

Baron, Alexandre; Devaux, Eloïse; Rodier, Jean-Claude; Hugonin, Jean-Paul; Rousseau, Emmanuel; Genet, Cyriaque; Ebbesen, Thomas W; Lalanne, Philippe

2011-10-12

Controlling the launching efficiencies and the directionality of surface plasmon polaritons (SPPs) and their decoupling to freely propagating light is a major goal for the development of plasmonic devices and systems. Here, we report on the design and experimental observation of a highly efficient unidirectional surface plasmon launcher composed of eleven subwavelength grooves, each with a distinct depth and width. Our observations show that, under normal illumination by a focused Gaussian beam, unidirectional SPP launching with an efficiency of at least 52% is achieved experimentally with a compact device of total length smaller than 8 μm. Reciprocally, we report that the same device can efficiently convert SPPs into a highly directive light beam emanating perpendicularly to the sample.

Direct micromachining of quartz glass plates using pulsed laser plasma soft x-rays

NASA Astrophysics Data System (ADS)

Makimura, Tetsuya; Miyamoto, Hisao; Kenmotsu, Youichi; Murakami, Kouichi; Niino, Hiroyuki

2005-03-01

We have investigated direct micromachining of quartz glass, using pulsed laser plasma soft x-rays (LPSXs) having a potential capability of nanomachining because the diffraction limit is ˜10nm. The LPSX's were generated by irradiation of a Ta target with 532nm laser light from a conventional Q switched Nd :YAG laser at 700mJ/pulse. In order to achieve a sufficient power density of LPSX's beyond the ablation threshold, we developed an ellipsoidal mirror to obtain efficient focusing of LPSXs at around 10nm. It was found that quartz glass plates are smoothly ablated at 45nm/shot using the focused and pulsed LPSX's.

Using a plenoptic camera to measure distortions in wavefronts affected by atmospheric turbulence

NASA Astrophysics Data System (ADS)

Eslami, Mohammed; Wu, Chensheng; Rzasa, John; Davis, Christopher C.

2012-10-01

Ideally, as planar wave fronts travel through an imaging system, all rays, or vectors pointing in the direction of the propagation of energy are parallel, and thus the wave front is focused to a particular point. If the wave front arrives at an imaging system with energy vectors that point in different directions, each part of the wave front will be focused at a slightly different point on the sensor plane and result in a distorted image. The Hartmann test, which involves the insertion of a series of pinholes between the imaging system and the sensor plane, was developed to sample the wavefront at different locations and measure the distortion angles at different points in the wave front. An adaptive optic system, such as a deformable mirror, is then used to correct for these distortions and allow the planar wave front to focus at the point desired on the sensor plane, thereby correcting the distorted image. The apertures of a pinhole array limit the amount of light that reaches the sensor plane. By replacing the pinholes with a microlens array each bundle of rays is focused to brighten the image. Microlens arrays are making their way into newer imaging technologies, such as "light field" or "plenoptic" cameras. In these cameras, the microlens array is used to recover the ray information of the incoming light by using post processing techniques to focus on objects at different depths. The goal of this paper is to demonstrate the use of these plenoptic cameras to recover the distortions in wavefronts. Taking advantage of the microlens array within the plenoptic camera, CODE-V simulations show that its performance can provide more information than a Shack-Hartmann sensor. Using the microlens array to retrieve the ray information and then backstepping through the imaging system provides information about distortions in the arriving wavefront.

Enlightening Butterfly Conservation Efforts: The Importance of Natural Lighting for Butterfly Behavioral Ecology and Conservation

PubMed Central

2018-01-01

Light is arguably the most important abiotic factor for living organisms. Organisms evolved under specific lighting conditions and their behavior, physiology, and ecology are inexorably linked to light. Understanding light effects on biology could not be more important as present anthropogenic effects are greatly changing the light environments in which animals exist. The two biggest anthropogenic contributors changing light environments are: (1) anthropogenic lighting at night (i.e., light pollution); and (2) deforestation and the built environment. I highlight light importance for butterfly behavior, physiology, and ecology and stress the importance of including light as a conservation factor for conserving butterfly biodiversity. This review focuses on four parts: (1) Introducing the nature and extent of light. (2) Visual and non-visual light reception in butterflies. (3) Implications of unnatural lighting for butterflies across several different behavioral and ecological contexts. (4). Future directions for quantifying the threat of unnatural lighting on butterflies and simple approaches to mitigate unnatural light impacts on butterflies. I urge future research to include light as a factor and end with the hopeful thought that controlling many unnatural light conditions is simply done by flipping a switch. PMID:29439549

Hankel-Bessel laser beams.

PubMed

Kotlyar, Victor V; Kovalev, Alexey A; Soifer, Victor A

2012-05-01

An analytical solution of the scalar Helmholtz equation to describe the propagation of a laser light beam in the positive direction of the optical axis is derived. The complex amplitude of such a beam is found to be in direct proportion to the product of two linearly independent solutions of Kummer's differential equation. Relationships for a particular case of such beams-namely, the Hankel-Bessel (HB) beams-are deduced. The focusing of the HB beams is studied. © 2012 Optical Society of America

Method for Measuring the Volume-Scattering Function of Water

NASA Technical Reports Server (NTRS)

Agrawal, Yogesh C.

2009-01-01

The volume scattering function (VSF) of seawater affects visibility, remote sensing properties, in-water light propagation, lidar performance, and the like. Currently, it s possible to measure only small forward angles of VSF, or to use cumbersome, large, and non-autonomous systems. This innovation is a method of measuring the full range of VSF using a portable instrument. A single rapid-sensing photosensor is used to scan a green laser beam, which delivers the desired measurement. By using a single sensor, inter-calibration is avoided. A compact design is achieved by using drift-free detector electronics, fiber optics, and a new type of photomultiplier. This provides a high angular resolution of 1 or better, as well as the ability to focus in on a VSF region of particular interest. Currently, the total scattering of light is measured as a difference from the other two parts of the light budget equation. This innovation will allow the direct calculation of the total scattering of light by taking an integral of the VSF over all angles. This directly provides one of the three components of the light budget equation, allowing greater versatility in its calculation.

Toward the light field display: autostereoscopic rendering via a cluster of projectors.

PubMed

Yang, Ruigang; Huang, Xinyu; Li, Sifang; Jaynes, Christopher

2008-01-01

Ultimately, a display device should be capable of reproducing the visual effects observed in reality. In this paper we introduce an autostereoscopic display that uses a scalable array of digital light projectors and a projection screen augmented with microlenses to simulate a light field for a given three-dimensional scene. Physical objects emit or reflect light in all directions to create a light field that can be approximated by the light field display. The display can simultaneously provide many viewers from different viewpoints a stereoscopic effect without head tracking or special viewing glasses. This work focuses on two important technical problems related to the light field display; calibration and rendering. We present a solution to automatically calibrate the light field display using a camera and introduce two efficient algorithms to render the special multi-view images by exploiting their spatial coherence. The effectiveness of our approach is demonstrated with a four-projector prototype that can display dynamic imagery with full parallax.

The Importance of Stochastic Effects for Explaining Entrainment in the Zebrafish Circadian Clock.

PubMed

Heussen, Raphaela; Whitmore, David

2015-01-01

The circadian clock plays a pivotal role in modulating physiological processes and has been implicated, either directly or indirectly, in a range of pathological states including cancer. Here we investigate how the circadian clock is entrained by external cues such as light. Working with zebrafish cell lines and combining light pulse experiments with simulation efforts focused on the role of synchronization effects, we find that even very modest doses of light exposure are sufficient to trigger some entrainment, whereby a higher light intensity or duration correlates with strength of the circadian signal. Moreover, we observe in the simulations that stochastic effects may be considered an essential feature of the circadian clock in order to explain the circadian signal decay in prolonged darkness, as well as light initiated resynchronization as a strong component of entrainment.

Recent Advances in Alternating Current-Driven Organic Light-Emitting Devices.

PubMed

Pan, Yufeng; Xia, Yingdong; Zhang, Haijuan; Qiu, Jian; Zheng, Yiting; Chen, Yonghua; Huang, Wei

2017-11-01

Organic light-emitting devices (OLEDs), typically operated with constant-voltage or direct-current (DC) power sources, are candidates for next-generation solid-state lighting and displays, as they are light, thin, inexpensive, and flexible. However, researchers have focused mainly on the device itself (e.g., development of novel materials, design of the device structure, and optical outcoupling engineering), and little attention has been paid to the driving mode. Recently, an alternative concept to DC-driven OLEDs by directly driving devices using time-dependent voltages or alternating current (AC) has been explored. Here, the effects of different device structures of AC-driven OLEDs, for example, double-insulation, single-insulation, double-injection, and tandem structure, on the device performance are systematically investigated. The formation of excitons and the dielectric layer, which are important to achieve high-performance AC-driven OLEDs, are carefully considered. The importance of gaining further understanding of the fundamental properties of AC-driven OLEDs is then discussed, especially as they relate to device physics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved astigmatic focus error detection method

NASA Technical Reports Server (NTRS)

Bernacki, Bruce E.

1992-01-01

All easy-to-implement focus- and track-error detection methods presently used in magneto-optical (MO) disk drives using pre-grooved media suffer from a side effect known as feedthrough. Feedthrough is the unwanted focus error signal (FES) produced when the optical head is seeking a new track, and light refracted from the pre-grooved disk produces an erroneous FES. Some focus and track-error detection methods are more resistant to feedthrough, but tend to be complicated and/or difficult to keep in alignment as a result of environmental insults. The astigmatic focus/push-pull tracking method is an elegant, easy-to-align focus- and track-error detection method. Unfortunately, it is also highly susceptible to feedthrough when astigmatism is present, with the worst effects caused by astigmatism oriented such that the tangential and sagittal foci are at 45 deg to the track direction. This disclosure outlines a method to nearly completely eliminate the worst-case form of feedthrough due to astigmatism oriented 45 deg to the track direction. Feedthrough due to other primary aberrations is not improved, but performance is identical to the unimproved astigmatic method.

Aerosol beam-focus laser-induced plasma spectrometer device

DOEpatents

Cheng, Meng-Dawn

2002-01-01

An apparatus for detecting elements in an aerosol includes an aerosol beam focuser for concentrating aerosol into an aerosol beam; a laser for directing a laser beam into the aerosol beam to form a plasma; a detection device that detects a wavelength of a light emission caused by the formation of the plasma. The detection device can be a spectrometer having at least one grating and a gated intensified charge-coupled device. The apparatus may also include a processor that correlates the wavelength of the light emission caused by the formation of the plasma with an identity of an element that corresponds to the wavelength. Furthermore, the apparatus can also include an aerosol generator for forming an aerosol beam from bulk materials. A method for detecting elements in an aerosol is also disclosed.

Luneburg lens in silicon photonics.

PubMed

Di Falco, Andrea; Kehr, Susanne C; Leonhardt, Ulf

2011-03-14

The Luneburg lens is an aberration-free lens that focuses light from all directions equally well. We fabricated and tested a Luneburg lens in silicon photonics. Such fully-integrated lenses may become the building blocks of compact Fourier optics on chips. Furthermore, our fabrication technique is sufficiently versatile for making perfect imaging devices on silicon platforms.

Lights, Camera, Action! Learning about Management with Student-Produced Video Assignments

ERIC Educational Resources Information Center

Schultz, Patrick L.; Quinn, Andrew S.

2014-01-01

In this article, we present a proposal for fostering learning in the management classroom through the use of student-produced video assignments. We describe the potential for video technology to create active learning environments focused on problem solving, authentic and direct experiences, and interaction and collaboration to promote student…

Phosphor thermometry system

DOEpatents

Beshears, David L.; Sitter, Jr., David N.; Andrews, William H.; Simpson, Marc L.; Abston, Ruth A.; Cates, Michael R.; Allison, Steve W.

2000-01-01

An apparatus for measuring the temperature of a moving substrate includes an air gun with a powder inlet port in communication with the outlet port of a powder reservoir, an air inlet port in communication with a pressurized air source, and an outlet nozzle spaced from and directed toward the moving substrate. The air gun is activated by the air pulses to spray controlled amounts of the powdered phosphor onto the moving substrate, where the phosphor assumes the temperature of the moving substrate. A laser produces light pulses, and optics direct the light pulses onto the phosphor on the moving substrate, in response to which the phosphor emits a luminescence with a decay rate indicative of the temperature of the phosphor. A collection lens is disposed to focus the luminescence, and a photodetector detects the luminescence focused by the collection lens and produces an electrical signal that is characteristic of the brightness of the luminescence. A processor analyzes the electrical signal to determine the decay characteristic of the luminescence and to determine the temperature of the phosphor from the decay characteristic.

REVIEWS OF TOPICAL PROBLEMS: Spiral light beams

NASA Astrophysics Data System (ADS)

Abramochkin, Evgenii G.; Volostnikov, Vladimir G.

2004-12-01

This paper discusses theoretical and experimental results of the investigation of light beams that retain their intensity strusture during propagation and focusing. We describe a family of laser beams termed spiral whose intensity remains invariable, up to scale and rotation, during propagation. Several properties of spiral beams are of practical interest for laser technologies, medicine, and microbiology. The problem of synthesis of spiral beams with the intensity distribution given by an arbitrary planar curve is considered. We emphasize the feasibility, in principle, of making lasers that directly generate beams with desired properties without additional unconventional optics.

Wavelength-scale light concentrator made by direct 3D laser writing of polymer metamaterials.

PubMed

Moughames, J; Jradi, S; Chan, T M; Akil, S; Battie, Y; Naciri, A En; Herro, Z; Guenneau, S; Enoch, S; Joly, L; Cousin, J; Bruyant, A

2016-10-04

We report on the realization of functional infrared light concentrators based on a thick layer of air-polymer metamaterial with controlled pore size gradients. The design features an optimum gradient index profile leading to light focusing in the Fresnel zone of the structures for two selected operating wavelength domains near 5.6 and 10.4 μm. The metamaterial which consists in a thick polymer containing air holes with diameters ranging from λ/20 to λ/8 is made using a 3D lithography technique based on the two-photon polymerization of a homemade photopolymer. Infrared imaging of the structures reveals a tight focusing for both structures with a maximum local intensity increase by a factor of 2.5 for a concentrator volume of 1.5 λ 3 , slightly limited by the residual absorption of the selected polymer. Such porous and flat metamaterial structures offer interesting perspectives to increase infrared detector performance at the pixel level for imaging or sensing applications.

Wavelength-scale light concentrator made by direct 3D laser writing of polymer metamaterials

PubMed Central

Moughames, J.; Jradi, S.; Chan, T. M.; Akil, S.; Battie, Y.; Naciri, A. En; Herro, Z.; Guenneau, S.; Enoch, S.; Joly, L.; Cousin, J.; Bruyant, A.

2016-01-01

We report on the realization of functional infrared light concentrators based on a thick layer of air-polymer metamaterial with controlled pore size gradients. The design features an optimum gradient index profile leading to light focusing in the Fresnel zone of the structures for two selected operating wavelength domains near 5.6 and 10.4 μm. The metamaterial which consists in a thick polymer containing air holes with diameters ranging from λ/20 to λ/8 is made using a 3D lithography technique based on the two-photon polymerization of a homemade photopolymer. Infrared imaging of the structures reveals a tight focusing for both structures with a maximum local intensity increase by a factor of 2.5 for a concentrator volume of 1.5 λ3, slightly limited by the residual absorption of the selected polymer. Such porous and flat metamaterial structures offer interesting perspectives to increase infrared detector performance at the pixel level for imaging or sensing applications. PMID:27698476

High-resolution light-sheet microscopy: a simulation of an optical illumination system for oil immersion

NASA Astrophysics Data System (ADS)

Lu, Xiang; Heintzmann, Rainer; Leischner, Ulrich

2015-09-01

Light sheet microscopy is a microscopy technique characterized by an illumination from the side, perpendicular to the direction of observation. While this is often used and easy to implement for imaging samples with water-immersion, the application in combination with oil-immersion is less often used and requires a specific optimization. In this paper we present our design of a light-sheet illumination optical system with a ~1μm illumination thickness, a long working distance through the immersion oil, and including a focusing system allowing for moving the focus-spot of the lightsheet laterally through the field of view. This optical design allows for the acquisition of fluorescence images in 3D with isotropic resolution of below 1 micrometer of whole-mount samples with a size of ~1mm diameter. This technique enables high-resolution insights in the 3D structure of biological samples, e.g. for research of insect anatomy or for imaging of biopsies in medical diagnostics.

A Difference in Cutaneous Pigmentary Response to LED Versus Halogen Incandescent Visible Light: A Case Report from a Single Center, Investigational Clinical Trial Determining a Minimal Pigmentary Visible Light Dose.

PubMed

Soleymani, Teo; Soter, Nicholas A; Folan, Lorcan M; Elbuluk, Nada; Okereke, Uchenna R; Cohen, David E

2017-04-01

BACKGROUND: While most of the attention regarding skin pigmentation has focused on the effects on ultraviolet radiation, the cutaneous effects of visible light (400 to 700nm) are rarely reported. In this report, we describe a case of painful erythema and induration that resulted from direct irradiation of UV-naïve skin with visible LED light in a patient with Fitzpatrick type II skin.

METHODS AND RESULTS: A 24-year-old healthy woman with Fitzpatrick type II skin presented to our department to participate in a clinical study. As part of the study, the subject underwent visible light irradiation with an LED and halogen incandescent visible light source. After 5 minutes of exposure, the patient complained of appreciable pain at the LED exposed site. Evaluation demonstrated erythema and mild induration. There were no subjective or objective findings at the halogen incandescent irradiated site, which received equivalent fluence (0.55 Watts / cm2). The study was halted as the subject was unable to tolerate the full duration of visible light irradiation.

CONCLUSION: This case illustrates the importance of recognizing the effects of visible light on skin. While the vast majority of investigational research has focused on ultraviolet light, the effects of visible light have been largely overlooked and must be taken into consideration, in all Fitzpatrick skin types.

J Drugs Dermatol. 2017;16(4):388-392.

Combinational light emitting diode-high frequency focused ultrasound treatment for HeLa cell.

PubMed

Choe, Se-Woon; Park, Kitae; Park, Chulwoo; Ryu, Jaemyung; Choi, Hojong

2017-12-01

Light sources such as laser and light emitting diode or ultrasound devices have been widely used for cancer therapy and regenerative medicines, since they are more cost-effective and less harmful than radiation therapy, chemotherapy or magnetic treatment. Compared to laser and low intensity ultrasound techniques, light emitting diode and high frequency focused ultrasound shows enhanced therapeutic effects, especially for small tumors. We propose combinational light emitting diode-high frequency focused ultrasound treatment for human cervical cancer HeLa cells. Individual red, green, and blue light emitting diode light only, high frequency focused ultrasound only, or light emitting diode light combined with high frequency focused ultrasound treatments were applied in order to characterize the responses of HeLa cells. Cell density exposed by blue light emitting diode light combined with high frequency focused ultrasound (2.19 ± 0.58%) was much lower than that of cells exposed by red and green light emitting diode lights (81.71 ± 9.92% and 61.81 ± 4.09%), blue light emitting diode light (11.19 ± 2.51%) or high frequency focused ultrasound only (9.72 ± 1.04%). We believe that the proposed combinational blue light emitting diode-high frequency focused ultrasound treatment could have therapeutic benefits to alleviate cancer cell proliferation.

Self-aligning concave relativistic plasma mirror with adjustable focus

NASA Astrophysics Data System (ADS)

Tsai, Hai-En; Arefiev, Alexey V.; Shaw, Joseph M.; Stark, David J.; Wang, Xiaoming; Zgadzaj, Rafal; Downer, M. C.

2017-01-01

We report an experimental-computational study of the optical properties of plasma mirrors (PMs) at the incident laser frequency when irradiated directly at relativistic intensity ( 10 18 < I 0 < 10 19 W / cm 2 ) by near-normally incident ( 4 ° ), high-contrast, 30 fs, 800 nm laser pulses. We find that such relativistic PMs are highly reflective ( 0.6 - 0.8 ) and focus a significant fraction of reflected light to intensity as large as ˜ 10 I 0 at distance f as small as ˜ 25 μ m from the PM, provided that pre-pulses do not exceed 1014 W/cm2 prior to ˜ 20 ps before arrival of the main pulse peak. Particle-in-cell simulations show that focusing results from denting of the reflecting surface by light pressure combined with relativistic transparency and that reflectivity and f can be adjusted by controlling pre-plasma length L over the range 0.5 ≲ L ≲ 3 μ m. Pump-probe reflectivity measurements show that the PM's focusing properties evolve on a ps time scale.

Assessment of mesh simplification algorithm quality

NASA Astrophysics Data System (ADS)

Roy, Michael; Nicolier, Frederic; Foufou, S.; Truchetet, Frederic; Koschan, Andreas; Abidi, Mongi A.

2002-03-01

Traditionally, medical geneticists have employed visual inspection (anthroposcopy) to clinically evaluate dysmorphology. In the last 20 years, there has been an increasing trend towards quantitative assessment to render diagnosis of anomalies more objective and reliable. These methods have focused on direct anthropometry, using a combination of classical physical anthropology tools and new instruments tailor-made to describe craniofacial morphometry. These methods are painstaking and require that the patient remain still for extended periods of time. Most recently, semiautomated techniques (e.g., structured light scanning) have been developed to capture the geometry of the face in a matter of seconds. In this paper, we establish that direct anthropometry and structured light scanning yield reliable measurements, with remarkably high levels of inter-rater and intra-rater reliability, as well as validity (contrasting the two methods).

Optical tweezers based force measurement system for quantitating binding interactions: system design and application for the study of bacterial adhesion.

PubMed

Fällman, Erik; Schedin, Staffan; Jass, Jana; Andersson, Magnus; Uhlin, Bernt Eric; Axner, Ove

2004-06-15

An optical force measurement system for quantitating forces in the pN range between micrometer-sized objects has been developed. The system was based upon optical tweezers in combination with a sensitive position detection system and constructed around an inverted microscope. A trapped particle in the focus of the high numerical aperture microscope-objective behaves like an omnidirectional mechanical spring in response to an external force. The particle's displacement from the equilibrium position is therefore a direct measure of the exerted force. A weak probe laser beam, focused directly below the trapping focus, was used for position detection of the trapped particle (a polystyrene bead). The bead and the condenser focus the light to a distinct spot in the far field, monitored by a position sensitive detector. Various calibration procedures were implemented in order to provide absolute force measurements. The system has been used to measure the binding forces between Escherichia coli bacterial adhesins and galabiose-functionalized beads.

Directional sensitivity of the retina: A layered scattering model of outer-segment photoreceptor pigments

PubMed Central

Vohnsen, Brian

2014-01-01

Photoreceptor outer segments have been modeled as stacked arrays of discs or membrane infoldings containing visual pigments with light-induced dipole moments. Waveguiding has been excluded so fields diffract beyond the physical boundaries of each photoreceptor cell. Optical reciprocity is used to argue for identical radiative and light gathering properties of pigments to model vision. Two models have been introduced: one a macroscopic model that assumes a uniform pigment density across each layer and another microscopic model that includes the spatial location of each pigment molecule within each layer. Both models result in highly similar directionality at the pupil plane which proves to be insensitive to the exact details of the outer-segment packing being predominantly determined by the first and last contributing layers as set by the fraction of bleaching. The versatility of the microscopic model is demonstrated with an array of examples that includes the Stiles-Crawford effect, visibility of a focused beam of light and the role of defocus. PMID:24877016

Magnetic and Electric Transverse Spin Density of Spatially Confined Light

NASA Astrophysics Data System (ADS)

Neugebauer, Martin; Eismann, Jörg S.; Bauer, Thomas; Banzer, Peter

2018-04-01

When a beam of light is laterally confined, its field distribution can exhibit points where the local magnetic and electric field vectors spin in a plane containing the propagation direction of the electromagnetic wave. The phenomenon indicates the presence of a nonzero transverse spin density. Here, we experimentally investigate this transverse spin density of both magnetic and electric fields, occurring in highly confined structured fields of light. Our scheme relies on the utilization of a high-refractive-index nanoparticle as a local field probe, exhibiting magnetic and electric dipole resonances in the visible spectral range. Because of the directional emission of dipole moments that spin around an axis parallel to a nearby dielectric interface, such a probe particle is capable of locally sensing the magnetic and electric transverse spin density of a tightly focused beam impinging under normal incidence with respect to said interface. We exploit the achieved experimental results to emphasize the difference between magnetic and electric transverse spin densities.

Focusing Light Beams To Improve Atomic-Vapor Optical Buffers

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy

2010-01-01

Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal to improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal to use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible to optimize the physical conditions throughout a cell, thereby making it impossible to optimize the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, "to optimize" as used here means to design the cell so as to maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal to use incoherent optical pumping: For reasons too complex to describe here, residual absorption of light is one of the main impediments to achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior to that of a medium that exhibits EIT without Raman gain.

The Role of Serotonin (5-HT) in Behavioral Control: Findings from Animal Research and Clinical Implications

PubMed Central

Sanchez, CL; Biskup, CS; Herpertz, S; Gaber, TJ; Kuhn, CM; Hood, SH

2015-01-01

The neurotransmitters serotonin and dopamine both have a critical role in the underlying neurobiology of different behaviors. With focus on the interplay between dopamine and serotonin, it has been proposed that dopamine biases behavior towards habitual responding, and with serotonin offsetting this phenomenon and directing the balance toward more flexible, goal-directed responding. The present focus paper stands in close relationship to the publication by Worbe et al. (2015), which deals with the effects of acute tryptophan depletion, a neurodietary physiological method to decrease central nervous serotonin synthesis in humans for a short period of time, on the balance between hypothetical goal-directed and habitual systems. In that research, acute tryptophan depletion challenge administration and a following short-term reduction in central nervous serotonin synthesis were associated with a shift of behavioral performance towards habitual responding, providing further evidence that central nervous serotonin function modulates the balance between goal-directed and stimulus-response habitual systems of behavioral control. In the present focus paper, we discuss the findings by Worbe and colleagues in light of animal experiments as well as clinical implications and discuss potential future avenues for related research. PMID:25991656

Towards manipulating relativistic laser pulses with micro-tube plasma lenses

PubMed Central

Ji, L. L.; Snyder, J.; Pukhov, A.; Freeman, R. R.; Akli, K. U.

2016-01-01

Efficient coupling of intense laser pulses to solid-density matter is critical to many applications including ion acceleration for cancer therapy. At relativistic intensities, the focus has been mainly on investigating various laser beams irradiating initially overdense flat interfaces with little or no control over the interaction. Here, we propose a novel approach that leverages recent advancements in 3D direct laser writing (DLW) of materials and high contrast lasers to manipulate the laser-matter interactions on the micro-scales. We demonstrate, via simulations, that usable intensities ≥1023 Wcm−2 could be achieved with current tabletop lasers coupled to micro-engineered plasma lenses. We show that these plasma optical elements act as a lens to focus laser light. These results open new paths to engineering light-matter interactions at ultra-relativistic intensities. PMID:26979657

Differential optoacoustic absorption detector

NASA Technical Reports Server (NTRS)

Shumate, M. S. (Inventor)

1978-01-01

A differential optoacoustic absorption detector employed two tapered cells in tandem or in parallel. When operated in tandem, two mirrors were used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell was tapered to conform to the shape of the beam so that the volume of one was the same as for the other, and the volume of each received maximum illumination. The axes of the cells were placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employed a beam splitter and two lenses to operate the cells in parallel.

Exploring the feasibility of focusing CW light through a scattering medium into closely spaced twin peaks via numerical solutions of Maxwell’s equations

NASA Astrophysics Data System (ADS)

Tseng, Snow H.; Chang, Shih-Hui

2018-04-01

Here we present a numerical simulation to analyze the effect of scattering on focusing light into closely-spaced twin peaks. The pseudospectral time-domain (PSTD) is implemented to model continuous-wave (CW) light propagation through a scattering medium. Simulations show that CW light can propagate through a scattering medium and focus into closely-spaced twin peaks. CW light of various wavelengths focusing into twin peaks with sub-diffraction spacing is simulated. In advance, light propagation through scattering media of various number densities is simulated to decipher the dependence of CW light focusing phenomenon on the scattering medium. The reported simulations demonstrate the feasibility of focusing CW light into twin peaks with sub-diffraction dimensions. More importantly, based upon numerical solutions of Maxwell’s equations, research findings show that the sub-diffraction focusing phenomenon can be achieved with scarce or densely-packed scattering media.

Relativistic laser channeling in plasmas for fast ignition

NASA Astrophysics Data System (ADS)

Lei, A. L.; Pukhov, A.; Kodama, R.; Yabuuchi, T.; Adumi, K.; Endo, K.; Freeman, R. R.; Habara, H.; Kitagawa, Y.; Kondo, K.; Kumar, G. R.; Matsuoka, T.; Mima, K.; Nagatomo, H.; Norimatsu, T.; Shorokhov, O.; Snavely, R.; Yang, X. Q.; Zheng, J.; Tanaka, K. A.

2007-12-01

We report an experimental observation suggesting plasma channel formation by focusing a relativistic laser pulse into a long-scale-length preformed plasma. The channel direction coincides with the laser axis. Laser light transmittance measurement indicates laser channeling into the high-density plasma with relativistic self-focusing. A three-dimensional particle-in-cell simulation reproduces the plasma channel and reveals that the collimated hot-electron beam is generated along the laser axis in the laser channeling. These findings hold the promising possibility of fast heating a dense fuel plasma with a relativistic laser pulse.

Beam deviation method as a diagnostic tool for the plasma focus.

PubMed

Schmidt, H; Rückle, B

1978-04-15

The application of an optical method for density measurements in cylindrical plasmas is described. The angular deviation of a probing light beam sent through a plasma is proportional to the maximum of the density in the plasma column. The deviation does not depend on the plasma dimensions; however, it is influenced to a certain degree by the density profile. The method is successfully applied to the investigation of a dense plasma focus with a time resolution of 2 nsec and a spatial resolution (in axial direction) of 2 mm.

Atom optics in the time domain

NASA Astrophysics Data System (ADS)

Arndt, M.; Szriftgiser, P.; Dalibard, J.; Steane, A. M.

1996-05-01

Atom-optics experiments are presented using a time-modulated evanescent light wave as an atomic mirror in the trampoline configuration, i.e., perpendicular to the direction of the atomic free fall. This modulated mirror is used to accelerate cesium atoms, to focus their trajectories, and to apply a ``multiple lens'' to separately focus different velocity classes of atoms originating from a point source. We form images of a simple two-slit object to show the resolution of the device. The experiments are modelled by a general treatment analogous to classical ray optics.

Microspherical photonics: Sorting resonant photonic atoms by using light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maslov, Alexey V., E-mail: avmaslov@yandex.ru; Astratov, Vasily N., E-mail: astratov@uncc.edu

2014-09-22

A method of sorting microspheres by resonant light forces in vacuum, air, or liquid is proposed. Based on a two-dimensional model, it is shown that the sorting can be realized by allowing spherical particles to traverse a focused beam. Under resonance with the whispering gallery modes, the particles acquire significant velocity along the beam direction. This opens a unique way of large-volume sorting of nearly identical photonic atoms with 1/Q accuracy, where Q is the resonance quality factor. This is an enabling technology for developing super-low-loss coupled-cavity structures and devices.

Light field measurement based on the single-lens coherent diffraction imaging

NASA Astrophysics Data System (ADS)

Shen, Cheng; Tan, Jiubin; Liu, Zhengjun

2018-01-01

Plenoptic camera and holography are popular light field measurement techniques. However, the low resolution or the complex apparatus hinders their widespread application. In this paper, we put forward a new light field measurement scheme. The lens is introduced into coherent diffraction imaging to operate an optical transform, extended fractional Fourier transform. Combined with the multi-image phase retrieval algorithm, the scheme is proved to hold several advantages. It gets rid of the support requirement and is much easier to implement while keeping a high resolution by making full use of the detector plane. Also, it is verified that our scheme has a superiority over the direct lens focusing imaging in amplitude measurement accuracy and phase retrieval ability.

Heating up the Galaxy with hidden photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubovsky, Sergei; Hernández-Chifflet, Guzmán, E-mail: dubovsky@nyu.edu, E-mail: ghc236@nyu.edu

2015-12-01

We elaborate on the dynamics of ionized interstellar medium in the presence of hidden photon dark matter. Our main focus is the ultra-light regime, where the hidden photon mass is smaller than the plasma frequency in the Milky Way. We point out that as a result of the Galactic plasma shielding direct detection of ultra-light photons in this mass range is especially challenging. However, we demonstrate that ultra-light hidden photon dark matter provides a powerful heating source for the ionized interstellar medium. This results in a strong bound on the kinetic mixing between hidden and regular photons all the waymore » down to the hidden photon masses of order 10{sup −20} eV.« less

Heating up the Galaxy with hidden photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubovsky, Sergei; Hernández-Chifflet, Guzmán; Instituto de Física, Facultad de Ingeniería, Universidad de la República,Montevideo, 11300

2015-12-29

We elaborate on the dynamics of ionized interstellar medium in the presence of hidden photon dark matter. Our main focus is the ultra-light regime, where the hidden photon mass is smaller than the plasma frequency in the Milky Way. We point out that as a result of the Galactic plasma shielding direct detection of ultra-light photons in this mass range is especially challenging. However, we demonstrate that ultra-light hidden photon dark matter provides a powerful heating source for the ionized interstellar medium. This results in a strong bound on the kinetic mixing between hidden and regular photons all the waymore » down to the hidden photon masses of order 10{sup −20} eV.« less

Dual-foci detection in photoacoustic computed tomography with coplanar light illumination and acoustic detection: a phantom study.

PubMed

Lin, Xiangwei; Liu, Chengbo; Meng, Jing; Gong, Xiaojing; Lin, Riqiang; Sun, Mingjian; Song, Liang

2018-05-01

A dual-foci transducer with coplanar light illumination and acoustic detection was applied for the first time. It overcame the small directivity angle, low-sensitivity, and large datasets in conventional circular scanning or array-based photoacoustic computed tomography (PACT). The custom-designed transducer is focused on both the scanning plane with virtual-point detection and the elevation direction for large field of view (FOV) cross-sectional imaging. Moreover, a coplanar light illumination and acoustic detection configuration can provide ring-shaped light irradiation with highly efficient acoustic detection, which in principle has a better adaptability when imaging samples of irregular surfaces. Phantom experiments showed that our PACT system can achieve high resolution (∼0.5  mm), enhanced signal-to-noise ratio (16-dB improvement), and a more complete structure in a greater FOV with an equal number of sampling points compared with the results from a flat aperture transducer. This study provides the proof of concept for the fabrication of a sparse array with the dual-foci property and large aperture size for high-quality, low-cost, and high-speed photoacoustic imaging. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Repeated-measure validation of craniofacial metrics from three-dimensional surface scans: application to medical genetics

NASA Astrophysics Data System (ADS)

Lauer, Eric A.; Corner, Brian D.; Li, Peng; Beecher, Robert M.; Deutsch, Curtis

2002-03-01

Traditionally, medical geneticists have employed visual inspection (anthroposcopy) to clinically evaluate dysmorphology. In the last 20 years, there has been an increasing trend towards quantitative assessment to render diagnosis of anomalies more objective and reliable. These methods have focused on direct anthropometry, using a combination of classical physical anthropology tools and new instruments tailor-made to describe craniofacial morphometry. These methods are painstaking and require that the patient remain still for extended periods of time. Most recently, semiautomated techniques (e.g., structured light scanning) have been developed to capture the geometry of the face in a matter of seconds. In this paper, we establish that direct anthropometry and structured light scanning yield reliable measurements, with remarkably high levels of inter-rater and intra-rater reliability, as well as validity (contrasting the two methods).

Aureole lidar: Design, operation, and comparison with in-situ measurements

NASA Astrophysics Data System (ADS)

Hooper, William P.; Jensen, D. R.

1992-07-01

In 1986, H. Berber and Hooper examined the signals that could be detected by an airborne lidar flying above the marine boundary layer (MBL). One signal (aureole) formed from laser light returned to the receiver after a reflect off the ocean and forward scatter off the aerosol particles appeared to be both detectable and related to the optical depth of the MBL. Now, research has been directed towards developing a practical instrument to measure the aureole and finding an algorithm to use the information. Unlike the lidar backscatter which typically requires a telescope with a narrow field of view (0.5 mrad), the aureole signal occurs over a wide field of view (50 mrad). To accommodate the totally different needs, a standard commercial Cassegrainian telescope was modified to yield a telescope with two focal planes. The secondary mirror was replaced by a lens, whose front surface was half silvered and curved to match the replaced mirror. Light reflecting off the lens focused behind the primary mirror. The back lens surface was curved to allow unreflected light to focus at the natural focus of the primary mirror. This focal plane which is behind the lens has a wide field of view. To calculate an extinction profile, the aureole optical depth estimate is combined with the lidar backscatter profile.

Aureole lidar: Design, operation, and comparison with in-situ measurements

NASA Technical Reports Server (NTRS)

Hooper, William P.; Jensen, D. R.

1992-01-01

In 1986, H. Berber and Hooper examined the signals that could be detected by an airborne lidar flying above the marine boundary layer (MBL). One signal (aureole) formed from laser light returned to the receiver after a reflect off the ocean and forward scatter off the aerosol particles appeared to be both detectable and related to the optical depth of the MBL. Now, research has been directed towards developing a practical instrument to measure the aureole and finding an algorithm to use the information. Unlike the lidar backscatter which typically requires a telescope with a narrow field of view (0.5 mrad), the aureole signal occurs over a wide field of view (50 mrad). To accommodate the totally different needs, a standard commercial Cassegrainian telescope was modified to yield a telescope with two focal planes. The secondary mirror was replaced by a lens, whose front surface was half silvered and curved to match the replaced mirror. Light reflecting off the lens focused behind the primary mirror. The back lens surface was curved to allow unreflected light to focus at the natural focus of the primary mirror. This focal plane which is behind the lens has a wide field of view. To calculate an extinction profile, the aureole optical depth estimate is combined with the lidar backscatter profile.

White-light optical vortex coronagraph

NASA Astrophysics Data System (ADS)

Kanburapa, Prachyathit

An optical vortex is characterized by a dark core of destructive interference in a light beam. One of the methods commonly employed to create an optical vortex is by using a computer-generated hologram. A vortex hologram pattern is computed from the interference pattern between a reference plane wave and a vortex wave, resulting in a forked grating pattern. In astronomy, an optical vortex coronagraph is one of the most promising high contrast imaging techniques for the direct imaging of extra-solar planets. Direct imaging of extra-solar planets is a challenging task since the brightness of the parent star is extremely high compared to its orbiting planets. The on-axis light from the parent star gets diffracted in the coronagraph, forming a "ring of fire" pattern, whereas the slightly off-axis light from the planet remains intact. Lyot stop can then be used to block the ring of fire pattern, thus allowing only the planetary light to get through to the imaging camera. Contrast enhancements of 106 or more are possible, provided the vortex lens (spiral phase plate) has exceptional optical quality. By using a vortex hologram with a 4 microm pitch, and an f/300 focusing lens, we were able to demonstrate the creation of a "ring of fire" using a white light emitting diode as a source. A dispersion compensating linear diffraction grating of 4 microm pitch was used to bring the rings together to form a single white light ring of fire. To our knowledge, this is the first time a vortex hologram based OVC has been demonstrated, resulting in a well-formed white light ring of fire. Experimental results show measured power contrast of 1/515 when HeNe laser source was used as a light source and 1/77 when using a white light emitting diode.

Imaging System With Confocally Self-Detecting Laser.

DOEpatents

Webb, Robert H.; Rogomentich, Fran J.

1996-10-08

The invention relates to a confocal laser imaging system and method. The system includes a laser source, a beam splitter, focusing elements, and a photosensitive detector. The laser source projects a laser beam along a first optical path at an object to be imaged, and modulates the intensity of the projected laser beam in response to light reflected from the object. A beam splitter directs a portion of the projected laser beam onto a photodetector. The photodetector monitors the intensity of laser output. The laser source can be an electrically scannable array, with a lens or objective assembly for focusing light generated by the array onto the object of interest. As the array is energized, its laser beams scan over the object, and light reflected at each point is returned by the lens to the element of the array from which it originated. A single photosensitive detector element can generate an intensity-representative signal for all lasers of the array. The intensity-representative signal from the photosensitive detector can be processed to provide an image of the object of interest.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simmons, M.; McKinstry, C.; Cook, C.

Since 1995, the Confederated Tribes of the Colville Reservation (Colville Confederated Tribes) have managed the Chief Joseph Kokanee Enhancement Project as part of the Northwest Power Planning Council (NWPPC) Fish and Wildlife Program. Project objectives have focused on understanding natural production of kokanee (a land-locked sockeye salmon) and other fish stocks in the area above Grand Coulee and Chief Joseph Dams on the Columbia River. A 42-month investigation from 1996 to 1999 determined that from 211,685 to 576,676 fish were entrained annually at Grand Coulee Dam. Analysis of the entrainment data found that 85% of the total entrainment occurred atmore » the dam's third powerplant. These numbers represent a significant loss to the tribal fisheries upstream of the dam. In response to a suggestion by the NWPPC Independent Scientific Review Panel, the scope of work for the Chief Joseph Kokanee Enhancement Project was expanded to include a multiyear pilot test of a strobe light system to help mitigate fish entrainment. This report details the work conducted during the third year of the strobe light study by researchers of the Colville Confederated Tribes in collaboration with the Pacific Northwest National Laboratory. The objective of the study is to determine the efficacy of a prototype strobe light system to elicit a negative phototactic response in kokanee and rainbow trout under field conditions. The prototype system consists of six strobe lights affixed to an aluminum frame suspended 15 m vertically underwater from a barge secured in the center of the entrance to the third powerplant forebay. The lights, controlled by a computer, illuminate a region directly upstream of the barge. The 2003 study period extended from June 16 through August 1. Three light treatments were used: all six lights on for 24 hours, all lights off for 24 hours, and three of six lights cycled on and off every hour for 24 hours. These three treatment conditions were assigned randomly within a 3-day block throughout the study period. Hydroacoustic technology was used to evaluate the effectiveness of the strobe lights in eliciting a negative phototactic response in fish. The hydroacoustic system in 2003 comprised seven splitbeam transducers arrayed in front of the strobe lights, two multibeam transducers behind the lights, and a mobile splitbeam system. The seven splitbeam transducers were deployed so they tracked fish entering and within the region illuminated by the strobe lights. These transducers were spaced approximately 4 m apart on an aluminum frame floating upstream of the barge and looked vertically downward. The multibeam transducers monitored the distribution of fish directly behind and to both sides of the lights, while the mobile splitbeam system looked at the distribution of fish within the third powerplant forebay. To augment the hydroacoustic data, additional studies were conducted. The hydrodynamic characteristics of the third powerplant forebay were measured, and acoustically tagged juvenile kokanee were released upstream of the strobe lights and tracked within the forebay and downstream of the dam. Analysis of the effect of strobe lights on kokanee and rainbow trout focused on the number of fish detected in each of the areas covered by one of the downlooking transducers, the timing of fish arrivals after the status of the strobe lights changed, fish swimming effort (detected velocity minus flow velocity), and fish swimming direction. Water velocity measurements were used to determine fish swimming effort. The tracking of tagged kokanee provided data on fish movements into and out of the third powerplant forebay, including entrainment.« less

Energy density and energy flux in the focus of an optical vortex: reverse flux of light energy.

PubMed

Kotlyar, Victor V; Kovalev, Alexey A; Nalimov, Anton G

2018-06-15

Using the Richards-Wolf formulas for an arbitrary circularly polarized optical vortex with an integer topological charge m, we obtain explicit expressions for all components of the electric and magnetic field strength vectors near the focus, as well as expressions for the intensity (energy density) and for the energy flux (components of the Poynting vector) in the focal plane of an aplanatic optical system. For m=2, from the obtained expressions it follows that the energy flux near the optical axis propagates in the reversed direction, rotating along a spiral around the optical axis. On the optical axis itself, the reversed flux is maximal and decays rapidly with the distance from the axis. For m=3, in contrast, the reversed energy flux in the focal plane is minimal (zero) on the optical axis and increases (until the first ring of the light intensity) as a squared distance from the axis.

An artificial compound eye of photon Sieves

NASA Astrophysics Data System (ADS)

Jiang, Wenbo; Hu, Song; He, Yu; Bu, Yun

2015-11-01

The compound eye of insects has numerous extraordinary optical performances, such as minimum chromatic aberration, wide-angle field of view, and high sensitivity to the incidence light. Inspired by these unique performances, we present a novel artificial compound eye of photon sieves in this paper, where the photon sieves play the roles of insects' ommatidia. These photon sieves have the same focal length. The incidence light can be focused into the same focal plane and produce the superposition effect, the utilization ratio of energy can be largely improved. Through the numerical simulation, the results show that this novel structure has similar focusing performance with the conventional photon sieves, but has higher utilization ratio of energy and wider angle field of view than that of the conventional photon sieves. Our findings provide a new direction for optics and biology researchers, which will be beneficial for medical imaging, astronomy, etc.

Developments in the photonics program at OSC

NASA Astrophysics Data System (ADS)

Peyghambarian, N.

2014-10-01

The photonics program at the College of Optical Sciences started nearly 30 years ago. In 1984, the program was focused on development of femtosecond laser sources and their use in investigating semiconductor carrier dynamics. The program grew into polymer and organic optics in late 1989 and was strengthened by the winning of the CAMP MURI from ONR in 1995 that was focused on multifunctional polymers including photorefractive polymers, organic light emitting diodes and 3D direct laser writing. Also in 1995, the areas of glass waveguide and fiber optic materials and devices were added to the program. In 2008, the optical communication and future internet research was started through winning the CIAN NSF ERC. Expertise in thin films, optical storage and the fundamental aspects of light are elements of the overall research program. Holographic 3D display, autofocus lenses, bio-medical imaging and devices for vision have also been ongoing research areas.

Improving Focal Photostimulation of Cortical Neurons with Pre-derived Wavefront Correction

PubMed Central

Choy, Julian M. C.; Sané, Sharmila S.; Lee, Woei M.; Stricker, Christian; Bachor, Hans A.; Daria, Vincent R.

2017-01-01

Recent progress in neuroscience to image and investigate brain function has been made possible by impressive developments in optogenetic and opto-molecular tools. Such research requires advances in optical techniques for the delivery of light through brain tissue with high spatial resolution. The tissue causes distortions to the wavefront of the incoming light which broadens the focus and consequently reduces the intensity and degrades the resolution. Such effects are detrimental in techniques requiring focal stimulation. Adaptive wavefront correction has been demonstrated to compensate for these distortions. However, iterative derivation of the corrective wavefront introduces time constraints that limit its applicability to probe living cells. Here, we demonstrate that we can pre-determine and generalize a small set of Zernike modes to correct for aberrations of the light propagating through specific brain regions. A priori identification of a corrective wavefront is a direct and fast technique that improves the quality of the focus without the need for iterative adaptive wavefront correction. We verify our technique by measuring the efficiency of two-photon photolysis of caged neurotransmitters along the dendrites of a whole-cell patched neuron. Our results show that encoding the selected Zernike modes on the excitation light can improve light propagation through brain slices of rats as observed by the neuron's evoked excitatory post-synaptic potential in response to localized focal uncaging at the spines of the neuron's dendrites. PMID:28507508

Timing of light exposure affects mood and brain circuits

PubMed Central

Bedrosian, T A; Nelson, R J

2017-01-01

Temporal organization of physiology is critical for human health. In the past, humans experienced predictable periods of daily light and dark driven by the solar day, which allowed for entrainment of intrinsic circadian rhythms to the environmental light–dark cycles. Since the adoption of electric light, however, pervasive exposure to nighttime lighting has blurred the boundaries of day and night, making it more difficult to synchronize biological processes. Many systems are under circadian control, including sleep–wake behavior, hormone secretion, cellular function and gene expression. Circadian disruption by nighttime light perturbs those processes and is associated with increasing incidence of certain cancers, metabolic dysfunction and mood disorders. This review focuses on the role of artificial light at night in mood regulation, including mechanisms through which aberrant light exposure affects the brain. Converging evidence suggests that circadian disruption alters the function of brain regions involved in emotion and mood regulation. This occurs through direct neural input from the clock or indirect effects, including altered neuroplasticity, neurotransmission and clock gene expression. Recently, the aberrant light exposure has been recognized for its health effects. This review summarizes the evidence linking aberrant light exposure to mood. PMID:28140399

Global Night-Time Lights for Observing Human Activity

NASA Technical Reports Server (NTRS)

Hipskind, Stephen R.; Elvidge, Chris; Gurney, K.; Imhoff, Mark; Bounoua, Lahouari; Sheffner, Edwin; Nemani, Ramakrishna R.; Pettit, Donald R.; Fischer, Marc

2011-01-01

We present a concept for a small satellite mission to make systematic, global observations of night-time lights with spatial resolution suitable for discerning the extent, type and density of human settlements. The observations will also allow better understanding of fine scale fossil fuel CO2 emission distribution. The NASA Earth Science Decadal Survey recommends more focus on direct observations of human influence on the Earth system. The most dramatic and compelling observations of human presence on the Earth are the night light observations taken by the Defence Meteorological System Program (DMSP) Operational Linescan System (OLS). Beyond delineating the footprint of human presence, night light data, when assembled and evaluated with complementary data sets, can determine the fine scale spatial distribution of global fossil fuel CO2 emissions. Understanding fossil fuel carbon emissions is critical to understanding the entire carbon cycle, and especially the carbon exchange between terrestrial and oceanic systems.

Radially dependent angular acceleration of twisted light.

PubMed

Webster, Jason; Rosales-Guzmán, Carmelo; Forbes, Andrew

2017-02-15

While photons travel in a straight line at constant velocity in free space, the intensity profile of structured light may be tailored for acceleration in any degree of freedom. Here we propose a simple approach to control the angular acceleration of light. Using Laguerre-Gaussian modes as our twisted beams carrying orbital angular momentum, we show that superpositions of opposite handedness result in a radially dependent angular acceleration as they pass through a focus (waist plane). Due to conservation of orbital angular momentum, we find that propagation dynamics are complex despite the free-space medium: the outer part of the beam (rings) rotates in an opposite direction to the inner part (petals), and while the outer part accelerates, the inner part decelerates. We outline the concepts theoretically and confirm them experimentally. Such exotic structured light beams are topical due to their many applications, for instance in optical trapping and tweezing, metrology, and fundamental studies in optics.

Whole-body ring-shaped confocal photoacoustic computed tomography of small animals in vivo.

PubMed

Xia, Jun; Chatni, Muhammad R; Maslov, Konstantin; Guo, Zijian; Wang, Kun; Anastasio, Mark; Wang, Lihong V

2012-05-01

We report a novel small-animal whole-body imaging system called ring-shaped confocal photoacoustic computed tomography (RC-PACT). RC-PACT is based on a confocal design of free-space ring-shaped light illumination and 512-element full-ring ultrasonic array signal detection. The free-space light illumination maximizes the light delivery efficiency, and the full-ring signal detection ensures a full two-dimensional view aperture for accurate image reconstruction. Using cylindrically focused array elements, RC-PACT can image a thin cross section with 0.10 to 0.25 mm in-plane resolutions and 1.6  s/frame acquisition time. By translating the mouse along the elevational direction, RC-PACT provides a series of cross-sectional images of the brain, liver, kidneys, and bladder.

Whole-body ring-shaped confocal photoacoustic computed tomography of small animals in vivo

NASA Astrophysics Data System (ADS)

Xia, Jun; Chatni, Muhammad R.; Maslov, Konstantin; Guo, Zijian; Wang, Kun; Anastasio, Mark; Wang, Lihong V.

2012-05-01

We report a novel small-animal whole-body imaging system called ring-shaped confocal photoacoustic computed tomography (RC-PACT). RC-PACT is based on a confocal design of free-space ring-shaped light illumination and 512-element full-ring ultrasonic array signal detection. The free-space light illumination maximizes the light delivery efficiency, and the full-ring signal detection ensures a full two-dimensional view aperture for accurate image reconstruction. Using cylindrically focused array elements, RC-PACT can image a thin cross section with 0.10 to 0.25 mm in-plane resolutions and 1.6 s/frame acquisition time. By translating the mouse along the elevational direction, RC-PACT provides a series of cross-sectional images of the brain, liver, kidneys, and bladder.

Self-aligning concave relativistic plasma mirror with adjustable focus

DOE PAGES

Tsai, Hai-En; Arefiev, Alexey V.; Shaw, Joseph M.; ...

2017-01-04

We report an experimental-computational study of the optical properties of plasma mirrors (PMs) at the incident laser frequency when irradiated directly at relativistic intensity (10 180<10 19W/cm 2) by near-normally incident (4°), high-contrast, 30 fs, 800 nm laser pulses. We find that such relativistic PMs are highly reflective (0.6–0.8) and focus a significant fraction of reflected light to intensity as large as ~10I0 at distance f as small as ~25 μm from the PM, provided that pre-pulses do not exceed 10 14 W/cm 2 prior to ~20 ps before arrival of the main pulse peak. Particle-in-cell simulations show that focusingmore » results from denting of the reflecting surface by light pressure combined with relativistic transparency and that reflectivity and f can be adjusted by controlling pre-plasma length L over the range 0.5 ≲L ≲ 3 μm. Pump-probe reflectivity measurements show that the PM's focusing properties evolve on a ps time scale.« less

Reflecting on Learner Assessments and Their Validity in the Presence of Emerging Evidence from Neuroscience

ERIC Educational Resources Information Center

Watagodakumbura, Chandana

2015-01-01

We can now get purposefully directed in the way we assess our learners in light of the emergence of evidence from the field of neuroscience. Why higher-order learning or abstract concepts need to be the focus in assessment is elaborated using the knowledge of semantic and episodic memories. With most of our learning identified to be implicit, why…

Monolithic Ge-on-Si lasers for large-scale electronic-photonic integration

NASA Astrophysics Data System (ADS)

Liu, Jifeng; Kimerling, Lionel C.; Michel, Jurgen

2012-09-01

A silicon-based monolithic laser source has long been envisioned as a key enabling component for large-scale electronic-photonic integration in future generations of high-performance computation and communication systems. In this paper we present a comprehensive review on the development of monolithic Ge-on-Si lasers for this application. Starting with a historical review of light emission from the direct gap transition of Ge dating back to the 1960s, we focus on the rapid progress in band-engineered Ge-on-Si lasers in the past five years after a nearly 30-year gap in this research field. Ge has become an interesting candidate for active devices in Si photonics in the past decade due to its pseudo-direct gap behavior and compatibility with Si complementary metal oxide semiconductor (CMOS) processing. In 2007, we proposed combing tensile strain with n-type doping to compensate the energy difference between the direct and indirect band gap of Ge, thereby achieving net optical gain for CMOS-compatible diode lasers. Here we systematically present theoretical modeling, material growth methods, spontaneous emission, optical gain, and lasing under optical and electrical pumping from band-engineered Ge-on-Si, culminated by recently demonstrated electrically pumped Ge-on-Si lasers with >1 mW output in the communication wavelength window of 1500-1700 nm. The broad gain spectrum enables on-chip wavelength division multiplexing. A unique feature of band-engineered pseudo-direct gap Ge light emitters is that the emission intensity increases with temperature, exactly opposite to conventional direct gap semiconductor light-emitting devices. This extraordinary thermal anti-quenching behavior greatly facilitates monolithic integration on Si microchips where temperatures can reach up to 80 °C during operation. The same band-engineering approach can be extended to other pseudo-direct gap semiconductors, allowing us to achieve efficient light emission at wavelengths previously considered inaccessible.

Free-Standing Self-Assemblies of Gallium Nitride Nanoparticles: A Review

DOE PAGES

Lan, Yucheng; Li, Jianye; Wong-Ng, Winnie; ...

2016-08-23

Gallium nitride (GaN) is an III-V semiconductor with a direct band-gap of 3.4eV . GaN has important potentials in white light-emitting diodes, blue lasers, and field effect transistors because of its super thermal stability and excellent optical properties, playing main roles in future lighting to reduce energy cost and sensors to resist radiations. GaN nanomaterials inherit bulk properties of the compound while possess novel photoelectric properties of nanomaterials. The review focuses on self-assemblies of GaN nanoparticles without templates, growth mechanisms of self-assemblies, and potential applications of the assembled nanostructures on renewable energy.

Regeneration of Airy pulses in fiber-optic links with dispersion management of the two leading dispersion terms of opposite signs

NASA Astrophysics Data System (ADS)

Driben, R.; Meier, T.

2014-04-01

Dispersion management of periodically alternating fiber sections with opposite signs of two leading dispersion terms is applied for the regeneration of self-accelerating truncated Airy pulses. It is demonstrated that for such a dispersion management scheme, the direction of the acceleration of the pulse is reversed twice within each period. In this scheme the system features light hot spots in the center of each fiber section, where the energy of the light pulse is tightly focused in a short temporal slot. Comprehensive numerical studies demonstrate a long-lasting propagation also under the influence of a strong fiber Kerr nonlinearity.

Interactions between gravitropism and phototropism in plants

NASA Technical Reports Server (NTRS)

Correll, Melanie J.; Kiss, John Z.

2002-01-01

To receive adequate light and nutrients for survival, plants orient stems and stem-like organs toward light and away from the gravity vector and, conversely, orient roots into the soil, away from light toward the direction of gravity. Therefore, both gravity and light can influence the differential growth of plant organs. To add to the complexity of the interactions between gravity and light, each stimulus can enhance or reduce the effectiveness of the other. On earth, the constant presence of gravity makes it difficult to determine whether plant growth and development is influenced by gravity or light alone or the combination of the two stimuli. In the past decade, our understanding of the gravity and light transduction pathways has advanced through the use of mutants in either gravitropic or phototropic responses and the use of innovative techniques that reduce the effects of one stimulus on the other. Thus, both unique and common elements in the transduction pathways of the gravitropic and phototropic responses have been isolated. This article is focused on the interactions between the light- and gravity-transduction pathways and describes methods used to separate the influences of these two environmental stimuli.

Interactions between gravitropism and phototropism in plants.

PubMed

Correll, Melanie J; Kiss, John Z

2002-06-01

To receive adequate light and nutrients for survival, plants orient stems and stem-like organs toward light and away from the gravity vector and, conversely, orient roots into the soil, away from light toward the direction of gravity. Therefore, both gravity and light can influence the differential growth of plant organs. To add to the complexity of the interactions between gravity and light, each stimulus can enhance or reduce the effectiveness of the other. On earth, the constant presence of gravity makes it difficult to determine whether plant growth and development is influenced by gravity or light alone or the combination of the two stimuli. In the past decade, our understanding of the gravity and light transduction pathways has advanced through the use of mutants in either gravitropic or phototropic responses and the use of innovative techniques that reduce the effects of one stimulus on the other. Thus, both unique and common elements in the transduction pathways of the gravitropic and phototropic responses have been isolated. This article is focused on the interactions between the light- and gravity-transduction pathways and describes methods used to separate the influences of these two environmental stimuli.

Novel aplanatic designs for LED concentration

NASA Astrophysics Data System (ADS)

Ricketts, Melissa; Winston, Roland; Jiang, Lun

2014-09-01

Aplanats make great concentrators because of their near perfect imaging. Aplanatic conditions can be satisfied using two surface curves (generally mirrored surfaces) in two dimensions (see Figure 1) which are constructed by successive approximation to create a highly efficient concentrator for both concentration and illumination. For concentration purposes, having a two mirror system would be impossible because the front mirror would block incoming light (see figure 2) so the idea is to replace the front mirror with a "one-way" mirror. Light from a lower index can be transmitted, so if the aplanat surface is a higher index light is allowed to enter, and be trapped. In the Jellyfish design, TIR takes place except for light striking the surface within the range of critical angles. To combat that, a small area of reflective coating is applied to the central top part of the Jellyfish, where TIR fails (In the middle) to keep the light there from directly escaping (see figure 3). The design works in both forwards and reverse. Light entering can be focused to a collecter, or the collecter can be replaced with a light source to concentrate light out. In this case, LEDs are used for their highly efficienct properties.

Direct solar pumping of semiconductor lasers: A feasibility study

NASA Technical Reports Server (NTRS)

Anderson, Neal G.

1991-01-01

The primary goals of the feasibility study are the following: (1) to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space directly focused sunlight; and (2) to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or battery electrically pumping a current injection laser. With external modulation, such lasers may prove to be efficient sources for intersatellite communications. We proposed to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation for operation at low pump intensities. This report outlines our progress toward these goals. Discussion of several technical details are left to the attached summary abstract.

Effect of ultraviolet light on mood, depressive disorders and well-being.

PubMed

Veleva, Bistra I; van Bezooijen, Rutger L; Chel, Victor G M; Numans, Mattijs E; Caljouw, Monique A A

2018-06-01

Human and animal studies have shown that exposure to ultraviolet light can incite a chain of endocrine, immunologic, and neurohumoral reactions that might affect mood. This review focuses on the evidence from clinical trials and observational studies on the effect of ultraviolet light on mood, depressive disorders, and well-being. A search was made in PubMed, Embase, Web of Science, Cochrane, Psychinfo, CINAHL, Academic Search Premier and Science Direct, and the references of key papers, for clinical trials and observational studies describing the effect of ultraviolet light applied to skin or eyes on mood, depressive disorders, and well-being. Of the seven studies eligible for this review, the effect of ultraviolet light on mood, depressive symptoms and seasonal affective disorders was positive in six of them. Of the seven studies, six demonstrated benefit of exposure to ultraviolet radiation and improvement in mood which supports a positive effect of ultraviolet light on mood. Because of the small number of the studies and their heterogeneity, more research is warranted to confirm and document this correlation. © 2018 The Authors. Photodermatology, Photoimmunology & Photomedicine Published by John Wiley & Sons Ltd.

Simulation of a method to directly image exoplanets around multiple stars systems

NASA Astrophysics Data System (ADS)

Thomas, Sandrine J.; Bendek, Eduardo; Belikov, Ruslan

2014-08-01

Direct imaging of extra-solar planets has now become a reality, especially with the deployment and commissioning of the first generation of specialized ground-based instruments such as the GPI, SPHERE, P1640 and SCExAO. These systems will allow detection of planets 107 times fainter than their host star. For space- based missions, such as EXCEDE, EXO-C, EXO-S, WFIRST/AFTA, different teams have shown in laboratories contrasts reaching 10-10 within a few diffraction limits from the star using a combination of a coronagraph to suppress light coming from the host star and a wavefront control system. These demonstrations use a de- formable mirror (DM) to remove residual starlight (speckles) created by the imperfections of telescope. However, all these current and future systems focus on detecting faint planets around a single host star or unresolved bi- naries/multiples, while several targets or planet candidates are located around nearby binary stars such as our neighbor star Alpha Centauri. Until now, it has been thought that removing the light of a companion star is impossible with current technology, excluding binary star systems from target lists of direct imaging missions. Direct imaging around binaries/multiple systems at a level of contrast allowing Earth-like planet detection is challenging because the region of interest, where a dark zone is essential, is contaminated by the light coming from the hosts star companion. We propose a method to simultaneously correct aberrations and diffraction of light coming from the target star as well as its companion star in order to reveal planets orbiting the target star. This method works even if the companion star is outside the control region of the DM (beyond its half-Nyquist frequency), by taking advantage of aliasing effects.

Statics and dynamics of electrothermal micromirrors

NASA Astrophysics Data System (ADS)

Morrison, Jessica A.

Adaptive and smart systems are growing in popularity as we shift toward personalization as a culture. With progressive demands on energy efficiency, it is increasingly important to focus on the utilization of energy in a novel way. This thesis investigates a microelectromechanical system (MEMS) mirror with the express intent to provide flexibility in solid state lighting (SSL). By coupling the micromirror to an optical source, the reflected light may be reshaped and directed so as to optimize the overall illumination profile. In addition, the light may be redirected in order to provide improved signal strength in visible light communications (VLC) with negligible impact on energy demands. With flexibility and full analog control in mind, the design of a fully integrated tip-tilt-piston micromirror with an additional variable focus degree of freedom is outlined. Electrothermal actuators are used to both steer the light and tune the focal length. A detailed discussion of the underlying physics behind composite beams and thermal actuators is addressed. This leads directly into an overview of the two main mirror components, namely the segmented mirror and the deflection actuators. An in-depth characterization of the dynamics of the mirror is discussed including the linearity of the thermal response. Frequency domain analysis of such a system provides insight into tunable mechanical properties such as the resonant frequency and quality factor. The degenerate resonant modes can be separated significantly. It is shown that the frequency response may be tuned by straining specific actuators and that it follows a predictable pattern. As a result, the system can be scanned at increasingly large angles. In other words, coupled mechanical modes allow variable damping and amplification. A means to determine the level of coupling is examined and the mode shape variations are tracked as a function of the tuning parameters. Finally, the applications of such a device are explored and tested. Such applications include reliable signal-to-noise ratio (SNR) enhancements in VLC of 30 dB and color tunable steerable lights using laser diodes. A brief discussion of the implications of dynamic illumination and tunable systems is juxtaposed with an explanation behind the integration of an electrothermal micromirror and an all digital driver.

Molecular orientation sensitive second harmonic microscopy by radially and azimuthally polarized light

PubMed Central

Ehmke, Tobias; Nitzsche, Tim Heiko; Knebl, Andreas; Heisterkamp, Alexander

2014-01-01

We demonstrate the possibility to switch the z-polarization component of the illumination in the vicinity of the focus of high-NA objective lenses by applying radially and azimuthally polarized incident light. The influence of the field distribution on nonlinear effects was first investigated by the means of simulations. These were performed for high-NA objective lenses commonly used in nonlinear microscopy. Special attention is paid to the influence of the polarization of the incoming field. For linearly, circularly and radially polarized light a considerable polarization component in z-direction is generated by high NA focusing. Azimuthal polarization is an exceptional case: even for strong focusing no z-component arises. Furthermore, the influence of the input polarization on the intensity contributing to the nonlinear signal generation was computed. No distinct difference between comparable input polarization states was found for chosen thresholds of nonlinear signal generation. Differences in signal generation for radially and azimuthally polarized vortex beams were experimentally evaluated in native collagen tissue (porcine cornea). The findings are in good agreement with the theoretical predictions and display the possibility to probe the molecular orientation along the optical axis of samples with known nonlinear properties. The combination of simulations regarding the nonlinear response of materials and experiments with different sample orientations and present or non present z-polarization could help to increase the understanding of nonlinear signal formation in yet unstudied materials. PMID:25071961

Photonics Research and Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dickson, Elizabeth

During the period August 2005 through October 2009, the UNLV Research Foundation (UNLVRF), a non-profit affiliate of the University of Nevada, Las Vegas (UNLV), in collaboration with UNLV's Colleges of Science and Engineering; Boston University (BU); Oak Ridge National Laboratory (ORNL); and Sunlight Direct, LLC, has managed and conducted a diverse and comprehensive research and development program focused on light-emitting diode (LED) technologies that provide significantly improved characteristics for lighting and display applications. This final technical report provides detailed information on the nature of the tasks, the results of the research, and the deliverables. It is estimated that about fivemore » percent of the energy used in the nation is for lighting homes, buildings and streets, accounting for some 25 percent of the average home's electric bill. However, the figure is significantly higher for the commercial sector. About 60 percent of the electricity for businesses is for lighting. Thus replacement of current lighting with solid-state lighting technology has the potential to significantly reduce this nation's energy consumption by some estimates, possibly as high as 20%. The primary objective of this multi-year R&D project has been to develop and advance lighting technologies to improve national energy conversion efficiencies; reduce heat load; and significantly lower the cost of conventional lighting technologies. The UNLVRF and its partners have specifically focused these talents on (1) improving LED technologies; (2) optimizing hybrid solar lighting, a technology which potentially offers the benefits of blending natural with artificial lighting systems, thus improving energy efficiency; and (3) building a comprehensive academic infrastructure within UNLV which concentrates on photonics R&D. Task researchers have reported impressive progress in (1) the development of quantum dot laser emitting diodes (QDLEDs) which will ultimately improve energy efficiency and lower costs for display and lighting applications (UNLV College of Engineering); (2) advancing green LED technology based on the Indium-Gallium-Nitride system (BU), thus improving conversion efficiencies; (3) employing unique state-of-the-art X-ray, electron and optical spectroscopies with microscopic techniques to learn more about the electronic structure of materials and contacts in LED devices (UNLV College of Science); (4) establishing a UNLV Display Lighting Laboratory staffed with a specialized team of academic researchers, students and industrial partners focused on identifying and implementing engineering solutions for lighting display-related problems; and (5) conducting research, development and demonstration for HSL essential to the resolution of technological barriers to commercialization.« less

Fabrication of micromachined focusing mirrors with seamless reflective surface

NASA Astrophysics Data System (ADS)

Hou, Max Ti-Kuang; Liao, Ke-Min; Yeh, Hong-Zhen; Cheng, Bo-Wen; Hong, Pei-Yuan; Chen, Rongshun

2003-01-01

A surface-micromachined focusing mirror with variable focal length, which is controlled by adjusting the mirror"s curvature, is fabricated and characterized. The bowl-shaped micromirror, which is fabricated from the micro bilayer circular plate, focuses light beam through thermal actuation of the external heat source. Both the initial and operational curvatures are manipulated by the residual stresses in two layers of the mirror. Improper stresses would lead to the failure of the bowl-shaped structure. We analyze and design geometrical dimensions for simultaneously avoiding the structure failure and increasing the tuning range of the focal length. The interferometer has been used to measure the focal length and the focusing ability. Mirrors with nominal focal lengths approximately 730 μm, and tuning ranges of about 50 microns were demonstrated. The measurement directly through optical approach has also been tried, but requires further investigation, because the laser beam affects the focusing of the micromirror seriously.

The effect on emotions and brain activity by the direct/indirect lighting in the residential environment.

PubMed

Shin, Yu-Bin; Woo, Seung-Hyun; Kim, Dong-Hyeon; Kim, Jinseong; Kim, Jae-Jin; Park, Jin Young

2015-01-01

This study was performed to explore how direct/indirect lighting affects emotions and brain oscillations compared to the direct lighting when brightness and color temperature are controlled. Twenty-eight subjects (12 females; mean age 22.5) participated. The experimental conditions consisted of two lighting environments: direct/indirect lighting (400 lx downlight, 300 lx uplight) and direct lighting (700 lx downlight). On each trial, a luminance environment was presented for 4 min, followed by participants rated their emotional feelings of the lighting environment. EEG data were recorded during the experiment. Spectral analysis was performed for the range of delta, theta, alpha, beta, and gamma ranges. The participants felt cooler and more pleasant and theta oscillations on the F4, F8, T4, and TP7 electrodes were more enhanced in the direct/indirect lighting environment compared to the direct lighting environment. There was significant correlation between the "cool" rating and the theta power of the F8 electrode. The participants felt more pleasant in the direct/indirect lighting environment, indicating that space with direct/indirect lighting modulated subjective perception. Additionally, our results suggest that theta oscillatory activity can be used as a biological marker that reflects emotional status in different lighting environments. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Effect of wavefront aberrations on a focused plenoptic imaging system: a wave optics simulation approach

NASA Astrophysics Data System (ADS)

Turola, Massimo; Meah, Chris J.; Marshall, Richard J.; Styles, Iain B.; Gruppetta, Stephen

2015-06-01

A plenoptic imaging system records simultaneously the intensity and the direction of the rays of light. This additional information allows many post processing features such as 3D imaging, synthetic refocusing and potentially evaluation of wavefront aberrations. In this paper the effects of low order aberrations on a simple plenoptic imaging system have been investigated using a wave optics simulations approach.

Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Hadjiev, V. G.; Arepalli, S.; Nikolaev, P.; Jandl, S.; Yowell, L.

2003-01-01

We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization.

Enhanced control of light and sound trajectories with three-dimensional gradient index lenses

NASA Astrophysics Data System (ADS)

Chang, T. M.; Dupont, G.; Enoch, S.; Guenneau, S.

2012-03-01

We numerically study the focusing and bending effects of light and sound waves through heterogeneous isotropic cylindrical and spherical devices. We first point out that transformation optics and acoustics show that the control of light requires spatially varying anisotropic permittivity and permeability, while the control of sound is achieved via spatially anisotropic density and isotropic compressibility. Moreover, homogenization theory applied to electromagnetic and acoustic periodic structures leads to such artificial (although not spatially varying) anisotropic permittivity, permeability and density. We stress that homogenization is thus a natural mathematical tool for the design of structured metamaterials. To illustrate the two-step geometric transform-homogenization approach, we consider the design of cylindrical and spherical electromagnetic and acoustic lenses displaying some artificial anisotropy along their optical axis (direction of periodicity of the structural elements). Applications are sought in the design of Eaton and Luneburg lenses bending light at angles ranging from 90° to 360°, or mimicking a Schwartzchild metric, i.e. a black hole. All of these spherical metamaterials are characterized by a refractive index varying inversely with the radius which is approximated by concentric layers of homogeneous material. We finally propose some structured cylindrical metamaterials consisting of infinitely conducting or rigid toroidal channels in a homogeneous bulk material focusing light or sound waves. The functionality of these metamaterials is demonstrated via full-wave three-dimensional computations using nodal elements in the context of acoustics, and finite edge-elements in electromagnetics.

Does architectural lighting contribute to breast cancer?

PubMed Central

Figueiro, Mariana G; Rea, Mark S; Bullough, John D

2006-01-01

Objectives There is a growing interest in the role that light plays on nocturnal melatonin production and, perhaps thereby, the incidence of breast cancer in modern societies. The direct causal relationships in this logical chain have not, however, been fully established and the weakest link is an inability to quantitatively specify architectural lighting as a stimulus for the circadian system. The purpose of the present paper is to draw attention to this weakness. Data Sources and Extraction We reviewed the literature on the relationship between melatonin, light at night, and cancer risk in humans and tumor growth in animals. More specifically, we focused on the impact of light on nocturnal melatonin suppression in humans and on the applicability of these data to women in real-life situations. Photometric measurement data from the lighted environment of women at work and at home is also reported. Data Synthesis The literature review and measurement data demonstrate that more quantitative knowledge is needed about circadian light exposures actually experienced by women and girls in modern societies. Conclusion Without such quantitative knowledge, limited insights can be gained about the causal relationship between melatonin and the etiology of breast cancer from epidemiological studies and from parametric studies using animal models. PMID:16901343

Light stop mass limits from Higgs rate measurements in the MSSM: Is MSSM electroweak baryogenesis still alive after all?

DOE PAGES

Liebler, Stefan; Profumo, Stefano; Stefaniak, Tim

2016-04-22

We investigate the implications of the Higgs rate measurements from Run 1 of the LHC for the mass of the light scalar top partner (stop) in the Minimal Supersymmetric Standard Model (MSSM). We focus on light stop masses, and we decouple the second, heavy stop and the gluino to the multi-TeV range in order to obtain a Higgs mass of ~125 GeV. We derive lower mass limits for the light stop within various scenarios, taking into account the effects of a possibly light scalar tau partner (stau) or chargino on the Higgs rates, of additional Higgs decays to undetectable “newmore » physics”, as well as of non-decoupling of the heavy Higgs sector. Under conservative assumptions, the stop can be as light as 123 GeV. Relaxing certain theoretical and experimental constraints, such as vacuum stability and model-dependent bounds on sparticle masses from LEP, we find that the light stop mass can be as light as 116 GeV. Lastly, our indirect limits are complementary to direct limits on the light stop mass from collider searches and have important implications for electroweak baryogenesis in the MSSM as a possible explanation for the observed matter-antimatter asymmetry of the Universe.« less

Weak light emission of soft tissues induced by heating

NASA Astrophysics Data System (ADS)

Spinelli, Antonello E.; Durando, Giovanni; Boschi, Federico

2018-04-01

The main goal of this work is to show that soft tissue interaction with high-intensity focused ultrasound (HIFU) or direct heating leads to a weak light emission detectable using a small animal optical imaging system. Our results show that the luminescence signal is detectable after 30 min of heating, resembling the time scale of delayed luminescence. The imaging of a soft tissue after heating it using an HIFU field shows that the luminescence pattern closely matches the shape of the cone typical of the HIFU beam. We conclude that heating a soft tissue using two different sources leads to the emission of a weak luminescence signal from the heated region with a decay half-life of a few minutes (4 to 6 min). The origin of such light emission needs to be further investigated.

Utilizing Light-field Imaging Technology in Neurosurgery.

PubMed

Chen, Brian R; Buchanan, Ian A; Kellis, Spencer; Kramer, Daniel; Ohiorhenuan, Ifije; Blumenfeld, Zack; Grisafe Ii, Dominic J; Barbaro, Michael F; Gogia, Angad S; Lu, James Y; Chen, Beverly B; Lee, Brian

2018-04-10

Traditional still cameras can only focus on a single plane for each image while rendering everything outside of that plane out of focus. However, new light-field imaging technology makes it possible to adjust the focus plane after an image has already been captured. This technology allows the viewer to interactively explore an image with objects and anatomy at varying depths and clearly focus on any feature of interest by selecting that location during post-capture viewing. These images with adjustable focus can serve as valuable educational tools for neurosurgical residents. We explore the utility of light-field cameras and review their strengths and limitations compared to other conventional types of imaging. The strength of light-field images is the adjustable focus, as opposed to the fixed-focus of traditional photography and video. A light-field image also is interactive by nature, as it requires the viewer to select the plane of focus and helps with visualizing the three-dimensional anatomy of an image. Limitations include the relatively low resolution of light-field images compared to traditional photography and video. Although light-field imaging is still in its infancy, there are several potential uses for the technology to complement traditional still photography and videography in neurosurgical education.

Utilizing Light-field Imaging Technology in Neurosurgery

PubMed Central

Chen, Brian R; Kellis, Spencer; Kramer, Daniel; Ohiorhenuan, Ifije; Blumenfeld, Zack; Grisafe II, Dominic J; Barbaro, Michael F; Gogia, Angad S; Lu, James Y; Chen, Beverly B; Lee, Brian

2018-01-01

Traditional still cameras can only focus on a single plane for each image while rendering everything outside of that plane out of focus. However, new light-field imaging technology makes it possible to adjust the focus plane after an image has already been captured. This technology allows the viewer to interactively explore an image with objects and anatomy at varying depths and clearly focus on any feature of interest by selecting that location during post-capture viewing. These images with adjustable focus can serve as valuable educational tools for neurosurgical residents. We explore the utility of light-field cameras and review their strengths and limitations compared to other conventional types of imaging. The strength of light-field images is the adjustable focus, as opposed to the fixed-focus of traditional photography and video. A light-field image also is interactive by nature, as it requires the viewer to select the plane of focus and helps with visualizing the three-dimensional anatomy of an image. Limitations include the relatively low resolution of light-field images compared to traditional photography and video. Although light-field imaging is still in its infancy, there are several potential uses for the technology to complement traditional still photography and videography in neurosurgical education. PMID:29888163

Laser damage metrology in biaxial nonlinear crystals using different test beams

NASA Astrophysics Data System (ADS)

Hildenbrand, Anne; Wagner, Frank R.; Akhouayri, Hassan; Natoli, Jean-Yves; Commandre, Mireille

2008-01-01

Laser damage measurements in nonlinear optical crystals, in particular in biaxial crystals, may be influenced by several effects proper to these materials or greatly enhanced in these materials. Before discussion of these effects, we address the topic of error bar determination for probability measurements. Error bars for the damage probabilities are important because nonlinear crystals are often small and expensive, thus only few sites are used for a single damage probability measurement. We present the mathematical basics and a flow diagram for the numerical calculation of error bars for probability measurements that correspond to a chosen confidence level. Effects that possibly modify the maximum intensity in a biaxial nonlinear crystal are: focusing aberration, walk-off and self-focusing. Depending on focusing conditions, propagation direction, polarization of the light and the position of the focus point in the crystal, strong aberrations may change the beam profile and drastically decrease the maximum intensity in the crystal. A correction factor for this effect is proposed, but quantitative corrections are not possible without taking into account the experimental beam profile after the focusing lens. The characteristics of walk-off and self-focusing have quickly been reviewed for the sake of completeness of this article. Finally, parasitic second harmonic generation may influence the laser damage behavior of crystals. The important point for laser damage measurements is that the amount of externally observed SHG after the crystal does not correspond to the maximum amount of second harmonic light inside the crystal.

Stretched Lens Array Photovoltaic Concentrator Technology Developed

NASA Technical Reports Server (NTRS)

Piszczor, Michael F., Jr.; O'Neill, Mark J.

2004-01-01

Solar arrays have been and continue to be the mainstay in providing power to nearly all commercial and government spacecraft. Light from the Sun is directly converted into electrical energy using solar cells. One way to reduce the cost of future space power systems is by minimizing the size and number of expensive solar cells by focusing the sunlight onto smaller cells using concentrator optics. The stretched lens array (SLA) is a unique concept that uses arched Fresnel lens concentrators to focus sunlight onto a line of high-efficiency solar cells located directly beneath. The SLA concept is based on the Solar Concentrator Array with Refractive Linear Element Technology (SCARLET) design that was used on NASA's New Millennium Deep Space 1 mission. The highly successful asteroid/comet rendezvous mission (1998 to 2001) demonstrated the performance and long-term durability of the SCARLET/SLA solar array design and set the foundation for further improvements to optimize its performance.

Production of medical isotopes from a thorium target irradiated by light charged particles up to 70 MeV

NASA Astrophysics Data System (ADS)

Duchemin, C.; Guertin, A.; Haddad, F.; Michel, N.; Métivier, V.

2015-02-01

The irradiation of a thorium target by light charged particles (protons and deuterons) leads to the production of several isotopes of medical interest. Direct nuclear reaction allows the production of Protactinium-230 which decays to Uranium-230 the mother nucleus of Thorium-226, a promising isotope for alpha radionuclide therapy. The fission of Thorium-232 produces fragments of interest like Molybdenum-99, Iodine-131 and Cadmium-115g. We focus our study on the production of these isotopes, performing new cross section measurements and calculating production yields. Our new sets of data are compared with the literature and the last version of the TALYS code.

Production of medical isotopes from a thorium target irradiated by light charged particles up to 70 MeV.

PubMed

Duchemin, C; Guertin, A; Haddad, F; Michel, N; Métivier, V

2015-02-07

The irradiation of a thorium target by light charged particles (protons and deuterons) leads to the production of several isotopes of medical interest. Direct nuclear reaction allows the production of Protactinium-230 which decays to Uranium-230 the mother nucleus of Thorium-226, a promising isotope for alpha radionuclide therapy. The fission of Thorium-232 produces fragments of interest like Molybdenum-99, Iodine-131 and Cadmium-115g. We focus our study on the production of these isotopes, performing new cross section measurements and calculating production yields. Our new sets of data are compared with the literature and the last version of the TALYS code.

Single-beam, dark toroidal optical traps for cold atoms

NASA Astrophysics Data System (ADS)

Fatemi, Fredrik K.; Olson, Spencer E.; Bashkansky, Mark; Dutton, Zachary; Terraciano, Matthew

2007-02-01

We demonstrate the generation of single-beam dark toroidal optical intensity distributions, which are of interest for neutral atom storage and atom interferometry. We demonstrate experimentally and numerically optical potentials that contain a ring-shaped intensity minimum, bounded in all directions by higher intensity. We use a spatial light modulator to alter the phase of an incident laser beam, and analyze the resulting optical propagation characteristics. For small toroidal traps (< 50 μm diameter), we find an optimal superposition of Laguerre-Gaussian modes that allows the formation of single-beam toroidal traps. We generate larger toroidal bottle traps by focusing hollow beams with toroidal lenses imprinted onto the spatial light modulator.

Plant stem cells in cosmetics: current trends and future directions

PubMed Central

Trehan, Sonia; Michniak-Kohn, Bozena; Beri, Kavita

2017-01-01

Plant regeneration at the cellular and tissue level is a unique process. Similar to animals, the stem cells in plants have properties that help stimulate and regenerate plants after injury. The unique properties of plant stem cells have been a recent area of interest and focus both in developing new cosmetics and studying how these extracts/phytohormones will influence animal skin. This special report focuses on the current evidence-based trends in plant stem cell-based cosmetics and sheds light on the challenges that we need to overcome in order to see meaningful changes in human skin using topical cosmetics derived from plant stem cells. PMID:29134115

Qualitative psychotherapy research: the journey so far and future directions.

PubMed

Levitt, Heidi M

2015-03-01

This article documents the evolution of qualitative psychotherapy research over the past 3 decades. Clients' and therapists' accounts of their experiences in psychotherapy provide a window into the psychotherapy relationship and its mechanisms of change. A sizable body of literature has been generated that uses qualitative methods to collect and analyze these accounts and to shed light on the psychotherapy process. It notes changes in the field such as growing numbers of dissertations and publications using qualitative methods as well as a strengthening emphasis on qualitative research within graduate education and research funding bodies. Future recommendations include developing principles for practice from qualitative methods and conducting qualitative meta-analyses. Other recommendations include forming journal review policies that support the publication of qualitative research and that focus on coherence in adapting methods to meet research goals, in light of a study's characteristics and epistemological framework, rather than focusing on sets of procedures. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Large aperture diffractive space telescope

DOEpatents

Hyde, Roderick A.

2001-01-01

A large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary objective lens functioning as a magnifying glass and an optical secondary functioning as an eyepiece. The spacecraft are spaced up to several kilometers apart with the eyepiece directly behind the magnifying glass "aiming" at an intended target with their relative orientation determining the optical axis of the telescope and hence the targets being observed. The objective lens includes a very large-aperture, very-thin-membrane, diffractive lens, e.g., a Fresnel lens, which intercepts incoming light over its full aperture and focuses it towards the eyepiece. The eyepiece has a much smaller, meter-scale aperture and is designed to move along the focal surface of the objective lens, gathering up the incoming light and converting it to high quality images. The positions of the two space craft are controlled both to maintain a good optical focus and to point at desired targets which may be either earth bound or celestial.

Stereo multiplexed holographic particle image velocimeter

DOEpatents

Adrian, Ronald J.; Barnhart, Donald H.; Papen, George A.

1996-01-01

A holographic particle image velocimeter employs stereoscopic recording of particle images, taken from two different perspectives and at two distinct points in time for each perspective, on a single holographic film plate. The different perspectives are provided by two optical assemblies, each including a collecting lens, a prism and a focusing lens. Collimated laser energy is pulsed through a fluid stream, with elements carried in the stream scattering light, some of which is collected by each collecting lens. The respective focusing lenses are configured to form images of the scattered light near the holographic plate. The particle images stored on the plate are reconstructed using the same optical assemblies employed in recording, by transferring the film plate and optical assemblies as a single integral unit to a reconstruction site. At the reconstruction site, reconstruction beams, phase conjugates of the reference beams used in recording the image, are directed to the plate, then selectively through either one of the optical assemblies, to form an image reflecting the chosen perspective at the two points in time.

Stereo multiplexed holographic particle image velocimeter

DOEpatents

Adrian, R.J.; Barnhart, D.H.; Papen, G.A.

1996-08-20

A holographic particle image velocimeter employs stereoscopic recording of particle images, taken from two different perspectives and at two distinct points in time for each perspective, on a single holographic film plate. The different perspectives are provided by two optical assemblies, each including a collecting lens, a prism and a focusing lens. Collimated laser energy is pulsed through a fluid stream, with elements carried in the stream scattering light, some of which is collected by each collecting lens. The respective focusing lenses are configured to form images of the scattered light near the holographic plate. The particle images stored on the plate are reconstructed using the same optical assemblies employed in recording, by transferring the film plate and optical assemblies as a single integral unit to a reconstruction site. At the reconstruction site, reconstruction beams, phase conjugates of the reference beams used in recording the image, are directed to the plate, then selectively through either one of the optical assemblies, to form an image reflecting the chosen perspective at the two points in time. 13 figs.

Real-time black carbon emission factor measurements from light duty vehicles.

PubMed

Forestieri, Sara D; Collier, Sonya; Kuwayama, Toshihiro; Zhang, Qi; Kleeman, Michael J; Cappa, Christopher D

2013-11-19

Eight light-duty gasoline low emission vehicles (LEV I) were tested on a Chassis dynamometer using the California Unified Cycle (UC) at the Haagen-Smit vehicle test facility at the California Air Resources Board in El Monte, CA during September 2011. The UC includes a cold start phase followed by a hot stabilized running phase. In addition, a light-duty gasoline LEV vehicle and ultralow emission vehicle (ULEV), and a light-duty diesel passenger vehicle and gasoline direct injection (GDI) vehicle were tested on a constant velocity driving cycle. A variety of instruments with response times ≥0.1 Hz were used to characterize how the emissions of the major particulate matter components varied for the LEVs during a typical driving cycle. This study focuses primarily on emissions of black carbon (BC). These measurements allowed for the determination of BC emission factors throughout the driving cycle, providing insights into the temporal variability of BC emission factors during different phases of a typical driving cycle.

Investigating nonlinear distortion in the photopolymer materials

NASA Astrophysics Data System (ADS)

Malallah, Ra'ed; Cassidy, Derek; Muniraj, Inbarasan; Zhao, Liang; Ryle, James P.; Sheridan, John T.

2017-05-01

Propagation and diffraction of a light beam through nonlinear materials are effectively compensated by the effect of selftrapping. The laser beam propagating through photo-sensitive polymer PVA/AA can generate a waveguide of higher refractive index in direction of the light propagation. In order to investigate this phenomenon occurring in light-sensitive photopolymer media, the behaviour of a single light beam focused on the front surface of photopolymer bulk is investigated. As part of this work the self-bending of parallel beams separated in spaces during self-writing waveguides are studied. It is shown that there is strong correlation between the intensity of the input beams and their separation distance and the resulting deformation of waveguide trajectory during channels formation. This self-channeling can be modelled numerically using a three-dimension model to describe what takes place inside the volume of a photopolymer media. Corresponding numerical simulations show good agreement with experimental observations, which confirm the validity of the numerical model that was used to simulate these experiments.

Enhanced Automated Guidance System for Horizontal Auger Boring Based on Image Processing.

PubMed

Wu, Lingling; Wen, Guojun; Wang, Yudan; Huang, Lei; Zhou, Jiang

2018-02-15

Horizontal auger boring (HAB) is a widely used trenchless technology for the high-accuracy installation of gravity or pressure pipelines on line and grade. Differing from other pipeline installations, HAB requires a more precise and automated guidance system for use in a practical project. This paper proposes an economic and enhanced automated optical guidance system, based on optimization research of light-emitting diode (LED) light target and five automated image processing bore-path deviation algorithms. An LED light target was optimized for many qualities, including light color, filter plate color, luminous intensity, and LED layout. The image preprocessing algorithm, direction location algorithm, angle measurement algorithm, deflection detection algorithm, and auto-focus algorithm, compiled in MATLAB, are used to automate image processing for deflection computing and judging. After multiple indoor experiments, this guidance system is applied in a project of hot water pipeline installation, with accuracy controlled within 2 mm in 48-m distance, providing accurate line and grade controls and verifying the feasibility and reliability of the guidance system.

Near-field microscopy with a microfabricated solid immersion lens

NASA Astrophysics Data System (ADS)

Fletcher, Daniel Alden

2001-07-01

Diffraction of focused light prevents optical microscopes from resolving features in air smaller than half the wavelength, λ Spatial resolution can be improved by passing light through a sub-wavelength metal aperture scanned close to a sample, but aperture-based probes suffer from low optical throughput, typically below 10-4. An alternate and more efficient technique is solid immersion microscopy in which light is focused through a high refractive index Solid Immersion Lens (SIL). This work describes the fabrication, modeling, and use of a microfabricated SIL to obtain spatial resolution better than the diffraction limit in air with high optical throughput for infrared applications. SILs on the order of 10 μm in diameter are fabricated from single-crystal silicon and integrated onto silicon cantilevers with tips for scanning. We measure a focused spot size of λ/5 with optical throughput better than 10-1 at a wavelength of λ = 9.3 μm. Spatial resolution is improved to λ/10 with metal apertures fabricated directly on the tip of the silicon SIL. Microlenses have reduced spherical aberration and better transparency than large lenses but cannot be made arbitrarily small and still focus. We model the advantages and limitations of focusing in lenses close to the wavelength in diameter using an extension of Mie theory. We also investigate a new contrast mechanism unique to microlenses resulting from the decrease in field-of-view with lens diameter. This technique is shown to achieve λ/4 spatial resolution. We explore applications of the microfabricated silicon SIL for high spatial resolution thermal microscopy and biological spectroscopy. Thermal radiation is collected through the SIL from a heated surface with spatial resolution four times better than that of a diffraction- limited infrared microscope. Using a Fourier-transform infrared spectrometer, we observe absorption peaks in bacteria cells positioned at the focus of the silicon SIL.

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

DOE PAGES

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien; ...

2017-06-15

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

X ray sensitive area detection device

NASA Technical Reports Server (NTRS)

Carter, Daniel C. (Inventor); Witherow, William K. (Inventor); Pusey, Marc L. (Inventor); Yost, Vaughn H. (Inventor)

1990-01-01

A radiation sensitive area detection device is disclosed which comprises a phosphor-containing film capable of receiving and storing an image formed by a pattern of incoming x rays, UV, or other radiation falling on the film. The device is capable of fluorescing in response to stimulation by a light source in a manner directly proportional to the stored radiation pattern. The device includes: (1) a light source capable of projecting light or other appropriate electromagnetic wave on the film so as to cause it to fluoresce; (2) a means to focus the fluoresced light coming from the phosphor-containing film after light stimulation; and (3) at least one charged coupled detector or other detecting element capable of receiving and digitizing the pattern of fluoresced light coming from the phosphor-containing film. The device will be able to generate superior x ray images of high resolution from a crystal or other sample and will be particularly advantageous in that instantaneous near-real-time images of rapidly deteriorating samples can be obtained. Furthermore, the device can be made compact and sturdy, thus capable of carrying out x ray or other radiation imaging under a variety of conditions, including those experienced in space.

Real-time optical multiple object recognition and tracking system and method

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin (Inventor); Liu, Hua-Kuang (Inventor)

1990-01-01

System for optically recognizing and tracking a plurality of objects within a field of vision. Laser (46) produces a coherent beam (48). Beam splitter (24) splits the beam into object (26) and reference (28) beams. Beam expanders (50) and collimators (52) transform the beams (26, 28) into coherent collimated light beams (26', 28'). A two-dimensional SLM (54), disposed in the object beam (26'), modulates the object beam with optical information as a function of signals from a first camera (16) which develops X and Y signals reflecting the contents of its field of vision. A hololens (38), positioned in the object beam (26') subsequent to the modulator (54), focuses the object beam at a plurality of focal points (42). A planar transparency-forming film (32), disposed with the focal points on an exposable surface, forms a multiple position interference filter (62) upon exposure of the surface and development processing of the film (32). A reflector (53) directing the reference beam (28') onto the film (32), exposes the surface, with images focused by the hololens (38), to form interference patterns on the surface. There is apparatus (16', 64) for sensing and indicating light passage through respective ones of the positions of the filter (62), whereby recognition of objects corresponding to respective ones of the positions of the filter (62) is affected. For tracking, apparatus (64) focuses light passing through the filter (62) onto a matrix of CCD's in a second camera (16') to form a two-dimensional display of the recognized objects.

Exposure Render: An Interactive Photo-Realistic Volume Rendering Framework

PubMed Central

Kroes, Thomas; Post, Frits H.; Botha, Charl P.

2012-01-01

The field of volume visualization has undergone rapid development during the past years, both due to advances in suitable computing hardware and due to the increasing availability of large volume datasets. Recent work has focused on increasing the visual realism in Direct Volume Rendering (DVR) by integrating a number of visually plausible but often effect-specific rendering techniques, for instance modeling of light occlusion and depth of field. Besides yielding more attractive renderings, especially the more realistic lighting has a positive effect on perceptual tasks. Although these new rendering techniques yield impressive results, they exhibit limitations in terms of their exibility and their performance. Monte Carlo ray tracing (MCRT), coupled with physically based light transport, is the de-facto standard for synthesizing highly realistic images in the graphics domain, although usually not from volumetric data. Due to the stochastic sampling of MCRT algorithms, numerous effects can be achieved in a relatively straight-forward fashion. For this reason, we have developed a practical framework that applies MCRT techniques also to direct volume rendering (DVR). With this work, we demonstrate that a host of realistic effects, including physically based lighting, can be simulated in a generic and flexible fashion, leading to interactive DVR with improved realism. In the hope that this improved approach to DVR will see more use in practice, we have made available our framework under a permissive open source license. PMID:22768292

Light focusing using epsilon-near-zero metamaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Weiren, E-mail: weiren.zhu@monash.edu; Premaratne, Malin; Si, Li-Ming, E-mail: lms@bit.edu.cn

2013-11-15

We present a strategy of focusing light using epsilon-near-zero metamaterials with embedded dielectric cylinder. The focusing mechanism is analytically investigated, and its accuracy is substantiated by rigorous full-wave simulations. It is found that the focusing intensity is highly depend on the embedded medium and its size, and the magnetic field amplitude of the focused beam itself can reach as high as 98.2 times the incident field. Owing to its versatility, the proposed light focusing system is sure to find applications in fields such as bio-sensing and in nonlinear optics.

Focusing light inside dynamic scattering media with millisecond digital optical phase conjugation

PubMed Central

Liu, Yan; Ma, Cheng; Shen, Yuecheng; Shi, Junhui; Wang, Lihong V.

2017-01-01

Wavefront shaping based on digital optical phase conjugation (DOPC) focuses light through or inside scattering media, but the low speed of DOPC prevents it from being applied to thick, living biological tissue. Although a fast DOPC approach was recently developed, the reported single-shot wavefront measurement method does not work when the goal is to focus light inside, instead of through, highly scattering media. Here, using a ferroelectric liquid crystal based spatial light modulator, we develop a simpler but faster DOPC system that focuses light not only through, but also inside scattering media. By controlling 2.6 × 105 optical degrees of freedom, our system focused light through 3 mm thick moving chicken tissue, with a system latency of 3.0 ms. Using ultrasound-guided DOPC, along with a binary wavefront measurement method, our system focused light inside a scattering medium comprising moving tissue with a latency of 6.0 ms, which is one to two orders of magnitude shorter than those of previous digital wavefront shaping systems. Since the demonstrated speed approaches tissue decorrelation rates, this work is an important step toward in vivo deep-tissue non-invasive optical imaging, manipulation, and therapy. PMID:28815194

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy

PubMed Central

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM). PMID:29568263

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy.

PubMed

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM).

Power-controlled transition from standard to negative refraction in reorientational soft matter.

PubMed

Piccardi, Armando; Alberucci, Alessandro; Kravets, Nina; Buchnev, Oleksandr; Assanto, Gaetano

2014-11-25

Refraction at a dielectric interface can take an anomalous character in anisotropic crystals, when light is negatively refracted with incident and refracted beams emerging on the same side of the interface normal. In soft matter subject to reorientation, such as nematic liquid crystals, the nonlinear interaction with light allows tuning of the optical properties. We demonstrate that in such material a beam of light can experience either positive or negative refraction depending on input power, as it can alter the spatial distribution of the optic axis and, in turn, the direction of the energy flow when traveling across an interface. Moreover, the nonlinear optical response yields beam self-focusing and spatial localization into a self-confined solitary wave through the formation of a graded-index waveguide, linking the refractive transition to power-driven readdressing of copolarized guided-wave signals, with a number of output ports not limited by diffraction.

Direct measurement and characterization of active photosynthesis zones inside biofuel producing and wastewater remediating microalgal biofilms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstein, Hans C.; Kesaano, Maureen; Moll, Karen

2014-03-01

Abstract: Microalgal biofilm based technologies are of keen interest due to their high biomass concentrations and ability to utilize renewable resources, such as light and CO2. While photoautotrophic biofilms have long been used for wastewater remediation applications, biofuel production represents a relatively new and under-represented focus area. However, the direct measurement and characterization of fundamental parameters required for physiological analyses are challenging due to biofilm heterogeneity. This study evaluated oxygenic photosynthesis and biofuel precursor molecule production using a novel rotating algal biofilm reactor (RABR) operated at field- and laboratory-scales for wastewater remediation and biofuel production, respectively. Clear differences in oxygenic-photosynthesis,more » respiration and biofuel-precursor capacities were observed between the two systems and different conditions based on light and nitrogen availability. Nitrogen depletion was not found to have the same effect on lipid accumulation compared to prior planktonic studies. Physiological characterizations of these microalgal biofilms identify potential areas for future process optimization.« less

Holographic Reconstruction of Photoelectron Diffraction and Its Circular Dichroism for Local Structure Probing

NASA Astrophysics Data System (ADS)

Matsui, Fumihiko; Matsushita, Tomohiro; Daimon, Hiroshi

2018-06-01

The local atomic structure around a specific element atom can be recorded as a photoelectron diffraction pattern. Forward focusing peaks and diffraction rings around them indicate the directions and distances from the photoelectron emitting atom to the surrounding atoms. The state-of-the-art holography reconstruction algorithm enables us to image the local atomic arrangement around the excited atom in a real space. By using circularly polarized light as an excitation source, the angular momentum transfer from the light to the photoelectron induces parallax shifts in these diffraction patterns. As a result, stereographic images of atomic arrangements are obtained. These diffraction patterns can be used as atomic-site-resolved probes for local electronic structure investigation in combination with spectroscopy techniques. Direct three-dimensional atomic structure visualization and site-specific electronic property analysis methods are reviewed. Furthermore, circular dichroism was also found in valence photoelectron and Auger electron diffraction patterns. The investigation of these new phenomena provides hints for the development of new techniques for local structure probing.

Direct measurement and characterization of active photosynthesis zones inside wastewater remediating and biofuel producing microalgal biofilms.

PubMed

Bernstein, Hans C; Kesaano, Maureen; Moll, Karen; Smith, Terence; Gerlach, Robin; Carlson, Ross P; Miller, Charles D; Peyton, Brent M; Cooksey, Keith E; Gardner, Robert D; Sims, Ronald C

2014-03-01

Microalgal biofilm based technologies are of keen interest due to their high biomass concentrations and ability to utilize light and CO2. While photoautotrophic biofilms have long been used for wastewater remediation, biofuel production represents a relatively new and under-represented focus area. However, the direct measurement and characterization of fundamental parameters required for industrial control are challenging due to biofilm heterogeneity. This study evaluated oxygenic photosynthesis and respiration on two distinct microalgal biofilms cultured using a novel rotating algal biofilm reactor operated at field- and laboratory-scales. Clear differences in oxygenic photosynthesis and respiration were observed based on different culturing conditions, microalgal composition, light intensity and nitrogen availability. The cultures were also evaluated as potential biofuel synthesis strategies. Nitrogen depletion was not found to have the same effect on lipid accumulation compared to traditional planktonic microalgal studies. Physiological characterizations of these microalgal biofilms identify fundamental parameters needed to understand and control process optimization. Published by Elsevier Ltd.

Nanomaterial-Enabled Neural Stimulation

PubMed Central

Wang, Yongchen; Guo, Liang

2016-01-01

Neural stimulation is a critical technique in treating neurological diseases and investigating brain functions. Traditional electrical stimulation uses electrodes to directly create intervening electric fields in the immediate vicinity of neural tissues. Second-generation stimulation techniques directly use light, magnetic fields or ultrasound in a non-contact manner. An emerging generation of non- or minimally invasive neural stimulation techniques is enabled by nanotechnology to achieve a high spatial resolution and cell-type specificity. In these techniques, a nanomaterial converts a remotely transmitted primary stimulus such as a light, magnetic or ultrasonic signal to a localized secondary stimulus such as an electric field or heat to stimulate neurons. The ease of surface modification and bio-conjugation of nanomaterials facilitates cell-type-specific targeting, designated placement and highly localized membrane activation. This review focuses on nanomaterial-enabled neural stimulation techniques primarily involving opto-electric, opto-thermal, magneto-electric, magneto-thermal and acousto-electric transduction mechanisms. Stimulation techniques based on other possible transduction schemes and general consideration for these emerging neurotechnologies are also discussed. PMID:27013938

Apparatus for Direct Optical Fiber Through-Lens Illumination of Microscopy or Observational Objects

NASA Technical Reports Server (NTRS)

Kadogawa, Hiroshi (Inventor)

2001-01-01

In one embodiment of the invention, a microscope or other observational apparatus, comprises a hollow tube, a lens mounted to the tube, a light source and at least one flexible optical fiber having an input end and an output end. The input end is positioned to receive light from the light source, and the output end is positioned within the tube so as to directly project light along a straight path to the lens to illuminate an object to be viewed. The path of projected light is uninterrupted and free of light deflecting elements. By passing the light through the lens, the light can be diffused or otherwise defocused to provide more uniform illumination across the surface of the object, increasing the quality of the image of the object seen by the viewer. The direct undeflected and uninterrupted projection of light, without change of direction, eliminates the need for light-deflecting elements, such as beam-splitters, mirrors, prisms, or the like, to direct the projected light towards the object.

Apparatus and method for a light direction sensor

NASA Technical Reports Server (NTRS)

Leviton, Douglas B. (Inventor)

2011-01-01

The present invention provides a light direction sensor for determining the direction of a light source. The system includes an image sensor; a spacer attached to the image sensor, and a pattern mask attached to said spacer. The pattern mask has a slit pattern that as light passes through the slit pattern it casts a diffraction pattern onto the image sensor. The method operates by receiving a beam of light onto a patterned mask, wherein the patterned mask as a plurality of a slit segments. Then, diffusing the beam of light onto an image sensor and determining the direction of the light source.

PVMirror: A New Concept for Tandem Solar Cells and Hybrid Solar Converters

DOE PAGES

Yu, Zhengshan J.; Fisher, Kathryn C.; Wheelwright, Brian M.; ...

2015-08-25

As the solar electricity market has matured, energy conversion efficiency and storage have joined installed system cost as significant market drivers. In response, manufacturers of flatplate silicon photovoltaic (PV) cells have pushed cell efficiencies above 25%—nearing the 29.4% detailed-balance efficiency limit— and both solar thermal and battery storage technologies have been deployed at utility scale. This paper introduces a new tandem solar collector employing a “PVMirror” that has the potential to both increase energy conversion efficiency and provide thermal storage. A PVMirror is a concentrating mirror, spectrum splitter, and light-to-electricity converter all in one: It consists of a curved arrangementmore » of PV cells that absorb part of the solar spectrum and reflect the remainder to their shared focus, at which a second solar converter is placed. A strength of the design is that the solar converter at the focus can be of a radically different technology than the PV cells in the PVMirror; another is that the PVMirror converts a portion of the diffuse light to electricity in addition to the direct light. Here, we consider two case studies—a PV cell located at the focus of the PVMirror to form a four-terminal PV–PV tandem, and a thermal receiver located at the focus to form a PV–CSP (concentrating solar thermal power) tandem—and compare the outdoor energy outputs to those of competing technologies. PVMirrors can outperform (idealized) monolithic PV–PV tandems that are under concentration, and they can also generate nearly as much energy as silicon flat-plate PV while simultaneously providing the full energy storage benefit of CSP.« less

Self-action of Bessel wave packets in a system of coupled light guides and formation of light bullets

NASA Astrophysics Data System (ADS)

Balakin, A. A.; Mironov, V. A.; Skobelev, S. A.

2017-01-01

The self-action of two-dimensional and three-dimensional Bessel wave packets in a system of coupled light guides is considered using the discrete nonlinear Schrödinger equation. The features of the self-action of such wave fields are related to their initial strong spatial inhomogeneity. The numerical simulation shows that for the field amplitude exceeding a critical value, the development of an instability typical of a medium with the cubic nonlinearity is observed. Various regimes are studied: the self-channeling of a wave beam in one light guide at powers not strongly exceeding a critical value, the formation of the "kaleidoscopic" picture of a wave packet during the propagation of higher-power radiation along a stratified medium, the formation of light bullets during competition between self-focusing and modulation instabilities in the case of three-dimensional wave packets, etc. In the problem of laser pulse shortening, the situation is considered when the wave-field stratification in the transverse direction dominates. This process is accompanied by the self-compression of laser pulses in well enough separated light guides. The efficiency of conversion of the initial Bessel field distribution to two flying parallel light bullets is about 50%.

Self-action of Bessel wave packets in a system of coupled light guides and formation of light bullets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balakin, A. A., E-mail: balakin.alexey@yandex.ru; Mironov, V. A.; Skobelev, S. A., E-mail: sk.sa1981@gmail.com

The self-action of two-dimensional and three-dimensional Bessel wave packets in a system of coupled light guides is considered using the discrete nonlinear Schrödinger equation. The features of the self-action of such wave fields are related to their initial strong spatial inhomogeneity. The numerical simulation shows that for the field amplitude exceeding a critical value, the development of an instability typical of a medium with the cubic nonlinearity is observed. Various regimes are studied: the self-channeling of a wave beam in one light guide at powers not strongly exceeding a critical value, the formation of the “kaleidoscopic” picture of a wavemore » packet during the propagation of higher-power radiation along a stratified medium, the formation of light bullets during competition between self-focusing and modulation instabilities in the case of three-dimensional wave packets, etc. In the problem of laser pulse shortening, the situation is considered when the wave-field stratification in the transverse direction dominates. This process is accompanied by the self-compression of laser pulses in well enough separated light guides. The efficiency of conversion of the initial Bessel field distribution to two flying parallel light bullets is about 50%.« less

Constraints on JP-900 Jet Fuel Production Concepts

DTIC Science & Technology

2007-01-01

most of this research effort has focused on a coal-tar blending process. Penn State currently plans to build a one-barrel- per-day pilot plant and...which a mixture of solid coal and a refinery intermediate, decant oil, is used to pro- duce a combination of liquid fuels and coke. The findings and...petroleum refinery intermedi- ate (specifically, light cycle oil). More recently, attention has been directed toward a co-coking process, in which a

Physical behaviour of anthropogenic light propagation into the nocturnal environment

PubMed Central

Aubé, Martin

2015-01-01

Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane. PMID:25780231

Physical behaviour of anthropogenic light propagation into the nocturnal environment.

PubMed

Aubé, Martin

2015-05-05

Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Deep tissue optical focusing and optogenetic modulation with time-reversed ultrasonically encoded light

PubMed Central

Ruan, Haowen; Brake, Joshua; Robinson, J. Elliott; Liu, Yan; Jang, Mooseok; Xiao, Cheng; Zhou, Chunyi; Gradinaru, Viviana; Yang, Changhuei

2017-01-01

Noninvasive light focusing deep inside living biological tissue has long been a goal in biomedical optics. However, the optical scattering of biological tissue prevents conventional optical systems from tightly focusing visible light beyond several hundred micrometers. The recently developed wavefront shaping technique time-reversed ultrasonically encoded (TRUE) focusing enables noninvasive light delivery to targeted locations beyond the optical diffusion limit. However, until now, TRUE focusing has only been demonstrated inside nonliving tissue samples. We present the first example of TRUE focusing in 2-mm-thick living brain tissue and demonstrate its application for optogenetic modulation of neural activity in 800-μm-thick acute mouse brain slices at a wavelength of 532 nm. We found that TRUE focusing enabled precise control of neuron firing and increased the spatial resolution of neuronal excitation fourfold when compared to conventional lens focusing. This work is an important step in the application of TRUE focusing for practical biomedical uses. PMID:29226248

Note: Automated optical focusing on encapsulated devices for scanning light stimulation systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bitzer, L. A.; Benson, N., E-mail: niels.benson@uni-due.de; Schmechel, R.

Recently, a scanning light stimulation system with an automated, adaptive focus correction during the measurement was introduced. Here, its application on encapsulated devices is discussed. This includes the changes an encapsulating optical medium introduces to the focusing process as well as to the subsequent light stimulation measurement. Further, the focusing method is modified to compensate for the influence of refraction and to maintain a minimum beam diameter on the sample surface.

Separate and Simultaneous Adjustment of Light Qualities in a Real Scene

PubMed Central

Pont, Sylvia C.; Heynderick, Ingrid

2017-01-01

Humans are able to estimate light field properties in a scene in that they have expectations of the objects’ appearance inside it. Previously, we probed such expectations in a real scene by asking whether a “probe object” fitted a real scene with regard to its lighting. But how well are observers able to interactively adjust the light properties on a “probe object” to its surrounding real scene? Image ambiguities can result in perceptual interactions between light properties. Such interactions formed a major problem for the “readability” of the illumination direction and diffuseness on a matte smooth spherical probe. We found that light direction and diffuseness judgments using a rough sphere as probe were slightly more accurate than when using a smooth sphere, due to the three-dimensional (3D) texture. We here extended the previous work by testing independent and simultaneous (i.e., the light field properties separated one by one or blended together) adjustments of light intensity, direction, and diffuseness using a rough probe. Independently inferred light intensities were close to the veridical values, and the simultaneously inferred light intensity interacted somewhat with the light direction and diffuseness. The independently inferred light directions showed no statistical difference with the simultaneously inferred directions. The light diffuseness inferences correlated with but contracted around medium veridical values. In summary, observers were able to adjust the basic light properties through both independent and simultaneous adjustments. The light intensity, direction, and diffuseness are well “readable” from our rough probe. Our method allows “tuning the light” (adjustment of its spatial distribution) in interfaces for lighting design or perception research. PMID:28203350

Prevention of the adverse photic effects of peripheral light-focusing using UV-blocking contact lenses.

PubMed

Kwok, L Stephen; Kuznetsov, Valerian A; Ho, Arthur; Coroneo, Minas T

2003-04-01

Peripheral light-focusing (PLF) is an occult form of ultraviolet radiation (UVR) hazardous to the human eye. In PLF, obliquely incident light is refracted from the peripheral cornea to concentrated sites inside the anterior segment. In the current study, the directionality of this phenomenon for UVR and whether PLF is established in outdoor settings exposed to sunlight were investigated. The protection provided by a UV-blocking contact lens was also evaluated. UVA and UVB sensors were placed on the nasal limbus of an anatomically based model eye. The temporal limbus was exposed to a UV light source placed at various angles behind the frontal plane. PLF was quantified with the sensor output. The ensemble was mounted in the orbit of a mannequin head and exposed to sunlight in three insolation environments within the region of Sydney, Australia. PLF for UVA and UVB was determined with no eyewear or with sunglasses and commercially available soft contact lenses, with and without UV-blocking capability. The intensity of UVA peaked at approximately 120 degrees incidence, the level at which the UVB response was also at its maximum. The intensification of UVA was up to x18.3. The intensity of PLF for UVA and UVB was reduced by an order of magnitude by a UV-blocking contact lens, whereas a clear contact lenses had a much lesser effect. Only the UV-blocking contact lens achieved a significant effect on UVA and UVB irradiance in the urban, beach, and mountain locales (P < 0.056). The results identify another type of sunlight hazard: the peripheral focusing of obliquely incident light. UVR from albedo (reflected ambient light) is capable of establishing PLF in the anterior segment, but this can be shielded by UV-blocking soft contact lenses. Sunglasses may be unable to shield oblique rays, unless side protection is incorporated. Contact lenses can offer UVR protection against all angles of incidence, including the peak-response angle. They can also protect the eye in settings in which the wearing of sunglasses is not feasible or convenient.

Characterizing and Understanding Aerosol Optical Properties: CARES - Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cappa, Christopher D; Atkinson, Dean B

The scientific focus of this study was to use ambient measurements to develop new insights into the understanding of the direct radiative forcing by atmospheric aerosol particles. The study used data collected by the PI’s and others as part of both the 2010 U.S. Department of Energy (DOE) sponsored Carbonaceous Aerosols and Radiative Effects Study (CARES), which took place in and around Sacramento, CA, and the 2012 Clean Air for London (ClearfLo) study. We focus on measurements that were made of aerosol particle optical properties, namely the wavelength-dependent light absorption, scattering and extinction. Interpretation of these optical property measurements ismore » facilitated through consideration of complementary measurements of the aerosol particle chemical composition and size distributions. With these measurements, we addressed the following general scientific questions: 1. How does light scattering and extinction by atmospheric aerosol particles depend on particle composition, water uptake, and size? 2. To what extent is light absorption by aerosol particles enhanced through the mixing of black carbon with other particulate components? 3. What relationships exist between intensive aerosol particle optical properties, and how do these depend on particle source and photochemical aging? 4. How well do spectral deconvolution methods, which are commonly used in remote sensing, retrieve information about particle size distributions?« less

On the nature of directed behavior to drug-associated light cues in rhesus monkeys (Macaca mulatta).

PubMed

Reilly, Mark P; Berndt, Sonja I; Woods, James H

2016-11-01

The present study investigated the role of drug-paired stimuli in controlling the behavior of rhesus monkeys. Systematic observations were made with nine monkeys who had a history of drug self-administration; they had been lever pressing to produce intravenous infusions of various drugs. These observations revealed that the stimulus light co-occurring with drug infusion produced robust and cue-directed behavior such as orienting, touching and biting. Experiment 1 showed that this light-directed behavior would occur in naïve monkeys exposed to a Pavlovian pairing procedure. Four monkeys were given response-independent injections of cocaine. In two monkeys, a red light preceded cocaine injections by 5 s, and a green light co-occurred with the 5-s cocaine injections. In the other two monkeys, the light presentations and cocaine injections occurred independently. Light-directed behavior occurred in all four monkeys within the first couple of trials and at high levels but decreased across sessions. The cocaine-paired stimulus maintained behavior longer and at higher levels than the uncorrelated stimuli. Furthermore, light-directed behavior was not maintained when cocaine was replaced with saline. Light-directed behavior did not occur in the absence of the lights. When these monkeys were subsequently trained to lever press for cocaine, light-directed behavior increased to levels higher than previously observed. Behavior directed towards drug-paired stimuli is robust, reliable and multiply determined; the mechanisms underlying this activity likely include Pavlovian conditioning, stimulus novelty, habituation and operant conditioning.

Scattering of a Tightly Focused Beam by an Optically Trapped Particle

NASA Technical Reports Server (NTRS)

Lock, James A.; Wrbanek, Susan Y.; Weiland, Kenneth E.

2006-01-01

Near-forward scattering of an optically trapped 5 m radius polystyrene latex sphere by the trapping beam was examined both theoretically and experimentally. Since the trapping beam is tightly focused, the beam fields superpose and interfere with the scattered fields in the forward hemisphere. The observed light intensity consists of a series of concentric bright and dark fringes centered about the forward scattering direction. Both the number of fringes and their contrast depend on the position of the trapping beam focal waist with respect to the sphere. The fringes are caused by diffraction due to the truncation of the tail of the trapping beam as the beam is transmitted through the sphere.

Ellipsoid-conic radiation collector and method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brunsting, A.; Hogg, W.R.

Disclosed is a radiation collector apparatus and method primarily for counting and analyzing a flow of dilute particulate material, such as blood cells, sperm cells and the like, through the use of light detection. The radiation collector apparatus comprises a reflector chamber having an ellipsoidal reflector surface with a pair of elipsoidal foci defining a first focus, f11, and second focus, f12, and a second reflector surface with a primary focus, f21, positioned at the same point as focus f12, and a secondary focus, f22. The second reflector surface has the configuration of one of the conic sections of revolution.more » In operation the radiation collector apparatus is provided with an intensifed beam of light and a stream of particulate material aligned to intersect the intensifed beam of light at focus f11. Detectable light signals, after two reflections, are received in a focused beam by a photosensitive detector.« less

Refractive Errors

MedlinePlus

... Read in Chinese How does the eye focus light? In order to see clearly, light rays from an object must focus onto the ... mechanism (the cornea and crystalline lens), and a light-sensing portion at the back (the retina). If ...

Focusing light through dynamical samples using fast continuous wavefront optimization.

PubMed

Blochet, B; Bourdieu, L; Gigan, S

2017-12-01

We describe a fast continuous optimization wavefront shaping system able to focus light through dynamic scattering media. A micro-electro-mechanical system-based spatial light modulator, a fast photodetector, and field programmable gate array electronics are combined to implement a continuous optimization of a wavefront with a single-mode optimization rate of 4.1 kHz. The system performances are demonstrated by focusing light through colloidal solutions of TiO 2 particles in glycerol with tunable temporal stability.

The effect of red light and far-red light conditions on secondary metabolism in agarwood.

PubMed

Kuo, Tony Chien-Yen; Chen, Chuan-Hung; Chen, Shu-Hwa; Lu, I-Hsuan; Chu, Mei-Ju; Huang, Li-Chun; Lin, Chung-Yen; Chen, Chien-Yu; Lo, Hsiao-Feng; Jeng, Shih-Tong; Chen, Long-Fang O

2015-06-12

Agarwood, a heartwood derived from Aquilaria trees, is a valuable commodity that has seen prevalent use among many cultures. In particular, it is widely used in herbal medicine and many compounds in agarwood are known to exhibit medicinal properties. Although there exists much research into medicinal herbs and extraction of high value compounds, few have focused on increasing the quantity of target compounds through stimulation of its related pathways in this species. In this study, we observed that cucurbitacin yield can be increased through the use of different light conditions to stimulate related pathways and conducted three types of high-throughput sequencing experiments in order to study the effect of light conditions on secondary metabolism in agarwood. We constructed genome-wide profiles of RNA expression, small RNA, and DNA methylation under red light and far-red light conditions. With these profiles, we identified a set of small RNA which potentially regulates gene expression via the RNA-directed DNA methylation pathway. We demonstrate that light conditions can be used to stimulate pathways related to secondary metabolism, increasing the yield of cucurbitacins. The genome-wide expression and methylation profiles from our study provide insight into the effect of light on gene expression for secondary metabolism in agarwood and provide compelling new candidates towards the study of functional secondary metabolic components.

Light-switchable systems for remotely controlled drug delivery.

PubMed

Shim, Gayong; Ko, Seungbeom; Kim, Dongyoon; Le, Quoc-Viet; Park, Gyu Thae; Lee, Jaiwoo; Kwon, Taekhyun; Choi, Han-Gon; Kim, Young Bong; Oh, Yu-Kyoung

2017-12-10

Light-switchable systems have recently received attention as a new mode of remotely controlled drug delivery. In the past, a multitude of nanomedicine studies have sought to enhance the specificity of drug delivery to target sites by focusing on receptors overexpressed on malignant cells or environmental features of diseases sites. Despite these immense efforts, however, there are few clinically available nanomedicines. We need a paradigm shift in drug delivery. One strategy that may overcome the limitations of pathophysiology-based drug delivery is the use of remotely controlled delivery technology. Unlike pathophysiology-based active drug targeting strategies, light-switchable systems are not affected by the heterogeneity of cells, tissue types, and/or microenvironments. Instead, they are triggered by remote light (i.e., near-infrared) stimuli, which are absorbed by photoresponsive molecules or three-dimensional nanostructures. The sequential conversion of light to heat or reactive oxygen species can activate drug release and allow it to be spatio-temporally controlled. Light-switchable systems have been used to activate endosomal drug escape, modulate the release of chemical and biological drugs, and alter nanoparticle structures to control the release rates of drugs. This review will address the limitations of pathophysiology-based drug delivery systems, the current status of light-based remote-switch systems, and future directions in the application of light-switchable systems for remotely controlled drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Generation of an axially super-resolved quasi-spherical focal spot using an amplitude-modulated radially polarized beam.

PubMed

Lin, Han; Jia, Baohua; Gu, Min

2011-07-01

An axially super-resolved quasi-spherical focal spot can be generated by focusing an amplitude-modulated radially polarized beam through a high numerical aperture objective. A method based on the unique depolarization properties of a circular focus is proposed to design the amplitude modulation. The generated focal spot shows a ratio of x:y:z=1:1:1.48 for the normalized FWHM in three dimensions, compared to that of x:y:z=1:0.74:1.72 under linear polarization (in the x direction) illumination. Moreover, the focusable light efficiency of the designed amplitude-modulated beam is 65%, which is more than 3 times higher than the optimized case under linear polarization and thus make the amplitude-modulated radial polarization beam more suitable for a wide range of applications.

On the alignment and focusing of the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)

NASA Astrophysics Data System (ADS)

Champey, Patrick; Winebarger, Amy; Kobayashi, Ken; Savage, Sabrina; Cirtain, Jonathan; Cheimets, Peter; Hertz, Edward; Golub, Leon; Ramsey, Brian; McCracken, Jeff; Marquez, Vanessa; Allured, Ryan; Heilmann, Ralf K.; Schattenburg, Mark; Bruccoleri, Alexander

2016-07-01

The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument that is designed to observe soft X-ray emissions from 24 - 6.0 Å (0.5 - 2.0 keV energies) in the solar atmosphere. For the first time, high-temperature, low-emission plasma will be observed directly with 5 arcsecond spatial resolution and 22 mÅ spectral resolution. The unique optical design consists of a Wolter - I telescope and a 3-optic grazing- incidence spectrometer. The spectrometer utilizes a finite conjugate mirror pair and a blazed planar, varied line spaced grating, which is directly printed on a silicon substrate using e-beam lithography. The grating design is being finalized and the grating will be fabricated by the Massachusetts Institute of Technology (MIT) and Izentis LLC. Marshall Space Flight Center (MSFC) is producing the nickel replicated telescope and spectrometer mirrors using the same facilities and techniques as those developed for the ART-XC and FOXSI mirrors. The Smithsonian Astrophysical Observatory (SAO) will mount and align the optical sub-assemblies based on previous experience with similar instruments, such as the Hinode X-Ray Telescope (XRT). The telescope and spectrometer assembly will be aligned in visible light through the implementation of a theodolite and reference mirrors, in addition to the centroid detector assembly (CDA) - a device designed to align the AXAF-I nested mirrors. Focusing of the telescope and spectrometer will be achieved using the X-ray source in the Stray Light Facility (SLF) at MSFC. We present results from an alignment sensitivity analysis performed on the on the system and we also discuss the method for aligning and focusing MaGIXS.

On the Alignment and Focusing of the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)

NASA Technical Reports Server (NTRS)

Champey, Patrick; Winebarger, Amy; Kobayashi, Ken; Savage, Sabrina; Cirtain, Jonathan; Cheimets, Peter; Hertz, Edward; Golub, Leon; Ramsey, Brian; McCracken, Jeff

2016-01-01

The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument that is designed to observe soft X-ray emissions from 24 - 6.0 A (0.5 - 2.0 keV energies) in the solar atmosphere. For the rst time, high-temperature, low-emission plasma will be observed directly with 5 arcsecond spatial resolution and 22 mA spectral resolution. The unique optical design consists of a Wolter - I telescope and a 3-optic grazing- incidence spectrometer. The spectrometer utilizes a nite conjugate mirror pair and a blazed planar, varied line spaced grating, which is directly printed on a silicon substrate using e-beam lithography. The grating design is being nalized and the grating will be fabricated by the Massachusetts Institute of Technology (MIT) and Izentis LLC. Marshall Space Flight Center (MSFC) is producing the nickel replicated telescope and spectrometer mirrors using the same facilities and techniques as those developed for the ART-XC and FOXSI mirrors. The Smithsonian Astrophysical Observatory (SAO) will mount and align the optical sub-assemblies based on previous experience with similar instruments, such as the Hinode X-Ray Telescope (XRT). The telescope and spectrometer assembly will be aligned in visible light through the implementation of a theodolite and reference mirrors, in addition to the centroid detector assembly (CDA) { a device designed to align the AXAF-I nested mirrors. Focusing of the telescope and spectrometer will be achieved using the X-ray source in the Stray Light Facility (SLF) at MSFC. We present results from an alignment sensitivity analysis performed on the on the system and we also discuss the method for aligning and focusing MaGIXS.

A measurement concept for hot-spot BRDFs from space

NASA Technical Reports Server (NTRS)

Gerstl, S.A.W.

1996-01-01

Several concepts for canopy hot-spot measurements from space have been investigated. The most promising involves active illumination and bistatic detection that would allow hot-spot angular distribution (BRDF) measurements from space in a search-light mode. The concept includes a pointable illumination source, such as a laser operating at an atmospheric window wavelength, coupled with a number of high spatial-resolution detectors that are clustered around the illumination source in space, receiving photons nearly coaxial with the reto-reflection direction. Microwave control and command among the satellite cluster would allow orienting the direction of the laser beam as well as the focusing detectors simultaneously so that the coupled system can function like a search light with almost unlimited pointing capabilities. The concept is called the Hot-Spot Search-Light (HSSL) satellite. A nominal satellite altitude of 600 km will allow hot-spot BRDF measurements out to about 18 degrees phase angle. The distributed are taking radiometric measurements of the intensity wings of the hot-spot angular distribution without the need for complex imaging detectors. The system can be operated at night for increased signal-to-noise ratio. This way the hot-spot angular signatures can be quantified and parameterized in sufficient detail to extract the biophysical information content of plant architectures.

Eternal triangle: the interaction of light source, electrical control gear, and optics

NASA Astrophysics Data System (ADS)

S'heeren, Griet

1998-04-01

In this particular 'affair' the participants are less than human but have individual personalities they bring to their relationship with each other. High pressure metal halide lamps such as BriteArc lamps have the highest luminance and radiance of all continuously operating practical light source. Since these lamps have short arcs and are available in power ratings from about 30W to 30kW they have found applications with various optical systems. Besides the lamps, such systems include an electrical control device and an optical system. To fulfil the user's requirements for a specific application, it is not only important to choose the right lamp, but crucial to achieve a harmonious marriage between the light source, electrical control device and the optics. To run a high pressure discharge lamp an ignitor/ballast system is essential This stabilizes the lamp parameters. The chemical components inside the lamp determine the lamp voltage and the gear determines, via the current, the lamp power. These are directly related in the luminance and color temperature of the emitted light. Therefore lamp performance and effective life are dependent on the ignitor, control gear and lamp combination. Since the lamp emits radiation in all directions, collection of the light from a lamp can be improved by using reflectors to deliver the light into a lens system. Since lamps with short arc gaps approach a point source they appear ideal for optical system applications. The shape of the reflector and the focusing of the lamp determine which part of the light is collected out of the light-arc. In the case of an LCD projector, the final light output also depends on the transmission characteristics of the LCD panels. Their nonlinearity causes the color of the emitted light to be different from the lamp color. All these parameters have to be optimized to obtain the highest performance. This leads to the conclusion that a carefully matched combination of lamp, ignitor/ballast and optics should guarantee the best system performance. This paper sets out to provide some guidelines on attempting to achieve a harmonious relationship between the three partners in this particular eternal triangle.

Photographic Equipment Test System (PETS)

NASA Technical Reports Server (NTRS)

1975-01-01

The Photographic Equipment Test System is presented. The device is a mobile optical system designed for evaluating performance of various sensors in a laboratory, in a vacuum chamber or on a flight line. The carriage is designed to allow elevation as well as azimuth control of the direction of the light from the collimator. The pneumatic tires provide an effective vibration isolation system. A target/illumination system is mounted on a motor driven linear slide, and focusing and exposure control can be operated remotely from the small electronics control console.

High Power Dye Lasers

DTIC Science & Technology

1975-09-30

sphere is greatly reduced when compared to the axial flow dye cell. This is because the focusing optics can only direct light from a limited angle into...Distribution in Flashlamp . . . „ [ [ TTIH Flashlamp Cooling and Thermal Limits [ [ [ ii~ik Optical Characteristics ’,,: •*••••••••••• il-ib...Tracing Program e Dye Pumping System Laser Tests ! 1 i * * TTT’I Laser Output Fall Off !!!.’!!!" ’ TTT’H Single Shot Optical Distortion TTT’I

Thomson-backscattered x rays from laser-accelerated electrons.

PubMed

Schwoerer, H; Liesfeld, B; Schlenvoigt, H-P; Amthor, K-U; Sauerbrey, R

2006-01-13

We present the first observation of Thomson-backscattered light from laser-accelerated electrons. In a compact, all-optical setup, the "photon collider," a high-intensity laser pulse is focused into a pulsed He gas jet and accelerates electrons to relativistic energies. A counterpropagating laser probe pulse is scattered from these high-energy electrons, and the backscattered x-ray photons are spectrally analyzed. This experiment demonstrates a novel source of directed ultrashort x-ray pulses and additionally allows for time-resolved spectroscopy of the laser acceleration of electrons.

Focusing light through scattering media by polarization modulation based generalized digital optical phase conjugation

NASA Astrophysics Data System (ADS)

Yang, Jiamiao; Shen, Yuecheng; Liu, Yan; Hemphill, Ashton S.; Wang, Lihong V.

2017-11-01

Optical scattering prevents light from being focused through thick biological tissue at depths greater than ˜1 mm. To break this optical diffusion limit, digital optical phase conjugation (DOPC) based wavefront shaping techniques are being actively developed. Previous DOPC systems employed spatial light modulators that modulated either the phase or the amplitude of the conjugate light field. Here, we achieve optical focusing through scattering media by using polarization modulation based generalized DOPC. First, we describe an algorithm to extract the polarization map from the measured scattered field. Then, we validate the algorithm through numerical simulations and find that the focusing contrast achieved by polarization modulation is similar to that achieved by phase modulation. Finally, we build a system using an inexpensive twisted nematic liquid crystal based spatial light modulator (SLM) and experimentally demonstrate light focusing through 3-mm thick chicken breast tissue. Since the polarization modulation based SLMs are widely used in displays and are having more and more pixel counts with the prevalence of 4 K displays, these SLMs are inexpensive and valuable devices for wavefront shaping.

Theory of CW lidar aerosol backscatter measurements and development of a 2.1 microns solid-state pulsed laser radar for aerosol backscatter profiling

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Henderson, Sammy W.; Frehlich, R. G.

1991-01-01

The performance and calibration of a focused, continuous wave, coherent detection CO2 lidar operated for the measurement of atmospheric backscatter coefficient, B(m), was examined. This instrument functions by transmitting infrared (10 micron) light into the atmosphere and collecting the light which is scattered in the rearward direction. Two distinct modes of operation were considered. In volume mode, the scattered light energy from many aerosols is detected simultaneously, whereas in the single particle mode (SPM), the scattered light energy from a single aerosol is detected. The analysis considered possible sources of error for each of these two cases, and also considered the conditions where each technique would have superior performance. The analysis showed that, within reasonable assumptions, the value of B(m) could be accurately measured by either the VM or the SPM method. The understanding of the theory developed during the analysis was also applied to a pulsed CO2 lidar. Preliminary results of field testing of a solid state 2 micron lidar using a CW oscillator is included.

Focusing optical waves with a rotationally symmetric sharp-edge aperture

NASA Astrophysics Data System (ADS)

Hu, Yanwen; Fu, Shenhe; Li, Zhen; Yin, Hao; Zhou, Jianying; Chen, Zhenqiang

2018-04-01

While there has been various kinds of patterned structures proposed for wave focusing, these patterned structures usually involve complicated lithographic techniques since the element size of the patterned structures should be precisely controlled in microscale or even nanoscale. Here we propose a new and straightforward method for focusing an optical plane wave in free space with a rotationally symmetric sharp-edge aperture. The focusing phenomenon of wave is realized by superposition of a portion of the higher-order symmetric plane waves generated from the sharp edges of the apertures, in contrast to previously focusing techniques which usually depend on a curved phase. We demonstrate both experimentally and theoretically the focusing effect with a series of apertures having different rotational symmetry, and find that the intensity of the hotspots could be controlled by the symmetric strength of the sharp-edge apertures. The presented results would advance the conventional wisdom that light would diffract in all directions and become expanding when it propagates through an aperture. The proposed method is easy to be processed, and might open potential applications in interferometry, image, and superresolution.

InGaN directional coupler made with a one-step etching technique

NASA Astrophysics Data System (ADS)

Gao, Xumin; Yuan, Jialei; Yang, Yongchao; Zhang, Shuai; Shi, Zheng; Li, Xin; Wang, Yongjin

2017-06-01

We propose, fabricate and characterize an on-chip integration of light source, InGaN waveguide, directional coupler and photodiode, in which AlGaN layers are used as top and bottom optical claddings to form an InGaN waveguide for guiding the in-plane emitted light from the InGaN/GaN multiple-quantum-well light-emitting diode (MQW-LED). The difference in etch rate caused by different exposure windows leads to an etching depth discrepancy using the one-step etching technique, which forms the InGaN directional coupler with the overlapped underlying slab. Light propagation results directly confirm effective light coupling in the InGaN directional coupler, which is achieved through high-order guided modes. The InGaN waveguide couples the modulated light from the InGaN/GaN MQW-LED and transfers part of light to the coupled waveguide via the InGaN directional coupler. The in-plane InGaN/GaN MQW-photodiode absorbs the guided light by the coupled InGaN waveguide and induces the photocurrent. The on-chip InGaN photonic integration experimentally demonstrates an in-plane light communication with a data transmission of 50 Mbps.

Imaging spectrometer wide field catadioptric design

DOEpatents

Chrisp,; Michael, P [Danville, CA

2008-08-19

A wide field catadioptric imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The catadioptric design has zero Petzval field curvature. The imaging spectrometer comprises an entrance slit for transmitting light, a system with a catadioptric lens and a dioptric lens for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the system for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the system for receiving the light and the system for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light through the system for receiving the light to the detector array.

Efficient Solar Concentrators: Affordable Energy from Water and Sunlight

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-01-01

Broad Funding Opportunity Announcement Project: Teledyne is developing a liquid prism panel that tracks the position of the sun to help efficiently concentrate its light onto a solar cell to produce power. Typically, solar tracking devices have bulky and expensive mechanical moving parts that require a lot of power and are often unreliable. Teledyne’s liquid prism panel has no bulky and heavy supporting parts—instead it relies on electrowetting. Electrowetting is a process where an electric field is applied to the liquid to control the angle at which it meets the sunlight above and to control the angle of the sunlightmore » to the focusing lensthe more direct the angle to the focusing lens, the more efficiently the light can be concentrated to solar panels and converted into electricity. This allows the prism to be tuned like a radio to track the sun across the sky and steer sunlight into the solar cell without any moving mechanical parts. This process uses very little power and requires no expensive supporting hardware or moving parts, enabling efficient and quiet rooftop operation for integration into buildings.« less

Metal oxide semiconductors for dye degradation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adhikari, Sangeeta; Sarkar, Debasish, E-mail: dsarkar@nitrkl.ac.in

2015-12-15

Highlights: • Hydrothermal synthesis of monoclinic and hexagonal WO{sub 3} nanostructures. • Nanocuboid and nanofiber growth using different structure directing agents. • WO{sub 3}–ZnO nanocomposites for dye degradation under UV and visible light. • High photocatalytic efficiency is achieved by 10 wt% monoclinic WO{sub 3}. • WO{sub 3} assists to trap hole in UV and arrests electron in visible light irradiation. - Abstract: Organic contaminants are a growing threat to the environment that widely demands their degradation by high efficient photocatalysts. Thus, the proposed research work primely focuses on the efficient degradation of methyl orange using designed WO{sub 3}–ZnO photocatalystsmore » under both UV and visible light irradiation. Two different sets of WO{sub 3} nanostructures namely, monoclinic WO{sub 3} (m-WO{sub 3}) and hexagonal WO{sub 3} (h-WO{sub 3}) synthesizes in presence of a different structure directing agents. A specific dispersion technique allows the intimate contact of as-synthesized WO{sub 3} and ultra-violet active commercial ZnO photocatalyst in different weight variations. ZnO nanocrystal in presence of an optimum 10 wt% m-WO{sub 3} shows a high degree of photocatalytic activity under both UV and visible light irradiation compared to counterpart h-WO{sub 3}. Symmetrical monoclinic WO{sub 3} assists to trap hole in UV, but electron arresting mechanism predominates in visible irradiation. Coupling of monoclinic nanocuboid WO{sub 3} with ZnO proves to be a promising photocatalyst in both wavelengths.« less

Gravity, light and plant form

NASA Technical Reports Server (NTRS)

Hangarter, R. P.

1997-01-01

Plants have evolved highly sensitive and selective mechanisms that detect and respond to various aspects of their environment. As a plant develops, it integrates the environmental information perceived by all of its sensory systems and adapts its growth to the prevailing environmental conditions. Light is of critical importance because plants depend on it for energy and, thus, survival. The quantity, quality and direction of light are perceived by several different photosensory systems that together regulate nearly all stages of plant development, presumably in order to maintain photosynthetic efficiency. Gravity provides an almost constant stimulus that is the source of critical spatial information about its surroundings and provides important cues for orientating plant growth. Gravity plays a particularly important role during the early stages of seedling growth by stimulating a negative gravitropic response in the primary shoot that orientates it towards the source of light, and a positive gravitropic response in the primary root that causes it to grow down into the soil, providing support and nutrient acquisition. Gravity also influences plant form during later stages of development through its effect on lateral organs and supporting structures. Thus, the final form of a plant depends on the cumulative effects of light, gravity and other environmental sensory inputs on endogenous developmental programs. This article is focused on developmental interactions modulated by light and gravity.

Gravity, light and plant form.

PubMed

Hangarter, R P

1997-06-01

Plants have evolved highly sensitive and selective mechanisms that detect and respond to various aspects of their environment. As a plant develops, it integrates the environmental information perceived by all of its sensory systems and adapts its growth to the prevailing environmental conditions. Light is of critical importance because plants depend on it for energy and, thus, survival. The quantity, quality and direction of light are perceived by several different photosensory systems that together regulate nearly all stages of plant development, presumably in order to maintain photosynthetic efficiency. Gravity provides an almost constant stimulus that is the source of critical spatial information about its surroundings and provides important cues for orientating plant growth. Gravity plays a particularly important role during the early stages of seedling growth by stimulating a negative gravitropic response in the primary shoot that orientates it towards the source of light, and a positive gravitropic response in the primary root that causes it to grow down into the soil, providing support and nutrient acquisition. Gravity also influences plant form during later stages of development through its effect on lateral organs and supporting structures. Thus, the final form of a plant depends on the cumulative effects of light, gravity and other environmental sensory inputs on endogenous developmental programs. This article is focused on developmental interactions modulated by light and gravity.

Improving the axial resolution in time-reversed ultrasonically encoded (TRUE) optical focusing with dual ultrasonic waves

NASA Astrophysics Data System (ADS)

Yang, Qiang; Xu, Xiao; Lai, Puxiang; Sang, Xinzhu; Wang, Lihong V.

2014-03-01

Focusing light inside highly scattering media beyond the ballistic regime is a challenging task in biomedical optical imaging, manipulation, and therapy. This challenge can be overcome by time reversing ultrasonically encoded (TRUE) diffuse light to the ultrasonic focus inside a turbid medium. In TRUE optical focusing, a photorefractive crystal or polymer is used as the phase conjugate mirror for optical time reversal. Accordingly, a relatively long ultrasound burst, whose duration matches the response time of the photorefractive material, is used to encode the diffuse light. With this long ultrasound burst, the resolution of the TRUE focus along the acoustic axis is poor. In this work, we used two transducers, emitting two intersecting ultrasound beams at 3.4 MHz and 3.6 MHz respectively, to modulate the diffuse light within their intersection volume at the beat frequency. We show that light encoded at the beat frequency can be time-reversed and converge to the intersection volume. Experimentally, TRUE focusing with an acoustic axial resolution of ~1.1 mm was demonstrated inside turbid media, agreeing with the theoretical estimation.

The use of total human bone marrow fraction in a direct three-dimensional expansion approach for bone tissue engineering applications: focus on angiogenesis and osteogenesis.

PubMed

Guerrero, Julien; Oliveira, Hugo; Catros, Sylvain; Siadous, Robin; Derkaoui, Sidi-Mohammed; Bareille, Reine; Letourneur, Didier; Amédée, Joëlle

2015-03-01

Current approaches in bone tissue engineering have shown limited success, mostly owing to insufficient vascularization of the construct. A common approach consists of co-culture of endothelial cells and osteoblastic cells. This strategy uses cells from different sources and differentiation states, thus increasing the complexity upstream of a clinical application. The source of reparative cells is paramount for the success of bone tissue engineering applications. In this context, stem cells obtained from human bone marrow hold much promise. Here, we analyzed the potential of human whole bone marrow cells directly expanded in a three-dimensional (3D) polymer matrix and focused on the further characterization of this heterogeneous population and on their ability to promote angiogenesis and osteogenesis, both in vitro and in vivo, in a subcutaneous model. Cellular aggregates were formed within 24 h and over the 12-day culture period expressed endothelial and bone-specific markers and a specific junctional protein. Ectopic implantation of the tissue-engineered constructs revealed osteoid tissue and vessel formation both at the periphery and within the implant. This work sheds light on the potential clinical use of human whole bone marrow for bone regeneration strategies, focusing on a simplified approach to develop a direct 3D culture without two-dimensional isolation or expansion.

Luminaires for Advanced Lighting in Education

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, J. Lynn

Evolving education methods and greater use of technology in the classroom are dictating the need to rethink facility designs, including classroom lighting. Advances in LED-based lighting technology have created the possibility of lighting systems that are not only cost effective and energy efficient, but also color-tunable and as durable as other facility infrastructures (a 20-30 year life expectancy). Thus, there is the opportunity that the modern lighting system can be used by educators as a tool in their teaching strategy. To meet this need, RTI International and Finelite, Inc. teamed to develop and test the Next Generation Integrated Classroom Lightingmore » System (NICLS). The NICLS technology incorporates a high performance, color-tunable light engine into new luminaire designs (e.g., pendant, direct-indirect, downlight, troffers) that are acceptable for use in classrooms. During this project, we successfully demonstrated that the NICLS technology achieves exceptional performance and exceeds all DOE goals for the classroom of the future, including: Luminous efficacy value for NICLS luminaires in excess of 125 lpw at all CCT values; TWL range of 2,700 K to 6,500 K while maintaining a CRI of 82 or higher at all values; Capability for full-range dimming (100% to 1%) at all CCT values with flicker levels below industry guidelines; Performance of the lighting system in a classroom mock-up, incorporating daylight and occupancy sensing to provide automatic control of lighting zones to further reduce energy consumption; Rated lifetime on the system exceeding 50,000 hours with a lumen maintenance of at least 85% at 50,000 hours; and Teacher-focused UI located at the front of the classroom to operate the lighting system. A smartphone-based UI is also available to accommodate teacher movement in the classroom. A critical element of developing this technology is designing the user interface to be compatible with modern teaching methods, including increased use of icons and colors and intuitive appearance. The design of the NICLS technology and the user interface was modified with assistance from focus groups consisting of more than 80 teachers and educational professionals total. The focus groups were held in a full-sized classroom that served as a technology demonstration site for the NICLS. The NICLS technology is an advanced lighting system for educational settings that meets or exceeds all DOE photometric, electrical, and reliability goals for the COF. The NICLS technology has been demonstrated at the classroom level, and the feedback from the dozens of teachers and educational professionals who visited the demonstration site has been overwhelmingly positive. NICLS provides a state-of-the-art lighting environment that adjusts the lighting conditions—both color and illuminance levels—to the needs of students and teachers for the task at hand. Early research has suggested that such lighting conditions will improve not only teacher effectiveness but also a student’s ability to concentrate on learning activities.« less

Diode-laser-pump module with integrated signal ports for pumping amplifying fibers and method

DOEpatents

Savage-Leuchs,; Matthias, P [Woodinville, WA

2009-05-26

Apparatus and method for collimating pump light of a first wavelength from laser diode(s) into a collimated beam within an enclosure having first and second optical ports, directing pump light from the collimated beam to the first port; and directing signal light inside the enclosure between the first and second port. The signal and pump wavelengths are different. The enclosure provides a pump block having a first port that emits pump light to a gain fiber outside the enclosure and that also passes signal light either into or out of the enclosure, and another port that passes signal light either out of or into the enclosure. Some embodiments use a dichroic mirror to direct pump light to the first port and direct signal light between the first and second ports. Some embodiments include a wavelength-conversion device to change the wavelength of at least some of the signal light.

Positive focal shift of gallium nitride high contrast grating focusing reflectors

NASA Astrophysics Data System (ADS)

He, Shumin; Wang, Zhenhai; Liu, Qifa

2016-09-01

We design a type of metasurfaces capable of serving as a visible-light focusing reflector based on gallium nitride (GaN) high contrast gratings (HCGs). The wavefront of the reflected light is precisely manipulated by spatial variation of the grating periods along the subwavelength ridge array to achieve light focusing. Different from conventional negative focal shift effect, a positive focal shift is observed in such focusing reflectors. Detailed investigations of the influence of device size on the focusing performance, especially the focal length, are preformed via a finite element method . The results show that all performance parameters are greatly affected by the reflector size. A more concentrated focal point, or a better focusing capability, can be achieved by larger size. With increasing reflector size, the achieved focal length decreases and gradually approaches to the design, thus the corresponding positive focal shift decreases. Our results are helpful for understanding the visible-light control of the planar HCG-based focusing reflectors.

Particle measurement systems and methods

DOEpatents

Steele, Paul T [Livermore, CA

2011-10-04

A system according to one embodiment includes a light source for generating light fringes; a sampling mechanism for directing a particle through the light fringes; and at least one light detector for detecting light scattered by the particle as the particle passes through the light fringes. A method according to one embodiment includes generating light fringes using a light source; directing a particle through the light fringes; and detecting light scattered by the particle as the particle passes through the light fringes using at least one light detector.

Focusing light through strongly scattering media by controlling binary amplitude optimization using genetic algorithm

NASA Astrophysics Data System (ADS)

Liu, Zhipeng; Zhang, Bin; Feng, Qi; Chen, Zhaoyang; Lin, Chengyou; Ding, Yingchun

2017-06-01

Focusing light through strongly scattering media plays an important role in biomedical imaging and therapy. Here, we experimentally demonstrate light focusing through ZnO sample by controlling binary amplitude optimization using genetic algorithm. In the experiment, we use a Micro Electro-Mechanical System (MEMS)-based digital micromirror device (DMD) which is in amplitude-only modulation mode. The DMD consists of 1920×1080 square mirrors that can be independently controlled to reflect light to a desired position. We control only 160 thousand mirrors which are divided into 400 segments to modulate light focusing through the scattering media using advanced genetic algorithm. Light intensity at the target position is enhanced up to 50+/-5 times the average speckle intensity. The diameters of focusing spot can be changed ranging from 7 μm to 70 μm at arbitrary positions and multiple foci are obtained simultaneously. The spatial arrangement of multiple foci can be flexibly controlled. The advantage of DMDs lies in their switching speed up to 30 kHz, which has the potential to generate a focus in an ultra-short period of time. Our work provides a reference for the study of high speed wavefront shaping that is required in vivo tissues imaging.

Multiple-Point Mass Flux Measurement System Using Rayleigh Scattering

NASA Technical Reports Server (NTRS)

Mielke, Amy F.; Elam, Kristie A.; Clem, Michelle M.

2009-01-01

A multiple-point Rayleigh scattering diagnostic is being developed to provide mass flux measurements in gas flows. Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous density, temperature, and velocity measurements. Rayleigh scattered light from a focused 18 Watt continuous-wave laser beam is directly imaged through a solid Fabry-Perot etalon onto a CCD detector which permits spectral analysis of the light. The spatial resolution of the measurements is governed by the locations of interference fringes, which can be changed by altering the etalon characteristics. A prototype system has been used to acquire data in a Mach 0.56 flow to demonstrate feasibility of using this system to provide mass flux measurements. Estimates of measurement uncertainty and recommendations for system improvements are presented

Focusing and imaging with increased numerical apertures through multimode fibers with micro-fabricated optics.

PubMed

Bianchi, S; Rajamanickam, V P; Ferrara, L; Di Fabrizio, E; Liberale, C; Di Leonardo, R

2013-12-01

The use of individual multimode optical fibers in endoscopy applications has the potential to provide highly miniaturized and noninvasive probes for microscopy and optical micromanipulation. A few different strategies have been proposed recently, but they all suffer from intrinsically low resolution related to the low numerical aperture of multimode fibers. Here, we show that two-photon polymerization allows for direct fabrication of micro-optics components on the fiber end, resulting in an increase of the numerical aperture to a value that is close to 1. Coupling light into the fiber through a spatial light modulator, we were able to optically scan a submicrometer spot (300 nm FWHM) over an extended region, facing the opposite fiber end. Fluorescence imaging with improved resolution is also demonstrated.

Light. Stop Faking It! Finally Understanding Science So You Can Teach It.

ERIC Educational Resources Information Center

Robertson, William C.

This book is designed to help teachers bolster their content knowledge by focusing on specific science concepts regarding the topic of light. The book covers three scientific models of light and discusses the observations that can be explained by each model. Chapters include: (1) "LightN-The Early Years"; (2) "Colorful Waves"; (3) "Focus, People,…

Differential evolution algorithm based photonic structure design: numerical and experimental verification of subwavelength λ/5 focusing of light.

PubMed

Bor, E; Turduev, M; Kurt, H

2016-08-01

Photonic structure designs based on optimization algorithms provide superior properties compared to those using intuition-based approaches. In the present study, we numerically and experimentally demonstrate subwavelength focusing of light using wavelength scale absorption-free dielectric scattering objects embedded in an air background. An optimization algorithm based on differential evolution integrated into the finite-difference time-domain method was applied to determine the locations of each circular dielectric object with a constant radius and refractive index. The multiobjective cost function defined inside the algorithm ensures strong focusing of light with low intensity side lobes. The temporal and spectral responses of the designed compact photonic structure provided a beam spot size in air with a full width at half maximum value of 0.19λ, where λ is the wavelength of light. The experiments were carried out in the microwave region to verify numerical findings, and very good agreement between the two approaches was found. The subwavelength light focusing is associated with a strong interference effect due to nonuniformly arranged scatterers and an irregular index gradient. Improving the focusing capability of optical elements by surpassing the diffraction limit of light is of paramount importance in optical imaging, lithography, data storage, and strong light-matter interaction.

Differential evolution algorithm based photonic structure design: numerical and experimental verification of subwavelength λ/5 focusing of light

PubMed Central

Bor, E.; Turduev, M.; Kurt, H.

2016-01-01

Photonic structure designs based on optimization algorithms provide superior properties compared to those using intuition-based approaches. In the present study, we numerically and experimentally demonstrate subwavelength focusing of light using wavelength scale absorption-free dielectric scattering objects embedded in an air background. An optimization algorithm based on differential evolution integrated into the finite-difference time-domain method was applied to determine the locations of each circular dielectric object with a constant radius and refractive index. The multiobjective cost function defined inside the algorithm ensures strong focusing of light with low intensity side lobes. The temporal and spectral responses of the designed compact photonic structure provided a beam spot size in air with a full width at half maximum value of 0.19λ, where λ is the wavelength of light. The experiments were carried out in the microwave region to verify numerical findings, and very good agreement between the two approaches was found. The subwavelength light focusing is associated with a strong interference effect due to nonuniformly arranged scatterers and an irregular index gradient. Improving the focusing capability of optical elements by surpassing the diffraction limit of light is of paramount importance in optical imaging, lithography, data storage, and strong light-matter interaction. PMID:27477060

Chromatic aberration of light focusing in hyperbolic anisotropic metamaterial made of metallic slit array.

PubMed

Guo, Kai; Liu, Jianlong; Zhang, Yan; Liu, Shutian

2012-12-17

The dispersion of a hyperbolic anisotropic metamaterial (HAM) and the chromatic aberration of light focusing in this kind of HAM are studied. The HAM is formed by alternately stacking metal and dielectric layers. The rules of materials and filling factors affecting the optical property of HAM are given. The chromatic aberration of light focusing is demonstrated both theoretically and numerically. By comparing the theory with the simulation results, the factors influencing the focal length, including the heat loss of material and low spatial frequency modes, are discussed. The investigation emphasizes the anomalous properties, such as chromatic aberration and low spatial frequency modes influencing focus position, of HAM compared with that in conventional lens. Based on the analysis, the possibility of using HAM to focus light with two different wavelengths at the same point is studied.

LEARNING FROM OTHERS: CHILDREN’S CONSTRUCTION OF CONCEPTS

PubMed Central

Gelman, Susan A.

2010-01-01

Much of children’s knowledge is derived not from their direct experiences with the environment but rather from the input of others. However, until recently, the focus in studies of concept development was primarily on children’s knowledge, with relatively little attention paid to the nature of the input. The last 10 years have seen an important shift in focus. This chapter reviews this approach, by examining the nature of the input, and the nature of the learner, to shed light on early conceptual learning. These findings argue against the simple notion that conceptual development is either supplied by the environment or innately specified, and instead demonstrate how the two work together. The implications for how children reconcile competing belief systems are also discussed. PMID:18631027

Insights into animal and plant lectins with antimicrobial activities.

PubMed

Dias, Renata de Oliveira; Machado, Leandro Dos Santos; Migliolo, Ludovico; Franco, Octavio Luiz

2015-01-05

Lectins are multivalent proteins with the ability to recognize and bind diverse carbohydrate structures. The glyco -binding and diverse molecular structures observed in these protein classes make them a large and heterogeneous group with a wide range of biological activities in microorganisms, animals and plants. Lectins from plants and animals are commonly used in direct defense against pathogens and in immune regulation. This review focuses on sources of animal and plant lectins, describing their functional classification and tridimensional structures, relating these properties with biotechnological purposes, including antimicrobial activities. In summary, this work focuses on structural-functional elucidation of diverse lectin groups, shedding some light on host-pathogen interactions; it also examines their emergence as biotechnological tools through gene manipulation and development of new drugs.

White-Light Phase-Conjugate Mirrors as Distortion Correctors

NASA Technical Reports Server (NTRS)

Frazier, Donald; Smith, W. Scott; Abdeldayem, Hossin; Banerjee, Partha

2010-01-01

White-light phase-conjugate mirrors would be incorporated into some optical systems, according to a proposal, as means of correcting for wavefront distortions caused by imperfections in large optical components. The proposal was given impetus by a recent demonstration that white, incoherent light can be made to undergo phase conjugation, whereas previously, only coherent light was known to undergo phase conjugation. This proposal, which is potentially applicable to almost any optical system, was motivated by a need to correct optical aberrations of the primary mirror of the Hubble Space telescope. It is difficult to fabricate large optical components like the Hubble primary mirror and to ensure the high precision typically required of such components. In most cases, despite best efforts, the components as fabricated have small imperfections that introduce optical aberrations that adversely affect imaging quality. Correcting for such aberrations is difficult and costly. The proposed use of white-light phase conjugate mirrors offers a relatively simple and inexpensive solution of the aberration-correction problem. Indeed, it should be possible to simplify the entire approach to making large optical components because there would be no need to fabricate those components with extremely high precision in the first place: A white-light phase-conjugate mirror could correct for all the distortions and aberrations in an optical system. The use of white-light phase-conjugate mirrors would be essential for ensuring high performance in optical systems containing lightweight membrane mirrors, which are highly deformable. As used here, "phase-conjugate mirror" signifies, more specifically, an optical component in which incident light undergoes time-reversal phase conjugation. In practice, a phase-conjugate mirror would typically be implemented by use of a suitably positioned and oriented photorefractive crystal. In the case of a telescope comprising a primary and secondary mirror (see figure) white light from a distant source would not be brought to initial focus on one or more imaging scientific instrument(s) as in customary practice. Instead, the light would be brought to initial focus on a phase-conjugate mirror. The phase-conjugate mirror would send a phase-conjugate image back, along the path of the incoming light, to the primary mirror. A transparent, highly efficient diffractive thin film deposited on the primary mirror would direct the phase-conjugate image to the imaging instrument(s).

Focusing light through random scattering media by four-element division algorithm

NASA Astrophysics Data System (ADS)

Fang, Longjie; Zhang, Xicheng; Zuo, Haoyi; Pang, Lin

2018-01-01

The focusing of light through random scattering materials using wavefront shaping is studied in detail. We propose a newfangled approach namely four-element division algorithm to improve the average convergence rate and signal-to-noise ratio of focusing. Using 4096 independently controlled segments of light, the intensity at the target is 72 times enhanced over the original intensity at the same position. The four-element division algorithm and existing phase control algorithms of focusing through scattering media are compared by both of the numerical simulation and the experiment. It is found that four-element division algorithm is particularly advantageous to improve the average convergence rate of focusing.

Vertically Emitting Indium Phosphide Nanowire Lasers.

PubMed

Xu, Wei-Zong; Ren, Fang-Fang; Jevtics, Dimitars; Hurtado, Antonio; Li, Li; Gao, Qian; Ye, Jiandong; Wang, Fan; Guilhabert, Benoit; Fu, Lan; Lu, Hai; Zhang, Rong; Tan, Hark Hoe; Dawson, Martin D; Jagadish, Chennupati

2018-06-13

Semiconductor nanowire (NW) lasers have attracted considerable research effort given their excellent promise for nanoscale photonic sources. However, NW lasers currently exhibit poor directionality and high threshold gain, issues critically limiting their prospects for on-chip light sources with extremely reduced footprint and efficient power consumption. Here, we propose a new design and experimentally demonstrate a vertically emitting indium phosphide (InP) NW laser structure showing high emission directionality and reduced energy requirements for operation. The structure of the laser combines an InP NW integrated in a cat's eye (CE) antenna. Thanks to the antenna guidance with broken asymmetry, strong focusing ability, and high Q-factor, the designed InP CE-NW lasers exhibit a higher degree of polarization, narrower emission angle, enhanced internal quantum efficiency, and reduced lasing threshold. Hence, this NW laser-antenna system provides a very promising approach toward the achievement of high-performance nanoscale lasers, with excellent prospects for use as highly localized light sources in present and future integrated nanophotonics systems for applications in advanced sensing, high-resolution imaging, and quantum communications.

A method to directly image exoplanets in multi-star systems such as Alpha-Centauri

NASA Astrophysics Data System (ADS)

Thomas, Sandrine J.; Belikov, Ruslan; Bendek, Eduardo

2015-09-01

Direct imaging of extra-solar planets is now a reality, especially with the deployment and commissioning of the first generation of specialized ground-based instruments such as the Gemini Planet Imager and SPHERE. These systems will allow detection of Jupiter-like planets 107 times fainter than their host star. Obtaining this contrast level and beyond requires the combination of a coronagraph to suppress light coming from the host star and a wavefront control system including a deformable mirror (DM) to remove residual starlight (speckles) created by the imperfections of telescope. However, all these current and future systems focus on detecting faint planets around single host stars, while several targets or planet candidates are located around nearby binary stars such as our neighboring star Alpha Centauri. Here, we present a method to simultaneously correct aberrations and diffraction of light coming from the target star as well as its companion star in order to reveal planets orbiting the target star. This method works even if the companion star is outside the control region of the DM (beyond its half-Nyquist frequency), by taking advantage of aliasing effects.

Direct imaging of exoplanets around multiple star systems

NASA Astrophysics Data System (ADS)

Thomas, Sandrine

2015-01-01

Direct imaging of extra-solar planets is now a reality, especially with the deployment and commissioning of the first generation of specialized ground-based instruments such as the Gemini Planet Imager and SPHERE. These systems will allow detection of Jupiter-like planets 10^7 times fainter than their host star. Obtaining this contrast level and beyond requires the combination of a coronagraph to suppress light coming from the host star and a wavefront control system including a deformable mirror (DM) to remove residual starlight (speckles) created by the imperfections of telescope. However, all these current and future systems focus on detecting faint planets around a single host star or unresolved binaries/multiples, while several targets or planet candidates are located around nearby binary stars such as our neighboring star Alpha Centauri.Here, we present a method to simultaneously correct aberrations and diffraction of light coming from the target star as well as its companion star in order to reveal planets orbiting the target star. This method works even if the companion star is outside the control region of the DM (beyond its half-Nyquist frequency), by taking advantage of aliasing effects.

Measurement of Laser Plasma Instability (LPI) Driven Light Scattering from Plasmas Produced by Nike KrF Laser

NASA Astrophysics Data System (ADS)

Oh, Jaechul; Weaver, J. L.; Phillips, L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Serlin, V.; Lehmberg, R. H.; McLean, E. A.; Manka, C. K.

2010-11-01

With short wavelength (248 nm), large bandwidth (1˜3 THz), and ISI beam smoothing, Nike KrF laser provides unique research opportunities and potential for direct-drive inertial confinement fusion. Previous Nike experiments observed two plasmon decay (TPD) driven signals from CH plasmas at the laser intensities above ˜2x10^15 W/cm^2 with total laser energies up to 1 kJ of ˜350 ps FWHM pulses. We have performed a further experiment with longer laser pulses (0.5˜4.0 ns FWHM) and will present combined results of the experiments focusing on light emission data in spectral ranges relevant to the Raman (SRS) and TPD instabilities. Time- or space-resolved spectral features of TPD were detected at different viewing angles and the absolute intensity calibrated spectra of thermal background were used to obtain blackbody temperatures in the plasma corona. The wave vector distribution in k-space of the participating TPD plasmons will be also discussed. These results show promise for the proposed direct-drive designs.

Changes in morphology and optical properties of sclera and choroidal layers due to hyperosmotic agent.

PubMed

Zaman, Raiyan T; Rajaram, Narasimhan; Nichols, Brandon S; Rylander, Henry G; Wang, Tianyi; Tunnell, James W; Welch, Ashley J

2011-07-01

Light scattering in the normally white sclera prevents diagnostic imaging or delivery of a focused laser beam to a target in the underlying choroid layer. In this study, we examine optical clearing of the sclera and changes in blood flow resulting from the application of glycerol to the sclera of rabbits. Recovery dynamics are monitored after the application of saline. The speed of clearing for injection delivery is compared to the direct application of glycerol through an incision in the conjunctiva. Although, the same volume of glycerol was applied, the sclera cleared much faster (5 to 10 s) with the topical application of glycerol compared to the injection method (3 min). In addition, the direct topical application of glycerol spreads over a larger area in the sclera than the latter method. A diffuse optical spectroscopy system provided spectral analysis of the remitted light every two minutes during clearing and rehydration. Comparison of measurements to those obtained from phantoms with various absorption and scattering properties provided estimates of the absorption coefficient and reduced scattering coefficient of rabbit eye tissue.

Monte Carlo simulation of zinc protoporphyrin fluorescence in the retina

NASA Astrophysics Data System (ADS)

Chen, Xiaoyan; Lane, Stephen

2010-02-01

We have used Monte Carlo simulation of autofluorescence in the retina to determine that noninvasive detection of nutritional iron deficiency is possible. Nutritional iron deficiency (which leads to iron deficiency anemia) affects more than 2 billion people worldwide, and there is an urgent need for a simple, noninvasive diagnostic test. Zinc protoporphyrin (ZPP) is a fluorescent compound that accumulates in red blood cells and is used as a biomarker for nutritional iron deficiency. We developed a computational model of the eye, using parameters that were identified either by literature search, or by direct experimental measurement to test the possibility of detecting ZPP non-invasively in retina. By incorporating fluorescence into Steven Jacques' original code for multi-layered tissue, we performed Monte Carlo simulation of fluorescence in the retina and determined that if the beam is not focused on a blood vessel in a neural retina layer or if part of light is hitting the vessel, ZPP fluorescence will be 10-200 times higher than background lipofuscin fluorescence coming from the retinal pigment epithelium (RPE) layer directly below. In addition we found that if the light can be focused entirely onto a blood vessel in the neural retina layer, the fluorescence signal comes only from ZPP. The fluorescence from layers below in this second situation does not contribute to the signal. Therefore, the possibility that a device could potentially be built and detect ZPP fluorescence in retina looks very promising.

Perspectives of Nurses and Patients on Call Light Technology.

PubMed

Galinato, Jose; Montie, Mary; Patak, Lance; Titler, Marita

2015-08-01

Call lights are prevalent in inpatient healthcare facilities across the nation. While call light use directly influences the delivery of nursing care, there remain significant gaps both in research and technology that can affect the quality of care and patient satisfaction. This study examines nurse and patient perceptions of the use of a new call communication solution, Eloquence, in the acute care inpatient setting. Eighteen patients were recruited for the study and participated in individual semistructured interviews during their hospital stay. Eighteen nurses were recruited and participated in focus groups for this study. Qualitative descriptive methods were used to analyze the data. Results revealed themes of usability, improved communication, and suggestions for improvement to the alpha prototype design. After a demonstration of the use and capability of Eloquence, nurse and patient participants found Eloquence as a welcomed advancement in nurse call technology that has the potential to improve workflow and patient outcomes. In addition, the participants also proposed ideas on how to further develop the technology to improve its use.

Photochemical Study of Silver Nanoparticles Formed from the Reduction of Silver Ions by Humic Acid

NASA Astrophysics Data System (ADS)

Leslie, Renee M.

This study focuses on the ability of silver ions and humic acid to form silver nanoparticles in the presence of UV and visible light. Silver nanoparticles have a number of industrial applications due primarily to their antimicrobial properties, but these properties pose an environmental threat. Silver nanoparticles can directly disrupt sensitive ecosystems by harming bacteria. Consumption of silver nanoparticles results in silver ions and silver nanoparticles entering waterways; the presence of silver ions raises the question of whether nanoparticles can reform in environmental waters. As our data show, silver nanoparticles can form from the reduction of silver ions by humic acid after irradiation with UV and visible light. In order to better understand the mechanism of these naturally synthesized silver nanoparticles, we investigated the effects of reactant concentration, experimental conditions and presence of ions/reactive species. We monitored silver nanoparticle growth with UV-visible spectroscopy. The evolution in time of nanoparticle size was monitored by dynamic light scattering (DLS).

Signal for a light singlet scalar at the LHC

NASA Astrophysics Data System (ADS)

Chang, We-Fu; Modak, Tanmoy; Ng, John N.

2018-03-01

In the general Higgs portal-like models, the extra neutral scalar, S , can mix with the Standard Model (SM) Higgs boson, H . We perform an exploratory study focusing on the direct search for such a light singlet S at the Large Hadron Collider (LHC). After careful study of the SM background, we find the process p p →t t ¯ S followed by S →b b ¯ can be used to investigate S with mass in the 20

Subdiffraction focusing of scanning beams by a negative-refraction layer combined with a nonlinear layer.

PubMed

Husakou, A; Herrmann, J

2006-11-13

We evaluate the possibility to focus scanning light beams below the diffraction limit by using the combination of a nonlinear material with a Kerr-type nonlinearity or two-photon absorption to create seed evanescent components of the beam and a negative-refraction material to enhance them. Superfocusing to spots with a FWHM in the range of 0.2 lambda is theoretically predicted both in the context of the effective-medium theory and by the direct numerical solution of Maxwell equations for an inhomogeneous pho-tonic crystal. The evolution of the transverse spectrum and the dependence of superfocusing on the parameters of the negative-refraction material are also studied. We show that the use of a Kerr-type nonlinear layer for the creation of seed evanescent components yields focused spots with a higher intensity compared with those obtained by the application of a saturable absorber.

A new adaptive light beam focusing principle for scanning light stimulation systems.

PubMed

Bitzer, L A; Meseth, M; Benson, N; Schmechel, R

2013-02-01

In this article a novel principle to achieve optimal focusing conditions or rather the smallest possible beam diameter for scanning light stimulation systems is presented. It is based on the following methodology: First, a reference point on a camera sensor is introduced where optimal focusing conditions are adjusted and the distance between the light focusing optic and the reference point is determined using a laser displacement sensor. In a second step, this displacement sensor is used to map the topography of the sample under investigation. Finally, the actual measurement is conducted, using optimal focusing conditions in each measurement point at the sample surface, that are determined by the height difference between camera sensor and the sample topography. This principle is independent of the measurement values, the optical or electrical properties of the sample, the used light source, or the selected wavelength. Furthermore, the samples can be tilted, rough, bent, or of different surface materials. In the following the principle is implemented using an optical beam induced current system, but basically it can be applied to any other scanning light stimulation system. Measurements to demonstrate its operation are shown, using a polycrystalline silicon solar cell.

Apparatus and method for generating partially coherent illumination for photolithography

DOEpatents

Sweatt, William C.

2001-01-01

The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system comprises a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination image of the source in a camera entrance pupil. The light passing through the field lens illuminates a mask which interrupts the source light as either a positive or negative image of the object to be replicated. Light passing by the mask is focused into the entrance pupil of the lithographic camera creating an image of the mask onto a receptive media.

Optical phase conjugation assisted scattering lens: variable focusing and 3D patterning

PubMed Central

Ryu, Jihee; Jang, Mooseok; Eom, Tae Joong; Yang, Changhuei; Chung, Euiheon

2016-01-01

Variable light focusing is the ability to flexibly select the focal distance of a lens. This feature presents technical challenges, but is significant for optical interrogation of three-dimensional objects. Numerous lens designs have been proposed to provide flexible light focusing, including zoom, fluid, and liquid-crystal lenses. Although these lenses are useful for macroscale applications, they have limited utility in micron-scale applications due to restricted modulation range and exacting requirements for fabrication and control. Here, we present a holographic focusing method that enables variable light focusing without any physical modification to the lens element. In this method, a scattering layer couples low-angle (transverse wave vector) components into a full angular spectrum, and a digital optical phase conjugation (DOPC) system characterizes and plays back the wavefront that focuses through the scattering layer. We demonstrate micron-scale light focusing and patterning over a wide range of focal distances of 22–51 mm. The interferometric nature of the focusing scheme also enables an aberration-free scattering lens. The proposed method provides a unique variable focusing capability for imaging thick specimens or selective photoactivation of neuronal networks. PMID:27049442

Focusing light inside dynamic scattering media with millisecond digital optical phase conjugation (Conference Presentation)

NASA Astrophysics Data System (ADS)

Liu, Yan; Ma, Cheng; Shen, Yuecheng; Wang, Lihong V.

2017-02-01

Optical phase conjugation based wavefront shaping techniques are being actively developed to focus light through or inside scattering media such as biological tissue, and they promise to revolutionize optical imaging, manipulation, and therapy. The speed of digital optical phase conjugation (DOPC) has been limited by the low speeds of cameras and spatial light modulators (SLMs), preventing DOPC from being applied to thick living tissue. Recently, a fast DOPC system was developed based on a single-shot wavefront measurement method, a field programmable gate array (FPGA) for data processing, and a digital micromirror device (DMD) for fast modulation. However, this system has the following limitations. First, the reported single-shot wavefront measurement method does not work when our goal is to focus light inside, instead of through, scattering media. Second, the DMD performed binary amplitude modulation, which resulted in a lower focusing contrast compared with that of phase modulations. Third, the optical fluence threshold causing DMDs to malfunction under pulsed laser illumination is lower than that of liquid crystal based SLMs, and the system alignment is significantly complicated by the oblique reflection angle of the DMD. Here, we developed a simple but high-speed DOPC system using a ferroelectric liquid crystal based SLM (512 × 512 pixels), and focused light through three diffusers within 4.7 ms. Using focused-ultrasound-guided DOPC along with a double exposure scheme, we focused light inside a scattering medium containing two diffusers within 7.7 ms, thus achieving the fastest digital time-reversed ultrasonically encoded (TRUE) optical focusing to date.

Pupillary response to direct and consensual chromatic light stimuli.

PubMed

Traustason, Sindri; Brondsted, Adam Elias; Sander, Birgit; Lund-Andersen, Henrik

2016-02-01

To assess whether the direct and consensual postillumination (ipRGC-driven) pupil light responses to chromatic light stimuli are equal in healthy subjects. Pupil responses in healthy volunteers were recorded using a prototype binocular chromatic pupillometer (IdeaMedical, Copenhagen), which is capable of both direct and consensual pupillometry measurements. The device uses a pair of dual monochromatic narrow bandwidth LED light sources, red (660 nm) and blue (470 nm). Pupil light responses were recorded with infrared video cameras and analysed using custom-made circuitry and software. Subjects were randomized to receive light stimuli at either the right or left eye after 5 min of dark adaptation. Pupil light responses were recorded in both eyes for 10 seconds before illumination, during illumination and 50 seconds after illumination with red and blue light. Three variables were defined for the recorded pupil responses: the maximal constriction amplitude (CAmax ), the pupil response during illumination and postillumination pupil response (PIPR). No difference was found in the pupil response to blue light. With red light, the pupil response during illumination was slightly larger during consensual illumination compared to direct illumination (0.54 and 0.52, respectively, p = 0.027, paired Wilcoxon's test, n = 12), while no differences were found for CAmax or the PIPR. No difference was found between direct and consensual pupil response to either red or blue light in the postillumination period. Direct and consensual responses can readily be compared when examining the postillumination pupil response to blue light as estimation of photosensitive retinal ganglion cell activation. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Multi-pass light amplifier

NASA Technical Reports Server (NTRS)

Plaessmann, Henry (Inventor); Grossman, William M. (Inventor); Olson, Todd E. (Inventor)

1996-01-01

A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A resonator or a White Cell cavity is provided, including two or more mirrors (planar or curvilinearly shaped) facing each other along a resonator axis and an optical gain medium positioned on a resonator axis between the mirrors or adjacent to one of the mirrors. In a first embodiment, two curvilinear mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. A second embodiment uses two curvilinear mirrors and one planar mirror, with a gain medium positioned in the optical path between each curvilinear mirror and the planar mirror. A third embodiment uses two curvilinear mirrors and two planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses a curvilinear mirror and three planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses four planar mirrors and a focusing lens system, with a gain medium positioned between the four mirrors. A fifth embodiment uses first and second planar mirrors, a focusing lens system and a third mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the third mirror. A sixth embodiment uses two planar mirrors and a curvilinear mirror and a fourth mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the fourth mirror. In a seventh embodiment, first and second mirrors face a third mirror, all curvilinear, in a White Cell configuration, and a gain medium is positioned adjacent to one of the mirrors.

Frequency tripling of convergent beam employing crystals tiling in large-aperture high-energy laser facilities

NASA Astrophysics Data System (ADS)

Wang, Junhua; Li, Dazhen; Wang, Bo; Yang, Jing; Yang, Houwen; Wang, Xiaoqian; Cheng, Wenyong

2017-11-01

In inertial confinement fusion, ultraviolet laser damage of the fused silica lens is an important limiting factor for load capability of the laser driver. To solve this problem, a new configuration of frequency tripling is proposed in this paper. The frequency tripling crystal is placed on downstream of the focusing lens, thus sum frequency generation of fundamental frequency light and doubling frequency light occurs in the beam convergence path. The focusing lens is only irradiated by fundamental light and doubling frequency lights. Thus, its damage threshold will increase. LiB3O5 (LBO) crystals are employed as frequency tripling crystals for its larger acceptance angle and higher damage threshold than KDP/DKDP crystals'. With the limitation of acceptance angle and crystal growth size are taken into account, the tiling scheme of LBO crystals is proposed and designed optimally to adopt to the total convergence angle of 36.0 mrad. Theoretical results indicate that 3 LBO crystals titling with different cutting angles in θ direction can meet the phase matching condition. Compared with frequency tripling of parallel beam using one LBO crystal, 83.8% (93.1% with 5 LBO crystals tiling) of the frequency tripling conversion efficiency can be obtained employing this new configuration. The results of a principle experiment also support this scheme. By employing this new design, not only the load capacity of a laser driver will be significantly improved, but also the fused silica lens can be changed to K9 glass lens which has the mature technology and low cost.

Measuring Light at Night and Melatonin Levels in Shift Workers: A Review of the Literature.

PubMed

Hunter, Claudia M; Figueiro, Mariana G

2017-07-01

Shift work, especially that involving rotating and night shifts, is associated with an increased risk of diseases, including cancer. Attempts to explain the association between shift work and cancer in particular have focused on the processes of melatonin production and suppression. One hypothesis postulates that exposure to light at night (LAN) suppresses melatonin, whose production is known to slow the development of cancerous cells, while another proposes that circadian disruption associated with shift work, and not just LAN, increases health risks. This review focuses on six studies that employed quantitative measurement of LAN and melatonin levels to assess cancer risks in shift workers. These studies were identified via searching the PubMed database for peer-reviewed, English-language articles examining the links between shift work, LAN, and disease using the terms light at night, circadian disruption, health, risk, cancer, shift work, or rotating shift. While the results indicate a growing consensus on the relationship between disease risks (particularly cancer) and circadian disruption associated with shift work, the establishment of a direct link between LAN and disease has been impeded by contradictory studies and a lack of consistent, quantitative methods for measuring LAN in the research to date. Better protocols for assessing personal LAN exposure are required, particularly those employing calibrated devices that measure and sample exposure to workplace light conditions, to accurately assess LAN's effects on the circadian system and disease. Other methodologies, such as measuring circadian disruption and melatonin levels in the field, may also help to resolve discrepancies in the findings.

Importance of holographic light in the emerging field of mind-body healing

NASA Astrophysics Data System (ADS)

Booth, Roberta

2000-10-01

Healing with color has been researched and documented worldwide for centuries. Every single part of the brain and every cell in the body is effected by light. Chinese and Russian scientists demonstrated that the acupuncture meridians transmit light. Dr. Peter Mandel, German chiropractic physician and acupuncturist, states that the acupuncture points are especially sensitive to electromagnetic waves within the spectrum of visible light and microwave energy, and all cells constantly emit and absorb small pockets of electromagnetic radiation or light, called biophotons. The harmony or disharmony of cells has been documented. Kirlian photography, to photography the aura was invented by Russians Semyon and Valentina Kirlian. Photo therapy and light research are being practiced worldwide. In the United States, Dr. Jacob Lieberman has written an influential book Light Medicine of the Future. In 1992 the first Light Years Ahead conference was held. (#5 1996) Dr. Brian Breiling and Dr. Lee Hartley brought together experts in the field to discuss the many potentials of light therapy. My present research in this area has focused on narrow band frequencies through the use of holography. Its therapeutic applications of color healing in this research are both critical and fundamental. My current work, The Chakras, seven reflection holograms on silver halide, relate to the wheels of light described in the earliest recorded Indian history. I will discus the chakras, this ancient metaphysical system under the new light of popular western metaphors and visionary art, how the chakras relate to the seven colors of the rainbow, the electromagnetic waves, and the connection to color holography in healing light therapy. I will be citing concurrent research in color healing, and the important areas of research that are necessary to have significant impact on future directions. Holography in the future will constitute a major frontier in discovery.

Surface Habitat Systems

NASA Technical Reports Server (NTRS)

Kennedy, Kriss J.

2009-01-01

The Surface Habitat Systems (SHS) Focused Investment Group (FIG) is part of the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) effort to provide a focused direction and funding to the various projects that are working on human surface habitat designs and technologies for the planetary exploration missions. The overall SHS-FIG effort focuses on directing and guiding those projects that: 1) develop and demonstrate new surface habitat system concepts, innovations, and technologies to support human exploration missions, 2) improve environmental systems that interact with human habitats, 3) handle and emplace human surface habitats, and 4) focus on supporting humans living and working in habitats on planetary surfaces. The activity areas of the SHS FIG described herein are focused on the surface habitat project near-term objectives as described in this document. The SHS-FIG effort focuses on mitigating surface habitat risks (as identified by the Lunar Surface Systems Project Office (LSSPO) Surface Habitat Element Team; and concentrates on developing surface habitat technologies as identified in the FY08 gap analysis. The surface habitat gap assessment will be updated annually as the surface architecture and surface habitat definition continues to mature. These technologies are mapped to the SHS-FIG Strategic Development Roadmap. The Roadmap will bring to light the areas where additional innovative efforts are needed to support the development of habitat concepts and designs and the development of new technologies to support of the LSSPO Habitation Element development plan. Three specific areas of development that address Lunar Architecture Team (LAT)-2 and Constellation Architecture Team (CxAT) Lunar habitat design issues or risks will be focused on by the SHS-FIG. The SHS-FIG will establish four areas of development that will help the projects prepare in their planning for surface habitat systems development. Those development areas are the 1) surface habitat concept definition, 2) inflatable surface habitat development, and 3) autonomous habitat operations, and 4) cross-cutting / systems engineering. In subsequent years, the SHS-FIG will solicit a call for innovations and technologies that will support the development of these four development areas. The other development areas will be assessed yearly and identified on the SHS-FIG s Strategic Development Roadmap. Initial investment projects that are funded by the Constellation Program Office (CxPO), LSSPO, or the Exploration Technology Development Projects (ETDP) will also be included on the Roadmap. For example, in one or two years from now, the autonomous habitat operations and testbed would collaborations with the Integrated Systems Health Management (ISHM) and Automation for Operations ETDP projects, which will give the surface habitat projects an integrated habitat autonomy testbed to test software and systems. The SHS-FIG scope is to provide focused direction for multiple innovations, technologies and subsystems that are needed to support humans at a remote planetary surface habitat during the concept development, design definition, and integration phases of that project. Subsystems include: habitability, lightweight structures, power management, communications, autonomy, deployment, outfitting, life support, wireless connectivity, lighting, thermal and more.

Workplace lighting for improving alertness and mood in daytime workers.

PubMed

Pachito, Daniela V; Eckeli, Alan L; Desouky, Ahmed S; Corbett, Mark A; Partonen, Timo; Rajaratnam, Shantha Mw; Riera, Rachel

2018-03-02

Exposure to light plays a crucial role in biological processes, influencing mood and alertness. Daytime workers may be exposed to insufficient or inappropriate light during daytime, leading to mood disturbances and decreases in levels of alertness. To assess the effectiveness and safety of lighting interventions to improve alertness and mood in daytime workers. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, seven other databases; ClinicalTrials.gov and the World Health Organization trials portal up to January 2018. We included randomised controlled trials (RCTs), and non-randomised controlled before-after trials (CBAs) that employed a cross-over or parallel-group design, focusing on any type of lighting interventions applied for daytime workers. Two review authors independently screened references in two stages, extracted outcome data and assessed risk of bias. We used standardised mean differences (SMDs) and 95% confidence intervals (CI) to pool data from different questionnaires and scales assessing the same outcome across different studies. We combined clinically homogeneous studies in a meta-analysis. We used the GRADE system to rate quality of evidence. The search yielded 2844 references. After screening titles and abstracts, we considered 34 full text articles for inclusion. We scrutinised reports against the eligibility criteria, resulting in the inclusion of five studies (three RCTs and two CBAs) with 282 participants altogether. These studies evaluated four types of comparisons: cool-white light, technically known as high correlated colour temperature (CCT) light versus standard illumination; different proportions of indirect and direct light; individually applied blue-enriched light versus no treatment; and individually applied morning bright light versus afternoon bright light for subsyndromal seasonal affective disorder.We found no studies comparing one level of illuminance versus another.We found two CBA studies (163 participants) comparing high CCT light with standard illumination. By pooling their results via meta-analysis we found that high CCT light may improve alertness (SMD -0.69, 95% CI -1.28 to -0.10; Columbia Jet Lag Scale and the Karolinska Sleepiness Scale) when compared to standard illumination. In one of the two CBA studies with 94 participants there was no difference in positive mood (mean difference (MD) 2.08, 95% CI -0.1 to 4.26) or negative mood (MD -0.45, 95% CI -1.84 to 0.94) assessed using the Positive and Negative Affect Schedule (PANAS) scale. High CCT light may have fewer adverse events than standard lighting (one CBA; 94 participants). Both studies were sponsored by the industry. We graded the quality of evidence as very low.We found no studies comparing light of a particular illuminance and light spectrum or CCT versus another combination of illuminance and light spectrum or CCT.We found no studies comparing daylight versus artificial light.We found one RCT (64 participants) comparing the effects of different proportions of direct and indirect light: 100% direct lighting, 70% direct lighting plus 30% indirect lighting, 30% direct lighting plus 70% indirect lighting and 100% indirect lighting. There was no substantial difference in mood, as assessed by the Beck Depression Inventory, or in adverse events, such as ocular, reading or concentration problems, in the short or medium term. We graded the quality of evidence as low.We found two RCTs comparing individually administered light versus no treatment. According to one RCT with 25 participants, blue-enriched light individually applied for 30 minutes a day may enhance alertness (MD -3.30, 95% CI -6.28 to -0.32; Epworth Sleepiness Scale) and may improve mood (MD -4.8, 95% CI -9.46 to -0.14; Beck Depression Inventory). We graded the quality of evidence as very low. One RCT with 30 participants compared individually applied morning bright light versus afternoon bright light for subsyndromal seasonal affective disorder. There was no substantial difference in alertness levels (MD 7.00, 95% CI -10.18 to 24.18), seasonal affective disorder symptoms (RR 1.60, 95% CI 0.81, 3.20; number of participants presenting with a decrease of at least 50% in SIGH-SAD scores) or frequency of adverse events (RR 0.53, 95% CI 0.26 to 1.07). Among all participants, 57% had a reduction of at least 50% in their SIGH-SAD score. We graded the quality of evidence as low.Publication bias could not be assessed for any of these comparisons. There is very low-quality evidence based on two CBA studies that high CCT light may improve alertness, but not mood, in daytime workers. There is very low-quality evidence based on one CBA study that high CCT light may also cause less irritability, eye discomfort and headache than standard illumination. There is low-quality evidence based on one RCT that different proportions of direct and indirect light in the workplace do not affect alertness or mood. There is very low-quality evidence based on one RCT that individually applied blue-enriched light improves both alertness and mood. There is low-quality evidence based on one RCT that individually administered bright light during the afternoon is as effective as morning exposure for improving alertness and mood in subsyndromal seasonal affective disorder.

Recent Advances in Lighting Science

NASA Astrophysics Data System (ADS)

Lapatovich, Walter P.

2004-10-01

Lighting is a global industry supplying a wide array of devices and systems that emit light ranging from incandescent lamps to light emitting diodes to electric discharge lamps. Electric discharge lamps are the most familiar plasma devices to most people. This work focuses on plasma light sources, some advances in this area and recent trends. Plasma light sources fall into two broad categories, namely low pressure and high pressure. The low-pressure lamps operate in the range of 40 to 500 Pa while the high-pressure lamps operate in the range of 0.1 to 15 MPa. The corresponding electron temperatures are about 1eV and 0.5 eV for the low and high-pressure lamps respectively. High-pressure lamps are treated under the assumption of local thermodynamic equilibrium wherein the gas temperature is equilibrated with the electron temperature. They are often called high intensity discharge lamps because of their intrinsically high radiance. Within these two broad categories are many subgroups, perhaps the most important being mercury and non-mercury containing lamps. An example of a low pressure, mercury-containing lamp is the ubiquitous fluorescent lamp. Attempts to improve the efficiency of these lamps center around inductive excitation techniques and two-photon phosphor development. The plasma research on mercury-free low-pressure lamps is focused on finding substitutes for a mercury-rare gas discharge. Several ultraviolet emitting candidates have been explored which emit both UV and visible. Longer wavelength UV is of interest because of the parallel development of phosphors mated with LED excitation wavelengths around 380nm. Several examples will be discussed. There have been major advances in high intensity discharge lamps with and without mercury. Mercury containing metal halide lamps are now being fabricated from translucent ceramic envelopes instead of the conventional vitreous silica. The higher temperature tolerant envelope materials permit using discharges in vapors hitherto unacceptable because of chemical reactions. Temperature driven chemical reactions (which affect lamp life, starting and stability) are better understood. Lamps are better designed with finite element thermal modeling and thermodynamic computational tools. Improved understanding of molecular processes in the energy transport within the plasma has opened possibilities for new types of light sources relying heavily on molecular emission. Examples of lamps containing sulfur, indium, thallium and rare earth halides will be discussed. General trends in plasma based light source have been towards lower wattage, directed visible output, high quality visible output, longer life and mercury-free lamps. Consumer demand for high tech, high performance lighting devices has broadened the use of HID lamps in automobiles, video/data display and medical/technical applications. Short arc gap lamps (1mm) with a luminance exceeding that of the sun's surface (1600cd/mm2 -as observed from earth), and operating with extreme line broadening lead the video projection market. Low wattage HID lamps coupled with tailored optics can direct the light output more precisely leading to reduced light pollution and better system throughput. Tailoring of the driving electrical waveforms have enabled stable operation, controlled the effects of species segregation and improved lamp life and performance.

Motives Underlying Food Choice for Children and Perception of Nutritional Information Among Low-Income Mothers in a Latin American Country.

PubMed

Machín, Leandro; Giménez, Ana; Curutchet, María Rosa; Martínez, Joseline; Ares, Gastón

2016-01-01

The aim of the present study was to investigate the influence of nutritional information on how low-income mothers select food for their children. Five focus groups, each consisting of 5-10 participants, were conducted. Women, older than 18 years, mothers of young children who were beneficiaries of one of the national food stamps programs in Uruguay. Focus group discussions were held around motives underlying food choices for children and perception of labeling systems. Transcripts of the focus group discussions were analyzed using inductive coding. Forty-two women, aged between 18 and 40 years, participated in 5 focus groups. Results showed that low-income mothers do not consider nutritional information when selecting food their children. Traditional nutritional labeling was perceived as complex, difficult to find, and difficult to understand. Participants stressed that they relied on the nutrition claims included on labels for assessing the healthfulness of food products. Semi-directive and directive front-of-pack labels were positively evaluated in terms of ease of interpretation. Participants preferred the traffic light system over other alternatives. Results suggest the need to implement simplified nutritional labeling and to regulate the use of nutrition claims on products targeted at children. Copyright © 2016 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

DARK-FIELD ILLUMINATION SYSTEM

DOEpatents

Norgren, D.U.

1962-07-24

A means was developed for viewing objects against a dark background from a viewing point close to the light which illuminates the objects and under conditions where the back scattering of light by the objects is minimal. A broad light retro-directing member on the opposite side of the objects from the light returns direct light back towards the source while directing other light away from the viewing point. The viewing point is offset from the light and thus receives only light which is forwardly scattered by an object while returning towards the source. The object is seen, at its true location, against a dark background. The invention is particularly adapted for illuminating and viewing nuclear particle tracks in a liquid hydrogen bubble chamber through a single chamber window. (AEC)

Minimizing the Delay at Traffic Lights

ERIC Educational Resources Information Center

Van Hecke, Tanja

2009-01-01

Vehicles holding at traffic lights is a typical queuing problem. At crossings the vehicles experience delay in both directions. Longer periods with green lights in one direction are disadvantageous for the vehicles coming from the other direction. The total delay for getting through the traffic point is what counts. This article presents an…

Unidirectional ring lasers

DOEpatents

Hohimer, John P.; Craft, David C.

1994-01-01

Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction.

Three-dimensional light trap for reflective particles

DOEpatents

Neal, D.R.

1999-08-17

A system is disclosed for containing either a reflective particle or a particle having an index of refraction lower than that of the surrounding media in a three-dimensional light cage. A light beam from a single source illuminates an optics system and generates a set of at least three discrete focused beams that emanate from a single exit aperture and focus on to a focal plane located close to the particle. The set of focal spots defines a ring that surrounds the particle. The set of focused beams creates a ``light cage`` and circumscribes a zone of no light within which the particle lies. The surrounding beams apply constraining forces (created by radiation pressure) to the particle, thereby containing it in a three-dimensional force field trap. A diffractive element, such as an aperture multiplexed lens, or either a Dammann grating or phase element in combination with a focusing lens, may be used to generate the beams. A zoom lens may be used to adjust the size of the light cage, permitting particles of various sizes to be captured and contained. 10 figs.

Nonlinear effects during interaction of femtosecond doughnut-shaped laser pulses with glasses: overcoming intensity clamping

NASA Astrophysics Data System (ADS)

Bulgakova, Nadezhda M.; Zhukov, Vladimir P.; Fedoruk, Mikhail P.; Rubenchik, Alexander M.

2017-05-01

Interaction of femtosecond laser pulses with a bulk glass (fused silica as an example) has been studied numerically based on non-linear Maxwell's equations supplemented by the hydrodynamics-type equations for free electron plasma for the cases of Gaussian linearly-polarized and doughnut-shaped radially-polarized laser beams. For Gaussian pulses focused inside glass (800 nm wavelength, 45 fs duration, numerical aperture of 0.25), the free electron density in the laser-excited region remains subcritical while the locally absorbed energy density does not exceed 2000 J/cm3 in the range of pulse energies of 200 nJ - 2 μJ. For doughnut-shaped pulses, the initial high-intensity ring of light is shrinking upon focusing. Upon reaching a certain ionization level on its way, the light ring splits into two branches, one of which shrinks swiftly toward the beam axis well before the geometrical focus, leading to generation of supercritical free electron density. The second branch represents the laser light scattered by the electron plasma away from the beam axis. The final laserexcited volume represents a tube of 0.5-1 μm in radius and 10-15 μm long. The local maximum of absorbed energy can be more than 10 times higher compared to the case of Gaussian beams of the same energy. The corresponding pressure levels have been evaluated. It is anticipated that, in the case of doughnut-shaped pulses, the tube-like shape of the deposited energy should lead to implosion of material that can be used for improving the direct writing of high-refractive index optical structures inside glass or for achieving extreme thermodynamic states of matter.

Natural Ventilation of Buildings through Light Shafts. Design-Based Solution Proposals

NASA Astrophysics Data System (ADS)

Ángel Padilla-Marcos, Miguel; Meiss, Alberto; Feijó-Muñoz, Jesús

2017-10-01

This work analyses how the built environment affects the quality of the air to be introduced into buildings from light shafts. Several factors such as urban environment and building design intervene in the ability of the light shaft to produce its air change process. Urban areas continuously pollute the air in cities which affects the human health and the environment sustainability. Poor air quality outside buildings supposes a big energy waste to promote an acceptable air quality inside buildings. That requires a large flow rate to maintain the indoor air quality which is translated to an energy efficiency term. The main objective focuses on the impact of standardized architecture design in the quality of the indoor air dependent on the air change in the light shaft. The air change capacity of the outdoor space is numbered analysed using the concept of air change efficiency (ACE). ACE is determined by the built environment, the wind conditions and the design of the building containing light shafts. This concept is comparatively evaluated inside a control domain virtually defined to obtain the mean age of the air for a known air volume. The longer the light shaft in the wind direction is, the better the ACE is compared with other options. Light shafts up to 12 metres high are the most suitable in order to obtain acceptable efficiency results. Other studied cases verify that assumption. Different simplified tools for the technicians to evaluate the design of buildings containing light shafts are proposed. Some strategies of architectural design of buildings with light shafts to be used for ventilation are presented.

Survey of on-road image projection with pixel light systems

NASA Astrophysics Data System (ADS)

Rizvi, Sadiq; Knöchelmann, Marvin; Ley, Peer-Phillip; Lachmayer, Roland

2017-12-01

HID, LED and laser-based high resolution automotive headlamps, as of late known as `pixel light systems', are at the forefront of the developing technologies paving the way for autonomous driving. In addition to light distribution capabilities that outperform Adaptive Front Lighting and Matrix Beam systems, pixel light systems provide the possibility of image projection directly onto the street. The underlying objective is to improve the driving experience, in any given scenario, in terms of safety, comfort and interaction for all road users. The focus of this work is to conduct a short survey on this state-of-the-art image projection functionality. A holistic research regarding the image projection functionality can be divided into three major categories: scenario selection, technological development and evaluation design. Consequently, the work presented in this paper is divided into three short studies. Section 1 provides a brief introduction to pixel light systems and a justification for the approach adopted for this study. Section 2 deals with the selection of scenarios (and driving maneuvers) where image projection can play a critical role. Section 3 discusses high power LED and LED array based prototypes that are currently under development. Section 4 demonstrates results from an experiment conducted to evaluate the illuminance of an image space projected using a pixel light system prototype developed at the Institute of Product Development (IPeG). Findings from this work can help to identify and advance future research work relating to: further development of pixel light systems, scenario planning, examination of optimal light sources, behavioral response studies etc.

Testing Limits on Matte Surface Color Perception in Three-Dimensional Scenes with Complex Light Fields

PubMed Central

Doerschner, K.; Boyaci, H.; Maloney, L. T.

2007-01-01

We investigated limits on the human visual system’s ability to discount directional variation in complex lights field when estimating Lambertian surface color. Directional variation in the light field was represented in the frequency domain using spherical harmonics. The bidirectional reflectance distribution function of a Lambertian surface acts as a low-pass filter on directional variation in the light field. Consequently, the visual system needs to discount only the low-pass component of the incident light corresponding to the first nine terms of a spherical harmonics expansion (Basri & Jacobs, 2001; Ramamoorthi & Hanrahan, 2001) to accurately estimate surface color. We test experimentally whether the visual system discounts directional variation in the light field up to this physical limit. Our results are consistent with the claim that the visual system can compensate for all of the complexity in the light field that affects the appearance of Lambertian surfaces. PMID:18053846

Surface Tension Mediated Conversion of Light to Work

PubMed Central

Okawa, David; Pastine, Stefan J.; Zettl, Alex; Fréchet, Jean M. J.

2009-01-01

As energy demands increase, new, more direct, energy collection and utilization processes must be explored. We present a system that intrinsically combines the absorption of sunlight with the production of useful work in the form of locomotion of objects on liquids. Focused sunlight is locally absorbed by a nanostructured composite, creating a thermal surface tension gradient and, subsequently, motion. Controlled linear motion and rotational motion are demonstrated. The system is scale independent, with remotely powered and controlled motion shown for objects in the milligram to tens of grams range. PMID:20560635

Model wavefront sensor for adaptive confocal microscopy

NASA Astrophysics Data System (ADS)

Booth, Martin J.; Neil, Mark A. A.; Wilson, Tony

2000-05-01

A confocal microscope permits 3D imaging of volume objects by the inclusion of a pinhole in the detector path which eliminates out of focus light. This configuration is however very sensitive to aberrations induced by the specimen or the optical system and would therefore benefit from an adaptive optics approach. We present a wavefront sensor capable of measuring directly the Zernike components of an aberrated wavefront and show that it is particularly applicable to the confocal microscope since only those wavefronts originating in the focal region contribute to the measured aberration.

[Research of controlling of smart home system based on P300 brain-computer interface].

PubMed

Wang, Jinjia; Yang, Chengjie

2014-08-01

Using electroencephalogram (EEG) signal to control external devices has always been the research focus in the field of brain-computer interface (BCI). This is especially significant for those disabilities who have lost capacity of movements. In this paper, the P300-based BCI and the microcontroller-based wireless radio frequency (RF) technology are utilized to design a smart home control system, which can be used to control household appliances, lighting system, and security devices directly. Experiment results showed that the system was simple, reliable and easy to be populirised.

Volume holographic lens spectrum-splitting photovoltaic system for high energy yield with direct and diffuse solar illumination

NASA Astrophysics Data System (ADS)

Chrysler, Benjamin D.; Wu, Yuechen; Yu, Zhengshan; Kostuk, Raymond K.

2017-08-01

In this paper a prototype spectrum-splitting photovoltaic system based on volume holographic lenses (VHL) is designed, fabricated and tested. In spectrum-splitting systems, incident sunlight is divided in spectral bands for optimal conversion by a set of single-junction PV cells that are laterally separated. The VHL spectrumsplitting system in this paper has a form factor similar to conventional silicon PV modules but with higher efficiencies (>30%). Unlike many other spectrum-splitting systems that have been proposed in the past, the system in this work converts both direct and diffuse sunlight while using inexpensive 1-axis tracking systems. The VHL system uses holographic lenses that focus light at a transition wavelength to the boundary between two PV cells. Longer wavelength light is dispersed to the narrow bandgap cell and shorter wavelength light to the wide bandgap cell. A prototype system is designed with silicon and GaAs PV cells. The holographic lenses are fabricated in Covestro Bayfol HX photopolymer by `stitching' together lens segments through sequential masked exposures. The PV cells and holographic lenses were characterized and the data was used in a raytrace simulation and predicts an improvement in total power output of 15.2% compared to a non-spectrum-splitting reference. A laboratory measurement yielded an improvement in power output of 8.5%.

Fixing the Leak: Empirical Corrections for the Small Light Leak in Hinode XRT

NASA Astrophysics Data System (ADS)

Saar, Steven H.; DeLuca, E. E.; McCauley, P.; Kobelski, A.

2013-07-01

On May 9, 2012, the the straylight level of XRT on Hinode suddenly increased, consistent with the appearance of a pinhole in the entrance filter (possibly a micrometeorite breach). The effect of this event is most noticeable in the optical G band data, which shows an average light excess of ~30%. However, data in several of the X-ray filters is also affected, due to low sensitivity "tails" of their filter responses into the visible. Observations taken with the G band filter but with the visible light shutter (VLS) closed show a weak, slightly shifted, out-of-focus image, revealing the leaked light. The intensity of the leak depends on telescope pointing, dropping strongly for images taken off-disk. By monitoring light levels in the corners of full-Sun Ti-poly filter images, we determine the approximate time of the event: ~13:30 UT. We use pairs of images taken just-before and after the filter breach to directly measure the leakage in two affected X-ray filters. We then develop a model using a scaled, shifted, and smoothed versions of the VLS closed images to remove the contamination. We estimate the uncertainties involved in our proposed correction procedure. This research was supported under NASA contract NNM07AB07C for Hinode XRT.

Importance of Light Filters in Modern Vitreoretinal Surgery: An Update of the Literature.

PubMed

Coppola, Michele; Cicinelli, Maria Vittoria; Rabiolo, Alessandro; Querques, Giuseppe; Bandello, Francesco

2017-01-01

Direct endobulbar illumination during vitreoretinal surgery causes light-induced retinal damage known as phototoxicity. Spectral filters have been proposed to eliminate hazardous wavelengths from the emission spectrum before entering the eye. The purpose of our paper is to review advances in vitreoretinal surgery, focusing on intraoperative light filters. A PubMed and Medline database search was carried out using the terms "spectral filters" associated with "vitreoretinal surgery," "phototoxicity," and "vitrectomy." Original articles, reviews, and book chapters up to March 2017 were reviewed; a few select articles published before 2000 are included for historical purposes. Material from recent meeting presentations was also added. The preferred language for the reviewed literature was English. Spectral filters significantly reduce the risk of phototoxicity associated with endoillumination in vitreoretinal surgery, allowing higher exposure times than with optic light fibers alone. Spectral filters may affect intraoperative luminance, but do not alter color contrast. Amber filters showed superiority over green and yellow filters. The choice of light sources coupled to spectral filters is strongly suggested, especially in dye-assisted chromovitrectomy. Histological donor eye studies and large multicenter trials are needed to validate the amount of photoprotection provided by spectral filters before a general recommendation can be made. © 2017 S. Karger AG, Basel.

Astronomy LITE Demonstrations

NASA Astrophysics Data System (ADS)

Brecher, Kenneth

2006-12-01

Project LITE (Light Inquiry Through Experiments) is a materials, software, and curriculum development project. It focuses on light, optics, color and visual perception. According to two recent surveys of college astronomy faculty members, these are among the topics most often included in the large introductory astronomy courses. The project has aimed largely at the design and implementation of hands-on experiences for students. However, it has also included the development of lecture demonstrations that employ novel light sources and materials. In this presentation, we will show some of our new lecture demonstrations concerning geometrical and physical optics, fluorescence, phosphorescence and polarization. We have developed over 200 Flash and Java applets that can be used either by teachers in lecture settings or by students at home. They are all posted on the web at http://lite.bu.edu. For either purpose they can be downloaded directly to the user's computer or run off line. In lecture demonstrations, some of these applets can be used to control the light emitted by video projectors to produce physical effects in materials (e.g. fluorescence). Other applets can be used, for example, to demonstrate that the human percept of color does not have a simple relationship with the physical frequency of the stimulating source of light. Project LITE is supported by Grant #DUE-0125992 from the NSF Division of Undergraduate Education.

Black thin film silicon

NASA Astrophysics Data System (ADS)

Koynov, Svetoslav; Brandt, Martin S.; Stutzmann, Martin

2011-08-01

"Black etching" has been proposed previously as a method for the nanoscale texturing of silicon surfaces, which results in an almost complete suppression of reflectivity in the spectral range of absorption relevant for photovoltaics. The method modifies the topmost 150 to 300 nm of the material and thus also is applicable for thin films of silicon. The present work is focused on the optical effects induced by the black-etching treatment on hydrogenated amorphous and microcrystalline silicon thin films, in particular with respect to their application in solar cells. In addition to a strong reduction of the reflectivity, efficient light trapping within the modified thin films is found. The enhancement of the optical absorption due to the light trapping is investigated via photometric measurements and photothermal deflection spectroscopy. The correlation of the texture morphology (characterized via atomic force microscopy) with the optical effects is discussed in terms of an effective medium with gradually varying optical density and in the framework of the theory of statistical light trapping. Photoconductivity spectra directly show that the light trapping causes a significant prolongation of the light path within the black silicon films by up to 15 μm for ˜1 μm thick films, leading to a significant increase of the absorption in the red.

Green laser light activates the inner ear

NASA Astrophysics Data System (ADS)

Wenzel, Gentiana I.; Balster, Sven; Zhang, Kaiyin; Lim, Hubert H.; Reich, Uta; Massow, Ole; Lubatschowski, Holger; Ertmer, Wolfgang; Lenarz, Thomas; Reuter, Guenter

2009-07-01

The hearing performance with conventional hearing aids and cochlear implants is dramatically reduced in noisy environments and for sounds more complex than speech (e. g. music), partially due to the lack of localized sensorineural activation across different frequency regions with these devices. Laser light can be focused in a controlled manner and may provide more localized activation of the inner ear, the cochlea. We sought to assess whether visible light with parameters that could induce an optoacoustic effect (532 nm, 10-ns pulses) would activate the cochlea. Auditory brainstem responses (ABRs) were recorded preoperatively in anesthetized guinea pigs to confirm normal hearing. After opening the bulla, a 50-μm core-diameter optical fiber was positioned in the round window niche and directed toward the basilar membrane. Optically induced ABRs (OABRs), similar in shape to those of acoustic stimulation, were elicited with single pulses. The OABR peaks increased with energy level (0.6 to 23 μJ/pulse) and remained consistent even after 30 minutes of continuous stimulation at 13 μJ, indicating minimal or no stimulation-induced damage within the cochlea. Our findings demonstrate that visible light can effectively and reliably activate the cochlea without any apparent damage. Further studies are in progress to investigate the frequency-specific nature and mechanism of green light cochlear activation.

Generation of an incident focused light pulse in FDTD.

PubMed

Capoğlu, Ilker R; Taflove, Allen; Backman, Vadim

2008-11-10

A straightforward procedure is described for accurately creating an incident focused light pulse in the 3-D finite-difference time-domain (FDTD) electromagnetic simulation of the image space of an aplanatic converging lens. In this procedure, the focused light pulse is approximated by a finite sum of plane waves, and each plane wave is introduced into the FDTD simulation grid using the total-field/scattered-field (TF/SF) approach. The accuracy of our results is demonstrated by comparison with exact theoretical formulas.

Generation of an incident focused light pulse in FDTD

PubMed Central

Çapoğlu, İlker R.; Taflove, Allen; Backman, Vadim

2009-01-01

A straightforward procedure is described for accurately creating an incident focused light pulse in the 3-D finite-difference time-domain (FDTD) electromagnetic simulation of the image space of an aplanatic converging lens. In this procedure, the focused light pulse is approximated by a finite sum of plane waves, and each plane wave is introduced into the FDTD simulation grid using the total-field/scattered-field (TF/SF) approach. The accuracy of our results is demonstrated by comparison with exact theoretical formulas. PMID:19582013

A Model of the Temporal Variability of Optical Light from Extrasolar Terrestrial Planets

NASA Astrophysics Data System (ADS)

Ford, E. B.; Seager, S.; Turner, E. L.

2001-05-01

New observatories such as TPF (NASA) and Darwin (ESA) are being designed to detect light directly from terrestrial-mass planets. Such observations will provide new data to constrain theories of planet formation and may identify the possible presence of liquid water and even spectroscopic signatures suggestive of life. We model the light scattered by Earth-like planets focusing on temporal variability due to planetary rotation and weather. Since a majority of the scattered light comes from only a small fraction of the planet's surface, significant variations in brightness are possible. The variations can be as large as a factor of two for a cloud-free planet which has a range of albedos similar to those of the different surfaces found on Earth. If a significant fraction of the observed light is scattered by the planet's atmosphere, including clouds, then the amplitude of variations due to surface features will be diluted. Atmospheric variability (e.g. clouds) itself is extremely interesting because it provides evidence for weather. The planet's rotation period, fractional ice and cloud cover, gross distribution of land and water on the surface, large scale weather patterns, large regions of unusual reflectivity or color (such as major desserts or vegetation's "red edge") as well as the geometry of its spin, orbit, and illumination relative to the observer all have substantial effects on the planet's rotational light curve.

Light Pollution and Wildlife

NASA Astrophysics Data System (ADS)

Duffek, J.

2008-12-01

for Educational Program IYA Dark Skies Education Session Fall American Geophysical Union San Francisco, December 15-19, 2008 Light Pollution and Wildlife This is a very exciting time to be a part of the mission to keep the nighttime skies natural. The International Year of Astronomy (IYA) 2009 is developing programs for all areas of Dark Skies Awareness. For many years the issue of light pollution focused on the impact to the astronomy industry. While this is an important area, research has shown that light pollution negatively impacts wildlife, their habitat, human health, and is a significant waste of energy. Since the message and impact of the effects of light pollution are much broader now, the message conveyed to the public must also be broader. Education programs directed at youth are a new frontier to reach out to a new audience about the adverse effects of too much artificial light at night. The International Dark-Sky Association (IDA) has developed educational presentations using the National Science Teachers Association Education Standards. These programs focus on youth between the ages of 5 to 17exploring new territory in the education of light pollution. The IDA education programs are broken down into three age groups; ages 5-9, 8-13, 12 and older. The presentations come complete with PowerPoint slides, discussion notes for each slide, and workbooks including age appropriate games to keep young audiences involved. A new presentation reflects the growing area of interest regarding the effects of too much artificial light at night on wildlife. This presentation outlines the known problems for ecosystems caused by artificial light at night. Insects are attracted to artificial lights and may stay near that light all night. This attraction interferes with their ability to migrate, mate, and look for food. Such behavior leads to smaller insect populations. Fewer insects in turn affect birds and bats, because they rely on insects as a food source. The IDA education programs show children how all of these issues are interrelated. Insects are not the only organisms adversely affected by light at night. Reptiles, mammals, birds and amphibians are also negatively impacted. All creatures have a biological clock which determines when they rest, hunt, migrate, and mate. Bright lights create confusion in many species by disrupting this internal biological clock. IDA presents the solutions to these problems as quality outdoor lighting, and the presentations show examples of dark sky friendly lighting. The youth audience is an excellent venue for wildlife education outreach. The IDA youth education programs are completed and ready for use. They can be used by professional teachers, parents, community organizers, or anyone advocating to keep the skies natural. This is a great time to promote the win-win benefits of good nighttime lighting.

More are better, but the details matter: combinations of multiple Fresnel zone plates for improved resolution and efficiency in X-ray microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Kenan; Jacobsen, Chris

Fresnel zone plates used for X-ray nanofocusing face high-aspect-ratio nanofabrication challenges in combining narrow transverse features (for high spatial resolution) along with extended optical modulation along the X-ray beam direction (to improve efficiency). The stacking of multiple Fresnel zone plates along the beam direction has already been shown to offer improved characteristics of resolution and efficiency when compared with thin single zone plates. Using multislice wave propagation simulation methods, here a number of new schemes for the stacking of multiple Fresnel zone plates are considered. These include consideration of optimal thickness and spacing in the axial direction, and methods tomore » capture a fraction of the light otherwise diffracted into unwanted orders, and instead bring it into the desired first-order focus. In conclusion, the alignment tolerances for stacking multiple Fresnel zone plates are also considered.« less

ZnSe based semiconductor core-shell structures: From preparation to application

NASA Astrophysics Data System (ADS)

Sun, Chengcheng; Gu, Yarong; Wen, Weijia; Zhao, Lijuan

2018-07-01

Inorganic core-shell semiconductor materials have attracted increasing interest in recent years because of the unique structure, stable chemical properties and high performance in devices. With special properties such as a direct band-gap and excellent photoelectrical characteristics, ZnSe based semiconductor core-shell structures are promising materials for applications in such fields as photocatalysts, light-emitting diodes, solar cells, photodetectors, biomedical science and so on. However, few reviews on ZnSe based semiconductor core-shell structures have been reported so far. Therefore this manuscript mainly focuses on the research activities on ZnSe based semiconductor core-shell composites including various preparation methods and the applications of these core-shell structures, especially in photocatalysts, light emitting, solar cells and photodetectors. The possibilities and limitations of studies on ZnSe based semiconductor core-shell composites are also highlighted.

Real-time focus controller for laser welding with fibre optic noninvasive capture of light

NASA Astrophysics Data System (ADS)

Cobo, Adolfo; Bardin, F.; Hand, Duncan P.; Jones, Julian D.; Collin, O.; Aubry, P.; Dubois, Thierry; Hoegstroem, M.; Nylen, P.; Jonsson, P.; Lopez-Higuera, Jose M.

2004-06-01

Laser welding is being introduced in the aerospace industry due to its many advantages over traditional techniques. However, welding of parts with complex shapes requires precise control of the focal point of the laser in order to achieve full penetration over the entire seam. In this paper, we present an improved control system for real-time adjustment of the correct focal position, which is based on the monitoring of the light emitted by the process in two different spectral bands. The reported system has been optimized for use in a real environment: it is robust, compact, easy to operate, able to adjust itself to different welding conditions, materials and laser setups, and includes a direct connection to an external PC. Results from recent field trials on complex aerospace structures are provided.

Impact of doping on the carrier dynamics in graphene

PubMed Central

Kadi, Faris; Winzer, Torben; Knorr, Andreas; Malic, Ermin

2015-01-01

We present a microscopic study on the impact of doping on the carrier dynamics in graphene, in particular focusing on its influence on the technologically relevant carrier multiplication in realistic, doped graphene samples. Treating the time- and momentum-resolved carrier-light, carrier-carrier, and carrier-phonon interactions on the same microscopic footing, the appearance of Auger-induced carrier multiplication up to a Fermi level of 300 meV is revealed. Furthermore, we show that doping favors the so-called hot carrier multiplication occurring within one band. Our results are directly compared to recent time-resolved ARPES measurements and exhibit an excellent agreement on the temporal evolution of the hot carrier multiplication for n- and p-doped graphene. The gained insights shed light on the ultrafast carrier dynamics in realistic, doped graphene samples. PMID:26577536

Method and apparatus for two-dimensional spectroscopy

DOEpatents

DeCamp, Matthew F.; Tokmakoff, Andrei

2010-10-12

Preferred embodiments of the invention provide for methods and systems of 2D spectroscopy using ultrafast, first light and second light beams and a CCD array detector. A cylindrically-focused second light beam interrogates a target that is optically interactive with a frequency-dispersed excitation (first light) pulse, whereupon the second light beam is frequency-dispersed at right angle orientation to its line of focus, so that the horizontal dimension encodes the spatial location of the second light pulse and the first light frequency, while the vertical dimension encodes the second light frequency. Differential spectra of the first and second light pulses result in a 2D frequency-frequency surface equivalent to double-resonance spectroscopy. Because the first light frequency is spatially encoded in the sample, an entire surface can be acquired in a single interaction of the first and second light pulses.

Hydrodynamic metamaterials: Microfabricated arrays to steer, refract, and focus streams of biomaterials

PubMed Central

Morton, Keith J.; Loutherback, Kevin; Inglis, David W.; Tsui, Ophelia K.; Sturm, James C.; Chou, Stephen Y.; Austin, Robert H.

2008-01-01

We show that it is possible to direct particles entrained in a fluid along trajectories much like rays of light in classical optics. A microstructured, asymmetric post array forms the core hydrodynamic element and is used as a building block to construct microfluidic metamaterials and to demonstrate refractive, focusing, and dispersive pathways for flowing beads and cells. The core element is based on the concept of deterministic lateral displacement where particles choose different paths through the asymmetric array based on their size: Particles larger than a critical size are displaced laterally at each row by a post and move along the asymmetric axis at an angle to the flow, while smaller particles move along streamline paths. We create compound elements with complex particle handling modes by tiling this core element using multiple transformation operations; we show that particle trajectories can be bent at an interface between two elements and that particles can be focused into hydrodynamic jets by using a single inlet port. Although particles propagate through these elements in a way that strongly resembles light rays propagating through optical elements, there are unique differences in the paths of our particles as compared with photons. The unusual aspects of these modular, microfluidic metamaterials form a rich design toolkit for mixing, separating, and analyzing cells and functional beads on-chip. PMID:18495920

The CLAS12-RICH hybrid geometry

NASA Astrophysics Data System (ADS)

Angelini, Giovanni; CLAS12-RICH Collaboration

2017-01-01

A Ring-imaging Cherenkov detector (RICH) has been designed for the CLAS12 spectrometer (JLAB, Hall B) in order to increase the particle identification. Among the approved physics program focused upon 3D imaging of the nucleon, some Semi Inclusive Deep Inelastic Scattering experiments (E12-09-007, E12-09-008, E12-09-009) demand an efficient kaon identification across the momentum range from 3 to 8 GeV/c. The detector exploits a novel elaborated hybrid geometry based on a complex focusing mirror system that will reduce the area instrumented with photon detectors. For forward scattered particles (θ <12°) with momenta p = 3-8 GeV/c, a proximity imaging method with direct Cherenkov light detection will be used. For larger angles of 12° < θ <35° and momenta of p = 3-6 GeV/c, the Cherenkov light will be focused by a spherical mirror, undergo two further passes through the aerogel radiator and will be reflected from planar mirrors before detection. A carefully study on reflections has been performed considering microscopic and macroscopic effects. In addition, a new feature has been introduced in the CLAS12 simulation software in order to generate the geometry of the detector by using a computer-aided design (CAD) file for an accurate geometrical description. U.S. Department of Energy, GWU Columbian College Art and Science Facilitating Fund Award (CCAS CCFF).

Polarization selecting optical element using a porro prism incorporating a thin film polarizer in a single element

DOEpatents

Hendrix, James Lee

2001-05-08

A Porro prism and a light polarizer are combined in a single optical element termed a Hendrix Prism. The design provides retro-reflection of incoming light of a predetermined polarization in a direction anti-parallel to the direction of light incidence, while reflecting undesired light, i.e., that having a polarization orthogonal to the predetermined polarization, from the surface of the light polarizer. The undesired light is reflected in a direction that does not interfere with the intended operation of the device in which the Hendrix Prism is installed yet provides feedback to the system in which it is used.

Multiple Drosophila Tracking System with Heading Direction

PubMed Central

Sirigrivatanawong, Pudith; Arai, Shogo; Thoma, Vladimiros; Hashimoto, Koichi

2017-01-01

Machine vision systems have been widely used for image analysis, especially that which is beyond human ability. In biology, studies of behavior help scientists to understand the relationship between sensory stimuli and animal responses. This typically requires the analysis and quantification of animal locomotion. In our work, we focus on the analysis of the locomotion of the fruit fly Drosophila melanogaster, a widely used model organism in biological research. Our system consists of two components: fly detection and tracking. Our system provides the ability to extract a group of flies as the objects of concern and furthermore determines the heading direction of each fly. As each fly moves, the system states are refined with a Kalman filter to obtain the optimal estimation. For the tracking step, combining information such as position and heading direction with assignment algorithms gives a successful tracking result. The use of heading direction increases the system efficiency when dealing with identity loss and flies swapping situations. The system can also operate with a variety of videos with different light intensities. PMID:28067800

Inhomogeneous ensembles of radical pairs in chemical compasses

PubMed Central

Procopio, Maria; Ritz, Thorsten

2016-01-01

The biophysical basis for the ability of animals to detect the geomagnetic field and to use it for finding directions remains a mystery of sensory biology. One much debated hypothesis suggests that an ensemble of specialized light-induced radical pair reactions can provide the primary signal for a magnetic compass sensor. The question arises what features of such a radical pair ensemble could be optimized by evolution so as to improve the detection of the direction of weak magnetic fields. Here, we focus on the overlooked aspect of the noise arising from inhomogeneity of copies of biomolecules in a realistic biological environment. Such inhomogeneity leads to variations of the radical pair parameters, thereby deteriorating the signal arising from an ensemble and providing a source of noise. We investigate the effect of variations in hyperfine interactions between different copies of simple radical pairs on the directional response of a compass system. We find that the choice of radical pair parameters greatly influences how strongly the directional response of an ensemble is affected by inhomogeneity. PMID:27804956

Inhomogeneous ensembles of radical pairs in chemical compasses

NASA Astrophysics Data System (ADS)

Procopio, Maria; Ritz, Thorsten

2016-11-01

The biophysical basis for the ability of animals to detect the geomagnetic field and to use it for finding directions remains a mystery of sensory biology. One much debated hypothesis suggests that an ensemble of specialized light-induced radical pair reactions can provide the primary signal for a magnetic compass sensor. The question arises what features of such a radical pair ensemble could be optimized by evolution so as to improve the detection of the direction of weak magnetic fields. Here, we focus on the overlooked aspect of the noise arising from inhomogeneity of copies of biomolecules in a realistic biological environment. Such inhomogeneity leads to variations of the radical pair parameters, thereby deteriorating the signal arising from an ensemble and providing a source of noise. We investigate the effect of variations in hyperfine interactions between different copies of simple radical pairs on the directional response of a compass system. We find that the choice of radical pair parameters greatly influences how strongly the directional response of an ensemble is affected by inhomogeneity.

Computer-mediated communication and interpersonal attraction: an experimental test of two explanatory hypotheses.

PubMed

Antheunis, Marjolijn L; Valkenburg, Patti M; Peter, Jochen

2007-12-01

The aims of this study were (a) to investigate the influence of computer-mediated communication (CMC) on interpersonal attraction and (b) to examine two underlying processes in the CMC-interpersonal attraction relationship. We identified two variables that may mediate the influence of CMC on interpersonal attraction: self-disclosure and direct questioning. Focusing on these potential mediating variables, we tested two explanatory hypotheses: the CMC-induced direct questioning hypothesis and the CMC-induced self-disclosure hypothesis. Eighty-one cross-sex dyads were randomly assigned to one of three experimental conditions: text-only CMC, visual CMC, and face-to-face communication. We did not find a direct effect of CMC on interpersonal attraction. However, we did find two positive indirect effects of text-only CMC on interpersonal attraction: text-only CMC stimulated both self-disclosure and direct questioning, both of which in turn enhanced interpersonal attraction. Results are discussed in light of uncertainty reduction theory and CMC theories.

Allosteric conformational barcodes direct signaling in the cell.

PubMed

Nussinov, Ruth; Ma, Buyong; Tsai, Chung-Jung; Csermely, Peter

2013-09-03

The cellular network is highly interconnected. Pathways merge and diverge. They proceed through shared proteins and may change directions. How are cellular pathways controlled and their directions decided, coded, and read? These questions become particularly acute when we consider that a small number of pathways, such as signaling pathways that regulate cell fates, cell proliferation, and cell death in development, are extensively exploited. This review focuses on these signaling questions from the structural standpoint and discusses the literature in this light. All co-occurring allosteric events (including posttranslational modifications, pathogen binding, and gain-of-function mutations) collectively tag the protein functional site with a unique barcode. The barcode shape is read by an interacting molecule, which transmits the signal. A conformational barcode provides an intracellular address label, which selectively favors binding to one partner and quenches binding to others, and, in this way, determines the pathway direction, and, eventually, the cell's response and fate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Large area pulsed solar simulator

NASA Technical Reports Server (NTRS)

Kruer, Mark A. (Inventor)

1999-01-01

An advanced solar simulator illuminates the surface a very large solar array, such as one twenty feet by twenty feet in area, from a distance of about twenty-six feet with an essentially uniform intensity field of pulsed light of an intensity of one AMO, enabling the solar array to be efficiently tested with light that emulates the sun. Light modifiers sculpt a portion of the light generated by an electrically powered high power Xenon lamp and together with direct light from the lamp provide uniform intensity illumination throughout the solar array, compensating for the square law and cosine law reduction in direct light intensity, particularly at the corner locations of the array. At any location within the array the sum of the direct light and reflected light is essentially constant.

Calcitic microlenses as part of the photoreceptor system in brittlestars

NASA Astrophysics Data System (ADS)

Aizenberg, Joanna; Tkachenko, Alexei; Weiner, Steve; Addadi, Lia; Hendler, Gordon

2001-08-01

Photosensitivity in most echinoderms has been attributed to `diffuse' dermal receptors. Here we report that certain single calcite crystals used by brittlestars for skeletal construction are also a component of specialized photosensory organs, conceivably with the function of a compound eye. The analysis of arm ossicles in Ophiocoma showed that in light-sensitive species, the periphery of the labyrinthic calcitic skeleton extends into a regular array of spherical microstructures that have a characteristic double-lens design. These structures are absent in light-indifferent species. Photolithographic experiments in which a photoresist film was illuminated through the lens array showed selective exposure of the photoresist under the lens centres. These results provide experimental evidence that the microlenses are optical elements that guide and focus the light inside the tissue. The estimated focal distance (4-7µm below the lenses) coincides with the location of nerve bundles-the presumed primary photoreceptors. The lens array is designed to minimize spherical aberration and birefringence and to detect light from a particular direction. The optical performance is further optimized by phototropic chromatophores that regulate the dose of illumination reaching the receptors. These structures represent an example of a multifunctional biomaterial that fulfills both mechanical and optical functions.

Micro-Optic Color Separation Technology for Efficient Projection Displays

NASA Technical Reports Server (NTRS)

Gunning, W. J.; Boehmer, E.

1997-01-01

Phase 1 of this project focused on development of an overall optical concept which incorporated a single liquid crystal spatial light modulator. The system achieved full color by utilizing an echelon grating, which diffracted the incident light into three orders with different color spectra, in combination with a microlens array, which spatially separated RGB bands and directed the light of the appropriate wavelength to the appropriate color dot. Preliminary echelon grating designs were provided by MIT/LL and reviewed by Rockwell. Additional Rockwell activities included the Identification of microlens designs, light sources (ILC), and projection optics to fulfill the overall design requirements. An Internal subcontract was established with Rockwell's Collins Avionics and Communications Division (CACD) which specified the liquid crystal SLM (Sharp Model No. LQ 46EO2) and built the projection display baseline projector. Full Color projected video images were produced and shown at the 1995 HDS meeting in Washington. Analysis of the luminance performance of the projector and detailed parameter trade studies helped define the dependence of overall display efficiency on lamp collimation, and indicated that a lamp with very small arc dimension is required for the optical concept to be viable.

Method for fabrication of cylindrical microlenses of selected shape

DOEpatents

Snyder, J.J.; Baer, T.M.

1992-01-14

The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing. The present invention has many applications, such as integrated optics, optical detectors and laser diodes. The lens, when connected to a laser diode bar, can provide a high intensity source of laser radiation for pumping a high average power solid state laser. In integrated optics, a lens can be used to couple light into and out of apertures such as waveguides. The lens can also be used to collect light, and focus it on a detector. 11 figs.

Method for fabrication of cylindrical microlenses of selected shape

DOEpatents

Snyder, James J.; Baer, Thomas M.

1992-01-01

The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing. The present invention has many applications, such as integrated optics, optical detectors and laser diodes. The lens, when connected to a laser diode bar, can provide a high intensity source of laser radiation for pumping a high average power solid state laser. In integrated optics, a lens can be used to couple light into and out of apertures such as waveguides. The lens can also be used to collect light, and focus it on a detector.

Multi-facet concentrator of solar setup for irradiating the objects placed in a target plane with solar light

DOEpatents

Lewandowski, Allan A.; Yampolskiy, Vladislav; Alekseev, Valerie; Son, Valentin

2001-01-01

According to the proposed invention, this technical result is achieved so that many-facet concentrator of a solar setup for exposure of objects, placed in a target plane, to the action of solar radiation containing a supporting frame and facets differing by that the facets of the concentrator are chosen with spherical focusing reflective surfaces of equal focal lengths and with selective coatings reflecting a desired spectral fraction of solar radiation, and are arranged on the supporting frame symmetrically with respect to the common axis of the concentrator, their optical axes being directed to the single point on the optical axis of the concentrator located before the nominal focus point of the concentrator and determining the position of arranging the target plane.

The Born approximation, multiple scattering, and the butterfly algorithm

NASA Astrophysics Data System (ADS)

Martinez, Alejandro F.

Radar works by focusing a beam of light and seeing how long it takes to reflect. To see a large region the beam is pointed in different directions. The focus of the beam depends on the size of the antenna (called an aperture). Synthetic aperture radar (SAR) works by moving the antenna through some region of space. A fundamental assumption in SAR is that waves only bounce once. Several imaging algorithms have been designed using that assumption. The scattering process can be described by iterations of a badly behaving integral. Recently a method for efficiently evaluating these types of integrals has been developed. We will give a detailed implementation of this algorithm and apply it to study the multiple scattering effects in SAR using target estimates from single scattering algorithms.

Flexible liquid core light guide with focusing and light shaping attachments

DOEpatents

Kross, B.J.; Majewski, S.; Zorn, C.J.; Majewski, L.A.

1997-11-04

A liquid light guide system for ultraviolet light is disclosed that has a light shaping arrangement for the emitted light, a stable liquid core and sheath and reliable and effective end closures. 12 figs.

Use of diffusive optical fibers for plant lighting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozai, T.; Kitaya, Y.; Fujiwara, K.

1994-12-31

Lighting is one of the most critical aspects in plant production and environmental research with plants. Much research has been repeated on the effect of light intensity, spectral distribution of light and lighting cycle, but comparatively little research done on the effect of lighting direction on the growth, development and morphology of plants. When plants are grown with lamps above, light is directed downward to the plants. Downward or overhead lighting is utilized in almost all cases. However, downward lighting does not always give the best result in terms of lighting efficiency, growth, development and morphology of plants. Kitaya etmore » al. (1988) developed a lighting system in which two rooting beds were arranged; one above and the other under fluorescent lamps. Lettuce plants grew normally in the lower bed and suspended upside-down under the upper bed. The lettuce plants suspended upside-down were given the light in upward direction (upward lighting). No significant difference in growth, development and morphology was found between the lettuce plants grown by the downward and upward lighting. Combining upward and downward lighting, improved spacing efficiency and reduced electricity cost per plant compared with conventional, downward lighting. From the above example, when designing a lighting system for plants with lamps more lighting direction should be considered. In the present study, a sideward lighting system was developed using diffusive optical fiber belts. More higher quality tissue-cultured transplants could be produced in reduced space with sideward lighting system than with a downward lighting system. An application of the sideward lighting system using diffusive optical fiber belts is described and advantages and disadvantages are discussed.« less

Tight focusing of radially polarized circular Airy vortex beams

NASA Astrophysics Data System (ADS)

Chen, Musheng; Huang, Sujuan; Shao, Wei

2017-11-01

Tight focusing properties of radially polarized circular Airy vortex beams (CAVB) are studied numerically. The light field expressions for the focused fields are derived based on vectorial Debye theory. We also study the relationship between focal profiles, such as light intensity distribution, radius of focal spot and focal length, and the parameters of CAVB. Numerical results demonstrate that we can generate a radially polarized CAVB with super-long focal length, super-strong longitudinal intensity or subwavelength focused spot at the focal plane by properly choosing the parameters of incident light and high numerical aperture (NA) lens. These results have potential applications for optical trapping, optical storage and particle acceleration.

Through-Focus Vision Performance and Light Disturbances of 3 New Intraocular Lenses for Presbyopia Correction

PubMed Central

Escandón-García, Santiago; Ribeiro, Filomena J.; McAlinden, Colm

2018-01-01

Purpose To compare the through-focus visual performance in a clinical population of pseudophakic patients implanted with two new trifocal intraocular lenses (IOLs) and one extended depth of focus IOL. Methods Prospective, nonrandomized, examiner-masked case series. Twenty-three patients received the FineVision® and seven patients received the PanOptix™ trifocal IOLs. Fifteen patients received the Symfony extended depth of focus IOL. Mean age of patients was 63 ± 8 years. Through-focus visual acuity was measured from –3.00 to +1.00 D vergences. Contrast sensitivity was measured with and without a source of glare. Light disturbances were evaluated with the Light Distortion Analyzer. Results Though-focus evaluation showed that trifocal IOLs performed significantly better at near distance (33 and 40 cm), and extended depth of focus performed significantly better at intermediate distance (1.0 m). Contrast sensitivity function with glare and dysphotopsia was similar between the three IOLs and subjective response to questionnaire showed a significantly higher score (worse performance) for the extended depth of focus IOL compared to both trifocal IOLs in the bothersome subscale (p < 0.05). Conclusions Trifocal IOLs grant better performance at near distance while extended depth of focus IOL performs better at intermediate distance. Objective dysphotopsia measured with the Light Distortion Analyzer is not reduced in extended depth of focus IOL compared to trifocal IOLs. PMID:29651343

Visible light focusing flat lenses based on hybrid dielectric-metal metasurface reflector-arrays

PubMed Central

Fan, Qingbin; Huo, Pengcheng; Wang, Daopeng; Liang, Yuzhang; Yan, Feng; Xu, Ting

2017-01-01

Conventional metasurface reflector-arrays based on metallic resonant nanoantenna to control the wavefront of light for focusing always suffer from strong ohmic loss at optical frequencies. Here, we overcome this challenge by constructing a non-resonant, hybrid dielectric-metal configuration consisting of TiO2 nanofins associated with an Ag reflector substrate that provides a broadband response and high polarization conversion efficiency in the visible range. A reflective flat lens based on this configuration shows an excellent focusing performance with the spot size close to the diffraction limit. Furthermore, by employing the superimposed phase distribution design to manipulate the wavefront of the reflected light, various functionalities, such as multifocal and achromatic focusing, are demonstrated for the flat lenses. Such a reflective flat lens will find various applications in visible light imaging and sensing systems. PMID:28332611

Direct slow-light excitation in photonic crystal waveguides forming ultra-compact splitters.

PubMed

Zhang, Min; Groothoff, Nathaniel; Krüger, Asger Christian; Shi, Peixing; Kristensen, Martin

2011-04-11

Based on a series of 1x2 beam splitters, novel direct excitation of slow-light from input- to output-region in photonic crystal waveguides is investigated theoretically and experimentally. The study shows that the slow-light excitation provides over 50 nm bandwidth for TE-polarized light splitting between two output ports, and co-exists together with self-imaging leading to ~20 nm extra bandwidth. The intensity of the direct excitation is qualitatively explained by the overlap integral of the magnetic fields between the ground input- and excited output-modes. The direct excitation of slow light is practically lossless compared with transmission in a W1 photonic crystal waveguides, which broadens the application-field for slow-light and further minimizes the size of a 1x2 splitter. © 2011 Optical Society of America

Characterization of Light Lesion Paradigms and Optical Coherence Tomography as Tools to Study Adult Retina Regeneration in Zebrafish

PubMed Central

Weber, Anke; Hochmann, Sarah; Cimalla, Peter; Gärtner, Maria; Kuscha, Veronika; Hans, Stefan; Geffarth, Michaela; Kaslin, Jan; Koch, Edmund; Brand, Michael

2013-01-01

Light-induced lesions are a powerful tool to study the amazing ability of photoreceptors to regenerate in the adult zebrafish retina. However, the specificity of the lesion towards photoreceptors or regional differences within the retina are still incompletely understood. We therefore characterized the process of degeneration and regeneration in an established paradigm, using intense white light from a fluorescence lamp on swimming fish (diffuse light lesion). We also designed a new light lesion paradigm where light is focused through a microscope onto the retina of an immobilized fish (focused light lesion). Focused light lesion has the advantage of creating a locally restricted area of damage, with the additional benefit of an untreated control eye in the same animal. In both paradigms, cell death is observed as an immediate early response, and proliferation is initiated around 2 days post lesion (dpl), peaking at 3 dpl. We furthermore find that two photoreceptor subtypes (UV and blue sensitive cones) are more susceptible towards intense white light than red/green double cones and rods. We also observed specific differences within light lesioned areas with respect to the process of photoreceptor degeneration: UV cone debris is removed later than any other type of photoreceptor in light lesions. Unspecific damage to retinal neurons occurs at the center of a focused light lesion territory, but not in the diffuse light lesion areas. We simulated the fish eye optical properties using software simulation, and show that the optical properties may explain the light lesion patterns that we observe. Furthermore, as a new tool to study retinal degeneration and regeneration in individual fish in vivo, we use spectral domain optical coherence tomography. Collectively, the light lesion and imaging assays described here represent powerful tools for studying degeneration and regeneration processes in the adult zebrafish retina. PMID:24303018

Translation and articulation in biological motion perception.

PubMed

Masselink, Jana; Lappe, Markus

2015-08-01

Recent models of biological motion processing focus on the articulational aspect of human walking investigated by point-light figures walking in place. However, in real human walking, the change in the position of the limbs relative to each other (referred to as articulation) results in a change of body location in space over time (referred to as translation). In order to examine the role of this translational component on the perception of biological motion we designed three psychophysical experiments of facing (leftward/rightward) and articulation discrimination (forward/backward and leftward/rightward) of a point-light walker viewed from the side, varying translation direction (relative to articulation direction), the amount of local image motion, and trial duration. In a further set of a forward/backward and a leftward/rightward articulation task, we additionally tested the influence of translational speed, including catch trials without articulation. We found a perceptual bias in translation direction in all three discrimination tasks. In the case of facing discrimination the bias was limited to short stimulus presentation. Our results suggest an interaction of articulation analysis with the processing of translational motion leading to best articulation discrimination when translational direction and speed match articulation. Moreover, we conclude that the global motion of the center-of-mass of the dot pattern is more relevant to processing of translation than the local motion of the dots. Our findings highlight that translation is a relevant cue that should be integrated in models of human motion detection.

Unidirectional ring lasers

DOEpatents

Hohimer, J.P.; Craft, D.C.

1994-09-20

Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity is disclosed. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction. 21 figs.

Remote excitation and detection of surface-enhanced Raman scattering from graphene.

PubMed

Coca-López, Nicolás; Hartmann, Nicolai F; Mancabelli, Tobia; Kraus, Jürgen; Günther, Sebastian; Comin, Alberto; Hartschuh, Achim

2018-06-07

We demonstrate the remote excitation and detection of surface-enhanced Raman scattering (SERS) from graphene using a silver nanowire as a plasmonic waveguide. By investigating a nanowire touching a graphene sheet at only one terminal, we first show the remote excitation of SERS from graphene by propagating surface plasmon polaritons (SPPs) launched by a focused laser over distances on the order of 10 μm. Remote detection of SERS is then demonstrated for the same nanowire by detecting light emission at the distal end of the nanowire that was launched by graphene Raman scattering and carried to the end of the nanowire by SPPs. We then show that the transfer of the excitation and Raman scattered light along the nanowire can also be visualized through spectrally selective back focal plane imaging. Back focal plane images detected upon focused laser excitation at one of the nanowire's tips reveal propagating surface plasmon polaritons at the laser energy and at the energies of the most prominent Raman bands of graphene. With this approach the identification of remote excitation and detection of SERS for nanowires completely covering the Raman scatterer is achieved, which is typically not possible by direct imaging.

Volumetric bioimaging based on light field microscopy with temporal focusing illumination

NASA Astrophysics Data System (ADS)

Hsu, Feng-Chun; Sie, Yong Da; Lai, Feng-Jie; Chen, Shean-Jen

2018-02-01

Light field technique at a single shot can get the whole volume image of observed sample. Therefore, the original frame rate of the optical system can be taken as the volumetric image rate. For dynamically imaging whole micron-scale biosample, a light field microscope with temporal focusing illumination has been developed. In the light field microscope, the f-number of the microlens array (MLA) is adopted to match that of the objective; hence, the subimages via adjacent lenslets do not overlay each other. A three-dimensional (3D) deconvolution algorithm is utilized to deblur the out-of-focusing part. Conventional light field microscopy (LFM) illuminates whole volume sample even noninteresting parts; nevertheless, whole volume excitation causes even more damage on bio-sample and also increase the background noise from the out of range. Therefore, temporal focusing is integrated into the light field microscope for selecting the illumination volume. Herein, a slit on the back focal plane of the objective is utilized to control the axial excitation confinement for selecting the illumination volume. As a result, the developed light field microscope with the temporal focusing multiphoton illumination (TFMPI) can reconstruct 3D images within the selected volume, and the lateral resolution approaches to the theoretical value. Furthermore, the 3D Brownian motion of two-micron fluorescent beads is observed as the criterion of dynamic sample. With superior signal-to-noise ratio and less damage to tissue, the microscope is potential to provide volumetric imaging for vivo sample.

Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure

NASA Technical Reports Server (NTRS)

Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

1996-01-01

1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

Sculpting with light: Light/matter interactions in biocompatible polymers

NASA Astrophysics Data System (ADS)

Applegate, Matthew B.

When light interacts with matter either the light or the material can be changed. This dissertation focuses on light/matter interaction in silk fibroin and its utility for biomedical applications. Silk, a natural biocompatible, biodegradable polymer, has a large 3-photon absorption cross-section which allows modest peak intensity light to cause significant multiphoton absorption. This absorption allows voids to be formed with three dimensional control within soft, transparent silk hydrogels. A theoretical model of the void formation process is developed to allow the size of the voids to be predicted for a range of laser and sample parameters. Arbitrary 3D patterns are created in silk gels that allow cells to penetrate into the bulk of the gel both in vitro and in vivo. To explore how silk can be used to alter light, the creation of step-index optical waveguides, formed by encapsulating a silk film within a silk hydrogel, is described. These waveguides allow light to be delivered to targets through several centimeters of highly scattering biological tissue. Finally, the interaction of light with riboflavin is used to photocrosslink silk to form solid structures, rather than voids. The mechanism of crosslinking to be driven by radicalized tyrosine residues resulting in the formation of dityrosine bonds which lead to the gelation of a liquid silk solution. Riboflavin is a versatile photoinitiator and can be used to crosslink collagen as well as silk, which allows silk to be crosslinked directly to corneal collagen. When applied to the eye, an artificial corneal layer is formed which has the potential to treat various corneal diseases and allow for risk-free laser vision correction. These studies show the versatility of light-based processing of silk for a wide variety of medical applications.

Acquisition and replay systems for direct-to-digital holography and holovision

DOEpatents

Thomas, Clarence E.; Hanson, Gregory R.

2003-02-25

Improvements to the acquisition and replay systems for direct-to-digital holography and holovision are described. A method of recording an off-axis hologram includes: splitting a laser beam into an object beam and a reference beam; reflecting the reference beam from a reference beam mirror; reflecting the object beam from an illumination beamsplitter; passing the object beam through an objective lens; reflecting the object beam from an object; focusing the reference beam and the object beam at a focal plane of a digital recorder to form an off-axis hologram; digitally recording the off-axis hologram; and transforming the off-axis hologram in accordance with a Fourier transform to obtain a set of results. A method of writing an off-axis hologram includes: passing a laser beam through a spatial light modulator; and focusing the laser beam at a focal plane of a photorefractive crystal to impose a holographic diffraction grating pattern on the photorefractive crystal. A method of replaying an off-axis hologram includes: illuminating a photorefractive crystal having a holographic diffraction grating with a replay beam.

Echelle grating multi-order imaging spectrometer utilizing a catadioptric lens

DOEpatents

Chrisp, Michael P; Bowers, Joel M

2014-05-27

A cryogenically cooled imaging spectrometer that includes a spectrometer housing having a first side and a second side opposite the first side. An entrance slit is on the first side of the spectrometer housing and directs light to a cross-disperser grating. An echelle immersions grating and a catadioptric lens are positioned in the housing to receive the light. A cryogenically cooled detector is located in the housing on the second side of the spectrometer housing. Light from the entrance slit is directed to the cross-disperser grating. The light is directed from the cross-disperser grating to the echelle immersions grating. The light is directed from the echelle immersions grating to the cryogenically cooled detector on the second side of the spectrometer housing.

Direction-division multiplexed holographic free-electron-driven light sources

NASA Astrophysics Data System (ADS)

Clarke, Brendan P.; MacDonald, Kevin F.; Zheludev, Nikolay I.

2018-01-01

We report on a free-electron-driven light source with a controllable direction of emission. The source comprises a microscopic array of plasmonic surface-relief holographic domains, each tailored to direct electron-induced light emission at a selected wavelength into a collimated beam in a prescribed direction. The direction-division multiplexed source is tested by driving it with the 30 kV electron beam of a scanning electron microscope: light emission, at a wavelength of 800 nm in the present case, is switched among different output angles by micron-scale repositioning of the electron injection point among domains. Such sources, with directional switching/tuning possible at picosecond timescales, may be applied to field-emission and surface-conduction electron-emission display technologies, optical multiplexing, and charged-particle-beam position metrology.

Nanoplasmonic lenses for bacteria sorting (Presentation Recording)

NASA Astrophysics Data System (ADS)

Zhu, Xiangchao; Yanik, Ahmet A.

2015-08-01

We demonstrate that patches of two dimensional arrays of circular plasmonic nanoholes patterned on gold-titanium thin film enables subwavelength focusing of visible light in far field region. Efficient coupling of the light with the excited surface plasmon at metal dielectric interface results in strong light transmission. As a result, surface plasmon plays an important role in the far field focusing behavior of the nanohole-aperture patches device. Furthermore, the focal length of the focused beam was found to be predominantly dependent on the overall size of the patch, which is in good agreement with that calculated by Rayleigh-Sommerfield integral formula. The focused light beam can be utilized to separate bio-particles in the dynamic range from 0.1 μm to 1 μm through mainly overcoming the drag force induced by fluid flow. In our proposed model, focused light generated by our plasmonic lenses will push the larger bio-particles in size back to the source of fluid flow and allow the smaller particles to move towards the central aperture of the patch. Such a new kind of plasmonic lenses open up possibility of sorting bacterium-like particles with plasmonic nanolenses, and also represent a promising tool in the field of virology.

Apparatus and method for generating partially coherent illumination for photolithography

DOEpatents

Sweatt, W.C.

1999-07-06

The present invention relates an apparatus and method for creating a bright, uniform source of partially coherent radiation for illuminating a pattern, in order to replicate an image of said pattern with a high degree of acuity. The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system includes a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination image of the source in a camera entrance pupil. The light passing through the field lens illuminates a mask which interrupts the source light as either a positive or negative image of the object to be replicated. Light passing by the mask is focused into the entrance pupil of the lithographic camera creating an image of the mask onto a receptive media. 7 figs.

Apparatus and method for generating partially coherent illumination for photolithography

DOEpatents

Sweatt, William C.

1999-01-01

The present invention relates an apparatus and method for creating a bright, uniform source of partially coherent radiation for illuminating a pattern, in order to replicate an image of said pattern with a high degree of acuity. The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system includes a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination image of the source in a camera entrance pupil. The light passing through the field lens illuminates a mask which interrupts the source light as either a positive or negative image of the object to be replicated. Light passing by the mask is focused into the entrance pupil of the lithographic camera creating an image of the mask onto a receptive media.

Analysis of phase conjugation in a turbid medium

NASA Astrophysics Data System (ADS)

Hollmann, Joseph L.; Cantero, Sergio; Tseng, Snow; DiMarzio, Charles A.

2014-03-01

The ability to focus light in most tissue degrades quickly with depth due to high optical scattering. Recently, researchers have found they can concentrate light tightly despite these scattering effects by using a guidestar and optical phase conjugation to focus light to greater distances in tissue. An optical or probe signal is transmitted through a scattering medium and its resulting wavefront is detected. The wavefront is then conjugated and utilized as a new optical source or delivery wave that focuses back to the guidestar's location with minimal scattering. The power in the delivery wave may be greatly increased for enhanced energy delivery at the focus. Modulation by an ultrasound (US) beam may be utilized to generate the guidestar dynamically and allow for US-resolution at depths of several millimeters. The delivery wave is successful at focusing light back at the guidestar because it creates constructive interference at the desired focus. However, if the phases of the field contributions change, we expect the delivered power at the focus to be reduced. This paper will analyze the robustness of this method when the probe beam is at one wavelength and the delivery wave is at another. This will allow us to characterize the deleterious effects of varying the phase contributions at the focus.

Optimized achromatic phase-matching system and method

DOEpatents

Trebino, R.; DeLong, K.; Hayden, C.

1997-07-15

An optical system for efficiently directing a large bandwidth light (e.g., a femtosecond laser pulse) onto a nonlinear optical medium includes a plurality of optical elements for directing an input light pulse onto a nonlinear optical medium arranged such that the angle {theta}{sub in} which the light pulse directed onto the nonlinear optical medium is substantially independent of a position x of the light beam entering the optical system. The optical system is also constructed such that the group velocity dispersion of light pulses passing through the system can be tuned to a desired value including negative group velocity dispersion. 15 figs.

Optimized achromatic phase-matching system and method

DOEpatents

Trebino, Rick; DeLong, Ken; Hayden, Carl

1997-01-01

An optical system for efficiently directing a large bandwidth light (e.g., a femtosecond laser pulse) onto a nonlinear optical medium includes a plurality of optical elements for directing an input light pulse onto a nonlinear optical medium arranged such that the angle .theta..sub.in which the light pulse directed onto the nonlinear optical medium is substantially independent of a position x of the light beam entering the optical system. The optical system is also constructed such that the group velocity dispersion of light pulses passing through the system can be tuned to a desired value including negative group velocity dispersion.

Effective Light Directed Assembly of Building Blocks with Microscale Control.

PubMed

Dinh, Ngoc-Duy; Luo, Rongcong; Christine, Maria Tankeh Asuncion; Lin, Weikang Nicholas; Shih, Wei-Chuan; Goh, James Cho-Hong; Chen, Chia-Hung

2017-06-01

Light-directed forces have been widely used to pattern micro/nanoscale objects with precise control, forming functional assemblies. However, a substantial laser intensity is required to generate sufficient optical gradient forces to move a small object in a certain direction, causing limited throughput for applications. A high-throughput light-directed assembly is demonstrated as a printing technology by introducing gold nanorods to induce thermal convection flows that move microparticles (diameter = 40 µm to several hundreds of micrometers) to specific light-guided locations, forming desired patterns. With the advantage of effective light-directed assembly, the microfluidic-fabricated monodispersed biocompatible microparticles are used as building blocks to construct a structured assembly (≈10 cm scale) in ≈2 min. The control with microscale precision is approached by changing the size of the laser light spot. After crosslinking assembly of building blocks, a novel soft material with wanted pattern is approached. To demonstrate its application, the mesenchymal stem-cell-seeded hydrogel microparticles are prepared as functional building blocks to construct scaffold-free tissues with desired structures. This light-directed fabrication method can be applied to integrate different building units, enabling the bottom-up formation of materials with precise control over their internal structure for bioprinting, tissue engineering, and advanced manufacturing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Organic materials with nonlinear optical properties

DOEpatents

Stupp, Samuel I.; Son, Sehwan; Lin, Hong-Cheu

1995-01-01

The present invention is directed to organic materials that have the ability to double or triple the frequency of light that is directed through the materials. Particularly, the present invention is directed to the compound 4-[4-(2R)-2-cyano-7-(4'-pentyloxy-4-biphenylcarbonyloxy)phenylheptylidene) phenylcarbonyloxy]benzaldehyde, which can double the frequency of light that is directed through the compound. The invention is also directed to the compound (12-hydroxy-5,7-dodecadiynyl) 4'-[(4'-pentyloxy-4-biphenyl)carbonyloxy]-4-biphenylcarboxylate, and its polymeric form. The polymeric form can triple the frequency of light directed through it.

Organic materials with nonlinear optical properties

DOEpatents

Stupp, S.I.; Son, S.; Lin, H.C.

1995-05-02

The present invention is directed to organic materials that have the ability to double or triple the frequency of light that is directed through the materials. Particularly, the present invention is directed to the compound 4-[4-(2R)-2-cyano-7-(4{prime}-pentyloxy-4-biphenylcarbonyloxy)phenylheptylidenephenylcarbonyloxy]benzaldehyde, which can double the frequency of light that is directed through the compound. The invention is also directed to the compound (12-hydroxy-5,7-dodecadiynyl)-4{prime}-[(4{prime}-pentyloxy-4-biphenyl)carbonyloxy]-4-biphenylcarboxylate, and its polymeric form. The polymeric form can triple the frequency of light directed through it. 4 figs.

Variable Distance Angular Symbology Reader

NASA Technical Reports Server (NTRS)

Schramm, Harry F., Jr. (Inventor); Corder, Eric L. (Inventor)

2006-01-01

A variable distance angular symbology, reader utilizes at least one light source to direct light through a beam splitter and onto a target. A target may be angled relative to the impinging light beam up to and maybe even greater than 45deg. A reflected beam from the target passes through the beam splitter and is preferably directed 90deg relative to the light source through a telecentric lens to a scanner which records an image of the target such as a direct part marking code.

Reducing the ecological consequences of night-time light pollution: options and developments

PubMed Central

Gaston, Kevin J; Davies, Thomas W; Bennie, Jonathan; Hopkins, John

2012-01-01

1. Much concern has been expressed about the ecological consequences of night-time light pollution. This concern is most often focused on the encroachment of artificial light into previously unlit areas of the night-time environment, but changes in the spectral composition, duration and spatial pattern of light are also recognized as having ecological effects. 2. Here, we examine the potential consequences for organisms of five management options to reduce night-time light pollution. These are to (i) prevent areas from being artificially lit; (ii) limit the duration of lighting; (iii) reduce the ‘trespass’ of lighting into areas that are not intended to be lit (including the night sky); (iv) change the intensity of lighting; and (v) change the spectral composition of lighting. 3. Maintaining and increasing natural unlit areas is likely to be the most effective option for reducing the ecological effects of lighting. However, this will often conflict with other social and economic objectives. Decreasing the duration of lighting will reduce energy costs and carbon emissions, but is unlikely to alleviate many impacts on nocturnal and crepuscular animals, as peak times of demand for lighting frequently coincide with those in the activities of these species. Reducing the trespass of lighting will maintain heterogeneity even in otherwise well-lit areas, providing dark refuges that mobile animals can exploit. Decreasing the intensity of lighting will reduce energy consumption and limit both skyglow and the area impacted by high-intensity direct light. Shifts towards ‘whiter’ light are likely to increase the potential range of environmental impacts as light is emitted across a broader range of wavelengths. 4. Synthesis and applications. The artificial lightscape will change considerably over coming decades with the drive for more cost-effective low-carbon street lighting solutions and growth in the artificially lit area. Developing lighting strategies that minimize adverse ecological impacts while balancing the often conflicting requirements of light for human utility, comfort and safety, aesthetic concerns, energy consumption and carbon emission reduction constitute significant future challenges. However, as both lighting technology and understanding of its ecological effects develop, there is potential to identify adaptive solutions that resolve these conflicts. PMID:23335816

Reducing the ecological consequences of night-time light pollution: options and developments.

PubMed

Gaston, Kevin J; Davies, Thomas W; Bennie, Jonathan; Hopkins, John

2012-12-01

1. Much concern has been expressed about the ecological consequences of night-time light pollution. This concern is most often focused on the encroachment of artificial light into previously unlit areas of the night-time environment, but changes in the spectral composition, duration and spatial pattern of light are also recognized as having ecological effects.2. Here, we examine the potential consequences for organisms of five management options to reduce night-time light pollution. These are to (i) prevent areas from being artificially lit; (ii) limit the duration of lighting; (iii) reduce the 'trespass' of lighting into areas that are not intended to be lit (including the night sky); (iv) change the intensity of lighting; and (v) change the spectral composition of lighting.3. Maintaining and increasing natural unlit areas is likely to be the most effective option for reducing the ecological effects of lighting. However, this will often conflict with other social and economic objectives. Decreasing the duration of lighting will reduce energy costs and carbon emissions, but is unlikely to alleviate many impacts on nocturnal and crepuscular animals, as peak times of demand for lighting frequently coincide with those in the activities of these species. Reducing the trespass of lighting will maintain heterogeneity even in otherwise well-lit areas, providing dark refuges that mobile animals can exploit. Decreasing the intensity of lighting will reduce energy consumption and limit both skyglow and the area impacted by high-intensity direct light. Shifts towards 'whiter' light are likely to increase the potential range of environmental impacts as light is emitted across a broader range of wavelengths.4.Synthesis and applications. The artificial lightscape will change considerably over coming decades with the drive for more cost-effective low-carbon street lighting solutions and growth in the artificially lit area. Developing lighting strategies that minimize adverse ecological impacts while balancing the often conflicting requirements of light for human utility, comfort and safety, aesthetic concerns, energy consumption and carbon emission reduction constitute significant future challenges. However, as both lighting technology and understanding of its ecological effects develop, there is potential to identify adaptive solutions that resolve these conflicts.

Laser Range and Bearing Finder with No Moving Parts

NASA Technical Reports Server (NTRS)

Bryan, Thomas C.; Howard, Richard T.; Book, Michael L.

2007-01-01

A proposed laser-based instrument would quickly measure the approximate distance and approximate direction to the closest target within its field of view. The instrument would not contain any moving parts and its mode of operation would not entail scanning over of its field of view. Typically, the instrument would be used to locate a target at a distance on the order of meters to kilometers. The instrument would be best suited for use in an uncluttered setting in which the target is the only or, at worst, the closest object in the vicinity; for example, it could be used aboard an aircraft to detect and track another aircraft flying nearby. The proposed instrument would include a conventional time-of-flight or echo-phase-shift laser range finder, but unlike most other range finders, this one would not generate a narrow cylindrical laser beam; instead, it would generate a conical laser beam spanning the field of view. The instrument would also include a quadrant detector, optics to focus the light returning from the target onto the quadrant detector, and circuitry to synchronize the acquisition of the quadrant-detector output with the arrival of laser light returning from the nearest target. A quadrant detector constantly gathers information from the entire field of view, without scanning; its output is a direct measure of the position of the target-return light spot on the focal plane and is thus a measure of the direction to the target. The instrument should be able to operate at a repetition rate high enough to enable it to track a rapidly moving target. Of course, a target that is not sufficiently reflective could not be located by this instrument. Preferably, retroreflectors should be attached to the target to make it sufficiently reflective.

Ultra-high enhancement of light focusing through disordered media controlled by mega-pixel modes (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yu, Hyeonseung; Lee, KyeoReh; Park, YongKeun

2017-02-01

Developing an efficient strategy for light focusing through scattering media is an important topic in the study of multiple light scattering. The enhancement factor of the light focusing, defined as the ratio between the optimized intensity and the background intensity is proportional to the number of controlling modes in a spatial light modulator (SLM). The demonstrated enhancement factors in previous studies are typically less than 1,000 due to several limiting factors, such as the slow refresh rate of a LCoS SLM, long optimization time, and lack of an efficient algorithm for high controlling modes. A digital micro-mirror device is an amplitude modulator, which is recently widely used for fast optimization through dynamic biological tissues. The fast frame rate of the DMD up to 16 kHz can also be exploited for increasing the number of controlling modes. However, the manipulation of large pattern data and efficient calculation of the optimized pattern remained as an issue. In this work, we demonstrate the enhancement factor more than 100,000 in focusing through scattering media by using 1 Mega controlling modes of a DMD. Through careful synchronization between a DMD, a photo-detector and an additional computer for parallel optimization, we achieved the unprecedented enhancement factor with 75 mins of the optimization time. We discuss the design principles of the system and the possible applications of the enhanced light focusing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

David Kisailus; Lara Estroff; Himadri S. Gupta

The technical presentations and discussions at this symposium disseminated and assessed current research and defined future directions in biomaterials research, with a focus on structure-function relationships in biological and biomimetic composites. The invited and contributed talks covered a diverse range of topics from fundamental biology, physics, chemistry, and materials science to potential applications in developing areas such as light-weight composites, multifunctional and smart materials, biomedical engineering, and nanoscaled sensors. The invited speakers were chosen to create a stimulating program with a mixture of established and junior faculty, industrial and academic researchers, and American and international experts in the field. Thismore » symposium served as an excellent introduction to the area for younger scientists (graduate students and post-doctoral researchers). Direct interactions between participants also helped to promote potential future collaborations involving multiple disciplines and institutions.« less

Recent approaches for the direct use of elemental sulfur in the synthesis and processing of advanced materials.

PubMed

Lim, Jeewoo; Pyun, Jeffrey; Char, Kookheon

2015-03-09

Elemental sulfur is an abundant and inexpensive material obtained as a by-product of natural-gas and petroleum refining operations. Recently, the need for the development of new energy-storage systems brought into light the potential of sulfur as a high-capacity cathode material in secondary batteries. Sulfur-containing materials were also shown to have useful IR optical properties. These developments coupled with growing environmental concerns related to the global production of excess elemental sulfur have led to a keen interest in its utilization as a feedstock in materials applications. This Minireview focuses on the recent developments on physical and chemical methods for directly processing elemental sulfur to produce functional composites and polymers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multispectral imaging probe

DOEpatents

Sandison, David R.; Platzbecker, Mark R.; Descour, Michael R.; Armour, David L.; Craig, Marcus J.; Richards-Kortum, Rebecca

1999-01-01

A multispectral imaging probe delivers a range of wavelengths of excitation light to a target and collects a range of expressed light wavelengths. The multispectral imaging probe is adapted for mobile use and use in confined spaces, and is sealed against the effects of hostile environments. The multispectral imaging probe comprises a housing that defines a sealed volume that is substantially sealed from the surrounding environment. A beam splitting device mounts within the sealed volume. Excitation light is directed to the beam splitting device, which directs the excitation light to a target. Expressed light from the target reaches the beam splitting device along a path coaxial with the path traveled by the excitation light from the beam splitting device to the target. The beam splitting device directs expressed light to a collection subsystem for delivery to a detector.

Multispectral imaging probe

DOEpatents

Sandison, D.R.; Platzbecker, M.R.; Descour, M.R.; Armour, D.L.; Craig, M.J.; Richards-Kortum, R.

1999-07-27

A multispectral imaging probe delivers a range of wavelengths of excitation light to a target and collects a range of expressed light wavelengths. The multispectral imaging probe is adapted for mobile use and use in confined spaces, and is sealed against the effects of hostile environments. The multispectral imaging probe comprises a housing that defines a sealed volume that is substantially sealed from the surrounding environment. A beam splitting device mounts within the sealed volume. Excitation light is directed to the beam splitting device, which directs the excitation light to a target. Expressed light from the target reaches the beam splitting device along a path coaxial with the path traveled by the excitation light from the beam splitting device to the target. The beam splitting device directs expressed light to a collection subsystem for delivery to a detector. 8 figs.

Fast wavefront optimization for focusing through biological tissue (Conference Presentation)

NASA Astrophysics Data System (ADS)

Blochet, Baptiste; Bourdieu, Laurent; Gigan, Sylvain

2017-02-01

The propagation of light in biological tissues is rapidly dominated by multiple scattering: ballistic light is exponentially attenuated, which limits the penetration depth of conventional microscopy techniques. For coherent light, the recombination of the different scattered paths creates a complex interference: speckle. Recently, different wavefront shaping techniques have been developed to coherently manipulate the speckle. It opens the possibility to focus light through complex media and ultimately to image in them, provided however that the medium can be considered as stationary. We have studied the possibility to focus in and through time-varying biological tissues. Their intrinsic temporal dynamics creates a fast decorrelation of the speckle pattern. Therefore, focusing through biological tissues requires fast wavefront shaping devices, sensors and algorithms. We have investigated the use of a MEMS-based spatial light modulator (SLM) and a fast photodetector, combined with FPGA electronics to implement a closed-loop optimization. Our optimization process is just limited by the temporal dynamics of the SLM (200µs) and the computation time (45µs), thus corresponding to a rate of 4 kHz. To our knowledge, it's the fastest closed loop optimization using phase modulators. We have studied the focusing through colloidal solutions of TiO2 particles in glycerol, allowing tunable temporal stability, and scattering properties similar to biological tissues. We have shown that our set-up fulfills the required characteristics (speed, enhancement) to focus through biological tissues. We are currently investigating the focusing through acute rat brain slices and the memory effect in dynamic scattering media.

Monitoring and Detecting the Cigarette Beetle (Coleoptera: Anobiidae) Using Ultraviolet (LED) Direct and Reflected Lights and/or Pheromone Traps in a Laboratory and a Storehouse.

PubMed

Miyatake, Takahisa; Yokoi, Tomoyuki; Fuchikawa, Taro; Korehisa, Nobuyoshi; Kamura, Toru; Nanba, Kana; Ryouji, Shinsuke; Kamioka, Nagisa; Hironaka, Mantaro; Osada, Midori; Hariyama, Takahiko; Sasaki, Rikiya; Shinoda, Kazutaka

2016-12-01

The cigarette beetle, Lasioderma serricorne (F.), is an important stored-product pest worldwide because it damages dry foods. Detection and removal of the female L. serricorne will help to facilitate the control of the insect by removal of the egg-laying populations. In this manuscript, we examined the responses by L. serricorne to direct and reflected light in transparent cube (50 m3) set in a chamber (200 m3) and a stored facility with both direct and reflected UV-LED lights. The study also examined the responses by the beetles to light in the presence or absence of pheromone in traps that are placed at different heights. Reflected light attracted more beetles than the direct light in the experimental chamber, but the direct light traps attracted more beetles than the reflected light traps in the storehouse. Pheromone traps attracted only males; UV-LED traps attracted both sexes. The UV-LED traps with a pheromone, i.e., combined trap, attracted more males than UV-LED light traps without a pheromone, whereas the attraction of UV-LED traps with and without the pheromone was similar in females. The results suggest that UV-LED light trap combined with a sex pheromone is the best solution for monitoring and controlling L. serricorne. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Optical trapping, pulling, and Raman spectroscopy of airborne absorbing particles based on negative photophoretic force

NASA Astrophysics Data System (ADS)

Chen, Gui-hua; He, Lin; Wu, Mu-ying; Yang, Guang; Li, Y. Q.

2017-08-01

Optical pulling is the attraction of objects back to the light source by the use of optically induced "negative forces". The light-induced photophoretic force is generated by the momentum transfer between the heating particles and surrounding gas molecules and can be several orders of magnitude larger than the radiation force and gravitation force. Here, we demonstrate that micron-sized absorbing particles can be optically pulled and manipulated towards the light source over a long distance in air with a collimated Gaussian laser beam based on a negative photophoretic force. A variety of airborne absorbing particles can be pulled by this optical pipeline to the region where they are optically trapped with another focused laser beam and their chemical compositions are characterized with Raman spectroscopy. We found that micron-sized particles are pulled over a meter-scale distance in air with a pulling speed of 1-10 cm/s in the optical pulling pipeline and its speed can be controlled by changing the laser intensity. When an aerosol particle is optically trapped with a focused Gaussian beam, we measured its rotation motion around the laser propagation direction and measured its Raman spectroscopy for chemical identification by molecular fingerprints. The centripetal acceleration of the trapped particle as high as 20 times the gravitational acceleration was observed. Optical pulling over large distances with lasers in combination with Raman spectroscopy opens up potential applications for the collection and identification of atmospheric particles.

Portable biochip scanner device

DOEpatents

Perov, Alexander; Sharonov, Alexei; Mirzabekov, Andrei D.

2002-01-01

A portable biochip scanner device used to detect and acquire fluorescence signal data from biological microchips (biochips) is provided. The portable biochip scanner device employs a laser for emitting an excitation beam. An optical fiber delivers the laser beam to a portable biochip scanner. A lens collimates the laser beam, the collimated laser beam is deflected by a dichroic mirror and focused by an objective lens onto a biochip. The fluorescence light from the biochip is collected and collimated by the objective lens. The fluorescence light is delivered to a photomultiplier tube (PMT) via an emission filter and a focusing lens. The focusing lens focuses the fluorescence light into a pinhole. A signal output of the PMT is processed and displayed.

Sharp focusing of laser light by multilayer cylinders with circular cross-section

NASA Astrophysics Data System (ADS)

Kozlova, E. S.

2018-04-01

In this paper, the focusing of laser light at 532 nm by dielectric cylinders with a metal shells is studied by using COMSOL Multiphysics. The analysis of cylinder design which proposed multilayered shell shows that a microcylinder with a gold-silver (or silver-gold) shell can improve the focusing process, especially in the case of TM polarization. The microcylinder with thin internal silver layer of 1 nm and outside gold layer of 9 nm focus TE-polarized light to nanojet with maximal intensity of 5.65 a.u., full width and full length at half maximum of intensity of of 0.39λ and 0.72λ, respectively.

Phototropic growth in a reef flat acroporid branching coral species.

PubMed

Kaniewska, Paulina; Campbell, Paul R; Fine, Maoz; Hoegh-Guldberg, Ove

2009-03-01

Many terrestrial plants form complex morphological structures and will alter these growth patterns in response to light direction. Similarly reef building corals have high morphological variation across coral families, with many species also displaying phenotypic plasticity across environmental gradients. In particular, the colony geometry in branching corals is altered by the frequency, location and direction of branch initiation and growth. This study demonstrates that for the branching species Acropora pulchra, light plays a key role in axial polyp differentiation and therefore axial corallite development--the basis for new branch formation. A. pulchra branches exhibited a directional growth response, with axial corallites only developing when light was available, and towards the incident light. Field experimentation revealed that there was a light intensity threshold of 45 micromol m(-2) s(-1), below which axial corallites would not develop and this response was blue light (408-508 nm) dependent. There was a twofold increase in axial corallite growth above this light intensity threshold and a fourfold increase in axial corallite growth under the blue light treatment. These features of coral branch growth are highly reminiscent of the initiation of phototropic branch growth in terrestrial plants, which is directed by the blue light component of sunlight.

Method and apparatus for reading lased bar codes on shiny-finished fuel rod cladding tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldenfield, M.P.; Lambert, D.V.

1990-10-02

This patent describes, in a nuclear fuel rod identification system, a method of reading a bar code etched directly on a surface of a nuclear fuel rod. It comprises: defining a pair of light diffuser surfaces adjacent one another but in oppositely inclined relation to a beam of light emitted from a light reader; positioning a fuel rod, having a cylindrical surface portion with a bar code etched directly thereon, relative to the light diffuser surfaces such that the surfaces are disposed adjacent to and in oppositely inclined relation along opposite sides of the fuel rod surface portion and themore » fuel rod surface portion is aligned with the beam of light emitted from the light reader; directing the beam of light on the bar code on fuel rod cylindrical surface portion such that the light is reflected therefrom onto one of the light diffuser surfaces; and receiving and reading the reflected light from the bar code via the one of the light diffuser surfaces to the light reader.« less

[Effects of forest gap size and light intensity on herbaceous plants in Pinus koraiensis-dominated broadleaved mixed forest].

PubMed

Duan, Wen-Biao; Wang, Li-Xia; Chen, Li-Xin; Du, Shan; Wei, Quan-Shuai; Zhao, Jian-Hui

2013-03-01

1 m x 1 m fixed quadrats were parallelly arranged with a space of 2 m in each of six forest gaps in Pinus koraiensis-dominated broadleaved mixed forest, taking the gap center as the starting point and along east-west and south-north directions. In each quadrat, the coverage and abundance of herbaceous plants at different height levels were investigated by estimation method in June and September 2011, and the matrix characteristics within the quadrats were recorded. Canopy analyzer was used to take fish-eye photos in the selected overcast days in each month from June to September, 2011, and the relative light intensity was calculated by using Gap Light Analyzer 2.0 software. The differences in the relative light intensity and herbaceous plants coverage and richness between different gaps as well as the correlations between the coverage of each species and the direct light, diffuse light, and matrix were analyzed. The results showed that in opening areas and under canopy, the relative light intensity in large gaps was higher than that in small gaps, and the variation ranges of diffuse light and direct light from gap center to gap edge were bigger in large gaps than in small gaps. The direct light reaching at the ground both in large gaps and in small gaps was higher in the north than in the south direction. In the Z1, Z2, Z3, and Z4 zones, both the coverage and the richness of herbaceous plants were larger in large gaps than in small gaps, and the differences of species richness between large and small gaps reached significant level. The coverage of the majority of the herbaceous plants had significant correlations with diffuse light and matrix, and only the coverage of a few herbaceous plants was correlated with direct light.

Light field rendering with omni-directional camera

NASA Astrophysics Data System (ADS)

Todoroki, Hiroshi; Saito, Hideo

2003-06-01

This paper presents an approach to capture visual appearance of a real environment such as an interior of a room. We propose the method for generating arbitrary viewpoint images by building light field with the omni-directional camera, which can capture the wide circumferences. Omni-directional camera used in this technique is a special camera with the hyperbolic mirror in the upper part of a camera, so that we can capture luminosity in the environment in the range of 360 degree of circumferences in one image. We apply the light field method, which is one technique of Image-Based-Rendering(IBR), for generating the arbitrary viewpoint images. The light field is a kind of the database that records the luminosity information in the object space. We employ the omni-directional camera for constructing the light field, so that we can collect many view direction images in the light field. Thus our method allows the user to explore the wide scene, that can acheive realistic representation of virtual enviroment. For demonstating the proposed method, we capture image sequence in our lab's interior environment with an omni-directional camera, and succesfully generate arbitray viewpoint images for virual tour of the environment.

Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

NASA Astrophysics Data System (ADS)

Zhong, Kuo; Song, Kai; Clays, Koen

2018-03-01

In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal) lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs) of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM) inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

Retrieving the axial position of fluorescent light emitting spots by shearing interferometry

NASA Astrophysics Data System (ADS)

Schindler, Johannes; Schau, Philipp; Brodhag, Nicole; Frenner, Karsten; Osten, Wolfgang

2016-12-01

A method for the depth-resolved detection of fluorescent radiation based on imaging of an interference pattern of two intersecting beams and shearing interferometry is presented. The illumination setup provides the local addressing of the excitation of fluorescence and a coarse confinement of the excitation volume in axial and lateral directions. The reconstruction of the depth relies on the measurement of the phase of the fluorescent wave fronts. Their curvature is directly related to the distance of a source to the focus of the imaging system. Access to the phase information is enabled by a lateral shearing interferometer based on a Michelson setup. This allows the evaluation of interference signals even for spatially and temporally incoherent light such as emitted by fluorophors. An analytical signal model is presented and the relations for obtaining the depth information are derived. Measurements of reference samples with different concentrations and spatial distributions of fluorophors and scatterers prove the experimental feasibility of the method. In a setup optimized for flexibility and operating in the visible range, sufficiently large interference signals are recorded for scatterers placed in depths in the range of hundred micrometers below the surface in a material with scattering properties comparable to dental enamel.

Retrieving the axial position of fluorescent light emitting spots by shearing interferometry.

PubMed

Schindler, Johannes; Schau, Philipp; Brodhag, Nicole; Frenner, Karsten; Osten, Wolfgang

2016-12-01

A method for the depth-resolved detection of fluorescent radiation based on imaging of an interference pattern of two intersecting beams and shearing interferometry is presented. The illumination setup provides the local addressing of the excitation of fluorescence and a coarse confinement of the excitation volume in axial and lateral directions. The reconstruction of the depth relies on the measurement of the phase of the fluorescent wave fronts. Their curvature is directly related to the distance of a source to the focus of the imaging system. Access to the phase information is enabled by a lateral shearing interferometer based on a Michelson setup. This allows the evaluation of interference signals even for spatially and temporally incoherent light such as emitted by fluorophors. An analytical signal model is presented and the relations for obtaining the depth information are derived. Measurements of reference samples with different concentrations and spatial distributions of fluorophors and scatterers prove the experimental feasibility of the method. In a setup optimized for flexibility and operating in the visible range, sufficiently large interference signals are recorded for scatterers placed in depths in the range of hundred micrometers below the surface in a material with scattering properties comparable to dental enamel.

Thermodynamic and kinetic analysis of heterogeneous photocatalysis for semiconductor systems.

PubMed

Liu, Baoshun; Zhao, Xiujian; Terashima, Chiaki; Fujishima, Akira; Nakata, Kazuya

2014-05-21

Since the report of the Honda-Fujishima effect, heterogeneous photocatalysis has attracted much attention around the world because of its potential energy and environmental applications. Although great progresses have been made in recent years, most were focused on preparing highly-active photocatalysts and investigating visible light utilization. In fact, we are still unclear on the thermodynamic and kinetic nature of photocatalysis to date, which sometimes leads to misunderstandings for experimental results. It is timely to give a review and discussion on the thermodynamics and kinetics of photocatalysis, so as to direct future researches. However, there is an absence of a detailed review on this topic until now. In this article, we tried to review and discuss the thermodynamics and kinetics of photocatalysis. We explained the thermodynamic driving force of photocatalysis, and distinguished the functions of light and heat in photocatalysis. The Langmuir-Hinshelwood kinetic model, the ˙OH oxidation mechanism, and the direct-indirect (D-I) kinetic model were reviewed and compared. Some applications of the D-I model to study photocatalytic kinetics were also discussed. The electron transport mode and its importance in photocatalysis were investigated. Finally, the intrinsic relation between the kinetics and the thermodynamics of photocatalytic reactions was discussed.

Phototactic orientation mechanism in the ciliate Fabrea salina, as inferred from numerical simulations.

PubMed

Marangoni, R; Preosti, G; Colombetti, G

2000-02-01

The marine ciliate Fabrea salina shows a clear positive phototaxis, but the mechanism by which a single cell is able to detect the direction of light and orient its swimming accordingly is still unknown. A simple model of phototaxis is that of a biased random walk, where the bias due to light can affect one or more of the parameters that characterize a random walk, i.e., the mean speed, the frequency distribution of the angles of directional changes and the frequency of directional changes. Since experimental evidence has shown no effect of light on the mean speed of Fabrea salina, we have excluded models depending on this parameter. We have, therefore, investigated the phototactic orientation of Fabrea salina by computer simulation of two simple models, the first where light affects the frequency distribution of the angles of directional changes (model M1) and the second where the light bias modifies the frequency of directional changes (model M2). Simulated M1 cells directly orient their swimming towards the direction of light, regardless of their current swimming orientation; simulated M2 cells, on the contrary, are unable to actively orient their motion, but remain locked along the light direction once they find it by chance. The simulations show that these two orientation models lead to different macroscopic behaviours of the simulated cell populations. By comparing the results of the simulations with the experimental ones, we have found that the phototactic behaviour of real cells is more similar to that of the M2 model.

Distinguishing between forensic science and forensic pseudoscience: testing of validity and reliability, and approaches to forensic voice comparison.

PubMed

Morrison, Geoffrey Stewart

2014-05-01

In this paper it is argued that one should not attempt to directly assess whether a forensic analysis technique is scientifically acceptable. Rather one should first specify what one considers to be appropriate principles governing acceptable practice, then consider any particular approach in light of those principles. This paper focuses on one principle: the validity and reliability of an approach should be empirically tested under conditions reflecting those of the case under investigation using test data drawn from the relevant population. Versions of this principle have been key elements in several reports on forensic science, including forensic voice comparison, published over the last four-and-a-half decades. The aural-spectrographic approach to forensic voice comparison (also known as "voiceprint" or "voicegram" examination) and the currently widely practiced auditory-acoustic-phonetic approach are considered in light of this principle (these two approaches do not appear to be mutually exclusive). Approaches based on data, quantitative measurements, and statistical models are also considered in light of this principle. © 2013.

Mechanistic insights into plasmonic photocatalysts in utilizing visible light.

PubMed

Leong, Kah Hon; Aziz, Azrina Abd; Sim, Lan Ching; Saravanan, Pichiah; Jang, Min; Bahnemann, Detlef

2018-01-01

The utilisation of sunlight as an abundant and renewable resource has motivated the development of sustainable photocatalysts that can collectively harvest visible light. However, the bottleneck in utilising the low energy photons has led to the discovery of plasmonic photocatalysts. The presence of noble metal on the plasmonic photocatalyst enables the harvesting of visible light through the unique characteristic features of the noble metal nanomaterials. Moreover, the formation of interfaces between noble metal particles and semiconductor materials further results in the formation of a Schottky junction. Thereby, the plasmonic characteristics have opened up a new direction in promoting an alternative path that can be of value to the society through sustainable development derived through energy available for all for diverse applications. We have comprehensively prepared this review to specifically focus on fundamental insights into plasmonic photocatalysts, various synthesis routes, together with their strengths and weaknesses, and the interaction of the plasmonic photocatalyst with pollutants as well as the role of active radical generation and identification. The review ends with a pinnacle insight into future perspectives regarding realistic applications of plasmonic photocatalysts.

Noncontact optical motion sensing for real-time analysis

NASA Astrophysics Data System (ADS)

Fetzer, Bradley R.; Imai, Hiromichi

1990-08-01

The adaptation of an image dissector tube (IDT) within the OPTFOLLOW system provides high resolution displacement measurement of a light discontinuity. Due to the high speed response of the IDT and the advanced servo loop circuitry, the system is capable of real time analysis of the object under test. The image of the discontinuity may be contoured by direct or reflected light and ranges spectrally within the field of visible light. The image is monitored to 500 kHz through a lens configuration which transposes the optical image upon the photocathode of the IDT. The photoelectric effect accelerates the resultant electrons through a photomultiplier and an enhanced current is emitted from the anode. A servo loop controls the electron beam, continually centering it within the IDT using magnetic focusing of deflection coils. The output analog voltage from the servo amplifier is thereby proportional to the displacement of the target. The system is controlled by a microprocessor with a 32kbyte memory and provides a digital display as well as instructional readout on a color monitor allowing for offset image tracking and automatic system calibration.

Perspectives of Nurses and Patients on Call Light Technology

PubMed Central

Galinato, Jose; Montie, Mary; Patak, Lance; Titler, Marita

2015-01-01

Call lights are prevalent in inpatient healthcare facilities across the nation. While call light use directly influences the delivery of nursing care, there remain significant gaps both in research and technology that can impact the quality of care and patient satisfaction. This study examines the perception of nurses and patients on the use of a new call communication solution, Eloquence™, in the acute care inpatient setting. Eighteen patients were recruited for the study and participated in individual semi-structured interviews during their hospital stay. Eighteen nurses were recruited and participated in focus groups for this study. Qualitative descriptive methods were used to analyze the data. Results revealed themes of usability, improved communication, and suggestions for improvement to the alpha prototype design. After a demonstration of the use and capability of Eloquence™, nurse and patient participants found Eloquence™ as a welcomed advancement in nurse call technology that has the potential to improve workflow and patient outcomes. In addition, the participants also proposed ideas on how to further develop the technology to improve its use. PMID:26176639

Acoustic beam steering by light refraction: illustration with directivity patterns of a tilted volume photoacoustic source.

PubMed

Raetz, Samuel; Dehoux, Thomas; Perton, Mathieu; Audoin, Bertrand

2013-12-01

The symmetry of a thermoelastic source resulting from laser absorption can be broken when the direction of light propagation in an elastic half-space is inclined relatively to the surface. This leads to an asymmetry of the directivity patterns of both compressional and shear acoustic waves. In contrast to classical surface acoustic sources, the tunable volume source allows one to take advantage of the mode conversion at the surface to control the directivity of specific modes. Physical interpretations of the evolution of the directivity patterns with the increasing light angle of incidence and of the relations between the preferential directions of compressional- and shear-wave emission are proposed. In order to compare calculated directivity patterns with measurements of normal displacement amplitudes performed on plates, a procedure is proposed to transform the directivity patterns into pseudo-directivity patterns representative of the experimental conditions. The comparison of the theoretical with measured pseudo-directivity patterns demonstrates the ability to enhance bulk-wave amplitudes and to steer specific bulk acoustic modes by adequately tuning light refraction.

Excess Diffuse Light Absorption in Upper Mesophyll Limits CO2 Drawdown and Depresses Photosynthesis1[OPEN

PubMed Central

Gilbert, Matthew E.; McElrone, Andrew J.

2017-01-01

In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater irradiance of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared with direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level diffuse light photosynthetic depression effect is unknown. Here, we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown sunflower (Helianthus annuus) leaves underlies its previously observed diffuse light photosynthetic depression. Using a new one-dimensional porous medium finite element gas-exchange model parameterized with light absorption profiles, we found that weaker penetration of diffuse versus direct light into the mesophyll of sun-grown sunflower leaves led to a more heterogenous saturation of electron transport capacity and lowered its CO2 concentration drawdown capacity in the intercellular airspace and chloroplast stroma. This decoupling of light availability from photosynthetic capacity under diffuse light is sufficient to generate an 11% decline in photosynthesis in sun-grown but not shade-grown leaves, primarily because thin shade-grown leaves similarly distribute diffuse and direct light throughout the mesophyll. Finally, we illustrate how diffuse light photosynthetic depression could overcome enhancement in canopies with low light extinction coefficients and/or leaf area, pointing toward a novel direction for future research. PMID:28432257

Excess Diffuse Light Absorption in Upper Mesophyll Limits CO2 Drawdown and Depresses Photosynthesis.

PubMed

Earles, J Mason; Théroux-Rancourt, Guillaume; Gilbert, Matthew E; McElrone, Andrew J; Brodersen, Craig R

2017-06-01

In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater irradiance of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared with direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level diffuse light photosynthetic depression effect is unknown. Here, we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown sunflower ( Helianthus annuus ) leaves underlies its previously observed diffuse light photosynthetic depression. Using a new one-dimensional porous medium finite element gas-exchange model parameterized with light absorption profiles, we found that weaker penetration of diffuse versus direct light into the mesophyll of sun-grown sunflower leaves led to a more heterogenous saturation of electron transport capacity and lowered its CO 2 concentration drawdown capacity in the intercellular airspace and chloroplast stroma. This decoupling of light availability from photosynthetic capacity under diffuse light is sufficient to generate an 11% decline in photosynthesis in sun-grown but not shade-grown leaves, primarily because thin shade-grown leaves similarly distribute diffuse and direct light throughout the mesophyll. Finally, we illustrate how diffuse light photosynthetic depression could overcome enhancement in canopies with low light extinction coefficients and/or leaf area, pointing toward a novel direction for future research. © 2017 American Society of Plant Biologists. All Rights Reserved.

Influence of light absorption on relativistic self-focusing of Gaussian laser beam in cold quantum plasma

NASA Astrophysics Data System (ADS)

Patil, S. D.; Valkunde, A. T.; Vhanmore, B. D.; Urunkar, T. U.; Gavade, K. M.; Takale, M. V.

2018-05-01

When inter particle distance is comparable to the de Broglies wavelength of charged particles, quantum effects in plasmas are unavoidable. We have exploited an influence of light absorption on self-focusing of Gaussian laser beam in cold quantum plasma by considering relativistic nonlinearity. Nonlinear differential equation governing beam-width parameter has been established by using parabolic equation approach under paraxial and WKB approximations. The effect of light absorption on variation of beam-width parameter with dimensionless distance of propagation is presented graphically and discussed. It is found that light absorption plays vital role in weakening the relativistic self-focusing of laser beam during propagation in cold quantum plasma and gives reasonably interesting results.

Tunable pulsed narrow bandwidth light source

DOEpatents

Powers, Peter E.; Kulp, Thomas J.

2002-01-01

A tunable pulsed narrow bandwidth light source and a method of operating a light source are provided. The light source includes a pump laser, first and second non-linear optical crystals, a tunable filter, and light pulse directing optics. The method includes the steps of operating the pump laser to generate a pulsed pump beam characterized by a nanosecond pulse duration and arranging the light pulse directing optics so as to (i) split the pulsed pump beam into primary and secondary pump beams; (ii) direct the primary pump beam through an input face of the first non-linear optical crystal such that a primary output beam exits from an output face of the first non-linear optical crystal; (iii) direct the primary output beam through the tunable filter to generate a sculpted seed beam; and direct the sculpted seed beam and the secondary pump beam through an input face of the second non-linear optical crystal such that a secondary output beam characterized by at least one spectral bandwidth on the order of about 0.1 cm.sup.-1 and below exits from an output face of the second non-linear optical crystal.

Phototropism: translating light into directional growth.

PubMed

Hohm, Tim; Preuten, Tobias; Fankhauser, Christian

2013-01-01

Phototropism allows plants to align their photosynthetic tissues with incoming light. The direction of incident light is sensed by the phototropin family of blue light photoreceptors (phot1 and phot2 in Arabidopsis), which are light-activated protein kinases. The kinase activity of phototropins and phosphorylation of residues in the activation loop of their kinase domains are essential for the phototropic response. These initial steps trigger the formation of the auxin gradient across the hypocotyl that leads to asymmetric growth. The molecular events between photoreceptor activation and the growth response are only starting to be elucidated. In this review, we discuss the major steps leading from light perception to directional growth concentrating on Arabidopsis. In addition, we highlight links that connect these different steps enabling the phototropic response.

Direct and indirect effects of light pollution on the performance of an herbivorous insect.

PubMed

Grenis, Kylee; Murphy, Shannon M

2018-02-09

Light pollution is a global disturbance with resounding impacts on a wide variety of organisms, but our understanding of these impacts is restricted to relatively few higher vertebrate species. We tested the direct effects of light pollution on herbivore performance as well as indirect effects mediated by host plant quality. We found that artificial light from streetlights alters plant toughness. Additionally, we found evidence of both direct and indirect effects of light pollution on the performance of an herbivorous insect, which indicates that streetlights can have cascading impacts on multiple trophic levels. Our novel findings suggest that light pollution can alter plant-insect interactions and thus may have important community-wide consequences. © 2018 Institute of Zoology, Chinese Academy of Sciences.

Interaction of doughnut-shaped laser pulses with glasses

DOE PAGES

Zhukov, Vladimir P.; Rubenchik, Alexander M.; Fedoruk, Mikhail P.; ...

2017-01-26

Non-Gaussian laser beams can open new opportunities for microfabrication, including ultrashort laser direct writing. By using a model based on Maxwell’s equations, we investigate the dynamics of doughnut-shaped laser beams focused inside fused silica glass, in comparison with Gaussian pulses of the same energy. The laser propagation dynamics reveals intriguing features of beam splitting and sudden collapse toward the beam axis, overcoming the intensity clamping effect. The resulting structure of light absorption represents a very hot, hollow nanocylinder, which can lead to an implosion process that brings matter to extreme thermodynamic states. Furthermore, by monitoring the simulations of the lasermore » beam scattering we see a considerable difference in both the blueshift and the angular distribution of scattered light for different laser energies, suggesting that investigations of the spectra of scattered radiation can be used as a diagnostic of laser-produced electron plasmas in transparent materials.« less

Perspectives: Nanofibers and nanowires for disordered photonics

NASA Astrophysics Data System (ADS)

Pisignano, Dario; Persano, Luana; Camposeo, Andrea

2017-03-01

As building blocks of microscopically non-homogeneous materials, semiconductor nanowires and polymer nanofibers are emerging component materials for disordered photonics, with unique properties of light emission and scattering. Effects found in assemblies of nanowires and nanofibers include broadband reflection, significant localization of light, strong and collective multiple scattering, enhanced absorption of incident photons, synergistic effects with plasmonic particles, and random lasing. We highlight recent related discoveries, with a focus on material aspects. The control of spatial correlations in complex assemblies during deposition, the coupling of modes with efficient transmission channels provided by nanofiber waveguides, and the embedment of random architectures into individually coded nanowires will allow the potential of these photonic materials to be fully exploited, unconventional physics to be highlighted, and next-generation optical devices to be achieved. The prospects opened by this technology include enhanced random lasing and mode-locking, multi-directionally guided coupling to sensors and receivers, and low-cost encrypting miniatures for encoders and labels.

Analysis of particle in liquid using excitation-fluorescence spectral flow cytometer

NASA Astrophysics Data System (ADS)

Takenaka, Kei; Togashi, Shigenori

2018-01-01

We have developed a new flow cytometer that can measure the excitation-fluorescence spectra of a single particle. This system consists of a solution-transmitting unit and an optical unit. The solution-transmitting unit allows a sample containing particles to flow through the center of a flow cell by hydrodynamic focusing. The optical unit irradiates particles with dispersed white light (wavelength band: 400-650 nm) along the flow direction and measures their fluorescence spectra (wavelength band: 400-700 nm) using a spectroscopic photodetector array. The fluorescence spectrum of a particle changes with the shift of the wavelength of the excitation light. Using this system, the excitation-fluorescence spectra of a fluorescent particle were measured. Additionally, a homogenized tomato suspension and a homogenized spinach suspension were measured using the system. Measurement results show that it is possible to determine the components of vegetables by comparing measured fluorescence spectra of particles in a vegetable suspension.

Role of melatonin in the epigenetic regulation of breast cancer.

PubMed

Korkmaz, Ahmet; Sanchez-Barcelo, Emilio J; Tan, Dun-Xian; Reiter, Russel J

2009-05-01

The oncostatic properties of melatonin as they directly or indirectly involve epigenetic mechanisms of cancer are reviewed with a special focus on breast cancer. Five lines of evidence suggest that melatonin works via epigenetic processes: (1) melatonin influences transcriptional activity of nuclear receptors (ERalpha, GR and RAR) involved in the regulation of breast cancer cell growth; (2) melatonin down-regulates the expression of genes responsible for the local synthesis or activation of estrogens including aromatase, an effect which may be mediated by methylation of the CYP19 gene or deacetylation of CYP19 histones; (3) melatonin inhibits telomerase activity and expression induced by either natural estrogens or xenoestrogens; (4) melatonin modulates the cell cycle through the inhibition of cyclin D1 expression; (5) melatonin influences circadian rhythm disturbances dependent on alterations of the light/dark cycle (i.e., light at night) with the subsequent deregulation of PER2 which acts as a tumor suppressor gene.

In situ wavefront correction and its application to micromanipulation

NASA Astrophysics Data System (ADS)

Čižmár, Tomáš; Mazilu, Michael; Dholakia, Kishan

2010-06-01

In any optical system, distortions to a propagating wavefront reduce the spatial coherence of a light field, making it increasingly difficult to obtain the theoretical diffraction-limited spot size. Such aberrations are severely detrimental to optimal performance in imaging, nanosurgery, nanofabrication and micromanipulation, as well as other techniques within modern microscopy. We present a generic method based on complex modulation for true in situ wavefront correction that allows compensation of all aberrations along the entire optical train. The power of the method is demonstrated for the field of micromanipulation, which is very sensitive to wavefront distortions. We present direct trapping with optimally focused laser light carrying power of a fraction of a milliwatt as well as the first trapping through highly turbid and diffusive media. This opens up new perspectives for optical micromanipulation in colloidal and biological physics and may be useful for various forms of advanced imaging.

Generation of spiral optical beams using a spatial light modulator

NASA Astrophysics Data System (ADS)

Rodrigo, Peter J.; Alonzo, Carlo A.; Gluckstad, Jesper

2005-08-01

Recently, a new type of beam termed "spiral optical beam" has been introduced [Alonzo, et al., Opt. Express 13, 1749 (2005)]. Spiral beams are created from multiplicative mixtures of helical and conical phase distributions. Helico-conical phase fronts that generate these novel beams are not achieved with a sequence of a corkscrew wave-plate and an axicon (as this sequence gives a sum of helical and conical phase terms). Nevertheless, the availability of phase-only spatial light modulators (SLM) allows one to directly imprint helico-conical phase functions on an incident plane wave and provides an easy way to modify the profile of the encoded phase. Focusing the phase-modified field results in spiral intensity distributions that may find use for optical manipulation of mesoscopic particles. In this paper, we have extended the discussion to translation and rotation (as well as chirality switching) of the spiral beams using SLM control.

Accurate Modeling of Dark-Field Scattering Spectra of Plasmonic Nanostructures.

PubMed

Jiang, Liyong; Yin, Tingting; Dong, Zhaogang; Liao, Mingyi; Tan, Shawn J; Goh, Xiao Ming; Allioux, David; Hu, Hailong; Li, Xiangyin; Yang, Joel K W; Shen, Zexiang

2015-10-27

Dark-field microscopy is a widely used tool for measuring the optical resonance of plasmonic nanostructures. However, current numerical methods for simulating the dark-field scattering spectra were carried out with plane wave illumination either at normal incidence or at an oblique angle from one direction. In actual experiments, light is focused onto the sample through an annular ring within a range of glancing angles. In this paper, we present a theoretical model capable of accurately simulating the dark-field light source with an annular ring. Simulations correctly reproduce a counterintuitive blue shift in the scattering spectra from gold nanodisks with a diameter beyond 140 nm. We believe that our proposed simulation method can be potentially applied as a general tool capable of simulating the dark-field scattering spectra of plasmonic nanostructures as well as other dielectric nanostructures with sizes beyond the quasi-static limit.

Catalystlike effect of orbital angular momentum on the conversion of transverse to three-dimensional spin states within tightly focused radially polarized beams

NASA Astrophysics Data System (ADS)

Han, Lei; Liu, Sheng; Li, Peng; Zhang, Yi; Cheng, Huachao; Zhao, Jianlin

2018-05-01

We report on the catalystlike effect of orbital angular momentum (OAM) on local spin-state conversion within the tightly focused radially polarized beams associated with optical spin-orbit interaction. It is theoretically demonstrated that the incident OAM can lead to a conversion of purely transverse spin state to a three-dimensional spin state on the focal plane. This conversion can be conveniently manipulated by altering the sign and value of the OAM. By comparing the total OAM and spin angular momentum (SAM) on the incident plane to those on the focal plane, it is indicated that the incident OAM have no participation in the angular momentum intertransfer, and just play a role as a catalyst of local SAM conversion. Such an effect of OAM sheds new light on the optical spin-orbit interaction in tight-focusing processes. The resultant three-dimensional spin states may provide more degrees of freedom in optical manipulation and spin-dependent directive coupling.

Optical tweezers for the measurement of binding forces: system description and application for the study of E. coli adhesion

NASA Astrophysics Data System (ADS)

Fallman, Erik G.; Schedin, Staffan; Andersson, Magnus J.; Jass, Jana; Axner, Ove

2003-06-01

Optical tweezers together with a position sensitive detection system allows measurements of forces in the pN range between micro-sized biological objects. A prototype force measurement system has been constructed around in inverted microscope with an argon-ion pumped Ti:sapphire laser as light source for optical trapping. A trapped particle in the focus of the high numerical aperture microscope-objective behaves like an omni-directional mechanical spring if an external force displaces it. The displacement from the equilibrium position is a measure of the exerted force. For position detection of the trapped particle (polystyrene beads), a He-Ne laser beam is focused a small distance below the trapping focus. An image of the bead appears as a distinct spot in the far field, monitored by a photosensitive detector. The position data is converted to a force measurement by a calibration procedure. The system has been used for measuring the binding forces between E-coli bacterial adhesin and their receptor sugars.

Light collection optics for measuring flux and spectrum from light-emitting devices

DOEpatents

McCord, Mark A.; DiRegolo, Joseph A.; Gluszczak, Michael R.

2016-05-24

Systems and methods for accurately measuring the luminous flux and color (spectra) from light-emitting devices are disclosed. An integrating sphere may be utilized to directly receive a first portion of light emitted by a light-emitting device through an opening defined on the integrating sphere. A light collector may be utilized to collect a second portion of light emitted by the light-emitting device and direct the second portion of light into the integrating sphere through the opening defined on the integrating sphere. A spectrometer may be utilized to measure at least one property of the first portion and the second portion of light received by the integrating sphere.

Toward understanding as photosynthetic biosignatures: light harvesting and energy transfer calculation

NASA Astrophysics Data System (ADS)

Komatsu, Y.; Umemura, M.; Shoji, M.; Shiraishi, K.; Kayanuma, M.; Yabana, K.

2014-03-01

Among several proposed biosignatures, red edge is a direct evidence of photosynthetic life if it is detected (Kiang et al 2007). Red edge is a sharp change in reflectance spectra of vegetation in NIR region (about 700-750 nm). The sign of red edge is observed by Earthshine or remote sensing (Wolstencroft & Raven 2002, Woolf et al 2002). But, why around 700-750 nm? The photosynthetic organisms on Earth have evolved to optimize the sunlight condition. However, if we consider about photosynthetic organism on extrasolar planets, they should have developed to utilize the spectra of its principal star. Thus, it is not strange even if it shows different vegetation spectra. In this study, we focused on the light absorption mechanism of photosynthetic organisms on Earth and investigated the fundamental properties of the light harvesting mechanisms, which is the first stage for the light absorption. Light harvesting complexes contain photosynthetic pigments like chlorophylls. Effective light absorption and the energy transfer are accomplished by the electronic excitations of collective photosynthetic pigments. In order to investigate this mechanism, we constructed an energy transfer model by using a dipole-dipole approximation for the interactions between electronic excitations. Transition moments and transition energies of each pigment are calculated at the time-dependent density functional theory (TDDFT) level (Marques & Gross 2004). Quantum dynamics simulation for the excitation energy transfer was calculated by the Liouvelle's equation. We adopted the model to purple bacteria, which has been studied experimentally and known to absorb lower energy. It is meaningful to focus on the mechanism of this bacteria, since in the future mission, M planets will become a important target. We calculated the oscillator strengths in one light harvesting complex and confirmed the validity by comparing to the experimental data. This complex is made of an inner and an outer ring. The energy transfer from the outer to the inner ring can be reproduced. To deal with a realistic system, we calculated at a macro structural model. The energy transfer between light harvesting complexes is accomplished rapidly via inner rings. By exchange the original pigment to a pigment absorb lower energy, faster energy transfer occurs and the density was trapped in pigment having lower energy. We will compare the result of purple bacteria, which is considered to show longer red edge, cyanobacteria and plants.

The dark side of the alpha rhythm: fMRI evidence for induced alpha modulation during complete darkness.

PubMed

Ben-Simon, Eti; Podlipsky, Ilana; Okon-Singer, Hadas; Gruberger, Michal; Cvetkovic, Dean; Intrator, Nathan; Hendler, Talma

2013-03-01

The unique role of the EEG alpha rhythm in different states of cortical activity is still debated. The main theories regarding alpha function posit either sensory processing or attention allocation as the main processes governing its modulation. Closing and opening eyes, a well-known manipulation of the alpha rhythm, could be regarded as attention allocation from inward to outward focus though during light is also accompanied by visual change. To disentangle the effects of attention allocation and sensory visual input on alpha modulation, 14 healthy subjects were asked to open and close their eyes during conditions of light and of complete darkness while simultaneous recordings of EEG and fMRI were acquired. Thus, during complete darkness the eyes-open condition is not related to visual input but only to attention allocation, allowing direct examination of its role in alpha modulation. A data-driven ridge regression classifier was applied to the EEG data in order to ascertain the contribution of the alpha rhythm to eyes-open/eyes-closed inference in both lighting conditions. Classifier results revealed significant alpha contribution during both light and dark conditions, suggesting that alpha rhythm modulation is closely linked to the change in the direction of attention regardless of the presence of visual sensory input. Furthermore, fMRI activation maps derived from an alpha modulation time-course during the complete darkness condition exhibited a right frontal cortical network associated with attention allocation. These findings support the importance of top-down processes such as attention allocation to alpha rhythm modulation, possibly as a prerequisite to its known bottom-up processing of sensory input. © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Directional and Spectral Irradiance in Ocean Models: Effects on Simulated Global Phytoplankton, Nutrients, and Primary Production

NASA Technical Reports Server (NTRS)

Gregg, Watson W.; Rousseaux, Cecile S.

2016-01-01

The importance of including directional and spectral light in simulations of ocean radiative transfer was investigated using a coupled biogeochemical-circulation-radiative model of the global oceans. The effort focused on phytoplankton abundances, nutrient concentrations and vertically-integrated net primary production. The importance was approached by sequentially removing directional (i.e., direct vs. diffuse) and spectral irradiance and comparing results of the above variables to a fully directionally and spectrally-resolved model. In each case the total irradiance was kept constant; it was only the pathways and spectral nature that were changed. Assuming all irradiance was diffuse had negligible effect on global ocean primary production. Global nitrate and total chlorophyll concentrations declined by about 20% each. The largest changes occurred in the tropics and sub-tropics rather than the high latitudes, where most of the irradiance is already diffuse. Disregarding spectral irradiance had effects that depended upon the choice of attenuation wavelength. The wavelength closest to the spectrally-resolved model, 500 nm, produced lower nitrate (19%) and chlorophyll (8%) and higher primary production (2%) than the spectral model. Phytoplankton relative abundances were very sensitive to the choice of non-spectral wavelength transmittance. The combined effects of neglecting both directional and spectral irradiance exacerbated the differences, despite using attenuation at 500 nm. Global nitrate decreased 33% and chlorophyll decreased 24%. Changes in phytoplankton community structure were considerable, representing a change from chlorophytes to cyanobacteria and coccolithophores. This suggested a shift in community function, from light-limitation to nutrient limitation: lower demands for nutrients from cyanobacteria and coccolithophores favored them over the more nutrient-demanding chlorophytes. Although diatoms have the highest nutrient demands in the model, their relative abundances were generally unaffected because they only prosper in nutrient-rich regions, such as the high latitudes and upwelling regions, which showed the fewest effects from the changes in radiative simulations. The results showed that including directional and spectral irradiance when simulating the ocean light field can be important for ocean biology, but the magnitude varies with variables and regions. The quantitative results are intended to assist ocean modelers when considering improved irradiance representations relative to other processes or variables associated with the issues of interest.

Gregorian optical system with non-linear optical technology for protection against intense optical transients

DOEpatents

Ackermann, Mark R [Albuquerque, NM; Diels, Jean-Claude M [Albuquerque, NM

2007-06-26

An optical system comprising a concave primary mirror reflects light through an intermediate focus to a secondary mirror. The secondary mirror re-focuses the image to a final image plane. Optical limiter material is placed near the intermediate focus to optically limit the intensity of light so that downstream components of the optical system are protected from intense optical transients. Additional lenses before and/or after the intermediate focus correct optical aberrations.

Compact laser amplifier system

DOEpatents

Carr, R.B.

1974-02-26

A compact laser amplifier system is described in which a plurality of face-pumped annular disks, aligned along a common axis, independently radially amplify a stimulating light pulse. Partially reflective or lasing means, coaxially positioned at the center of each annualar disk, radially deflects a stimulating light directed down the common axis uniformly into each disk for amplification, such that the light is amplified by the disks in a parallel manner. Circumferential reflecting means coaxially disposed around each disk directs amplified light emission, either toward a common point or in a common direction. (Official Gazette)

Effect of health messages about "Light" and "Ultra Light" cigarettes on beliefs and quitting intent.

PubMed

Shiffman, S; Pillitteri, J L; Burton, S L; Rohay, J M; Gitchell, J G

2001-01-01

To test the impact of three health messages focusing on vent holes, sensory effects of Light and Ultra Light cigarettes, or health consequences of smoking, respectively, on beliefs and quitting intentions. In the course of a random digit dialed telephone survey, subjects were randomised to hear one of three messages. To test the effects of the messages, beliefs and quitting intentions were assessed both pre- and post-message. Daily smokers (n = 2120) of Regular (46%), Light (39%), and Ultra Light (15%) cigarettes in the USA. The sample was weighted to match the US smoker population on age, sex, and ethnicity. Beliefs were summarised on three dimensions: Safety (reduced health risk), Delivery (lower tar and nicotine delivery), and Sensation (less harsh). Quitting interest was captured by the "quit index", an aggregate measure of quitting interest and intent. The message focusing on smokers' sensory perceptions of Light and Ultra Light cigarettes resulted in the most positive change in beliefs about safety, delivery, and intent to quit, and was particularly effective among those who believed that these cigarettes were less harsh. The effect was most pronounced among young adults, and among smokers of Light and Ultra Light brands who most endorsed their sensory benefits. Addressing smokers' sensory experience that Light and Ultra Light cigarettes feel less harsh may be a promising strategy for changing their misconceptions about these cigarettes and enhancing their interest in quitting. Media counter-advertising on Lights and Ultra Lights, focusing on sensory aspects of these cigarettes, may be an important part of tobacco control efforts.

Detailed study on the statistical properties of optimized phase distribution in focusing light through turbid media

NASA Astrophysics Data System (ADS)

Zhang, Xicheng; Fang, Longjie; Zuo, Haoyi; Du, Jinglei; Gao, Fuhua; Pang, Lin

2018-07-01

It is studied in detail that whether the optimized phase distributions obtained from different approaches have relations in focusing light through turbid media. A view is proposed that there exists a strong correlation among the optimized phase distributions from different approaches. The numeric simulations and experiments indicate that the larger the number of segments is, the greater the correlation coefficient of optimized phase distributions from different approaches will be. This study might give an important insight into the essence of focusing light through turbid media by phase modulation.

Multi-pass light amplifier

NASA Technical Reports Server (NTRS)

Plaessmann, Henry (Inventor); Grossman, William M. (Inventor)

1997-01-01

A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A confocal resonator or White Cell resonator is provided, including two or three curvilinearly shaped mirrors facing each other along a resonator axis and an optical gain medium positioned on the resonator axis between the mirrors (confocal resonator) or adjacent to one of the mirrors (White Cell). In a first embodiment, two mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. The optical gain medium may be solid-state, liquid or gaseous medium and may be pumped longitudinally or transversely. In a second embodiment, first and second mirrors face a third mirror in a White Cell configuration, and the optical gain medium is positioned at or adjacent to one of the mirrors. Defocusing means and optical gain medium cooling means are optionally provided with either embodiment, to controllably defocus the light beam, to cool the optical gain medium and to suppress thermal lensing in the gain medium.

Experimental illumination of natural habitat—an experimental set-up to assess the direct and indirect ecological consequences of artificial light of different spectral composition

PubMed Central

Spoelstra, Kamiel; van Grunsven, Roy H. A.; Donners, Maurice; Gienapp, Phillip; Huigens, Martinus E.; Slaterus, Roy; Berendse, Frank; Visser, Marcel E.; Veenendaal, Elmar

2015-01-01

Artificial night-time illumination of natural habitats has increased dramatically over the past few decades. Generally, studies that assess the impact of artificial light on various species in the wild make use of existing illumination and are therefore correlative. Moreover, studies mostly focus on short-term consequences at the individual level, rather than long-term consequences at the population and community level—thereby ignoring possible unknown cascading effects in ecosystems. The recent change to LED lighting has opened up the exciting possibility to use light with a custom spectral composition, thereby potentially reducing the negative impact of artificial light. We describe here a large-scale, ecosystem-wide study where we experimentally illuminate forest-edge habitat with different spectral composition, replicated eight times. Monitoring of species is being performed according to rigid protocols, in part using a citizen-science-based approach, and automated where possible. Simultaneously, we specifically look at alterations in behaviour, such as changes in activity, and daily and seasonal timing. In our set-up, we have so far observed that experimental lights facilitate foraging activity of pipistrelle bats, suppress activity of wood mice and have effects on birds at the community level, which vary with spectral composition. Thus far, we have not observed effects on moth populations, but these and many other effects may surface only after a longer period of time. PMID:25780241

Experimental illumination of natural habitat--an experimental set-up to assess the direct and indirect ecological consequences of artificial light of different spectral composition.

PubMed

Spoelstra, Kamiel; van Grunsven, Roy H A; Donners, Maurice; Gienapp, Phillip; Huigens, Martinus E; Slaterus, Roy; Berendse, Frank; Visser, Marcel E; Veenendaal, Elmar

2015-05-05

Artificial night-time illumination of natural habitats has increased dramatically over the past few decades. Generally, studies that assess the impact of artificial light on various species in the wild make use of existing illumination and are therefore correlative. Moreover, studies mostly focus on short-term consequences at the individual level, rather than long-term consequences at the population and community level-thereby ignoring possible unknown cascading effects in ecosystems. The recent change to LED lighting has opened up the exciting possibility to use light with a custom spectral composition, thereby potentially reducing the negative impact of artificial light. We describe here a large-scale, ecosystem-wide study where we experimentally illuminate forest-edge habitat with different spectral composition, replicated eight times. Monitoring of species is being performed according to rigid protocols, in part using a citizen-science-based approach, and automated where possible. Simultaneously, we specifically look at alterations in behaviour, such as changes in activity, and daily and seasonal timing. In our set-up, we have so far observed that experimental lights facilitate foraging activity of pipistrelle bats, suppress activity of wood mice and have effects on birds at the community level, which vary with spectral composition. Thus far, we have not observed effects on moth populations, but these and many other effects may surface only after a longer period of time. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Light propagation analysis in nervous tissue for wireless optogenetic nanonetworks

NASA Astrophysics Data System (ADS)

Wirdatmadja, Stefanus; Johari, Pedram; Balasubramaniam, Sasitharan; Bae, Yongho; Stachowiak, Michal K.; Jornet, Josep M.

2018-02-01

In recent years, numerous methods have been sought for developing novel solutions to counter neurodegenerative diseases. An objective that is being investigated by researchers is to develop cortical implants that are able to wirelessly stimulate neurons at the single cell level. This is a major development compared to current solutions that use electrodes, which are only able to target a population of neurons, or optogenetics, which requires optical fiber-leads to be embedded deep into the brain. In this direction, the concept of wireless optogenetic nanonetworks has been recently introduced. In such architecture, miniature devices are implanted in the cortex for neuronal stimulation through optogenetics. One of the aspects that will determine the topology and performance of wireless optogenetic nanonetworks is related to light propagation in genetically-engineered neurons. In this paper, a channel model that captures the peculiarities of light propagation in neurons is developed. First, the light propagation behavior using the modified Beer-Lambert law is analyzed based on the photon transport through the nervous tissue. This includes analyzing the scattering light diffraction and diffusive reflection that results from the absorption of neural cell chromophores, as well as validating the results by means of extensive multiphysics simulations. Then, analysis is conducted on the path loss through cells at different layers of the cortex by taking into account the multi-path phenomenon. Results show that there is a light focusing effect in the soma of neurons that can potentially help the to stimulate the target cells.

GaAs/GaAlAs distributed Bragg reflector laser with a focused ion beam, low dose dopant implanted grating

NASA Technical Reports Server (NTRS)

Wu, M. C.; Boenke, M. M.; Wang, S.; Clark, W. M., Jr.; Stevens, E. H.

1988-01-01

The performance of a GaAs/GaAlAs distributed Bragg reflector (DBR) laser using a focused ion beam implanted grating (FIB-DBR) is reported for the first time. Stripes of Si(2+) with a period of 2300 A and a dose about 10 to the 14th/sq cm are directly implanted into the passive large optical cavity layer to provide the distributed feedback. Surface-emitting light from the second-order grating is observed. Threshold current of 110 mA and single DBR mode operation from 20 to 40 C are obtained. The wavelength tuning rate with temperature is 0.8 A/C. The coupling coefficient is estimated to be 15/cm. The results show that FIB technology is practical for distributed feedback and DBR lasers and optoelectronic integrated circuits.

New Assumptions to Guide SETI Research

NASA Technical Reports Server (NTRS)

Colombano, S. P.

2018-01-01

The recent Kepler discoveries of Earth-like planets offer the opportunity to focus our attention on detecting signs of life and technology in specific planetary systems, but I feel we need to become more flexible in our assumptions. The reason is that, while it is still reasonable and conservative to assume that life is most likely to have originated in conditions similar to ours, the vast time differences in potential evolutions render the likelihood of "matching" technologies very slim. In light of these challenges I propose a more "aggressive"� approach to future SETI exploration in directions that until now have received little consideration.

Influencing of various phosphor parameters on the LED performance

NASA Astrophysics Data System (ADS)

Wu, Yi Ping; Zhang, Shu Qin; Jin, Shang-zhong; Shi, Chang Shou; Li, Liang; Yu, RenYong

2012-10-01

In this paper ,the advantages and disadvantages of the methods to achieve White LED are reviewed, and phosphor-converted white LEDs are discussed in detail. In the case of blue chip exciting YAG phosphor to get white LED, use Mie scattering theory to construct physical model, then analyze how the package, concentration, thickness and particle size of phosphor work on extraction efficiency, spatial Chroma uniformity and color temperature of white LED. The conclusion of this paper advances the application of LED solid-state light source. In the end, the paper puts forward the direction and focus of phosphor research.

Contraceptives of the future in the light of HIV infection.

PubMed

Short, R V

1994-06-01

The AIDS and sexually transmissible disease pandemics have helped to focus the world's attention on the need for good protection against transmission of infections during sexual intercourse. Most of the highly effective modern contraceptives provide only limited protection against STD transmission, although recent progress with the development of loose-fitting plastic male condoms and new spermicides gives some hope. Urgent attention must continue to be given to contraceptives with STD protective qualities which are under the woman's control. Refinements of the female condom and vaginal sponges with new spermicides and microbicides may be a step in this direction.

Quenching of light flickering in synthetic guanine crystals in aqueous solutions under strong static magnetic fields

NASA Astrophysics Data System (ADS)

Mootha, A.; Takanezawa, Y.; Iwasaka, M.

2018-05-01

The present study focused on the vibration of micro crystal particles of guanine due to Brownian motion. The organic particle has a refractive index of 1.83 and caused a flickering of light. To test the possibility of using magnetic properties under wet conditions, changes in the frequency of particle vibration by applying magnetic fields were investigated. At first, we found that the exposure at 5 T inhibited the flickering light intensities and the particle vibration slightly decreased. Next, we carried out a high speed camera measurement of the Brownian motion of the particle with a time resolution of 100 flame per second (fps) with and without magnetic field exposures. It was revealed that the vibrational speed of synthetic particles was enhanced at 500 mT. Detailed analyses of the particle vibration by changing the direction of magnetic fields versus the light source revealed that the Brownian motion's vibrational frequency was entrained under magnetic fields at 500 mT, and an increase in vibration speed to 20Hz was observed. Additional measurements of light scattering fluctuation using photo-detector and analyses on auto-correlation also confirmed this speculation. The studied Brownian vibration may be influenced by the change in mechanical interactions between the vibration particles and surrounding medium. The discovered phenomena can be applied for molecular and biological interactions in future studies.

Standard guidelines of care: laser and IPL hair reduction.

PubMed

Buddhadev, Rajesh M

2008-01-01

Laser-assisted hair removal, Laser hair removal, Laser and light-assisted hair removal, Laser and light-assisted, long-term hair reduction, IPL photodepilation, LHE photodepilation; all these are acceptable synonyms. Laser (Ruby, Nd Yag, Alexandrite, Diode), intense pulse light, light and heat energy system are the different light-/Laser-based systems used for hair removal; each have its advantages and disadvantages. The word "LONG-TERM HAIR REDUCTION" should be used rather than permanent hair removal. Patient counseling is essential about the need for multiple sessions. PHYSICIANS' QUALIFICATIONS: Laser hair removal may be practiced by any dermatologist, who has received adequate background training during postgraduation or later at a centre that provides education and training in Lasers or in focused workshops providing such training. The dermatologist should have adequate knowledge of the machines, the parameters and aftercare. The physician may allow the actual procedure to be performed under his/her direct supervision by a trained nurse assistant/junior doctor. However, the final responsibility for the procedure would lie with the physician. The procedure may be performed in the physician's minor procedure room. Investigations to rule out any underlying cause for hair growth are important; concurrent drug therapy may be needed. Laser parameters vary with area, type of hair, and the machine used. Full knowledge about the machine and cooling system is important. Future maintenance treatments may be needed.

Wide acceptance angle, high concentration ratio, optical collector

NASA Technical Reports Server (NTRS)

Kruer, Mark Arthur (Inventor)

1990-01-01

The invention is directed to an optical collector requiring a wide acceptance angle, and a high concentration ratio. The invention is particularly adapted for use in solar collectors of cassegrain design. The optical collector system includes a parabolic circular concave primary mirror and a hyperbolic circular convex secondary mirror. The primary mirror includes a circular hole located at its center wherein a solar collector is located. The mirrored surface of the secondary mirror has three distinct zones: a center circle, an on-axis annulus, and an off-axis section. The parabolic shape of the primary mirror is chosen so that the primary mirror reflects light entering the system on-axis onto the on-axis annulus. A substantial amount of light entering the system off-axis is reflected by the primary mirror onto either the off-axis section or onto the center circle. Subsequently, the off-axis sections reflect the off-axis light toward the solar collector. Thus, off-axis light is captured which would otherwise be lost to the system. The novelty of the system appears to lie in the configuration of the primary mirror which focuses off-axis light onto an annular portion of the secondary mirror to enable capture thereof. This feature results in wide acceptance angle and a high concentration ratio, and also compensates for the effects of non-specular reflection, and enables a cassegrain configuration to be used where such characteristics are required.

How Noniridescent Colors Are Generated by Quasi-ordered Structures of Bird Feathers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noh, Heeso; Liew, Seng Fatt; Saranathan, Vinodkumar

2012-03-26

We investigate the mechanism of structural coloration by quasi-ordered nanostructures in bird feather barbs. Small-angle X-ray scattering (SAXS) data reveal the structures are isotropic and have short-range order on length scales comparable to optical wavelengths. We perform angle-resolved reflection and scattering spectrometry to fully characterize the colors under directional and omni-directional illumination of white light. Under directional lighting, the colors change with the angle between the directions of illumination and observation. The angular dispersion of the primary peaks in the scattering/reflection spectra can be well explained by constructive interference of light that is scattered only once in the quasi-ordered structures.more » Using the Fourier power spectra of structure from the SAXS data we calculate optical scattering spectra and explain why the light scattering peak is the highest in the backscattering direction. Under omni-directional lighting, colors from the quasi-ordered structures are invariant with the viewing angle. The non-iridescent coloration results from the isotropic nature of structures instead of strong backscattering.« less

In situ realization of asymmetric ratchet structures within microchannels by directionally guided light transmission and their directional flow behavior.

PubMed

Bae, Won-Gyu; Kim, Sang Moon; Choi, Se-Jin; Oh, Sang Geun; Yoon, Hyunsik; Char, Kookheon; Suh, Kahp Y

2014-05-01

An asymmetric ratchet structure within microchannels is demonstrated by directionally guided light transmission for controlled liquid flow. A direct and facile method is presented to realize programmed asymmetric structures, which control the fluid direction and speed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interactions between the visual and the magnetoreception system: different effects of bichromatic light regimes on the directional behavior of migratory birds.

PubMed

Wiltschko, Roswitha; Dehe, Lars; Gehring, Dennis; Thalau, Peter; Wiltschko, Wolfgang

2013-01-01

When magnetic compass orientation of migratory robins was tested, the birds proved well oriented under low intensity monochromatic light of shorter wavelengths up to 565 nm green; from 583 nm yellow onward, they were disoriented. In the present study, we tested robins under bichromatic lights composed (1) of 424 nm blue and 565 nm green and (2) of 565 nm green and 583 nm yellow at two intensities. Under dim blue-green light with a total quantal flux of ca. 8 × 10(15)quanta/sm(2), the birds were well oriented in their migratory direction by their inclination compass; under blue-green light of twice this intensity, their orientation became axial. In both cases, the magnetic directional information was mediated by the radical pair processes in the eye. When green and yellow light were combined, however, the nature of the behavior changed. Under green-yellow light of the higher intensity, the birds showed a 'fixed direction' response that was polar, no longer controlled by the normal inclination compass; under dim green-yellow light, the response became axial. Under these two light conditions, the respective directional information was mediated by the magnetite-based receptors in the skin of the upper beak. Apparently, yellow light leads to a change from one magnetoreception system to the other. How this change is effected is still unknown; it appears to reflect complex interactions between the visual and the two magnetoreception systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Computational Modeling to Limit the Impact Displays and Indicator Lights Have on Habitable Volume Operational Lighting Constraints

NASA Technical Reports Server (NTRS)

Clark, T. A.; Brainard, G.; Salazar, G.; Johnston, S.; Schwing, B.; Litaker, H.; Kolomenski, A.; Venus, D.; Tran, K.; Hanifin, J.;

Effects of Light Regimes on the Biomass and Morphological Characteristics of 2-Year-Old Cherrybark Oak Seedlings

Treesearch

Yanfei Guo; Michael G. Shelton

2004-01-01

We used modified shadehouses to simulate the complex light conditions within forest openings and tested the effects of time of direct light exposure, the ratio of direct light to day length, and daily photosynthetically active radiation on aboveground biomass and morphological characteristics of 2-year-old cherrybark oak (Quercus pagoda Raf.)...

Metrology System for a Large, Somewhat Flexible Telescope

NASA Technical Reports Server (NTRS)

Liebe, Carl Christian; Bartman, Randall; Cook, Walter; Craig, William

2009-01-01

A proposed metrology system would be incorporated into a proposed telescope that would include focusing optics on a rigid bench connected via a deployable mast to another rigid bench holding a focal-plane array of photon counting photodetectors. Deformations of the deployable mast would give rise to optical misalignments that would alter the directions (and, hence, locations) of incidence of photons on the focal plane. The metrology system would measure the relative displacement of the focusing- optics bench and the focal-plane array bench. The measurement data would be used in post-processing of the digitized photodetector outputs to compensate for the mast-deformation-induced changes in the locations of incidence of photons on the focal plane, thereby making it possible to determine the original directions of incidence of photons with greater accuracy. The proposed metrology system is designed specifically for the Nuclear Spectroscopic Telescope Array (NuSTAR) a proposed spaceborne x-ray telescope. The basic principles of design and operation are also applicable to other large, somewhat flexible telescopes, both terrestrial and spaceborne. In the NuSTAR, the structural member connecting the optical bench and the photodetector array would be a 10-m-long deployable mast, and there is a requirement to keep errors in measured directions of incidence of photons below 10 arc seconds (3 sigma). The proposed system would include three diode lasers that would be mounted on the focusing-optics bench. For clarity, only one laser is shown in the figure, which is a greatly simplified schematic diagram of the system. Each laser would be aimed at a position-sensitive photodiode that would be mounted on the detector bench alongside the aforementioned telescope photodetector array. The diode lasers would operate at a wavelength of 830 nm, each at a power of 200 mW. Each laser beam would be focused to a spot of .1-mm diameter on the corresponding position-sensitive photodiode. To reduce the effect of sunlight on the measurements, a one-stage light baffle and an 830-nm transmission filter of 10-nm bandwidth would be placed in front of the position- sensitive photodiode. For each metrology reading, the output of the position-sensitive detector would be sampled and digitized twice: once with the lasers turned on, then once with the lasers turned off. The data from these two sets of samples would be subtracted from each other to further reduce the effects of sun glints or other background light sources.

Maskless direct laser writing with visible light: Breaking through the optical resolving limit with cooperative manipulations of nonlinear reverse saturation absorption and thermal diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Jingsong, E-mail: weijingsong@siom.ac.cn; Wang, Rui; University of Chinese Academy of Sciences, Beijing 100049

In this work, the resolving limit of maskless direct laser writing is overcome by cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion, where the nonlinear reverse saturation absorption can induce the formation of below diffraction-limited energy absorption spot, and the thermal diffusion manipulation can make the heat quantity at the central region of energy absorption spot propagate along the thin film thickness direction. The temperature at the central region of energy absorption spot transiently reaches up to melting point and realizes nanolithography. The sample “glass substrate/AgInSbTe” is prepared, where AgInSbTe is taken as nonlinear reverse saturation absorption thinmore » film. The below diffraction-limited energy absorption spot is simulated theoretically and verified experimentally by near-field spot scanning method. The “glass substrate/Al/AgInSbTe” sample is prepared, where the Al is used as thermal conductive layer to manipulate the thermal diffusion channel because the thermal diffusivity coefficient of Al is much larger than that of AgInSbTe. The direct laser writing is conducted by a setup with a laser wavelength of 650 nm and a converging lens of NA=0.85, the lithographic marks with a size of about 100 nm are obtained, and the size is only about 1/10 the incident focused spot. The experimental results indicate that the cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion is a good method to realize nanolithography in maskless direct laser writing with visible light.« less

Light field image denoising using a linear 4D frequency-hyperfan all-in-focus filter

NASA Astrophysics Data System (ADS)

Dansereau, Donald G.; Bongiorno, Daniel L.; Pizarro, Oscar; Williams, Stefan B.

2013-02-01

Imaging in low light is problematic as sensor noise can dominate imagery, and increasing illumination or aperture size is not always effective or practical. Computational photography offers a promising solution in the form of the light field camera, which by capturing redundant information offers an opportunity for elegant noise rejection. We show that the light field of a Lambertian scene has a 4D hyperfan-shaped frequency-domain region of support at the intersection of a dual-fan and a hypercone. By designing and implementing a filter with appropriately shaped passband we accomplish denoising with a single all-in-focus linear filter. Drawing examples from the Stanford Light Field Archive and images captured using a commercially available lenselet- based plenoptic camera, we demonstrate that the hyperfan outperforms competing methods including synthetic focus, fan-shaped antialiasing filters, and a range of modern nonlinear image and video denoising techniques. We show the hyperfan preserves depth of field, making it a single-step all-in-focus denoising filter suitable for general-purpose light field rendering. We include results for different noise types and levels, over a variety of metrics, and in real-world scenarios. Finally, we show that the hyperfan's performance scales with aperture count.

A novel calibration method of focused light field camera for 3-D reconstruction of flame temperature

NASA Astrophysics Data System (ADS)

Sun, Jun; Hossain, Md. Moinul; Xu, Chuan-Long; Zhang, Biao; Wang, Shi-Min

2017-05-01

This paper presents a novel geometric calibration method for focused light field camera to trace the rays of flame radiance and to reconstruct the three-dimensional (3-D) temperature distribution of a flame. A calibration model is developed to calculate the corner points and their projections of the focused light field camera. The characteristics of matching main lens and microlens f-numbers are used as an additional constrains for the calibration. Geometric parameters of the focused light field camera are then achieved using Levenberg-Marquardt algorithm. Total focused images in which all the points are in focus, are utilized to validate the proposed calibration method. Calibration results are presented and discussed in details. The maximum mean relative error of the calibration is found less than 0.13%, indicating that the proposed method is capable of calibrating the focused light field camera successfully. The parameters obtained by the calibration are then utilized to trace the rays of flame radiance. A least square QR-factorization algorithm with Plank's radiation law is used to reconstruct the 3-D temperature distribution of a flame. Experiments were carried out on an ethylene air fired combustion test rig to reconstruct the temperature distribution of flames. The flame temperature obtained by the proposed method is then compared with that obtained by using high-precision thermocouple. The difference between the two measurements was found no greater than 6.7%. Experimental results demonstrated that the proposed calibration method and the applied measurement technique perform well in the reconstruction of the flame temperature.

Distance and direction, but not light cues, support response reversal learning.

PubMed

Wright, S L; Martin, G M; Thorpe, C M; Haley, K; Skinner, D M

2018-03-05

Across three experiments, we examined the cuing properties of metric (distance and direction) and nonmetric (lighting) cues in different tasks. In Experiment 1, rats were trained on a response problem in a T-maze, followed by four reversals. Rats that experienced a change in maze orientation (Direction group) or a change in the length of the start arm (Distance group) across reversals showed facilitation of reversal learning relative to a group that experienced changes in room lighting across reversals. In Experiment 2, rats learned a discrimination task more readily when distance or direction cues were used than when light cues were used as the discriminative stimuli. In Experiment 3, performance on a go/no-go task was equivalent using both direction and lighting cues. The successful use of both metric and nonmetric cues in the go/no-go task indicates that rats are sensitive to both types of cues and that the usefulness of different cues is dependent on the nature of the task.

An Overview of Monthly Rhythms and Clocks

PubMed Central

Raible, Florian; Takekata, Hiroki; Tessmar-Raible, Kristin

2017-01-01

Organisms have evolved to cope with geophysical cycles of different period lengths. In this review, we focus on the adaptations of animals to the lunar cycle, specifically, on the occurrence of biological rhythms with monthly (circalunar) or semi-monthly (circasemilunar) period lengths. Systematic experimental investigation, starting in the early twentieth century, has allowed scientists to distinguish between mythological belief and scientific facts concerning the influence of the lunar cycle on animals. These studies revealed that marine animals of various taxa exhibit circalunar or circasemilunar reproductive rhythms. Some of these rely on endogenous oscillators (circalunar or circasemilunar clocks), whereas others are directly driven by external cues, such as the changes in nocturnal illuminance. We review current insight in the molecular and cellular mechanisms involved in circalunar rhythms, focusing on recent work in corals, annelid worms, midges, and fishes. In several of these model systems, the transcript levels of some core circadian clock genes are affected by both light and endogenous circalunar oscillations. How these and other molecular changes relate to the changes in physiology or behavior over the lunar cycle remains to be determined. We further review the possible relevance of circalunar rhythms for terrestrial species, with a particular focus on mammalian reproduction. Studies on circalunar rhythms of conception or birth rates extend to humans, where the lunar cycle was suggested to also affect sleep and mental health. While these reports remain controversial, factors like the increase in “light pollution” by artificial light might contribute to discrepancies between studies. We finally discuss the existence of circalunar oscillations in mammalian physiology. We speculate that these oscillations could be the remnant of ancient circalunar oscillators that were secondarily uncoupled from a natural entrainment mechanism, but still maintained relevance for structuring the timing of reproduction or physiology. The analysis and comparison of circalunar rhythms and clocks are currently challenging due to the heterogeneity of samples concerning species diversity, environmental conditions, and chronobiological conditions. We suggest that future research will benefit from the development of standardized experimental paradigms, and common principles for recording and reporting environmental conditions, especially light spectra and intensities. PMID:28553258

Biomimetic light-harvesting funnels for re-directioning of diffuse light.

PubMed

Pieper, Alexander; Hohgardt, Manuel; Willich, Maximilian; Gacek, Daniel Alexander; Hafi, Nour; Pfennig, Dominik; Albrecht, Andreas; Walla, Peter Jomo

2018-02-14

Efficient sunlight harvesting and re-directioning onto small areas has great potential for more widespread use of precious high-performance photovoltaics but so far intrinsic solar concentrator loss mechanisms outweighed the benefits. Here we present an antenna concept allowing high light absorption without high reabsorption or escape-cone losses. An excess of randomly oriented pigments collects light from any direction and funnels the energy to individual acceptors all having identical orientations and emitting ~90% of photons into angles suitable for total internal reflection waveguiding to desired energy converters (funneling diffuse-light re-directioning, FunDiLight). This is achieved using distinct molecules that align efficiently within stretched polymers together with others staying randomly orientated. Emission quantum efficiencies can be >80% and single-foil reabsorption <0.5%. Efficient donor-pool energy funneling, dipole re-orientation, and ~1.5-2 nm nearest donor-acceptor transfer occurs within hundreds to ~20 ps. Single-molecule 3D-polarization experiments confirm nearly parallel emitters. Stacked pigment selection may allow coverage of the entire solar spectrum.

Fabrication of novel bundled fiber and performance assessment for clinical applications.

PubMed

Kim, Changhwan; Jeon, Myung Jin; Jung, Jin Hyang; Yang, Jung Dug; Park, Hoyong; Kang, Hyun Wook; Lee, Ho

2014-11-01

During laser vaporization of benign prostate hyperplasia (BPH), high precision of optical fiber handling is pivotal to minimize any post-operative complications. The aim of the study was to evaluate the feasible applications of a bundled fiber to treat BPH by directionally and selectively manipulating laser light onto the targeted tissue. A bundled optical fiber, consisting of four side-firing fibers, was fabricated to selectively emit laser beams in from one to four directions. Both transmission efficiency and light distribution were qualitatively and quantitatively characterized on the bundled fiber. In terms of interstitial application of the proposed fiber with 1064 nm on porcine liver tissue, the extent of thermal denaturation was estimated and compared at various laser parameterizations and for different directions of light. From the laser source to the fiber tip, the fabricated fiber device demonstrated a total light transmission of 52%. Due to internal light reflection, a secondary beam was emitted backward from the fiber tip and was responsible for 25% of the transmission loss. According to tissue testing, the extent of tissue denaturation generally increased with laser power, irradiation time, and number of light directions. The geometrical shape of thermal coagulation correlated well with the direction of light emission. Thermal damage to the glass tube occurred during excessive heat accumulation generated by continuous irradiation. The proposed fiber can be beneficial for laser vaporization of BPH by providing a selective light direction irradiation along with minimal thermal damage. Further studies will extend the applicability of the bundled fiber to treat tubular tissue structure. © 2014 Wiley Periodicals, Inc.

Light-controlled motility in prokaryotes and the problem of directional light perception

PubMed Central

Wilde, Annegret

2017-01-01

Abstract The natural light environment is important to many prokaryotes. Most obviously, phototrophic prokaryotes need to acclimate their photosynthetic apparatus to the prevailing light conditions, and such acclimation is frequently complemented by motility to enable cells to relocate in search of more favorable illumination conditions. Non-phototrophic prokaryotes may also seek to avoid light at damaging intensities and wavelengths, and many prokaryotes with diverse lifestyles could potentially exploit light signals as a rich source of information about their surroundings and a cue for acclimation and behavior. Here we discuss our current understanding of the ways in which bacteria can perceive the intensity, wavelength and direction of illumination, and the signal transduction networks that link light perception to the control of motile behavior. We discuss the problems of light perception at the prokaryotic scale, and the challenge of directional light perception in small bacterial cells. We explain the peculiarities and the common features of light-controlled motility systems in prokaryotes as diverse as cyanobacteria, purple photosynthetic bacteria, chemoheterotrophic bacteria and haloarchaea. PMID:29077840

Research on the speed of light transmission in a dual-frequency laser pumped single fiber with two directions

NASA Astrophysics Data System (ADS)

Qiu, Wei; Liu, Jianjun; Wang, Yuda; Yang, Yujing; Gao, Yuan; Lv, Pin; Jiang, Qiuli

2018-01-01

In this article a general theory of the coherent population oscillation effect in an erbium-doped fiber at room temperature is presented. We use dual pumping light waves with a simplified two-level system. Thus the time delay equations can be calculated from rate equations and the transmission equation. Using numerical simulation, in the case of dual-frequency pump light waves (1480 nm and 980 nm) with two directions, we analyze the influence of the pump power ratio on the group speed of light propagation. In addition, we compare slow light propagation with a single-pumping light and slow light propagation with a dual-pumping light at room temperature. The discussion shows that a larger time delay of slow light propagation can be obtained with a dual-frequency pumping laser. Compared to previous research methods, a dual-frequency laser pumped fiber with two directions is more controllable. Moreover, we conclude that the group velocity of light can be varied by changing the pump ratio.

Light-controlled motility in prokaryotes and the problem of directional light perception.

PubMed

Wilde, Annegret; Mullineaux, Conrad W

2017-11-01

The natural light environment is important to many prokaryotes. Most obviously, phototrophic prokaryotes need to acclimate their photosynthetic apparatus to the prevailing light conditions, and such acclimation is frequently complemented by motility to enable cells to relocate in search of more favorable illumination conditions. Non-phototrophic prokaryotes may also seek to avoid light at damaging intensities and wavelengths, and many prokaryotes with diverse lifestyles could potentially exploit light signals as a rich source of information about their surroundings and a cue for acclimation and behavior. Here we discuss our current understanding of the ways in which bacteria can perceive the intensity, wavelength and direction of illumination, and the signal transduction networks that link light perception to the control of motile behavior. We discuss the problems of light perception at the prokaryotic scale, and the challenge of directional light perception in small bacterial cells. We explain the peculiarities and the common features of light-controlled motility systems in prokaryotes as diverse as cyanobacteria, purple photosynthetic bacteria, chemoheterotrophic bacteria and haloarchaea. © FEMS 2017.

Front lighted optical tooling method and apparatus

DOEpatents

Stone, W.J.

1983-06-30

An optical tooling method and apparatus uses a front lighted shadowgraphic technique to enhance visual contrast of reflected light. The apparatus includes an optical assembly including a fiducial mark, such as cross hairs, reflecting polarized light with a first polarization, a polarizing element backing the fiducial mark and a reflective surface backing the polarizing element for reflecting polarized light bypassing the fiducial mark and traveling through the polarizing element. The light reflected by the reflecting surface is directed through a second pass of the polarizing element toward the frontal direction with a polarization differing from the polarization of the light reflected by the fiducial mark. When used as a tooling target, the optical assembly may be mounted directly to a reference surface or may be secured in a mounting, such as a magnetic mounting. The optical assembly may also be mounted in a plane defining structure and used as a spherometer in conjunction with an optical depth measuring instrument.

Direct measurement of light waves.

PubMed

Goulielmakis, E; Uiberacker, M; Kienberger, R; Baltuska, A; Yakovlev, V; Scrinzi, A; Westerwalbesloh, Th; Kleineberg, U; Heinzmann, U; Drescher, M; Krausz, F

2004-08-27

The electromagnetic field of visible light performs approximately 10(15) oscillations per second. Although many instruments are sensitive to the amplitude and frequency (or wavelength) of these oscillations, they cannot access the light field itself. We directly observed how the field built up and disappeared in a short, few-cycle pulse of visible laser light by probing the variation of the field strength with a 250-attosecond electron burst. Our apparatus allows complete characterization of few-cycle waves of visible, ultraviolet, and/or infrared light, thereby providing the possibility for controlled and reproducible synthesis of ultrabroadband light waveforms.

Multiphoton microscopy and image guided light activated therapy using nanomaterials (Conference Presentation)

NASA Astrophysics Data System (ADS)

Prasad, Paras N.

2017-02-01

This talk will focus on design and applications of nanomaterials exhibiting strong multiphoton upconversion for multiphoton microscopy as well as for image-guided and light activated therapy .1-3 Such processes can occur by truly nonlinear optical interactions proceeding through virtual intermediate states or by stepwise coupled linear excitations through real intermediate states. Multiphoton processes in biocompatible multifunctional nanoparticles allow for 3D deep tissue imaging. In addition, they can produce in-situ photon conversion of deep tissue penetrating near IR light into a needed shorter wavelength light for photo-activated therapy at a targeted site, thus overcoming the limited penetration of UV or visible light into biological media. We are using near IR emitters such as silicon quantum dots which also exhibit strong multiphoton excitation for multiphoton microscopy. Another approach involves nonlinear nanocrystals such as ZnO which can produce four wave mixing, sum frequency generation as well as second harmonic generation to convert a deep tissue penetrating Near IR light at the targeted biological site to a desired shorter wavelength light suitable for bio imaging or activation of a therapy. We have utilized this approach to activate a photosensitizer for photodynamic therapy. Yet another type of upconversion materials is rare-earth ion doped optical nanotransformers which transform a Near IR (NIR) light from an external source by sequential single photon absorption, in situ and on demand, to a needed wavelength. Applications of these nanotransformers in multiphoton photoacoustic imaging will also be presented. An exciting direction pursued by us using these multiphoton nanoparticles, is functional imaging of brain. Simultaneously, they can effect optogenetics for regioselective stimulation of neurons for providing an effective intervention/augmentation strategy to enhance the cognitive state and lead to a foundation for futuristic vision of super human capabilities. Challenges and opportunities will be discussed.

An extended model for the repression of photosynthesis genes by the AppA/PpsR system in Rhodobacter sphaeroides.

PubMed

Pandey, Rakesh; Flockerzi, Dietrich; Hauser, Marcus J B; Straube, Ronny

2012-09-01

Purple bacteria derive energy from aerobic respiration or photosynthesis depending on the availability of oxygen and light. Under aerobic conditions, photosynthesis genes are specifically repressed by the PpsR protein. In Rhodobacter sphaeroides, the repressive action of PpsR is antagonized by the blue-light and redox-sensitive flavoprotein AppA, which sequesters PpsR under anaerobic conditions into transcriptionally inactive complexes. However, under semi-aerobic conditions, blue-light excitation of AppA causes the AppA-PpsR complexes to dissociate, again leading to a repression of photosynthesis genes. We have recently developed a simple mathematical model suggesting that this phenotype arises from the formation of a maximum in the response curve of reduced PpsR at intermediate oxygen concentrations. However, this model focused mainly on the oxygen-dependent interactions whereas light regulation was only implemented in a simplified manner. In the present study, we incorporate a more detailed mechanism for the light-dependent interaction between AppA and PpsR, which now allows for a direct comparison with experiments. Specifically, we take into account that, upon blue-light excitation, AppA undergoes a conformational change, creating a long-lived signalling state causing the dissociation of the AppA-PpsR complexes. The predictions of the extended model are found to be in good agreement with experimental results on the light-dependent repression of photosynthesis genes under semi-aerobic conditions. We also identify the potential kinetic and stoichiometric constraints that the interplay between light and redox regulation imposes on the functionality of the AppA/PpsR system, especially with respect to a possible bistable response. © 2012 The Authors Journal compilation © 2012 FEBS.

Effect of magnetic fields on green color formation in frog skin

NASA Astrophysics Data System (ADS)

Kashiwagi, H.; Kashiwagi, A.; Iwasaka, M.

2017-05-01

The present work is focused on a dynamic and efficient optical control system that is made possible by investigation of the body surfaces of various animals. Specifically, we expect Japanese tree frog (Hyla japonica) skin to provide a model for a flexible display device actuator mechanism. Tree frogs change body color from their original green to other colors in response to background colors. The color formation is controlled not only by chromatophores, but also by guanine microcrystals in iridophores. We collected sample microcrystals from the frog's dorsal skin and made a model display sheet using the green skin layers. The transparent chamber that contained the crystal suspension was layered to enhance light reflection. Sheet color was observed while the angle of light incidence was varied, with and without magnetic field exposure at 0.3 T. A slight increase in red and green intensity was detected. Additionally, reflected intensity increased with increasing angle of incidence. These results indicate that the guanine crystal platelets in frog skin can efficiently switch the reflected light direction under application of a magnetic field. This in turn suggests that a several-micron-sized microcrystal of this type is a candidate material for development of flexible optical chips for ambient light control.

Bidirectional reflectance distribution function of Spectralon white reflectance standard illuminated by incoherent unpolarized and plane-polarized light.

PubMed

Bhandari, Anak; Hamre, Børge; Frette, Øvynd; Zhao, Lu; Stamnes, Jakob J; Kildemo, Morten

2011-06-01

A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence. Our measurements show deviations of the BRDF for the Spectralon white reflectance standard from that of a Lambertian reflector that depend both on the angle of incidence and the polarization states of the incident light and detected light. The non-Lambertian reflection characteristics were found to increase more toward the direction of specular reflection as the angle of incidence gets larger.

Focusing light through biological tissue and tissue-mimicking phantoms up to 9.6 cm in thickness with digital optical phase conjugation

NASA Astrophysics Data System (ADS)

Shen, Yuecheng; Liu, Yan; Ma, Cheng; Wang, Lihong V.

2016-08-01

Optical phase conjugation (OPC)-based wavefront shaping techniques focus light through or within scattering media, which is critically important for deep-tissue optical imaging, manipulation, and therapy. However, to date, the sample thickness in OPC experiments has been limited to only a few millimeters. Here, by using a laser with a long coherence length and an optimized digital OPC system that can safely deliver more light power, we focused 532-nm light through tissue-mimicking phantoms up to 9.6 cm thick, as well as through ex vivo chicken breast tissue up to 2.5 cm thick. Our results demonstrate that OPC can be achieved even when photons have experienced on average 1000 scattering events. The demonstrated penetration of nearly 10 cm (˜100 transport mean free paths) has never been achieved before by any optical focusing technique, and it shows the promise of OPC for deep-tissue noninvasive optical imaging, manipulation, and therapy.

Reduction of lighting energy consumption in office buildings through improved daylight design

NASA Astrophysics Data System (ADS)

Papadouri, Maria Violeta Prado

This study aims to investigate the lighting energy consumption in office buildings and the options for its reduction. One way to reduce lighting energy consumption is by improving the daylight design. A better use of daylight in buildings might be an outcome from the effort made in different directions. Like the improvement of a building's fabric and layout, the materials, even the furniture in a space influences the daylight quality considerably. Also very important role in lighting energy consumption has the development of more efficient lighting technology like the electric lighting control systems, such as photo sensors and occupancy sensors. Both systems are responsible so that the electric light is not used without reason. As the focusing area of this study, is to find ways to improve the daylight use in buildings, a consequent question is which are the methods provided in order to achieve this The accuracy of the methodology used is also an important issue in order to achieve reliable results. The methodology applied in this study includes the analysis of a case study by taking field measurements and computer simulations. The first stage included gathering information about the lighting design of the building and monitoring the light levels, both from natural and from the electric lighting. The second stage involved testing with computer simulations, different parameters that were expected to improve the daylight exploitation of the specific area. The results of the field measurements showed that the main problems of the space were the low natural light levels and the poor daylight distribution. The annual electric lighting energy consumption, as it was calculated with the use of computer simulations, represented the annual energy consumption of a typical air-conditioned prestige office building (energy consumption guide 19, for energy use in offices, 2000). After several computer simulations, the results showed that initial design parameters of the building can affect the lighting energy consumption of the space significantly. On the other hand, relatively small changes, like changing the reflectance of the surfaces and the lighting control systems can make even more difference to the light quality of the space and the reduction of lighting energy consumption.

High-efficiency directional backlight design for an automotive display.

PubMed

Chen, Bo-Tsuen; Pan, Jui-Wen

2018-06-01

We propose a high-efficiency directional backlight module (DBM) for automotive display applications. The DBM is composed of light sources, a light guide plate (LGP), and an optically patterned plate (OPP). The LGP has a collimator on the input surface that serves to control the angle of the light emitted to be in the horizontal direction. The OPP has an inverse prism to adjust the light emission angle in the vertical direction. The DBM has a simple structure and high optical efficiency. Compared with conventional backlight systems, the DBM has higher optical efficiency and a suitable viewing angle. This is an improvement in normalized on-axis luminous intensity of 2.6 times and a twofold improvement in optical efficiency. The viewing angles are 100° in the horizontal direction and 35° in the vertical direction. The angle of the half-luminous intensity is 72° in the horizontal direction and 20° in the vertical direction. The uniformity of the illuminance reaches 82%. The DBM is suitable for use in the center information displays of automobiles.

Light self-focusing in the atmosphere: Thin window model

DOE PAGES

Vaseva, Irina A.; Fedoruk, Mikhail P.; Rubenchik, Alexander M.; ...

2016-08-02

Ultra-high power (exceeding the self-focusing threshold by more than three orders of magnitude) light beams from ground-based laser systems may find applications in space-debris cleaning. The propagation of such powerful laser beams through the atmosphere reveals many novel interesting features compared to traditional light self-focusing. It is demonstrated here that for the relevant laser parameters, when the thickness of the atmosphere is much shorter than the focusing length (that is, of the orbit scale), the beam transit through the atmosphere in lowest order produces phase distortion only. This means that by using adaptive optics it may be possible to eliminatemore » the impact of self-focusing in the atmosphere on the laser beam. Furthermore, the area of applicability of the proposed “thin window” model is broader than the specific physical problem considered here. For instance, it might find applications in femtosecond laser material processing.« less

Image-Based Focusing

NASA Astrophysics Data System (ADS)

Selker, Ted

1983-05-01

Lens focusing using a hardware model of a retina (Reticon RL256 light sensitive array) with a low cost processor (8085 with 512 bytes of ROM and 512 bytes of RAM) was built. This system was developed and tested on a variety of visual stimuli to demonstrate that: a)an algorithm which moves a lens to maximize the sum of the difference of light level on adjacent light sensors will converge to best focus in all but contrived situations. This is a simpler algorithm than any previously suggested; b) it is feasible to use unmodified video sensor arrays with in-expensive processors to aid video camera use. In the future, software could be developed to extend the processor's usefulness, possibly to track an actor by panning and zooming to give a earners operator increased ease of framing; c) lateral inhibition is an adequate basis for determining best focus. This supports a simple anatomically motivated model of how our brain focuses our eyes.

Three-dimensional spatiotemporal focusing of holographic patterns

PubMed Central

Hernandez, Oscar; Papagiakoumou, Eirini; Tanese, Dimitrii; Fidelin, Kevin; Wyart, Claire; Emiliani, Valentina

2016-01-01

Two-photon excitation with temporally focused pulses can be combined with phase-modulation approaches, such as computer-generated holography and generalized phase contrast, to efficiently distribute light into two-dimensional, axially confined, user-defined shapes. Adding lens-phase modulations to 2D-phase holograms enables remote axial pattern displacement as well as simultaneous pattern generation in multiple distinct planes. However, the axial confinement linearly degrades with lateral shape area in previous reports where axially shifted holographic shapes were not temporally focused. Here we report an optical system using two spatial light modulators to independently control transverse- and axial-target light distribution. This approach enables simultaneous axial translation of single or multiple spatiotemporally focused patterns across the sample volume while achieving the axial confinement of temporal focusing. We use the system's capability to photoconvert tens of Kaede-expressing neurons with single-cell resolution in live zebrafish larvae. PMID:27306044

Direct optical measurement of light coupling into planar waveguide by plasmonic nanoparticles.

PubMed

Pennanen, Antti M; Toppari, J Jussi

2013-01-14

Coupling of light into a thin layer of high refractive index material by plasmonic nanoparticles has been widely studied for application in photovoltaic devices, such as thin-film solar cells. In numerous studies this coupling has been investigated through measurement of e.g. quantum efficiency or photocurrent enhancement. Here we present a direct optical measurement of light coupling into a waveguide by plasmonic nanoparticles. We investigate the coupling efficiency into the guided modes within the waveguide by illuminating the surface of a sample, consisting of a glass slide coated with a high refractive index planar waveguide and plasmonic nanoparticles, while directly measuring the intensity of the light emitted out of the waveguide edge. These experiments were complemented by transmittance and reflectance measurements. We show that the light coupling is strongly affected by thin-film interference, localized surface plasmon resonances of the nanoparticles and the illumination direction (front or rear).

Smart Optical Material Characterization System and Method

NASA Technical Reports Server (NTRS)

Choi, Sang Hyouk (Inventor); Park, Yeonjoon (Inventor)

2015-01-01

Disclosed is a system and method for characterizing optical materials, using steps and equipment for generating a coherent laser light, filtering the light to remove high order spatial components, collecting the filtered light and forming a parallel light beam, splitting the parallel beam into a first direction and a second direction wherein the parallel beam travelling in the second direction travels toward the material sample so that the parallel beam passes through the sample, applying various physical quantities to the sample, reflecting the beam travelling in the first direction to produce a first reflected beam, reflecting the beam that passes through the sample to produce a second reflected beam that travels back through the sample, combining the second reflected beam after it travels back though the sample with the first reflected beam, sensing the light beam produced by combining the first and second reflected beams, and processing the sensed beam to determine sample characteristics and properties.

Epifluorescent direct-write photolithography for microfluidic applications

NASA Astrophysics Data System (ADS)

Higgins, MacCallister; Geiger, Emil J.

2015-01-01

We present a technique for fabricating soft-lithography molds created using an epifluorescent microscope. By focusing the UV light emitted from a Hg arc lamp, we demonstrate the ability to direct-write photoresist features with a minimum resolution of 45 μm. This resolution is satisfactory for many microfluidic applications. A major advantage of this technique is its low cost, both in terms of capital investment and on-going expenditures. Furthermore, by using a motorized stage, we can quickly fabricate a design on demand, eliminating the need, cost, and lead-time required for a photomask. With the addition of an electronic shutter, complicated separate structures can be imaged and utilized to make a wide range of microfluidic devices. We demonstrate this technique using dry-film resist due to its low cost, ease of application, and less stringent safety protocols.

Direct detection of free radicals and reactive oxygen species in thylakoids.

PubMed

Hideg, Eva; Kálai, Tamás; Hideg, Kálmán

2011-01-01

In plants, reactive oxygen species (ROS), also known as active oxygen species (AOS), are associated with normal, physiologic processes as well as with responses to adverse conditions. ROS are connected to stress in many ways: as primary elicitors, as products and propagators of oxidative damage, or as signal molecules initiating defense or adaptation. The photosynthetic electron transport is a major site of oxidative stress by visible or ultraviolet light, high or low temperature, pollutants or herbicides. ROS production can be presumed from detecting oxidatively damaged lipids, proteins, or pigments as well as from the alleviating effects of added antioxidants. On the contrary, measuring ROS by special sensor molecules provides more direct information. This chapter focuses on the application of spin trapping electron paramagnetic resonance (EPR) spectroscopy for detecting ROS: singlet oxygen and oxygen free radicals in thylakoid membrane preparations.

New meteoroid model predictions for directional impacts on LDEF

NASA Technical Reports Server (NTRS)

Divine, Neil; Aguero, Rene C.

1992-01-01

An extensive body of data, from meteors, zodiacal light, spacecraft-borne impact detectors (helios, Pioneer, Galileo, and Ulysses), and other sources, forms the basis of a new numerical model for the distributions of interplanetary meteoroids. For each of the five populations in this model it is possible to evaluate meteoroid concentration and flux for oriented surfaces or detectors having arbitrary position and velocity in interplanetary space (Divine, 1992, in preparation). For a spacecraft in geocentric orbit, the effects of gravitational focusing and shielding by the Earth were derived with full attention to the directionality of the particles, both on approach (i.e., relative to a massless Earth) and at the target. This modeling approach was exercised to provide an estimate of meteoroid fluence for each of several oriented surfaces on the Long Duration Exposure Facility (LDEF).

Use of diffusive optical fibers for plant lighting

NASA Technical Reports Server (NTRS)

Kozai, T.; Kitaya, Y.; Fujiwara, K.; Kino, S.; Kinowaki, M.

1994-01-01

Lighting is one of the most critical aspects in plant production and environmental research with plants. Much research has been repeated on the effect of light intensity, spectral distribution of light and lighting cycle, but comparatively little research done on the effect of lighting direction on the growth, development and morphology of plants. When plants are grown with lamps above, light is directed downward to the plants. Downward or overhead lighting is utilized in almost all cases. However, downward lighting does not always give the best result in terms of lighting efficiency, growth, development and morphology of plants. In the present study, a sideward lighting system was developed using diffusive optical fiber belts. More higher quality tissue-cultured transplants could be produced in a reduced space with the sideward lighting system than with a downward lighting system. An application of the sideward lighting system using diffusive optical fiber belts is described and the advantages and disadvantages are discussed.

Use of diffusive optical fibers for plant lighting

NASA Astrophysics Data System (ADS)

Kozai, T.; Kitaya, Y.; Fujiwara, K.; Kino, S.; Kinowaki, M.

1994-03-01

Lighting is one of the most critical aspects in plant production and environmental research with plants. Much research has been repeated on the effect of light intensity, spectral distribution of light and lighting cycle, but comparatively little research done on the effect of lighting direction on the growth, development and morphology of plants. When plants are grown with lamps above, light is directed downward to the plants. Downward or overhead lighting is utilized in almost all cases. However, downward lighting does not always give the best result in terms of lighting efficiency, growth, development and morphology of plants. In the present study, a sideward lighting system was developed using diffusive optical fiber belts. More higher quality tissue-cultured transplants could be produced in a reduced space with the sideward lighting system than with a downward lighting system. An application of the sideward lighting system using diffusive optical fiber belts is described and the advantages and disadvantages are discussed.

Flexible, liquid core light guide with focusing and light shaping attachments

DOEpatents

Wojcik, Randolph Frank; Majewski, Stanislaw; Zorn, Carl John; Kross, Brian

1999-01-01

A liquid light guide system for ultraviolet light is disclosed that has a light shaping arrangement for the emitted light, a stable liquid core and sheath and reliable and effective end closures. The end closures include a metal crimping arrangement that utilizes two layers of deformable materials to prevent cracking of endplugs.

Direct Bandgap Group IV Materials

DTIC Science & Technology

2016-01-21

devices. In this project, we have accomplished (a) direct bandgap group IV materials of GeSn, (b) GeSn-based planar light - emitting diode operated at near...devices of planar light emitting diode , detector and laser ” 6/12/2015 PI and Co-PI information: - Name of Principal Investigators: Prof. H. H. Cheng...IV materials of GeSn, (b) GeSn-based planar light - emitting diode operated at near infrared with direct emission, and (c) the first planar

The theoretical simulation on electrostatic distribution of 1st proximity region in proximity focusing low-light-level image intensifier

NASA Astrophysics Data System (ADS)

Zhang, Liandong; Bai, Xiaofeng; Song, De; Fu, Shencheng; Li, Ye; Duanmu, Qingduo

2015-03-01

Low-light-level night vision technology is magnifying low light level signal large enough to be seen by naked eye, which uses the photons - photoelectron as information carrier. Until the micro-channel plate was invented, it has been possibility for the realization of high performance and miniaturization of low-light-level night vision device. The device is double-proximity focusing low-light-level image intensifier which places a micro-channel plate close to photocathode and phosphor screen. The advantages of proximity focusing low-light-level night vision are small size, light weight, small power consumption, no distortion, fast response speed, wide dynamic range and so on. It is placed parallel to each other for Micro-channel plate (both sides of it with metal electrode), the photocathode and the phosphor screen are placed parallel to each other. The voltage is applied between photocathode and the input of micro-channel plate when image intensifier works. The emission electron excited by photo on the photocathode move towards to micro-channel plate under the electric field in 1st proximity focusing region, and then it is multiplied through the micro-channel. The movement locus of emission electrons can be calculated and simulated when the distributions of electrostatic field equipotential lines are determined in the 1st proximity focusing region. Furthermore the resolution of image tube can be determined. However the distributions of electrostatic fields and equipotential lines are complex due to a lot of micro-channel existing in the micro channel plate. This paper simulates electrostatic distribution of 1st proximity region in double-proximity focusing low-light-level image intensifier with the finite element simulation analysis software Ansoft maxwell 3D. The electrostatic field distributions of 1st proximity region are compared when the micro-channel plates' pore size, spacing and inclination angle ranged. We believe that the electron beam movement trajectory in 1st proximity region will be better simulated when the electronic electrostatic fields are simulated.

Single objective light-sheet microscopy for high-speed whole-cell 3D super-resolution

PubMed Central

Meddens, Marjolein B. M.; Liu, Sheng; Finnegan, Patrick S.; Edwards, Thayne L.; James, Conrad D.; Lidke, Keith A.

2016-01-01

We have developed a method for performing light-sheet microscopy with a single high numerical aperture lens by integrating reflective side walls into a microfluidic chip. These 45° side walls generate light-sheet illumination by reflecting a vertical light-sheet into the focal plane of the objective. Light-sheet illumination of cells loaded in the channels increases image quality in diffraction limited imaging via reduction of out-of-focus background light. Single molecule super-resolution is also improved by the decreased background resulting in better localization precision and decreased photo-bleaching, leading to more accepted localizations overall and higher quality images. Moreover, 2D and 3D single molecule super-resolution data can be acquired faster by taking advantage of the increased illumination intensities as compared to wide field, in the focused light-sheet. PMID:27375939

LIGHT: A Novel Immunotherapy for Primary and Metastatic Prostate Cancer

DTIC Science & Technology

2013-09-01

and TRAMP-C2 LIGHT expressing cells to examine the frequency of Tregs subsequent to LIGHT interaction . These results reflect on the ability of LIGHT...cells. These data suggest that LIGHT interaction directly affects the induction of Tregs from a naïve CD4+ T cell population but also that this is not... interaction directly affects the induction of Tregs from a naïve CD4+ T cell population.  mPSCA TriVax induces infiltration of NK and MDSCs, whereas

Focusing light into desired patterns through turbid media by feedback-based wavefront shaping

NASA Astrophysics Data System (ADS)

Wan, Lipeng; Chen, Ziyang; Huang, Huiling; Pu, Jixiong

2016-07-01

We demonstrate that the focusing of light into desired patterns through turbid media can be realized using feedback-based wavefront shaping. Three desired focused patterns—a triangle, a circle, and a rectangle—are used as examples to study this ability. During the process of modulating scattered light, the Pearson's correlation coefficient is introduced as a feedback signal. It is found that the speckle field formed by the turbid media gradually transforms into the desired pattern through a process of modulation of the input beam wave front. The proposed approach has potential applications in biomedical treatment and laser material processing.

Three-dimensional integration of microoptical components buried inside photosensitive glass by femtosecond laser direct writing

NASA Astrophysics Data System (ADS)

Wang, Zhongke; Sugioka, Koji; Midorikawa, Katsumi

2007-12-01

We report the three-dimensional (3D) integration of microoptical components such as microlenses, micromirrors and optical waveguides in a single glass chip by femtosecond (fs) laser direct writing. First, two types of microoptical lenses were fabricated inside photosensitive Foturan glass by forming hollow microstructures using fs laser direct writing followed by thermal treatment, successive wet etching and additional annealing. One type of lens is the cylindrical microlens with a curvature radius R of 1.0 mm, and the other is the plano-convex microlens with radius R of 0.75 mm. Subsequently, by the continuous procedure of hollow microstructure fabrication, a micromirror was integrated with the plano-convex microlens in the single glass chip. Further integration of waveguides was performed by internal refractive index modification using fs laser direct writing after the hollow structure fabrication of the microlens and the micromirror. A demonstration of the laser beam transmission in the integrated optical microdevice shows that the 3D integration of waveguides with a micromirror and a microoptical lens in a single glass chip is highly effective for light beam guiding and focusing.

Test of the CLAS12 RICH large-scale prototype in the direct proximity focusing configuration

DOE PAGES

Anefalos Pereira, S.; Baltzell, N.; Barion, L.; ...

2016-02-11

A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c up to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Laboratory. The adopted solution foresees a novel hybrid optics design based on aerogel radiator, composite mirrors and high-packed and high-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). We report here the results of the tests of a large scale prototype of the RICH detector performed withmore » the hadron beam of the CERN T9 experimental hall for the direct detection configuration. As a result, the tests demonstrated that the proposed design provides the required pion-to-kaon rejection factor of 1:500 in the whole momentum range.« less

Adaptive array antenna for satellite cellular and direct broadcast communications

NASA Technical Reports Server (NTRS)

Horton, Charles R.; Abend, Kenneth

1993-01-01

Adaptive phased-array antennas provide cost-effective implementation of large, light weight apertures with high directivity and precise beamshape control. Adaptive self-calibration allows for relaxation of all mechanical tolerances across the aperture and electrical component tolerances, providing high performance with a low-cost, lightweight array, even in the presence of large physical distortions. Beam-shape is programmable and adaptable to changes in technical and operational requirements. Adaptive digital beam-forming eliminates uplink contention by allowing a single electronically steerable antenna to service a large number of receivers with beams which adaptively focus on one source while eliminating interference from others. A large, adaptively calibrated and fully programmable aperture can also provide precise beam shape control for power-efficient direct broadcast from space. Advanced adaptive digital beamforming technologies are described for: (1) electronic compensation of aperture distortion, (2) multiple receiver adaptive space-time processing, and (3) downlink beam-shape control. Cost considerations for space-based array applications are also discussed.

Not-so-well-tempered neutralino

NASA Astrophysics Data System (ADS)

Profumo, Stefano; Stefaniak, Tim; Stephenson-Haskins, Laurel

2017-09-01

Light electroweakinos, the neutral and charged fermionic supersymmetric partners of the standard model SU (2 )×U (1 ) gauge bosons and of the two SU(2) Higgs doublets, are an important target for searches for new physics with the Large Hadron Collider (LHC). However, if the lightest neutralino is the dark matter, constraints from direct dark matter detection experiments rule out large swaths of the parameter space accessible to the LHC, including in large part the so-called "well-tempered" neutralinos. We focus on the minimal supersymmetric standard model (MSSM) and explore in detail which regions of parameter space are not excluded by null results from direct dark matter detection, assuming exclusive thermal production of neutralinos in the early universe, and illustrate the complementarity with current and future LHC searches for electroweak gauginos. We consider both bino-Higgsino and bino-wino "not-so-well-tempered" neutralinos, i.e. we include models where the lightest neutralino constitutes only part of the cosmological dark matter, with the consequent suppression of the constraints from direct and indirect dark matter searches.

Lateralized direct and indirect semantic priming effects in subjects with paranormal experiences and beliefs.

PubMed

Pizzagalli, D; Lehmann, D; Brugger, P

2001-01-01

The present investigation tested the hypothesis that, as an aspect of schizotypal thinking, the formation of paranormal beliefs was related to spreading activation characteristics within semantic networks. From a larger student population (n = 117) prescreened for paranormal belief, 12 strong believers and 12 strong disbelievers (all women) were invited for a lateralized semantic priming task with directly and indirectly related prime-target pairs. Believers showed stronger indirect (but not direct) semantic priming effects than disbelievers after left (but not right) visual field stimulation, indicating faster appreciation of distant semantic relations specifically by the right hemisphere, reportedly specialized in coarse rather than focused semantic processing. These results are discussed in the light of recent findings in schizophrenic patients with thought disorders. They suggest that a disinhibition with semantic networks may underlie the formation of paranormal belief. The potential usefulness of work with healthy subjects for neuropsychiatric research is stressed. Copyright 2001 S. Karger AG, Basel

Social Work Field Training for the Community: A Student Self-Directed Approach in the Environmental Domain in Jordan

PubMed Central

Al-Makhamreh, Sahar; Alnabulsi, Hana; Asfour, Hana

2016-01-01

This article outlines innovative field training methods that foster the abilities of undergraduate social work students so that they are able to empower the local community and raise awareness of environmental issues. In this study, students were engaged in a local community assessment that sought to understand their views on environmental and community impacts of the Synchrotron-Light for Experimental Science and Applications in the Middle East (SESAME) Project on the lives of the host village's residents. A students' self-directed approach was applied for the fieldwork out of which interventions were developed ( Garrison, 1997). Quantitative data were gathered by eighteen students through a survey of 361 questionnaires targeting Allan society. In addition to students' field notes, pre and post focus groups were used to collect qualitative information. Study findings highlighted the effectiveness of students' self-directed projects in cultivating culturally competent practices; ensuring sustainable development; and providing evidence-based knowledge on social work practice involving environmental issues. PMID:27559202

Social Work Field Training for the Community: A Student Self-Directed Approach in the Environmental Domain in Jordan.

PubMed

Al-Makhamreh, Sahar; Alnabulsi, Hana; Asfour, Hana

2016-06-01

This article outlines innovative field training methods that foster the abilities of undergraduate social work students so that they are able to empower the local community and raise awareness of environmental issues. In this study, students were engaged in a local community assessment that sought to understand their views on environmental and community impacts of the Synchrotron-Light for Experimental Science and Applications in the Middle East (SESAME) Project on the lives of the host village's residents. A students' self-directed approach was applied for the fieldwork out of which interventions were developed ( Garrison, 1997). Quantitative data were gathered by eighteen students through a survey of 361 questionnaires targeting Allan society. In addition to students' field notes, pre and post focus groups were used to collect qualitative information. Study findings highlighted the effectiveness of students' self-directed projects in cultivating culturally competent practices; ensuring sustainable development; and providing evidence-based knowledge on social work practice involving environmental issues.

Pediatric vision screening using binocular retinal birefringencr scanning

NASA Astrophysics Data System (ADS)

Nassif, Deborah S.; Gramatikov, Boris; Guyton, David L.; Hunter, David G.

2003-07-01

Amblyopia, a leading cause of vision loss in childhood, is responsive to treatment if detected early in life. Risk factors for amblyopia, such as refractive error and strabismus, may be difficult to identify clinically in young children. Our laboratory has developed retinal birefringence scanning (RBS), in which a small spot of polarized light is scanned in a circle on the retina, and the returning light is measured for changes in polarization caused by the pattern of birefringent fibers that comprise the fovea. Binocular RBS (BRBS) detects the fixation of both eyes simultaneously and thus screens for strabismus, one of the risk factors of amblyopia. We have also developed a technique to automatically detect when the eye is in focus without measuring refractive error. This focus detection system utilizes a bull's eye photodetector optically conjugate to a point fixation source. Reflected light is focused back to the point source by the optical system of the eye, and if the subject focuses on the fixation source, the returning light will be focused on the detector. We have constructed a hand-held prototype combining BRBS and focus detection measurements in one quick (< 0.5 second) and accurate (theoretically detecting +/-1 of misalignment) measurement. This approach has the potential to reliably identify children at risk for amblyopia.

Development and testing of a homogenous multi-wavelength LED light source

NASA Astrophysics Data System (ADS)

Bolton, Frank J.; Bernat, Amir; Jacques, Steven L.; Levitz, David

2017-03-01

Multispectral imaging of human tissue is a powerful method that allows for quantify scattering and absorption parameters of the tissue and differentiate tissue types or identify pathology. This method requires imaging at multiple wavelengths and then fitting the measured data to a model based on light transport theory. Earlier, a mobile phone based multi-spectral imaging system was developed to image the uterine cervix from the colposcopy geometry, outside the patient's body at a distance of 200-300 mm. Such imaging of a distance object has inherent challenges, as bright and homogenous illumination is required. Several solutions addressing this problem were developed, with varied degrees of success. In this paper, several multi-spectral illumination setups were developed and tested for brightness and uniformity. All setups were specifically designed with low cost in mind, utilizing a printed circuit board with surface-mounted LEDs. The three setups include: LEDs illuminating the target directly, LEDs illuminating focused by a 3D printed miniature lens array, and LEDs coupled to a mixing lens and focusing optical system. In order to compare the illumination uniformity and intensity performance two experiments were performed. Test results are presented, and various tradeoffs between the three system configurations are discussed. Test results are presented, and various tradeoffs between the three system configurations are discussed.

Review: Post-translational cross-talk between brassinosteroid and sucrose signaling.

PubMed

Kühn, Christina

2016-07-01

A direct link has been elucidated between brassinosteroid function and perception, and sucrose partitioning and transport. Sucrose regulation and brassinosteroid signaling cross-talk at various levels, including the well-described regulation of transcriptional gene expression: BZR-like transcription factors link the signaling pathways. Since brassinosteroid responses depend on light quality and quantity, a light-dependent alternative pathway was postulated. Here, the focus is on post-translational events. Recent identification of sucrose transporter-interacting partners raises the question whether brassinosteroid and sugars jointly affect plant innate immunity and plant symbiotic interactions. Membrane permeability and sensitivity depends on the number of cell surface receptors and transporters. More than one endocytic route has been assigned to specific components, including brassinosteroid-receptors. The number of such proteins at the plasma membrane relies on endocytic recycling, internalization and/or degradation. Therefore, vesicular membrane trafficking is gaining considerable attention with regard to plant immunity. The organization of pattern recognition receptors (PRRs), other receptors or transporters in membrane microdomains participate in endocytosis and the formation of specific intracellular compartments, potentially impacting biotic interactions. This minireview focuses on post-translational events affecting the subcellular compartmentation of membrane proteins involved in signaling, transport, and defense, and on the cross-talk between brassinosteroid signals and sugar availability. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Migratory bird hunter opinions regarding potential management strategies for controlling light goose populations

USGS Publications Warehouse

Dinges, Andrew J.; Webb, Elisabeth B.; Vrtiska, Mark P.; Nilon, Charles H.; Wilhelm Stanis, Sonja A.

2014-01-01

We expanded the Nebraska Light Goose Conservation Order (LGCO) harvest survey (NE, USA) in spring 2012 to assess migratory bird hunter opinions regarding future management strategies for controlling light goose populations. Although hunters strongly agreed that population control of light geese was an important wildlife management issue, they were generally unsupportive of wildlife officials using forms of direct control methods to control light goose populations. Respondents who indicated participation in the 2012 LGCO were also less supportive of any form of direct control compared with migratory bird hunters who did not participate in the LGCO. When presented with alternative methods by wildlife officials for future light goose population control, respondents were most supportive of wildlife agencies selectively shooting light geese on migration and wintering areas and least supportive of wildlife officials using bait with approved chemicals to euthanize light geese. A clear understanding of public perception of various potential direct-control options will likely assist wildlife biologists in making informed decisions on how to proceed with population control of light geese.

Control over high peak-power laser light and laser-driven X-rays

NASA Astrophysics Data System (ADS)

Zhao, Baozhen; Banerjee, Sudeep; Yan, Wenchao; Zhang, Ping; Zhang, Jun; Golovin, Grigory; Liu, Cheng; Fruhling, Colton; Haden, Daniel; Chen, Shouyuan; Umstadter, Donald

2018-04-01

An optical system was demonstrated that enables continuous control over the peak power level of ultrashort duration laser light. The optical characteristics of amplified and compressed femtosecond-duration light from a chirped-pulse amplification laser are shown to remain invariant and maintain high-fidelity using this system. When the peak power was varied by an order-of-magnitude, up to its maximum attainable value, the phase, spectral bandwidth, polarization state, and focusability of the light remained constant. This capability led to precise control of the focused laser intensity and enabled a correspondingly high level of control over the power of an all-laser-driven Thomson X-ray light source.

Interaction of magnetite-based receptors in the beak with the visual system underlying 'fixed direction' responses in birds

PubMed Central

2010-01-01

Background European robins, Erithacus rubecula, show two types of directional responses to the magnetic field: (1) compass orientation that is based on radical pair processes and lateralized in favor of the right eye and (2) so-called 'fixed direction' responses that originate in the magnetite-based receptors in the upper beak. Both responses are light-dependent. Lateralization of the 'fixed direction' responses would suggest an interaction between the two magnetoreception systems. Results Robins were tested with either the right or the left eye covered or with both eyes uncovered for their orientation under different light conditions. With 502 nm turquoise light, the birds showed normal compass orientation, whereas they displayed an easterly 'fixed direction' response under a combination of 502 nm turquoise with 590 nm yellow light. Monocularly right-eyed birds with their left eye covered were oriented just as they were binocularly as controls: under turquoise in their northerly migratory direction, under turquoise-and-yellow towards east. The response of monocularly left-eyed birds differed: under turquoise light, they were disoriented, reflecting a lateralization of the magnetic compass system in favor of the right eye, whereas they continued to head eastward under turquoise-and-yellow light. Conclusion 'Fixed direction' responses are not lateralized. Hence the interactions between the magnetite-receptors in the beak and the visual system do not seem to involve the magnetoreception system based on radical pair processes, but rather other, non-lateralized components of the visual system. PMID:20707905

Advantages of diffuse light for horticultural production and perspectives for further research

PubMed Central

Li, Tao; Yang, Qichang

2015-01-01

Plants use diffuse light more efficiently than direct light, which is well established due to diffuse light penetrates deeper into the canopy and photosynthetic rate of a single leaf shows a non-linear response to the light flux density. Diffuse light also results in a more even horizontal and temporal light distribution in the canopy, which plays substantial role for crop photosynthesis enhancement as well as production improvement. Here we show some of the recent findings about the effect of diffuse light on light distribution over the canopy and its direct and indirect effects on crop photosynthesis and plant growth, and suggest some perspectives for further research which could strengthen the scientific understanding of diffuse light modulate plant processes and its application in horticultural production. PMID:26388890

A Tracking Sun Photometer Without Moving Parts

NASA Technical Reports Server (NTRS)

Strawa, Anthony W.

2012-01-01

This innovation is small, lightweight, and consumes very little electricity as it measures the solar energy attenuated by gases and aerosol particles in the atmosphere. A Sun photometer is commonly used on the Earth's surface, as well as on aircraft, to determine the solar energy attenuated by aerosol particles in the atmosphere and their distribution of sizes. This information is used to determine the spatial and temporal distribution of gases and aerosols in the atmosphere, as well as their distribution sizes. The design for this Sun photometer uses a combination of unique optics and a charge coupled device (CCD) array to eliminate moving parts and make the instrument more reliable. It could be selfcalibrating throughout the year. Data products would be down-welling flux, the direct-diffuse flux ratio, column abundance of gas phase constituents, aerosol optical depth at multiple-wavelengths, phase functions, cloud statistics, and an estimate of the representative size of atmospheric particles. These measurements can be used to obtain an estimate of aerosol size distribution, refractive index, and particle shape. Incident light is received at a light-reflecting (inner) surface, which is a truncated paraboloid. Light arriving from a hemispheric field of view (solid angle 2 steradians) enters the reflecting optic at an entrance aperture at, or adjacent to, the focus of the paraboloid, and is captured by the optic. Most of this light is reflected from an inner surface. The light proceeds substantially parallel to the paraboloid axis, and is detected by an array detector located near an exit aperture. Each of the entrance and exit apertures is formed by the intersection of the paraboloid with a plane substantially perpendicular to the paraboloid axis. Incident (non-reflected) light from a source of limited extent (the Sun) illuminates a limited area on the detector array. Both direct and diffuse illumination may be reflected, or not reflected, before being received on the detector array. As the Sun traverses a path in the sky over some time interval, the track of the Sun can be traced on the detector array. A suitably modified Sun photometer might be used to study the dynamics of an environment on another planet or satellite with an atmosphere.

Polarization of the diffuse galactic light.

NASA Technical Reports Server (NTRS)

Sparrow, J. G.; Ney, E. P.

1972-01-01

Polarization measurements made from the satellite OSO-5 show that the polarized intensity in the direction of the Scutum arm of the Galaxy is different in intensity and direction of the polarization from that observed due to the zodiacal light. The observations are consistent with polarized diffuse galactic light superposed on the zodiacal light. The results are interpreted in terms of a model in which the galactic starlight is scattered by interstellar dust.

Manipulation of Micro Scale Particles in Optical Traps Using Programmable Spatial Light Modulation

NASA Technical Reports Server (NTRS)

Seibel, Robin E.; Decker, Arthur J. (Technical Monitor)

2003-01-01

1064 nm light, from an Nd:YAG laser, was polarized and incident upon a programmable parallel aligned liquid crystal spatial light modulator (PAL-SLM), where it was phase modulated according to the program controlling the PAL-SLM. Light reflected from the PAL-SLM was injected into a microscope and focused. At the focus, multiple optical traps were formed in which 9.975 m spheres were captured. The traps and the spheres were moved by changing the program of the PAL-SLM. The motion of ordered groups of micro particles was clearly demonstrated.

Design and analysis of all-dielectric subwavelength focusing flat lens

NASA Astrophysics Data System (ADS)

Turduev, M.; Bor, E.; Kurt, H.

2017-09-01

In this letter, we numerically designed and experimentally demonstrated a compact photonic structure for the subwavelength focusing of light using all-dielectric absorption-free and nonmagnetic scattering objects distributed in an air medium. In order to design the subwavelength focusing flat lens, an evolutionary algorithm is combined with the finite-difference time-domain method for determining the locations of cylindrical scatterers. During the multi-objective optimization process, a specific objective function is defined to reduce the full width at half maximum (FWHM) and diminish side lobe level (SLL) values of light at the focal point. The time-domain response of the optimized flat lens exhibits subwavelength light focusing with an FWHM value of 0.19λ and an SLL value of 0.23, where λ denotes the operating wavelength of light. Experimental analysis of the proposed flat lens is conducted in a microwave regime and findings exactly verify the numerical results with an FWHM of 0.192λ and an SLL value of 0.311 at the operating frequency of 5.42 GHz. Moreover, the designed flat lens provides a broadband subwavelength focusing effect with a 9% bandwidth covering frequency range of 5.10 GHz-5.58 GHz, where corresponding FWHM values remain under 0.21λ. Also, it is important to note that the designed flat lens structure performs a line focusing effect. Possible applications of the designed structure in telecom wavelengths are speculated upon for future perspectives. Namely, the designed structure can perform well in photonic integrated circuits for different fields of applications such as high efficiency light coupling, imaging and optical microscopy, with its compact size and ability for strong focusing.

Anode catalysts for direct ethanol fuel cells utilizing directly solar light illumination.

PubMed

Chu, Daobao; Wang, Shuxi; Zheng, Peng; Wang, Jian; Zha, Longwu; Hou, Yuanyuan; He, Jianguo; Xiao, Ying; Lin, Huashui; Tian, Zhaowu

2009-01-01

Shine a light: A PtNiRu/TiO(2) anode catalyst for direct ethanol fuel cells shows photocatalytic activity. The peak current density for ethanol oxidation under solar light illumination is 2-3 times greater than that in the absence of solar light. Ethanol is oxidized by light-generated holes, and the electrons are collected by the TiO(2) support to generate the oxidation current.Novel PtNiRu/TiO(2) anode catalysts for direct ethanol fuel cells (DEFCs) were prepared from PtNiRu nanoparticles (1:1:1 atomic ratios) and a nanoporous TiO(2) film by a sol-gel and electrodeposition method. The performances of the catalysts for ethanol oxidation were investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results indicate a remarkable enhancement of activity for ethanol oxidation under solar light illumination. Under solar light illumination, the generated oxidation peak current density is 24.6 mA cm(-2), which is about 2.5 times higher than that observed without solar light (9.9 mA cm(-2)). The high catalytic activity of the PtNiRu/TiO(2) complex catalyst for the electrooxidation of ethanol may be attributed to the modified metal/nanoporous TiO(2) film, and the enhanced electrooxidation of ethanol under solar light may be due to the photogeneration of holes in the modified nanoporous TiO(2) film.

Superluminescent light emitting diodes: the best out of two worlds

NASA Astrophysics Data System (ADS)

Rossetti, M.; Napierala, J.; Matuschek, N.; Achatz, U.; Duelk, M.; Vélez, C.; Castiglia, A.; Grandjean, N.; Dorsaz, J.; Feltin, E.

2012-03-01

Since pico-projectors were starting to become the next electronic "must-have" gadget, the experts were discussing which light-source technology seems to be the best for the existing three major projection approaches for the optical scanning module such as digital light processing, liquid crystal on silica and laser beam steering. Both so-far used light source technologies have distinct advantages and disadvantages. Though laser-based pico-projectors are focus-free and deliver a wider color gamut, their major disadvantages are speckle noise, cost and safety issues. In contrast, projectors based on cheaper Light Emitting Diodes (LEDs) as light source are criticized for a lack of brightness and for having limited focus. Superluminescent Light Emitting Diodes (SLEDs) are temporally incoherent and spatially coherent light sources merging in one technology the advantages of both Laser Diodes (LDs) and LEDs. With almost no visible speckle noise, focus-free operation and potentially the same color gamut than LDs, SLEDs could potentially answer the question which light source to use in future projector applications. In this quest for the best light source, we realized visible SLEDs emitting both in the red and blue spectral region. While the technology required for the realization of red emitters is already well established, III-nitride compounds required for blue emission have experienced a major development only in relatively recent times and the technology is still under development. The present paper is a review of the status of development reached for the blue superluminescent diodes based on the GaN material system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meddens, Marjolein B. M.; Liu, Sheng; Finnegan, Patrick S.

Here, we have developed a method for performing light-sheet microscopy with a single high numerical aperture lens by integrating reflective side walls into a microfluidic chip. These 45° side walls generate light-sheet illumination by reflecting a vertical light-sheet into the focal plane of the objective. Light-sheet illumination of cells loaded in the channels increases image quality in diffraction limited imaging via reduction of out-of-focus background light. Single molecule super-resolution is also improved by the decreased background resulting in better localization precision and decreased photo-bleaching, leading to more accepted localizations overall and higher quality images. Moreover, 2D and 3D single moleculemore » super-resolution data can be acquired faster by taking advantage of the increased illumination intensities as compared to wide field, in the focused light-sheet.« less

Progress in dimethacrylate-based dental composite technology and curing efficiency.

PubMed

Leprince, Julian G; Palin, William M; Hadis, Mohammed A; Devaux, Jacques; Leloup, Gaetane

2013-02-01

This work aims to review the key factors affecting the polymerization efficiency of light-activated resin-based composites. The different properties and methods used to evaluate polymerization efficiency will also be critically appraised with focus on the developments in dental photopolymer technology and how recent advances have attempted to improve the shortcomings of contemporary resin composites. Apart from the classical literature on the subject, the review focused in particular on papers published since 2009. The literature research was performed in Scopus with the terms "dental resin OR dimethacrylate". The list was screened and all papers relevant to the objectives of this work were included. Though new monomer technologies have been developed and some of them already introduced to the dental market, dimethacrylate-based composites still currently represent the vast majority of commercially available materials for direct restoration. The photopolymerization of resin-based composites has been the subject of numerous publications, which have highlighted the major impact of the setting process on material properties and quality of the final restoration. Many factors affect the polymerization efficiency, be they intrinsic; photoinitiator type and concentration, viscosity (co-monomer composition and ratio, filler content) and optical properties, or extrinsic; light type and spectrum, irradiation parameters (radiant energy, time and irradiance), curing modes, temperature and light guide tip positioning. : This review further highlights the apparent need for a more informative approach by manufacturers to relay appropriate information in order for dentists to optimize material properties of resin composites used in daily practice. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Influence of the chopped frequency of light on optical transport characteristics of human skin including at acupuncture points

NASA Astrophysics Data System (ADS)

Yang, Hong-qin; Xie, Shu-sen; Liu, Song-hao; Li, Hui; Wang, Yu-hua; Guo, Zhou-yi

2007-11-01

An experimental protocol was established for noninvasively measuring the optical transport characteristics of skin tissue along human meridian direction over body surface including at acupuncture points. The diffuse remittance for 658 nm light radiation along the pericardium meridian and non-meridian directions were measured respectively. The influence of the chopped frequency of light on the detected light signal was investigated. It is shown that the optical transport characteristics of skin tissue accords with the Beer's exponential attenuation law along the meridian including at acupuncture points and non-median directions. However there is an obvious difference between the propagations along the meridian direction and non-meridian direction (P<0.05). Furthermore, the chopped frequency can affect the detected signal. The diffuse remittance signal decreased with the chopped frequency's increase and it was different between the meridian and non-meridian directions. These findings are important and meaningful for interpreting the human meridian phenomena by biomedical optics.

On small beams with large topological charge: II. Photons, electrons and gravitational waves

NASA Astrophysics Data System (ADS)

Krenn, Mario; Zeilinger, Anton

2018-06-01

Beams of light with a large topological charge significantly change their spatial structure when they are focused strongly. Physically, it can be explained by an emerging electromagnetic field component in the direction of propagation, which is neglected in the simplified scalar wave picture in optics. Here we ask: is this a specific photonic behavior, or can similar phenomena also be predicted for other species of particles? We show that the same modification of the spatial structure exists for relativistic electrons as well as for focused gravitational waves. However, this is for different physical reasons: for electrons, which are described by the Dirac equation, the spatial structure changes due to a spin–orbit coupling in the relativistic regime. In gravitational waves described with linearized general relativity, the curvature of space–time between the transverse and propagation direction leads to the modification of the spatial structure. Thus, this universal phenomenon exists for both massive and massless elementary particles with spin 1/2, 1 and 2. It would be very interesting whether other types of particles such as composite systems (neutrons or C60) or neutrinos show a similar behavior and how this phenomenon can be explained in a unified physical way.

The effect of light direction and suspended cell concentrations on algal biofilm growth rates.

PubMed

Schnurr, Peter J; Espie, George S; Allen, D Grant

2014-10-01

Algae biofilms were grown in a semicontinuous flat plate biofilm photobioreactor to study the effects of light direction and suspended algal cell populations on algal biofilm growth. It was determined that, under the growth conditions and biofilm thicknesses studied, light direction had no effect on long-term algal biofilm growth (26 days); however, light direction did affect the concentration of suspended algal cells by influencing the photon flux density in the growth medium in the photobioreactors. This suspended algal cell population affected short-term (7 days) algae cell recruitment and algal biofilm growth, but additional studies showed that enhanced suspended algal cell populations did not affect biofilm growth rates over the long term (26 days). Studying profiles of light transmittance through biofilms as they grew showed that most of the light became attenuated by the biomass after just a few days of growth (88 % after 3 days). The estimated biofilm thicknesses after these few days of growth were approximately 150 μm. The light attenuation data suggests that, although the biofilms grew to 700-900 μm, under these light intensities, only the first few hundred micrometers of the biofilm is receiving enough light to be photosynthetically active. We postulate that this photosynthetically active layer of the biofilm grows adjacent to the light source, while the rest of the biofilm is in a stationary growth phase. The results of this study have implications for algal biofilm photobioreactor design and operation.

Laser induced white lighting of tungsten filament

NASA Astrophysics Data System (ADS)

Strek, W.; Tomala, R.; Lukaszewicz, M.

2018-04-01

The sustained bright white light emission of thin tungsten filament was induced under irradiation with focused beam of CW infrared laser diode. The broadband emission centered at 600 nm has demonstrated the threshold behavior on excitation power. Its intensity increased non-linearly with excitation power. The emission occurred only from the spot of focused beam of excitation laser diode. The white lighting was accompanied by efficient photocurrent flow and photoelectron emission which both increased non-linearly with laser irradiation power.

Flexible, liquid core light guide with focusing and light shaping attachments

DOEpatents

Wojcik, R.F.; Majewski, S.; Zorn, C.J.; Kross, B.

1999-04-20

A liquid light guide system for ultraviolet light is disclosed that has a light shaping arrangement for the emitted light, a stable liquid core and sheath and reliable and effective end closures. The end closures include a metal crimping arrangement that utilizes two layers of deformable materials to prevent cracking of endplugs. 19 figs.

Fast optical switch having reduced light loss

NASA Technical Reports Server (NTRS)

Nelson, Bruce N. (Inventor); Cooper, Ronald F. (Inventor)

1992-01-01

An electrically controlled optical switch uses an electro-optic crystal of the type having at least one set of fast and slow optical axes. The crystal exhibits electric field induced birefringence such that a plane of polarization oriented along a first direction of a light beam passing through the crystal may be switched to a plane of polarization oriented along a second direction. A beam splitting polarizer means is disposed at one end of the crystal and directs a light beam passing through the crystal whose plane of polarization is oriented along the first direction differently from a light beam having a plane of polarization oriented along the second direction. The electro-optic crystal may be chosen from the crystal classes 43m, 42m, and 23. In a preferred embodiment, the electro-optic crystal is a bismuth germanium oxide crystal or a bismuth silicon oxide crystal. In another embodiment of the invention, polarization control optics are provided which transmit substantially all of the incident light to the electro-optic crystal, substantially reducing the insertion loss of the switch.

Honeybee navigation: critically examining the role of the polarization compass

PubMed Central

Evangelista, C.; Kraft, P.; Dacke, M.; Labhart, T.; Srinivasan, M. V.

2014-01-01

Although it is widely accepted that honeybees use the polarized-light pattern of the sky as a compass for navigation, there is little direct evidence that this information is actually sensed during flight. Here, we ask whether flying bees can obtain compass cues derived purely from polarized light, and communicate this information to their nest-mates through the ‘waggle dance’. Bees, from an observation hive with vertically oriented honeycombs, were trained to fly to a food source at the end of a tunnel, which provided overhead illumination that was polarized either parallel to the axis of the tunnel, or perpendicular to it. When the illumination was transversely polarized, bees danced in a predominantly vertical direction with waggles occurring equally frequently in the upward or the downward direction. They were thus using the polarized-light information to signal the two possible directions in which they could have flown in natural outdoor flight: either directly towards the sun, or directly away from it. When the illumination was axially polarized, the bees danced in a predominantly horizontal direction with waggles directed either to the left or the right, indicating that they could have flown in an azimuthal direction that was 90° to the right or to the left of the sun, respectively. When the first half of the tunnel provided axial illumination and the second half transverse illumination, bees danced along all of the four principal diagonal directions, which represent four equally likely locations of the food source based on the polarized-light information that they had acquired during their journey. We conclude that flying bees are capable of obtaining and signalling compass information that is derived purely from polarized light. Furthermore, they deal with the directional ambiguity that is inherent in polarized light by signalling all of the possible locations of the food source in their dances, thus maximizing the chances of recruitment to it. PMID:24395964

Honeybee navigation: critically examining the role of the polarization compass.

PubMed

Evangelista, C; Kraft, P; Dacke, M; Labhart, T; Srinivasan, M V

2014-01-01

Although it is widely accepted that honeybees use the polarized-light pattern of the sky as a compass for navigation, there is little direct evidence that this information is actually sensed during flight. Here, we ask whether flying bees can obtain compass cues derived purely from polarized light, and communicate this information to their nest-mates through the 'waggle dance'. Bees, from an observation hive with vertically oriented honeycombs, were trained to fly to a food source at the end of a tunnel, which provided overhead illumination that was polarized either parallel to the axis of the tunnel, or perpendicular to it. When the illumination was transversely polarized, bees danced in a predominantly vertical direction with waggles occurring equally frequently in the upward or the downward direction. They were thus using the polarized-light information to signal the two possible directions in which they could have flown in natural outdoor flight: either directly towards the sun, or directly away from it. When the illumination was axially polarized, the bees danced in a predominantly horizontal direction with waggles directed either to the left or the right, indicating that they could have flown in an azimuthal direction that was 90° to the right or to the left of the sun, respectively. When the first half of the tunnel provided axial illumination and the second half transverse illumination, bees danced along all of the four principal diagonal directions, which represent four equally likely locations of the food source based on the polarized-light information that they had acquired during their journey. We conclude that flying bees are capable of obtaining and signalling compass information that is derived purely from polarized light. Furthermore, they deal with the directional ambiguity that is inherent in polarized light by signalling all of the possible locations of the food source in their dances, thus maximizing the chances of recruitment to it.

Aqueous photolysis of the organic ultraviolet filter chemical octyl methoxycinnamate.

PubMed

MacManus-Spencer, Laura A; Tse, Monica L; Klein, Jacob L; Kracunas, Alison E

2011-05-01

Organic UV filter chemicals are the active ingredients in personal care products designed to protect the skin from UV radiation, and hundreds of tons are estimated to be produced annually. Despite their entrance into the aquatic environment by both direct and indirect routes and their detection in surface waters and fish, little is known about their environmental fate. UV filter chemicals are designed to be photostable, but some undergo transformation upon exposure to UV light. Octyl methoxycinnamate (OMC), a commonly used UV filter chemical, degrades rapidly by direct photolysis; previous studies have focused on its photoisomerization, and a few investigators have reported the formation of cyclodimers. Here, we present the kinetics and quantum efficiency of the direct photolysis of OMC and confirm that dimerization occurs as a result of direct photolysis in aqueous solution. Likely identities of the dimers are offered based on comparison to reported results for other cinnamate derivatives. We have identified additional products of direct photolysis that have not been previously reported and investigated their photostability, as well as the mechanism of product formation. There is also some evidence of indirect photolysis in the presence of dissolved natural organic matter.

A simulation investigation of scout/attack helicopter directional control requirements for hover and low-speed tasks

NASA Technical Reports Server (NTRS)

Bivens, Courtland C.; Guercio, Joseph G.

1987-01-01

A piloted simulator experiment was conducted to investigate directional axis handling qualities requirements for low speed and hover tasks performed by a Scout/Attack helicopter. Included were the directional characteristics of various candidate light helicopter family configurations. Also, the experiment focused on conventional single main/tail rotor configurations of the OH-58 series aircraft, where the first-order yaw-axis dynamic effects that contributed to the loss of tail rotor control were modeled. Five pilots flew 22 configurations under various wind conditions. Cooper-Harper handling quality ratings were used as the primary measure of merit of each configuration. The results of the experiment indicate that rotorcraft configurations with high directional gust sensitivity require greater minimum yaw damping to maintain satisfactory handling qualities during nap-of-the-Earth flying tasks. It was also determined that both yaw damping and control response are critical handling qualities parameters in performing the air-to-air target acquisition and tracking task. Finally, the lack of substantial yaw damping and larger values of gust sensitivity increased the possibility of loss of directional control at low airspeeds for the single main/tail rotor configurations.

Engineering of multi-segmented light tunnel and flattop focus with designed axial lengths and gaps

NASA Astrophysics Data System (ADS)

Yu, Yanzhong; Huang, Han; Zhou, Mianmian; Zhan, Qiwen

2018-01-01

Based on the radiation pattern from a sectional-uniform line source antenna, a three-dimensional (3D) focus engineering technique for the creation of multi-segmented light tunnel and flattop focus with designed axial lengths and gaps is proposed. Under a 4Pi focusing system, the fields radiated from sectional-uniform magnetic and electromagnetic current line source antennas are employed to generate multi-segmented optical tube and flattop focus, respectively. Numerical results demonstrate that the produced light tube and flattop focus remain homogeneous along the optical axis; and their lengths of the nth segment and the nth gap between consecutive segments can be easily adjusted and only depend on the sizes of the nth section and the nth blanking between adjacent sectional antennas. The optical tube is a pure azimuthally polarized field but for the flattop focus the longitudinal polarization is dominant on the optical axis. To obtain the required pupil plane illumination for constructing the above focal field with prescribed characteristics, the inverse problem of the antenna radiation field is solved. These peculiar focusing fields might find potential applications in multi-particle acceleration, multi-particle trapping and manipulation.

[Influence of ambient light and adjacent tooth in anterior tooth color measurement].

PubMed

Wang, Si-qian; Sean, S Lee; Wu, Zhang; Li, Yiming; Ma, Jian-feng

2007-10-01

To investigate the influence of different intensity and directions of ambient light and adjacent tooth in anterior tooth color measurement by using colorimeter. Fiber lite MI-150 was used as ambient illuminant and it irradiated from three or twelve o'clock direction through 45 degrees angle above. The light magnitude 0, 50, 75, 100, 125, 150 W were applied in this experiment. The values of CIE L* a* b* were measured by Minolta Chroma meter CR-321 colorimeter on the center labial surface of ten extracted human maxillary central incisors with or without adjacent teeth, then those data were analyzed statistically by using SPSS 11.5. Neither different intensities nor different directions of ambient light could influence the results of color measurement by using Minolta Chroma meter CR-321 colorimeter, so did the adjacent teeth whether those were exist or not. There is no influence of ambient light and adjacent teeth in the color measurement of anterior teeth under this experiment condition, and Minolta Chroma meter CR-321 colorimeter can be used to measure the color directly aside the chair with light.

Aberrant light directly impairs mood and learning through melanopsin-expressing neurons.

PubMed

LeGates, Tara A; Altimus, Cara M; Wang, Hui; Lee, Hey-Kyoung; Yang, Sunggu; Zhao, Haiqing; Kirkwood, Alfredo; Weber, E Todd; Hattar, Samer

2012-11-22

The daily solar cycle allows organisms to synchronize their circadian rhythms and sleep-wake cycles to the correct temporal niche. Changes in day-length, shift-work, and transmeridian travel lead to mood alterations and cognitive function deficits. Sleep deprivation and circadian disruption underlie mood and cognitive disorders associated with irregular light schedules. Whether irregular light schedules directly affect mood and cognitive functions in the context of normal sleep and circadian rhythms remains unclear. Here we show, using an aberrant light cycle that neither changes the amount and architecture of sleep nor causes changes in the circadian timing system, that light directly regulates mood-related behaviours and cognitive functions in mice. Animals exposed to the aberrant light cycle maintain daily corticosterone rhythms, but the overall levels of corticosterone are increased. Despite normal circadian and sleep structures, these animals show increased depression-like behaviours and impaired hippocampal long-term potentiation and learning. Administration of the antidepressant drugs fluoxetine or desipramine restores learning in mice exposed to the aberrant light cycle, suggesting that the mood deficit precedes the learning impairments. To determine the retinal circuits underlying this impairment of mood and learning, we examined the behavioural consequences of this light cycle in animals that lack intrinsically photosensitive retinal ganglion cells. In these animals, the aberrant light cycle does not impair mood and learning, despite the presence of the conventional retinal ganglion cells and the ability of these animals to detect light for image formation. These findings demonstrate the ability of light to influence cognitive and mood functions directly through intrinsically photosensitive retinal ganglion cells.

The revision of the European blood directives: A major challenge for transfusion medicine.

PubMed

Folléa, G; Aranko, K

2015-08-01

Using both patient-focused and donor-focused perspectives, to review the current EU blood directives, in order to derive proposals, in principle, for what should evolve during the revision process of these directives. Review of the EU blood directives in the light of scientific literature, related reports from the Directorate General Health and Consumers (DG SANTÉ), and from the Council of Europe (CoE). The analyses led us to present the main following proposals: developing voluntary unpaid donations: the directives should consider taking into consideration ethically acceptable forms of compensation consistent with altruistic donation (including plasma donations for fractionation); current expertise: more extensive utilization of the expertise of blood establishments and their consultants should be considered; donor selection: an evidence-based approach for basing donor deferral criteria on sound scientific evidence should be promoted; donor reactions: measures to prevent donor reactions and to make donations safer for the donors should also be included; quality control: The quality control requirements should relate to the Council of Europe Blood Guide specifications: these should become minimum standards (as is the case with monographs of the European Pharmacopeia), facilitating regular update of blood component lists and related specifications and compliance with the specifications; haemovigilance: because of reporting difficulties (e.g. lack of number of blood products transfused), the effectiveness of haemovigilance has so far been limited. This should lead appropriate bodies to investigate alternative or complementary ways to help improve patient safety, taking into consideration, in principle, patient blood management and the appropriate use of blood products. Furthermore, donor vigilance, which is still absent from the current directive should be included in a revised directive. These proposals for revising the current EU blood directives (if taken into account and given appropriate regulatory formulation) should help to optimize patient safety and donor care, progress the compliance with the ethical principles for donors and improve the efficiency of the healthcare systems dedicated to transfusion medicine. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

High-speed single-shot optical focusing through dynamic scattering media with full-phase wavefront shaping.

PubMed

Hemphill, Ashton S; Shen, Yuecheng; Liu, Yan; Wang, Lihong V

2017-11-27

In biological applications, optical focusing is limited by the diffusion of light, which prevents focusing at depths greater than ∼1 mm in soft tissue. Wavefront shaping extends the depth by compensating for phase distortions induced by scattering and thus allows for focusing light through biological tissue beyond the optical diffusion limit by using constructive interference. However, due to physiological motion, light scattering in tissue is deterministic only within a brief speckle correlation time. In in vivo tissue, this speckle correlation time is on the order of milliseconds, and so the wavefront must be optimized within this brief period. The speed of digital wavefront shaping has typically been limited by the relatively long time required to measure and display the optimal phase pattern. This limitation stems from the low speeds of cameras, data transfer and processing, and spatial light modulators. While binary-phase modulation requiring only two images for the phase measurement has recently been reported, most techniques require at least three frames for the full-phase measurement. Here, we present a full-phase digital optical phase conjugation method based on off-axis holography for single-shot optical focusing through scattering media. By using off-axis holography in conjunction with graphics processing unit based processing, we take advantage of the single-shot full-phase measurement while using parallel computation to quickly reconstruct the phase map. With this system, we can focus light through scattering media with a system latency of approximately 9 ms, on the order of the in vivo speckle correlation time.

Losing focus: how lens position and viewing angle affect the function of multifocal lenses in fishes.

PubMed

Gagnon, Yakir Luc; Wilby, David; Temple, Shelby Eric

2016-09-01

Light rays of different wavelengths are focused at different distances when they pass through a lens (longitudinal chromatic aberration [LCA]). For animals with color vision this can pose a serious problem, because in order to perceive a sharp image the rays must be focused at the shallow plane of the photoreceptor's outer segments in the retina. A variety of fish and tetrapods have been found to possess multifocal lenses, which correct for LCA by assigning concentric zones to correctly focus specific wavelengths. Each zone receives light from a specific beam entrance position (BEP) (the lateral distance between incoming light and the center of the lens). Any occlusion of incoming light at specific BEPs changes the composition of the wavelengths that are correctly focused on the retina. Here, we calculated the effect of lens position relative to the plane of the iris and light entering the eye at oblique angles on how much of the lens was involved in focusing the image on the retina (measured as the availability of BEPs). We used rotational photography of fish eyes and mathematical modeling to quantify the degree of lens occlusion. We found that, at most lens positions and viewing angles, there was a decrease of BEP availability and in some cases complete absence of some BEPs. Given the implications of these effects on image quality, we postulate that three morphological features (aphakic spaces, curvature of the iris, and intraretinal variability in spectral sensitivity) may, in part, be adaptations to mitigate the loss of spectral image quality in the periphery of the eyes of fishes.

High-speed single-shot optical focusing through dynamic scattering media with full-phase wavefront shaping

NASA Astrophysics Data System (ADS)

Hemphill, Ashton S.; Shen, Yuecheng; Liu, Yan; Wang, Lihong V.

2017-11-01

In biological applications, optical focusing is limited by the diffusion of light, which prevents focusing at depths greater than ˜1 mm in soft tissue. Wavefront shaping extends the depth by compensating for phase distortions induced by scattering and thus allows for focusing light through biological tissue beyond the optical diffusion limit by using constructive interference. However, due to physiological motion, light scattering in tissue is deterministic only within a brief speckle correlation time. In in vivo tissue, this speckle correlation time is on the order of milliseconds, and so the wavefront must be optimized within this brief period. The speed of digital wavefront shaping has typically been limited by the relatively long time required to measure and display the optimal phase pattern. This limitation stems from the low speeds of cameras, data transfer and processing, and spatial light modulators. While binary-phase modulation requiring only two images for the phase measurement has recently been reported, most techniques require at least three frames for the full-phase measurement. Here, we present a full-phase digital optical phase conjugation method based on off-axis holography for single-shot optical focusing through scattering media. By using off-axis holography in conjunction with graphics processing unit based processing, we take advantage of the single-shot full-phase measurement while using parallel computation to quickly reconstruct the phase map. With this system, we can focus light through scattering media with a system latency of approximately 9 ms, on the order of the in vivo speckle correlation time.

Convection currents enhancement of the spring constant in optical tweezers

NASA Astrophysics Data System (ADS)

Zenteno-Hernández, J. A.; Gómez-Vieyra, A.; Torres-Hurtado, S. A.; Ramirez-San-Juan, J. C.; Ramos-García, R.

2016-09-01

In this work we demonstrate the increasing of the trap stiffness (spring constant) constant of an optical trap of particles suspended in water by laser-induced convection currents. These currents are the result of thermal gradients created by a light absorption in a thin layer of hydrogenated amorphous silicon (a:Si-H) deposited at the bottom of cell. Since convection currents (and therefore drag forces) are symmetric around the beam focus particles trapped by the beam are further contained. Around the focus the drag force is directed upwards and partially compensated by radiation pressure depending on the laser power increasing the stiffness of the optical trapping increases significatively so a particle trapped could dragged (by moving the translation stage leaving the beam fixed) at velocities as high as 90μm/s without escaping the trap, whereas with no a:Si-H film, the particle escapes from the trap at lower velocities (30μm/s).

High energy physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kernan, A.; Shen, B.C.; Ma, E.

Hadron collider studies will focus on: (i) the search for the top quark with the newly installed D0 detector at the Fermilab Tevatron collider, (ii) the upgrade of the D0 detector to match the new main injector luminosity and (iii) R&D on silicon microstrip tracking devices for the SSC. High statistics studies of Z{sup 0} decay will continue with the OPAL detector at LEP. These studies will include a direct measurement of Z decay to neutrinos, the search for Higgs and heavy quark decays of Z. Preparations for the Large Scintillation Neutrino Detector (LSND) to measure neutrino oscillations at LAMPFmore » will focus on data acquisition and testing of photomultiplier tubes. In the theoretical area E. Ma will concentrate on mass-generating radiative mechanisms for light quarks and leptons in renormalizable gauge field theories. J. Wudka`s program includes a detailed investigation of the magnetic-flip approach to the solar neutrino.« less

A Review of Services and Interventions for Runaway and Homeless Youth: Moving Forward.

PubMed

Slesnick, Natasha; Dashora, Pushpanjali; Letcher, Amber; Erdem, Gizem; Serovich, Julianne

2009-07-01

Research focused on the impact of community-based services and treatment interventions designed to intervene in the lives of runaway and homeless youth has increased in the last two decades in the U.S. and internationally. In light of the tremendous need for identifying effective strategies to end homelessness and its associated problems among youth, this paper summarizes and critiques the findings of the extant literature including U.S., international, and qualitative studies. Thirty-two papers met criteria for inclusion in the review. Among the conclusions are that comprehensive interventions which target the varied and interconnected needs of these youth and families may be worthy of more study than studies that isolate the intervention focus on one problem. Also, more research incorporating design strategies that increase the reliability and validity of study findings is needed. Other preliminary conclusions and future directions are offered.

Method and apparatus for inspecting reflection masks for defects

DOEpatents

Bokor, Jeffrey; Lin, Yun

2003-04-29

An at-wavelength system for extreme ultraviolet lithography mask blank defect detection is provided. When a focused beam of wavelength 13 nm is incident on a defective region of a mask blank, three possible phenomena can occur. The defect will induce an intensity reduction in the specularly reflected beam, scatter incoming photons into an off-specular direction, and change the amplitude and phase of the electric field at the surface which can be monitored through the change in the photoemission current. The magnitude of these changes will depend on the incident beam size, and the nature, extent and size of the defect. Inspection of the mask blank is performed by scanning the mask blank with 13 nm light focused to a spot a few .mu.m in diameter, while measuring the reflected beam intensity (bright field detection), the scattered beam intensity (dark-field detection) and/or the change in the photoemission current.

Scanning optical microscope with long working distance objective

DOEpatents

Cloutier, Sylvain G.

2010-10-19

A scanning optical microscope, including: a light source to generate a beam of probe light; collimation optics to substantially collimate the probe beam; a probe-result beamsplitter; a long working-distance, infinity-corrected objective; scanning means to scan a beam spot of the focused probe beam on or within a sample; relay optics; and a detector. The collimation optics are disposed in the probe beam. The probe-result beamsplitter is arranged in the optical paths of the probe beam and the resultant light from the sample. The beamsplitter reflects the probe beam into the objective and transmits resultant light. The long working-distance, infinity-corrected objective is also arranged in the optical paths of the probe beam and the resultant light. It focuses the reflected probe beam onto the sample, and collects and substantially collimates the resultant light. The relay optics are arranged to relay the transmitted resultant light from the beamsplitter to the detector.

Single objective light-sheet microscopy for high-speed whole-cell 3D super-resolution

DOE PAGES

Meddens, Marjolein B. M.; Liu, Sheng; Finnegan, Patrick S.; ...

2016-01-01

Here, we have developed a method for performing light-sheet microscopy with a single high numerical aperture lens by integrating reflective side walls into a microfluidic chip. These 45° side walls generate light-sheet illumination by reflecting a vertical light-sheet into the focal plane of the objective. Light-sheet illumination of cells loaded in the channels increases image quality in diffraction limited imaging via reduction of out-of-focus background light. Single molecule super-resolution is also improved by the decreased background resulting in better localization precision and decreased photo-bleaching, leading to more accepted localizations overall and higher quality images. Moreover, 2D and 3D single moleculemore » super-resolution data can be acquired faster by taking advantage of the increased illumination intensities as compared to wide field, in the focused light-sheet.« less

Focusing of light energy inside a scattering medium by controlling the time-gated multiple light scattering

NASA Astrophysics Data System (ADS)

Jeong, Seungwon; Lee, Ye-Ryoung; Choi, Wonjun; Kang, Sungsam; Hong, Jin Hee; Park, Jin-Sung; Lim, Yong-Sik; Park, Hong-Gyu; Choi, Wonshik

2018-05-01

The efficient delivery of light energy is a prerequisite for the non-invasive imaging and stimulating of target objects embedded deep within a scattering medium. However, the injected waves experience random diffusion by multiple light scattering, and only a small fraction reaches the target object. Here, we present a method to counteract wave diffusion and to focus multiple-scattered waves at the deeply embedded target. To realize this, we experimentally inject light into the reflection eigenchannels of a specific flight time to preferably enhance the intensity of those multiple-scattered waves that have interacted with the target object. For targets that are too deep to be visible by optical imaging, we demonstrate a more than tenfold enhancement in light energy delivery in comparison with ordinary wave diffusion cases. This work will lay a foundation to enhance the working depth of imaging, sensing and light stimulation.

Polarized light sensitivity and orientation in coral reef fish post-larvae.

PubMed

Berenshtein, Igal; Kiflawi, Moshe; Shashar, Nadav; Wieler, Uri; Agiv, Haim; Paris, Claire B

2014-01-01

Recent studies of the larvae of coral-reef fishes reveal that these tiny vertebrates possess remarkable swimming capabilities, as well as the ability to orient to olfactory, auditory, and visual cues. While navigation according to reef-generated chemicals and sounds can significantly affect dispersal, the effect is limited to the vicinity of the reef. Effective long-distance navigation requires at least one other capacity-the ability to maintain a bearing using, for example, a sun compass. Directional information in the sun's position can take the form of polarized-light related cues (i.e., e-vector orientation and percent polarization) and/or non-polarized-light related cues (i.e., the direct image of the sun, and the brightness and spectral gradients). We examined the response to both types of cues using commercially-reared post-larvae of the spine-cheeked anemonefish Premnas biaculeatus. Initial optomotor trials indicated that the post-larval stages are sensitive to linearly polarized light. Swimming directionality was then tested using a Drifting In-Situ Chamber (DISC), which allowed us to examine the response of the post-larvae to natural variation in light conditions and to manipulated levels of light polarization. Under natural light conditions, 28 of 29 post-larvae showed significant directional swimming (Rayleigh's test p<0.05, R = 0.74±0.23), but to no particular direction. Swimming directionality was positively affected by sky clarity (absence of clouds and haze), which explained 38% of the observed variation. Moreover, post-larvae swimming under fully polarized light exhibited a distinct behavior of tracking the polarization axis, as it rotated along with the DISC. This behavior was not observed under partially-polarized illumination. We view these findings as an indication for the use of sun-related cues, and polarized light signal in specific, by orienting coral-reef fish larvae.

Polarized Light Sensitivity and Orientation in Coral Reef Fish Post-Larvae

PubMed Central

Berenshtein, Igal; Kiflawi, Moshe; Shashar, Nadav; Wieler, Uri; Agiv, Haim; Paris, Claire B.

2014-01-01

Recent studies of the larvae of coral-reef fishes reveal that these tiny vertebrates possess remarkable swimming capabilities, as well as the ability to orient to olfactory, auditory, and visual cues. While navigation according to reef-generated chemicals and sounds can significantly affect dispersal, the effect is limited to the vicinity of the reef. Effective long-distance navigation requires at least one other capacity–the ability to maintain a bearing using, for example, a sun compass. Directional information in the sun’s position can take the form of polarized-light related cues (i.e., e-vector orientation and percent polarization) and/or non-polarized-light related cues (i.e., the direct image of the sun, and the brightness and spectral gradients). We examined the response to both types of cues using commercially-reared post-larvae of the spine-cheeked anemonefish Premnas biaculeatus. Initial optomotor trials indicated that the post-larval stages are sensitive to linearly polarized light. Swimming directionality was then tested using a Drifting In-Situ Chamber (DISC), which allowed us to examine the response of the post-larvae to natural variation in light conditions and to manipulated levels of light polarization. Under natural light conditions, 28 of 29 post-larvae showed significant directional swimming (Rayleigh’s test p<0.05, R = 0.74±0.23), but to no particular direction. Swimming directionality was positively affected by sky clarity (absence of clouds and haze), which explained 38% of the observed variation. Moreover, post-larvae swimming under fully polarized light exhibited a distinct behavior of tracking the polarization axis, as it rotated along with the DISC. This behavior was not observed under partially-polarized illumination. We view these findings as an indication for the use of sun-related cues, and polarized light signal in specific, by orienting coral-reef fish larvae. PMID:24516662

Exploring direct 3D interaction for full horizontal parallax light field displays using leap motion controller.

PubMed

Adhikarla, Vamsi Kiran; Sodnik, Jaka; Szolgay, Peter; Jakus, Grega

2015-04-14

This paper reports on the design and evaluation of direct 3D gesture interaction with a full horizontal parallax light field display. A light field display defines a visual scene using directional light beams emitted from multiple light sources as if they are emitted from scene points. Each scene point is rendered individually resulting in more realistic and accurate 3D visualization compared to other 3D displaying technologies. We propose an interaction setup combining the visualization of objects within the Field Of View (FOV) of a light field display and their selection through freehand gesture tracked by the Leap Motion Controller. The accuracy and usefulness of the proposed interaction setup was also evaluated in a user study with test subjects. The results of the study revealed high user preference for free hand interaction with light field display as well as relatively low cognitive demand of this technique. Further, our results also revealed some limitations and adjustments of the proposed setup to be addressed in future work.

Thumb-actuated two-axis controller

NASA Technical Reports Server (NTRS)

Hollow, R. H. (Inventor)

1986-01-01

A two axis joystick controller is described. It produces at least one output signal in relation to pivotal displacement of a member with respect to an intersection of the two axes. The member is pivotally movable on a support with respect to the two axes. The support has a centrally disposed aperture. A light source is mounted on the pivotally movable member above the aperture to direct light through the aperture. A light sensor is mounted below the aperture in the support at the intersection of the two axes to receive the light from the light source directed through the aperture. The light sensor produces at least one output signal related to a location on the sensor at which the light from the light source strikes the sensor.

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors

PubMed Central

Li, T.; Heuvelink, E.; Dueck, T. A.; Janse, J.; Gort, G.; Marcelis, L. F. M.

2014-01-01

Background and Aims Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Methods Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. Key Results The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less photoinhibition at the top of the canopy when global irradiance was high. Conclusions Diffuse light enhanced crop photosynthesis. A more uniform horizontal PPFD distribution played the most important role in this enhancement, and a more uniform vertical PPFD distribution and higher leaf photosynthetic capacity contributed more to the enhancement of crop photosynthesis than did higher values of LAI. PMID:24782436

UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanders, N. E.; Soderberg, A. M.; Betancourt, M., E-mail: nsanders@cfa.harvard.edu

2015-02-10

Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. Wemore » present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST.« less

First Transmitted Hyperspectral Light Measurements and Cloud Properties from Recent Field Campaign Sampling Clouds Under Biomass Burning Aerosol

NASA Technical Reports Server (NTRS)

Leblanc, S.; Redemann, Jens; Shinozuka, Yohei; Flynn, Connor J.; Segal Rozenhaimer, Michal; Kacenelenbogen, Meloe Shenandoah; Pistone, Kristina Marie Myers; Schmidt, Sebastian; Cochrane, Sabrina

2016-01-01

We present a first view of data collected during a recent field campaign aimed at measuring biomass burning aerosol above clouds from airborne platforms. The NASA ObseRvations of CLouds above Aerosols and their intEractionS (ORACLES) field campaign recently concluded its first deployment sampling clouds and overlying aerosol layer from the airborne platform NASA P3. We present results from the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), in conjunction with the Solar Spectral Flux Radiometers (SSFR). During this deployment, 4STAR sampled transmitted solar light either via direct solar beam measurements and scattered light measurements, enabling the measurement of aerosol optical thickness and the retrieval of information on aerosol particles in addition to overlying cloud properties. We focus on the zenith-viewing scattered light measurements, which are used to retrieve cloud optical thickness, effective radius, and thermodynamic phase of clouds under a biomass burning layer. The biomass burning aerosol layer present above the clouds is the cause of potential bias in retrieved cloud optical depth and effective radius from satellites. We contrast the typical reflection based approach used by satellites to the transmission based approach used by 4STAR during ORACLES for retrieving cloud properties. It is suspected that these differing approaches will yield a change in retrieved properties since light transmitted through clouds is sensitive to a different cloud volume than reflected light at cloud top. We offer a preliminary view of the implications of these differences in sampling volumes to the calculation of cloud radiative effects (CRE).

Light Matters (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)

ScienceCinema

Atwater, Harry (Director, Light-Material Interactions in Energy Conversion (LMI), California Institute of Technology); LMI Staff

2017-12-09

'Light Matters' was submitted by the Center for Light-Material Interactions in Energy Conversion (LMI) to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. This video was selected as one of five winners by a distinguished panel of judges for its 'striking photography and visual impact'. LMI, an EFRC directed by Harry Atwater at the California Institute of Technology is a partnership of scientists from three institutions: CalTech (lead), University of California, Berkeley, and the University of Illinois at Urbana-Champaign. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of Light-Material Interactions in Energy Conversion is 'to tailor the morphology, complex dielectric structure, and electronic properties of matter to sculpt the flow of sunlight, enabling light conversion to electrical and chemical energy with unprecedented efficiency.' Research topics are: catalysis (imines hydrocarbons), solar photovoltaic, solar fuels, photonic, solid state lighting, metamaterial, optics, phonons, thermal conductivity, solar electrodes, photsynthesis, CO{sub 2} (convert), greenhouse gas, and matter by design.

Determination of wood grain direction from laser light scattering pattern

NASA Astrophysics Data System (ADS)

Simonaho, Simo-Pekka; Palviainen, Jari; Tolonen, Yrjö; Silvennoinen, Raimo

2004-01-01

Laser light scattering patterns from the grains of wood are investigated in detail to gain information about the characteristics of scattering patterns related to the direction of the grains. For this purpose, wood samples of Scots pine ( Pinus sylvestris L.) and silver birch ( Betula pubescens) were investigated. The orientation and shape of the scattering pattern of laser light in wood was found to correlate well with the direction of grain angles in a three-dimensional domain. The proposed method was also experimentally verified.

Directional imaging of the retinal cone mosaic

NASA Astrophysics Data System (ADS)

Vohnsen, Brian; Iglesias, Ignacio; Artal, Pablo

2004-05-01

We describe a near-IR scanning laser ophthalmoscope that allows the retinal cone mosaic to be imaged in the human eye in vivo without the use of wave-front correction techniques. The method takes advantage of the highly directional quality of cone photoreceptors that permits efficient coupling of light to individual cones and subsequent detection of most directional components of the backscattered light produced by the light-guiding effect of the cones. We discuss details of the system and describe cone-mosaic images obtained under different conditions.

Circular polarization analyzer with polarization tunable focusing of surface plasmon polaritons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Sen; Zhang, Yan, E-mail: yzhang@mail.cnu.edu.cn; Beijing Key Laboratory for Metamaterials and Devices, and Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048

2015-12-14

A practical circular polarization analyzer (CPA) that can selectively focus surface plasmon polaritons (SPPs) at two separate locations, according to the helicity of the circularly polarized light, is designed and experimentally verified in the terahertz frequency range. The CPA consists of fishbone-slit units and is designed using the simulated annealing algorithm. By differentially detecting the intensities of the two SPPs focuses, the helicity of the incident circularly polarized light can be obtained and the CPA is less vulnerable to the noise of incident light. The proposed device may also have wide potential applications in chiral SPPs photonics and the analysismore » of chiral molecules in biology.« less

Biconcave micro-optofluidic lens with low-refractive-index liquids.

PubMed

Song, Chaolong; Nguyen, Nam-Trung; Asundi, Anand Krishna; Low, Cassandra Lee-Ngo

2009-12-01

One of the current problems of micro-optofluidics is the choice of a suitable liquid with a high refractive index (RI). We report the use of a low-RI liquid in a biconcave liquid-core liquid-cladding lens for focusing light. For the characterization of the lens, a telescope system was constructed from polydimethylsiloxane lenses to collimate and expand a light beam emitted from an optical fiber. The tunable optofluidic biconcave lens focuses the parallel beam. Fluorescent dye diluted in an index-matching liquid was used for the visualization of the light rays in a beam-tracing chamber. The focused beam is tuned by adjusting the flow rate ratio between core and cladding streams.

Experimental and theoretical investigations on the validity of the geometrical optics model for calculating the stability of optical traps.

PubMed

Schut, T C; Hesselink, G; de Grooth, B G; Greve, J

1991-01-01

We have developed a computer program based on the geometrical optics approach proposed by Roosen to calculate the forces on dielectric spheres in focused laser beams. We have explicitly taken into account the polarization of the laser light and thd divergence of the laser beam. The model can be used to evaluate the stability of optical traps in a variety of different optical configurations. Our calculations explain the experimental observation by Ashkin that a stable single-beam optical trap, without the help of the gravitation force, can be obtained with a strongly divergent laser beam. Our calculations also predict a different trap stability in the directions orthogonal and parallel to the polarization direction of the incident light. Different experimental methods were used to test the predictions of the model for the gravity trap. A new method for measuring the radiation force along the beam axis in both the stable and instable regions is presented. Measurements of the radiation force on polystyrene spheres with diameters of 7.5 and 32 microns in a TEM00-mode laser beam showed a good qualitative correlation with the predictions and a slight quantitative difference. The validity of the geometrical approximations involved in the model will be discussed for spheres of different sizes and refractive indices.

Multi-contrast light profile microscopy for the depth-resolved imaging of the properties of multi-ply thin films.

PubMed

Power, J F

2009-06-01

Light profile microscopy (LPM) is a direct method for the spectral depth imaging of thin film cross-sections on the micrometer scale. LPM uses a perpendicular viewing configuration that directly images a source beam propagated through a thin film. Images are formed in dark field contrast, which is highly sensitive to subtle interfacial structures that are invisible to reference methods. The independent focusing of illumination and imaging systems allows multiple registered optical sources to be hosted on a single platform. These features make LPM a powerful multi-contrast (MC) imaging technique, demonstrated in this work with six modes of imaging in a single instrument, based on (1) broad-band elastic scatter; (2) laser excited wideband luminescence; (3) coherent elastic scatter; (4) Raman scatter (three channels with RGB illumination); (5) wavelength resolved luminescence; and (6) spectral broadband scatter, resolved in immediate succession. MC-LPM integrates Raman images with a wider optical and morphological picture of the sample than prior art microprobes. Currently, MC-LPM resolves images at an effective spectral resolution better than 9 cm(-1), at a spatial resolution approaching 1 microm, with optics that operate in air at half the maximum numerical aperture of the prior art microprobes.

High Intensity Organic Light-emitting Diodes

NASA Astrophysics Data System (ADS)

Qi, Xiangfei

This thesis is dedicated to the fabrication, modeling, and characterization to achieve high efficiency organic light-emitting diodes (OLEDs) for illumination applications. Compared to conventional lighting sources, OLEDs enabled the direct conversion of electrical energy into light emission and have intrigued the world's lighting designers with the long-lasting, highly efficient illumination. We begin with a brief overview of organic technology, from basic organic semiconductor physics, to its application in optoelectronics, i.e. light-emitting diodes, photovoltaics, photodetectors and thin-film transistors. Due to the importance of phosphorescent materials, we will focus on the photophysics of metal complexes that is central to high efficiency OLED technology, followed by a transient study to examine the radiative decay dynamics in a series of phosphorescent platinum binuclear complexes. The major theme of this thesis is the design and optimization of a novel architecture where individual red, green and blue phosphorescent OLEDs are vertically stacked and electrically interconnected by the compound charge generation layers. We modeled carrier generation from the metal-oxide/doped organic interface based on a thermally assisted tunneling mechanism. The model provides insights to the optimization of a stacked OLED from both electrical and optical point of view. To realize the high intensity white lighting source, the efficient removal of heat is of a particular concern, especially in large-area devices. A fundamental transfer matrix analysis is introduced to predict the thermal properties in the devices. The analysis employs Laplace transforms to determine the response of the system to the combined effects of conduction, convection, and radiation. This perspective of constructing transmission matrices greatly facilitates the calculation of transient coupled heat transfer in a general multi-layer composite. It converts differential equations to algebraic forms, and can be expanded to study other thermal issues in more sophisticated structures.

Chronic exposure to dim artificial light at night decreases fecundity and adult survival in Drosophila melanogaster.

PubMed

McLay, L K; Green, M P; Jones, T M

2017-07-01

The presence of artificial light at night is expanding in geographical range and increasing in intensity to such an extent that species living in urban environments may never experience natural darkness. The negative ecological consequences of artificial night lighting have been identified in several key life history traits across multiple taxa (albeit with a strong vertebrate focus); comparable data for invertebrates is lacking. In this study, we explored the effect of chronic exposure to different night-time lighting intensities on growth, reproduction and survival in Drosophila melanogaster. We reared three generations of flies under identical daytime light conditions (2600lx) and one of four ecologically relevant ALAN treatments (0, 1, 10 or 100lx), then explored variation in oviposition, number of eggs produced, juvenile growth and survival and adult survival. We found that, in the presence of light at night (1, 10 and 100lx treatments), the probability of a female commencing oviposition and the number of eggs laid was significantly reduced. This did not translate into differences at the juvenile phase: juvenile development times and the probability of eclosing as an adult were comparable across all treatments. However, we demonstrate for the first time a direct link between chronic exposure to light at night (greater than 1lx) and adult survival. Our data highlight that ALAN has the capacity to cause dramatic shifts in multiple life history traits at both the individual and population level. Such shifts are likely to be species-specific, however a more in depth understanding of the broad-scale impact of ALAN and the relevant mechanisms driving biological change is urgently required as we move into an increasing brightly lit future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Blue light dosage affects carotenoids and tocopherols in microgreens.

PubMed

Samuolienė, Giedrė; Viršilė, Akvilė; Brazaitytė, Aušra; Jankauskienė, Julė; Sakalauskienė, Sandra; Vaštakaitė, Viktorija; Novičkovas, Algirdas; Viškelienė, Alina; Sasnauskas, Audrius; Duchovskis, Pavelas

2017-08-01

Mustard, beet and parsley were grown to harvest time under selected LEDs: 638+660+731+0% 445nm; 638+660+731+8% 445nm; 638+660+731+16% 445nm; 638+660+731+25% 445nm; 638+660+731+33% 445nm. From 1.2 to 4.3 times higher concentrations of chlorophylls a and b, carotenoids, α- and β-carotenes, lutein, violaxanthin and zeaxanthin was found under blue 33% treatment in comparison to lower blue light dosages. Meanwhile, the accumulation of metabolites, which were not directly connected with light reactions, such as tocopherols, was more influenced by lower (16%) blue light dosage, increasing about 1.3 times. Thus, microgreen enrichment of carotenoid and xanthophyll pigments may be achieved using higher (16-33%) blue light intensities. Changes in metabolite quantities were not the result of changes of other carotenoid concentration, but were more influenced by light treatment and depended on the species. Significant quantitative changes in response to blue light percentage were obtained for both directly and not directly light-dependent metabolite groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Red Light Receptor Phytochrome B Directly Enhances Substrate-E3 Ligase Interactions to Attenuate Ethylene Responses.

PubMed

Shi, Hui; Shen, Xing; Liu, Renlu; Xue, Chang; Wei, Ning; Deng, Xing Wang; Zhong, Shangwei

2016-12-05

Plants germinating under subterranean darkness assume skotomorphogenesis, a developmental program strengthened by ethylene in response to mechanical pressure of soil. Upon reaching the surface, light triggers a dramatic developmental transition termed de-etiolation that requires immediate termination of ethylene responses. Here, we report that light activation of photoreceptor phyB results in rapid degradation of EIN3, the master transcription factor in the ethylene signaling pathway. As a result, light rapidly and efficiently represses ethylene actions. Specifically, phyB directly interacts with EIN3 in a light-dependent manner and also physically associates with F box protein EBFs. The light-activated association of phyB, EIN3, and EBF1/EBF2 proteins stimulates robust EIN3 degradation by SCF EBF1/EBF2 E3 ligases. We reveal that phyB manipulates substrate-E3 ligase interactions in a light-dependent manner, thus directly controlling the stability of EIN3. Our findings illustrate a mechanistic model of how plants transduce light information to immediately turn off ethylene signaling for de-etiolation initiation. Copyright © 2016 Elsevier Inc. All rights reserved.

A novel magnet focusing plate for matrix-assisted laser desorption/ionization analysis of magnetic bead-bound analytes.

PubMed

Gode, David; Volmer, Dietrich A

2013-05-15

Magnetic beads are often used for serum profiling of peptide and protein biomarkers. In these assays, the bead-bound analytes are eluted from the beads prior to mass spectrometric analysis. This study describes a novel matrix-assisted laser desorption/ionization (MALDI) technique for direct application and focusing of magnetic beads to MALDI plates by means of dedicated micro-magnets as sample spots. Custom-made MALDI plates with magnetic focusing spots were made using small nickel-coated neodymium micro-magnets integrated into a stainless steel plate in a 16 × 24 (384) pattern. For demonstrating the proof-of-concept, commercial C-18 magnetic beads were used for the extraction of a test compound (reserpine) from aqueous solution. Experiments were conducted to study focusing abilities, the required laser energies, the influence of a matrix compound, dispensing techniques, solvent choice and the amount of magnetic beads. Dispensing the magnetic beads onto the micro-magnet sample spots resulted in immediate and strong binding to the magnetic surface. Light microscope images illustrated the homogeneous distribution of beads across the surfaces of the magnets, when the entire sample volume containing the beads was pipetted onto the surface. Subsequent MALDI analysis of the bead-bound analyte demonstrated excellent and reproducible ionization yields. The surface-assisted laser desorption/ionization (SALDI) properties of the strongly light-absorbing γ-Fe2O3-based beads resulted in similar ionization efficiencies to those obtained from experiments with an additional MALDI matrix compound. This feasibility study successfully demonstrated the magnetic focusing abilities for magnetic bead-bound analytes on a novel MALDI plate containing small micro-magnets as sample spots. One of the key advantages of this integrated approach is that no elution steps from magnetic beads were required during analyses compared with conventional bead experiments. Copyright © 2013 John Wiley & Sons, Ltd.

Hydrogen bonds in crystalline D-alanine: diffraction and spectroscopic evidence for differences between enantiomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belo, Ezequiel A.; Pereira, Jose E. M.; Freire, Paulo T. C.

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of D-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of D-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of D-alanine compared with L-alanine.

Chapter 16: Retrocommissioning Evaluation Protocol. The Uniform Methods Project: Methods for Determining Energy Efficiency Savings for Specific Measures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurnik, Charles W.; Tiessen, Alex

Retrocommissioning (RCx) is a systematic process for optimizing energy performance in existing buildings. It specifically focuses on improving the control of energy-using equipment (e.g., heating, ventilation, and air conditioning [HVAC] equipment and lighting) and typically does not involve equipment replacement. Field results have shown proper RCx can achieve energy savings ranging from 5 percent to 20 percent, with a typical payback of two years or less (Thorne 2003). The method presented in this protocol provides direction regarding: (1) how to account for each measure's specific characteristics and (2) how to choose the most appropriate savings verification approach.

Collider study on the loop-induced dark matter mediation

NASA Astrophysics Data System (ADS)

Tsai, Yuhsin

2016-06-01

Collider experiments are one of the most promising ways to constrain Dark Matter (DM) interactions. For DM couplings involving light mediators, especially for the loop-mediated interactions, a meaningful interpretation of the results requires to go beyond effective field theory. In this note we discuss the study of the magnetic dipole interacting DM, focusing on a model with anarchic dark flavor structure. By including the momentum-dependent form factors that mediate the coupling - given by the Dark Penguin - in collider processes, we study bounds from monophoton, diphoton, and non-pointing photon searches at the LHC. We also compare our results to constraints from the direct detection experiments.

Hydrogen bonds in crystalline D-alanine: diffraction and spectroscopic evidence for differences between enantiomers

DOE PAGES

Belo, Ezequiel A.; Pereira, Jose E. M.; Freire, Paulo T. C.; ...

2018-01-01

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of D-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of D-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of D-alanine compared with L-alanine.