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Sample records for green-to-orange light based

  1. A Strategy to enhance Eu3+ emission from LiYF4:Eu nanophosphors and green-to-orange multicolor tunable, transparent nanophosphor-polymer composites

    PubMed Central

    Kim, Su Yeon; Won, Yu-Ho; Jang, Ho Seong

    2015-01-01

    LiYF4:Eu nanophosphors with a single tetragonal phase are synthesized, and various strategies to enhance the Eu3+ emission from the nanophosphors are investigated. The optimized Eu3+ concentration is 35 mol%, and the red emission peaks due to the 5D0 →7FJ (J = 1 and 2) transitions of Eu3+ ions are further enhanced by energy transfer from a sensitizer pair of Ce3+ and Tb3+. The triple doping of Ce, Tb, and Eu into the LiYF4 host more effectively enhances the Eu3+ emission than the core/shell strategies of LiYF4:Eu(35%)/LiYF4:Ce(15%), Tb(15%) and LiYF4:Ce(15%), Tb(15%)/LiYF4:Eu(35%) architectures. Efficient energy transfer from Ce3+ to Eu3+ through Tb3+ results in three times higher Eu3+ emission intensity from LiYF4:Ce(15%), Tb(15%), Eu(1%) nanophosphors compared with LiYF4:Eu(35%), which contains the optimized Eu3+ concentration. Owing to the energy transfer of Ce3+ → Tb3+ and Ce3+ → Tb3+ → Eu3+, intense green and red emission peaks are observed from LiYF4:Ce(13%), Tb(14%), Eu(1-5%) (LiYF4:Ce, Tb, Eu) nanophosphors, and the intensity ratio of green to red emission is controlled by adjusting the Eu3+ concentration. With increasing Eu3+ concentration, the LiYF4:Ce, Tb, Eu nanophosphors exhibit multicolor emission from green to orange. In addition, the successful incorporation of LiYF4:Ce, Tb, Eu nanophosphors into polydimethylsiloxane (PDMS) facilitates the preparation of highly transparent nanophosphor-PDMS composites that present excellent multicolor tunability. PMID:25597900

  2. Carbon Nanotube Based Light Sensor

    NASA Technical Reports Server (NTRS)

    Wincheski, russell A. (Inventor); Smits, Jan M. (Inventor); Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Ingram, JoAnne L. (Inventor)

    2006-01-01

    A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of electrically non-conductive material with the CNT-based conductors being distributed in a spaced apart fashion about a periphery of the first electrode. Each CNT-based conductor is coupled on one end thereof to the first electrode and extends away from the first electrode to terminate at a second free end. A second or gate electrode is positioned on the non-conductive material layer and is spaced apart from the second free end of each CNT-based conductor. Coupled to the first and second electrode is a device for detecting electron transfer along the CNT-based conductors resulting from light impinging on the CNT-based conductors.

  3. The International Year of Light and Light-based Technologies

    NASA Astrophysics Data System (ADS)

    Pendrill, Ann-Marie

    2015-05-01

    I report on the opening ceremony of the International Year of Light and Light-based Technologies 2015 (IYL2015), which took place at the UNESCO headquarters in Paris, France, on 19-20 January 2015. Over the two days, more than 1000 participants from all over the world learned more about the fundamental properties of light and advanced photonics applications, the history of optics and its applications through the centuries, light poverty and light pollution, and light for everyday life, health and research.

  4. Light pollution simulations for planar ground-based light sources.

    PubMed

    Kocifaj, Miroslav

    2008-02-20

    The light pollution model is employed to analyze spatial behavior of luminance at the night sky under cloudless and overcast conditions. Enhanced light excess is particularly identified at cloudy skies, because the clouds efficiently contribute to the downward luminous flux. It is evident that size of ground-based light sources can play an important role in the case of overcast sky conditions. Nevertheless, the realistically sized light sources are rarely embedded into light pollution modeling, and rather they are replaced by simple point sources. We discuss the discrepancies between sky luminance distributions when at first the planar light sources are considered and at second the point-source approximation is accepted. The found differences are noticeable if the size of the light source, distance to the observer, and altitude of a cloudy layer are comparable one to the other. Compared with point-source approximation, an inclusion of the size factor into modeling the light sources leads to partial elimination of the steep changes of sky luminance (typical for point sources of light). The narrow and sharp light pillars normally presented on the sky illuminated by point light sources can disappear or fuse together when two or more nearby light sources are considered with their real sizes. Sky elements situated close to the horizon will glow efficiently if luminous flux originates from two-dimensional ground-based entities (such as cities or villages). PMID:18288228

  5. Eu{sup 2+}, Mn{sup 2+} co-doped Ba{sub 9}Y{sub 2}Si{sub 6}O{sub 24} phosphors based on near-UV-excitable LED lights

    SciTech Connect

    Kim, Yoejin; Park, Sangmoon

    2014-01-01

    Graphical abstract: - Highlights: • New near-ultraviolet (NUV)-excitable materials composed of Ba{sub 9}Eu{sub m}Mn{sub n}Y{sub 2}Si{sub 6}O{sub 24} (m = 0.01–0.5, n = 0–0.7) were prepared. • High energy-transfer from Eu{sup 2+} to Mn{sup 2+} and their energy-transfer mechanism were discussed. • The co-doping of Eu{sup 2+} and Mn{sup 2+} in the orthosilicate structure resulted in the emission of white light under NUV LED light. - Abstract: New single-phase and near-ultraviolet (NUV)-excitable materials composed of Ba{sub 9}Eu{sub m}Mn{sub n}Y{sub 2}Si{sub 6}O{sub 24} (m = 0.01–0.5, n = 0–0.7) were prepared via a solid-state reaction in reducing atmosphere. X-ray diffraction patterns of the obtained phosphors were examined to index the peak positions. After doping the host structure with Eu{sup 2+} and Mn{sup 2+} emitters, the intense green, white, and orange emission lights that were observed in the photoluminescence spectra under NUV excitation were monitored. The dependence of the luminescent intensity of the Mn{sup 2+} co-doped (n = 0.1–0.7) host lattices on the fixed Eu{sup 2+} content (m = 0.1, 0.3, 0.5) is also investigated. Co-doping Mn{sup 2+} into the Eu{sup 2+}-doped host structure enabled a high energy-transfer from Eu{sup 2+} to Mn{sup 2+} and their energy-transfer mechanism were discussed. Using these phosphors, the desired CIE values including emissions throughout the green to orange regions of the spectra were achieved. Efficient white-light light-emitting diodes (LEDs) were fabricated using Eu{sup 2+} and Mn{sup 2+} co-doped phosphors based on NUV-excitable LED lights.

  6. Optical Receiver Based On Luminescent Light Trapping

    NASA Technical Reports Server (NTRS)

    Perry, Joseph W.; Cole, Terry; Zewail, Ahmed H.

    1991-01-01

    Experiment demonstrates feasibility of optical-communication receiver based on luminescent light trapping. Light-gathering element plate of transparent material impregnated with laser dye. Light from distant laser transmitter falls on plate and absorbed by dye molecules, which become excited and reradiate. Reradiated light confined within plate by total internal reflection as it propagates toward edge of plate. Light arriving at edge escapes from plate and detected by small, high-speed, high-gain photomultiplier tubes or other photosensitive devices. Simple, inexpensive, and accepts light from almost any angle. Receiver of this configuration supports reception of data at rate of 13 MHz and higher.

  7. Visible light communication based motion detection.

    PubMed

    Sewaiwar, Atul; Tiwari, Samrat Vikramaditya; Chung, Yeon-Ho

    2015-07-13

    In this paper, a unique and novel visible light communication based motion detection is presented. The proposed motion detection is performed based on white light LEDs and an array of photodetectors from existing visible light communication (VLC) links, thus providing VLC with three functionalities of illumination, communication and motion detection. The motion is detected by observing the pattern created by intentional obstruction of the VLC link. Experimental and simulation results demonstrate the validity of the proposed VLC based motion detection technique. The VLC based motion detection can benefit smart devices control in VLC based smart home environments. PMID:26191937

  8. A web-based virtual lighting simulator

    SciTech Connect

    Papamichael, Konstantinos; Lai, Judy; Fuller, Daniel; Tariq, Tara

    2002-05-06

    This paper is about a web-based ''virtual lighting simulator,'' which is intended to allow architects and lighting designers to quickly assess the effect of key parameters on the daylighting and lighting performance in various space types. The virtual lighting simulator consists of a web-based interface that allows navigation through a large database of images and data, which were generated through parametric lighting simulations. At its current form, the virtual lighting simulator has two main modules, one for daylighting and one for electric lighting. The daylighting module includes images and data for a small office space, varying most key daylighting parameters, such as window size and orientation, glazing type, surface reflectance, sky conditions, time of the year, etc. The electric lighting module includes images and data for five space types (classroom, small office, large open office, warehouse and small retail), varying key lighting parameters, such as the electric lighting system, surface reflectance, dimming/switching, etc. The computed images include perspectives and plans and are displayed in various formats to support qualitative as well as quantitative assessment. The quantitative information is in the form of iso-contour lines superimposed on the images, as well as false color images and statistical information on work plane illuminance. The qualitative information includes images that are adjusted to account for the sensitivity and adaptation of the human eye. The paper also includes a section on the major technical issues and their resolution.

  9. Broadband light based optoelectric tweezers

    NASA Astrophysics Data System (ADS)

    Mishra, Avanish; Clayton, Katherine; Wereley, Steve

    2015-11-01

    Trapping, sorting and transport of particles are fundamental operations in microfluidic platforms. However, very few methods exist that can dynamically trap and manipulate particles with high spatial resolution and accuracy. Recently, a new set of methods have emerged that can trap and sort particles by optically controlling electrokinetic effects. Rapid Electrokinetic Patterning (REP) is such an emerging optoelectric technique. It utilizes a laser activated electrothermal (ET) vortex and particle-electrode interactions for trapping particles. Trapped particles can be translated by optically steering the laser or by moving the trapping chamber. Previously demonstrated applications of REP have utilized a 1064 nm infrared laser, integrated in an inverted microscope, to create the necessary temperature rise for producing the ET flow. Use of an external laser for REP trapping is expensive and time intensive to integrate, making it difficult to design a portable REP system. Using experiments and simulations, we show that a non-coherent incandescent broadband light source can be used for REP trapping and manipulation. This allows for a microscope with a broadband lamp to be used for REP trapping without integrating an external laser.

  10. The Specter of Fuel-Based Light

    SciTech Connect

    Mills, Evan

    2005-05-16

    Contemporary questions about sustainable energy and development converge in unexpected ways around a technology that is at once an echo of the past and yet very much a part of the present: fuel-based lighting in the developing world. An emerging opportunity for reducing the global costs and greenhouse-gas emissions associated with this highly inefficient form of lighting energy use is to replace fuel-based lamps with white solid-state (''LED'') lighting, described in this Policy Forum, which can be affordably solar-powered. Doing so would allow those without access to electricity in developing world to affordably leapfrog over the prevailing incandescent and fluorescent lighting technologies in use today through the electrified world.

  11. Light sources based on semiconductor current filaments

    DOEpatents

    Zutavern, Fred J.; Loubriel, Guillermo M.; Buttram, Malcolm T.; Mar, Alan; Helgeson, Wesley D.; O'Malley, Martin W.; Hjalmarson, Harold P.; Baca, Albert G.; Chow, Weng W.; Vawter, G. Allen

    2003-01-01

    The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

  12. Plasma-based EUV light source

    DOEpatents

    Shumlak, Uri; Golingo, Raymond; Nelson, Brian A.

    2010-11-02

    Various mechanisms are provided relating to plasma-based light source that may be used for lithography as well as other applications. For example, a device is disclosed for producing extreme ultraviolet (EUV) light based on a sheared plasma flow. The device can produce a plasma pinch that can last several orders of magnitude longer than what is typically sustained in a Z-pinch, thus enabling the device to provide more power output than what has been hitherto predicted in theory or attained in practice. Such power output may be used in a lithography system for manufacturing integrated circuits, enabling the use of EUV wavelengths on the order of about 13.5 nm. Lastly, the process of manufacturing such a plasma pinch is discussed, where the process includes providing a sheared flow of plasma in order to stabilize it for long periods of time.

  13. New light field camera based on physical based rendering tracing

    NASA Astrophysics Data System (ADS)

    Chung, Ming-Han; Chang, Shan-Ching; Lee, Chih-Kung

    2014-03-01

    Even though light field technology was first invented more than 50 years ago, it did not gain popularity due to the limitation imposed by the computation technology. With the rapid advancement of computer technology over the last decade, the limitation has been uplifted and the light field technology quickly returns to the spotlight of the research stage. In this paper, PBRT (Physical Based Rendering Tracing) was introduced to overcome the limitation of using traditional optical simulation approach to study the light field camera technology. More specifically, traditional optical simulation approach can only present light energy distribution but typically lack the capability to present the pictures in realistic scenes. By using PBRT, which was developed to create virtual scenes, 4D light field information was obtained to conduct initial data analysis and calculation. This PBRT approach was also used to explore the light field data calculation potential in creating realistic photos. Furthermore, we integrated the optical experimental measurement results with PBRT in order to place the real measurement results into the virtually created scenes. In other words, our approach provided us with a way to establish a link of virtual scene with the real measurement results. Several images developed based on the above-mentioned approaches were analyzed and discussed to verify the pros and cons of the newly developed PBRT based light field camera technology. It will be shown that this newly developed light field camera approach can circumvent the loss of spatial resolution associated with adopting a micro-lens array in front of the image sensors. Detailed operational constraint, performance metrics, computation resources needed, etc. associated with this newly developed light field camera technique were presented in detail.

  14. Forecasting Urban Expansion Based on Night Lights

    NASA Astrophysics Data System (ADS)

    Stathakis, D.

    2016-06-01

    Forecasting urban expansion models are a very powerful tool in the hands of urban planners in order to anticipate and mitigate future urbanization pressures. In this paper, a linear regression forecasting urban expansion model is implemented based on the annual composite night lights time series available from National Oceanic and Atmospheric Administration (NOAA). The product known as 'stable lights' is used in particular, after it has been corrected with a standard intercalibration process to reduce artificial year-to-year fluctuations as much as possible. Forecasting is done for ten years after the end of the time series. Because the method is spatially explicit the predicted expansion trends are relatively accurately mapped. Two metrics are used to validate the process. The first one is the year-to-year Sum of Lights (SoL) variation. The second is the year-to-year image correlation coefficient. Overall it is evident that the method is able to provide an insight on future urbanization pressures in order to be taken into account in planning. The trends are quantified in a clear spatial manner.

  15. A universal, easy-to-apply light-quality index based on natural light spectrum resemblance

    NASA Astrophysics Data System (ADS)

    Jou, Jwo-Huei; Chou, Kun-Yi; Yang, Fu-Chin; Agrawal, Abhishek; Chen, Sun-Zen; Tseng, Jing-Ru; Lin, Ching-Chiao; Chen, Po-Wei; Wong, Ken-Tsung; Chi, Yun

    2014-05-01

    Light-quality is extremely crucial for any light source to be used for illumination. However, a proper light-quality index is still missing although numerous electricity-driven lighting measures have been introduced since past 150 yr. We present in this communication a universal and easy-to-apply index for quantifying the quality of any given lighting source, which is based on direct comparison of its lumen spectrum with the natural light counterpart having the same color temperature. A general principle for creating high quality pseudo-natural light is accordingly derived. By using organic light-emitting diode technology, for example, daylight-style emission with a 96% natural light resemblance is obtained as a high number of organic emitters with diffused colors spanning throughout the entire visible range are employed. The same principle can be extended to other lighting technology such as light-emitting diode to generate natural light-style emission.

  16. Light Based Cellular Interactions: hypotheses and perspectives

    NASA Astrophysics Data System (ADS)

    Laager, Frederic

    2015-08-01

    This work investigates the theoretical possibility of interactions between cells via light. We first take a brief look at the previous research done in the past to have a better understanding of the field and the origins of the concept of cellular interactions. Then we identify the different elements essential for interactions between two parties. We then compare the required elements with the known and studied elements and characteristics which are well defined in biology, chemistry and physics. This way we are able to set up four postulates required for cell interactions: I. A signal is present and subject to secondary modulation by the emitter cells. II. There is a plastic information medium that reacts directly to the metabolic state of the emitter and therefore carries information about the emitter. III. An optical signal can be perceived by cells on a molecular level by a multitude of different receptors. IV. The information can in theory be processed by cells and metabolic changes in reaction to the signals can be observed. We demonstrate that all required elements have been observed. Most of them have important and well-known roles in cells. Therefore we suggest that our hypothetical model is a good explanation for light based cellular interactions.

  17. 6. DETAIL VIEW SHOWING BASE OF LIGHT TOWER, LOOKING SOUTHEAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. DETAIL VIEW SHOWING BASE OF LIGHT TOWER, LOOKING SOUTHEAST - Monomoy Point Light Station, Approximately 3500 feet Northeast Powder Hole Pond, Monomoy National Wildlife Refuge, Chatham, Barnstable County, MA

  18. Headlamps for light based driver assistance

    NASA Astrophysics Data System (ADS)

    Götz, M.; Kleinkes, M.

    2008-04-01

    Driving at night is dangerous. Although only 25% of all driving tasks are performed at night, nearly half of all fatal accidents happen in this time. In order to increase safety when driving under poor visibility conditions, automotive front lighting systems have undergone a strong development in the last fifteen years. One important milestone was the introduction of Xenon headlamps in 1992, which provide more and brighter light for road illumination than ever before. Since then the paradigm of simply providing more light has changed toward providing optimised light distributions, which support the driver's perception. A first step in this direction was the introduction of dynamic bend lighting and cornering light in 2003. In 2006 the first full AFS headlamp (Adaptive Front Lighting System) allowed an optimised adoption of the light distribution to the driving situation. These systems use information provided by vehicle sensors and an intelligent algorithm to guide light towards those areas where needed. Nowadays, even more information about the vehicle's environment is available. Image processing systems, for example, allow to detect other traffic participants, their speed and their driving directions. In future headlamp systems these data will be used to constantly regulate the reach of the light distribution thus allowing a maximal reach without providing glare. Moreover, technologies that allow to constantly use a high-beam light distribution are under development. These systems will illuminate the whole traffic area only excluding other traffic participants. LED light sources will play a significant role in these scenarios, since they allow to precisely illuminate certain areas of the road, while neighbouring parts will be left in dark.

  19. Challenges and opportunities in LED based lighting

    NASA Astrophysics Data System (ADS)

    Panahi, Allen

    2013-05-01

    Solid state lighting technology has made great advances over the last decade and has become the technology of choice to displace legacy incandescent and as well as the more efficient fluorescent lights. While efficiencies have been improved and cost of the LEDs has been steadily lowered still many challenges exist in the thermal, electrical, optical, and packaging implementations.

  20. Optical design and lighting application of an LED-based sports lighting system

    NASA Astrophysics Data System (ADS)

    Boxler, Larry

    2011-10-01

    This paper describes both the optical development of an LED-based sports lighting system and the results of the application of the system to an actual sport field. A traditional sport lighting fixture is generally composed of a single 1500 watt High Intensity Discharge (HID) light source with reflectors used to control the light distribution. The efficacy of the HID light source is equivalent or nearly equivalent to most LED light sources, putting LEDs at a large cost disadvantage in a high light output application such as sports lighting due to the number of LEDs and supporting components required to run an LED system. To assess the feasibility and applicability of LEDs in a sports lighting application, an LED-based sport light has been developed and installed on a small soccer field specified to have an average maintained illuminance level of 30 footcandles. An existing HID sport lighting system was also installed on the same size soccer field adjacent to the LED field with the same average footcandle level for comparison. Results indicate that LEDs can provide equivalent average illumination; however the LED source and system component cost is substantially higher. Despite the high cost, it was found that improved optical control afforded by the optical design used in the system provides a significant improvement in offsite wasted spill light, glare control, and on field uniformity. This could provide an advantage for LED systems.

  1. Polymer and small molecule based hybrid light source

    DOEpatents

    Choong, Vi-En; Choulis, Stelios; Krummacher, Benjamin Claus; Mathai, Mathew; So, Franky

    2010-03-16

    An organic electroluminescent device, includes: a substrate; a hole-injecting electrode (anode) coated over the substrate; a hole injection layer coated over the anode; a hole transporting layer coated over the hole injection layer; a polymer based light emitting layer, coated over the hole transporting layer; a small molecule based light emitting layer, thermally evaporated over the polymer based light emitting layer; and an electron-injecting electrode (cathode) deposited over the electroluminescent polymer layer.

  2. Light-based therapies in acne treatment

    PubMed Central

    Pei, Susan; Inamadar, Arun C.; Adya, Keshavmurthy A.; Tsoukas, Maria M.

    2015-01-01

    The use of light and laser in the treatment of acne is increasing as these modalities are safe, effective, and associated with no or minimal complications when used appropriately. These light and laser sources are also being used in combination with pharmacological and/or physical measures to synergize their effects and optimize the therapeutic outcome. This review focuses on optical devices used in treating acne and serves to delineate the current application of various methods, including their utility and efficacy. PMID:26009707

  3. Light-field-based phase imaging

    NASA Astrophysics Data System (ADS)

    Liu, Jingdan; Xu, Tingfa; Yue, Weirui; Situ, Guohai

    2014-10-01

    Phase contains important information about the diffraction or scattering property of an object, and therefore the imaging of phase is vital to many applications including biomedicine and metrology, just name a few. However, due to the limited bandwidth of image sensors, it is not possible to directly detect the phase of an optical field. Many methods including the Transport of Intensity Equation (TIE) have been well demonstrated for quantitative and non-interferometric imaging of phase. The TIE offers an experimentally simple technique for computing phase quantitatively from two or more defocused images. Usually, the defocused images were experimentally obtained by shifting the camera along the optical axis with slight intervals. Note that light field imaging has the capability to take an image stack focused at different depths by digital refocusing the captured light field of a scene. In this paper, we propose to combine Light Field Microscopy and the TIE method for phase imaging, taking the digital-refocusing advantage of Light Field Microscopy. We demonstrate the propose technique by simulation results. Compare with the traditional camera-shifting technique, light-field imaging allows the capturing the defocused images without any mechanical instability and therefore demonstrate advantage in practical applications.

  4. Slow-light-based optical frequency shifter

    NASA Astrophysics Data System (ADS)

    Li, Qian; Bao, Yupan; Thuresson, Axel; Nilsson, Adam N.; Rippe, Lars; Kröll, Stefan

    2016-04-01

    We demonstrate experimentally and theoretically a controllable way of shifting the frequency of an optical pulse by using a combination of spectral hole burning, slow light effect, and linear Stark effect in a rare-earth-ion-doped crystal. We claim that the solid angle of acceptance of a frequency shift structure can be close to 2 π , which means that the frequency shifter could work not only for optical pulses propagating in a specific spatial mode but also for randomly scattered light. As the frequency shift is controlled solely by an external electric field, it works also for weak coherent light fields and can be used, for example, as a frequency shifter for quantum memory devices in quantum communication.

  5. Camera array based light field microscopy.

    PubMed

    Lin, Xing; Wu, Jiamin; Zheng, Guoan; Dai, Qionghai

    2015-09-01

    This paper proposes a novel approach for high-resolution light field microscopy imaging by using a camera array. In this approach, we apply a two-stage relay system for expanding the aperture plane of the microscope into the size of an imaging lens array, and utilize a sensor array for acquiring different sub-apertures images formed by corresponding imaging lenses. By combining the rectified and synchronized images from 5 × 5 viewpoints with our prototype system, we successfully recovered color light field videos for various fast-moving microscopic specimens with a spatial resolution of 0.79 megapixels at 30 frames per second, corresponding to an unprecedented data throughput of 562.5 MB/s for light field microscopy. We also demonstrated the use of the reported platform for different applications, including post-capture refocusing, phase reconstruction, 3D imaging, and optical metrology. PMID:26417490

  6. Camera array based light field microscopy

    PubMed Central

    Lin, Xing; Wu, Jiamin; Zheng, Guoan; Dai, Qionghai

    2015-01-01

    This paper proposes a novel approach for high-resolution light field microscopy imaging by using a camera array. In this approach, we apply a two-stage relay system for expanding the aperture plane of the microscope into the size of an imaging lens array, and utilize a sensor array for acquiring different sub-apertures images formed by corresponding imaging lenses. By combining the rectified and synchronized images from 5 × 5 viewpoints with our prototype system, we successfully recovered color light field videos for various fast-moving microscopic specimens with a spatial resolution of 0.79 megapixels at 30 frames per second, corresponding to an unprecedented data throughput of 562.5 MB/s for light field microscopy. We also demonstrated the use of the reported platform for different applications, including post-capture refocusing, phase reconstruction, 3D imaging, and optical metrology. PMID:26417490

  7. High Brightness GaN-Based Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Lee, Ya-Ju; Lu, Tien-Chang; Kuo, Hao-Chung; Wang, Shing-Chung

    2007-06-01

    This paper reviews our recent progress of GaN-based high brightness light-emitting diodes (LEDs). Firstly, by adopting chemical wet etching patterned sapphire substrates in GaN-based LEDs, not only could increase the extraction quantum efficiency, but also improve the internal quantum efficiency. Secondly, we present a high light-extraction 465-nm GaN-based vertical light-emitting diode structure with double diffuse surfaces. The external quantum efficiency was demonstrated to be about 40%. The high performance LED was achieved mainly due to the strong guided-light scattering efficiency while employing double diffuse surfaces.

  8. Immunoassay control method based on light scattering

    NASA Astrophysics Data System (ADS)

    Bilyi, Olexander I.; Kiselyov, Eugene M.; Petrina, R. O.; Ferensovich, Yaroslav P.; Yaremyk, Roman Y.

    1999-11-01

    The physics principle of registration immune reaction by light scattering methods is concerned. The operation of laser nephelometry for measuring antigen-antibody reaction is described. The technique of obtaining diagnostic and immune reactions of interaction latex agglutination for diphtheria determination is described.

  9. Visible light metasurfaces based on gallium nitride high contrast gratings

    NASA Astrophysics Data System (ADS)

    Wang, Zhenhai; He, Shumin; Liu, Qifa; Wang, Wei

    2016-05-01

    We propose visible-light metasurfaces (VLMs) capable of serving as lens and beam deflecting element based on gallium nitride (GaN) high contrast gratings (HCGs). By precisely manipulating the wavefront of the transmitted light, we theoretically demonstrate an HCG focusing lens with transmissivity of 86.3%, and a VLM with beam deflection angle of 6.09° and transmissivity as high as 91.4%. The proposed all-dielectric metasurfaces are promising for GaN-based visible light-emitting diodes (LEDs), which would be robust and versatile for controlling the output light propagation and polarization, as well as enhancing the extraction efficiency of the LEDs.

  10. Qualifying lighting remodelling in a Hungarian city based on light pollution effects

    NASA Astrophysics Data System (ADS)

    Kolláth, Z.; Dömény, A.; Kolláth, K.; Nagy, B.

    2016-09-01

    The public lighting system has been remodelled in several Hungarian cities. In some cases the majority of the old luminaries were fitted with high pressure sodium lamps and they were replaced with white LED lighting with a typical correlated colour temperature of about 4500 K. Therefore, these remodelling works provide a testbed for methods in measurements and modelling. We measured the luminance of the light domes of selected cities by DSLR photometry before and after the remodelling. Thanks to the full cut off design of the new lighting fixtures we obtained a slight decrease even in the blue part of the sky dome spectra of a tested city. However, we have to note that this positive change is the result of the bad geometry (large ULR) of the previous lighting system. Based on Monte Carlo radiative transfer calculations we provide a comparison of different indicators that can be used to qualify the remodelling, and to predict the possible changes in light pollution.

  11. Homeostasis lighting control based on relationship between lighting environment and human behavior

    NASA Astrophysics Data System (ADS)

    Ueda, Risa; Mita, Akira

    2015-03-01

    Although each person has own preferences, living spaces which can respond to various preferences and needs have not become reality. Focusing on the lighting environments which influence on the impression of living spaces, this research aims to offer comfortable lighting environments for each resident by a flexible control. This research examines the relationship between lighting environments and human behaviors considering colored lights. In accord with the relationship, this research proposes an illuminance-color control system which flexibly changes spatial environments responding to human conditions. Firstly, the psychological evaluation was conducted in order to build human models for various environments. As a result, preferred lighting environments for each examinee were determined for particular behaviors. Moreover, satisfaction levels of lighting environments were calculated by using seven types of impression of the environments as parameters. The results were summarized as human models. Secondly, this research proposed "Homeostasis Lighting Control System", which employs the human models. Homeostasis lighting control system embodies the algorithm of homeostasis, which is one of the functions of the physiological adaptation. Human discomfort feelings are obtained automatically by the sensor agent robot. The system can offer comfortable lighting environments without controlling environments by residents autonomously based on the information from the robot. This research takes into accounts both illuminance and color. The robot communicates with the server which contains human models, then the system corresponds to individuals. Combining these three systems, the proposed system can effectively control the lighting environment. At last, the feasibility of the proposed system was verified by simulation experiments.

  12. Improved Slow Light Capacity In Graphene-based Waveguide

    PubMed Central

    Hao, Ran; Peng, Xi-Liang; Li, Er-Ping; Xu, Yang; Jin, Jia-Min; Zhang, Xian-Min; Chen, Hong-Sheng

    2015-01-01

    We have systematically investigated the wideband slow light in two-dimensional material graphene, revealing that graphene exhibits much larger slow light capability than other materials. The slow light performances including material dispersion, bandwidth, dynamic control ability, delay-bandwidth product, propagation loss, and group-velocity dispersion are studied, proving graphene exhibits significant advantages in these performances. A large delay-bandwidth product has been obtained in a simple yet functional grating waveguide with slow down factor c/vg at 163 and slow light bandwidth Δω at 94.4 nm centered at 10.38 μm, which is several orders of magnitude larger than previous results. Physical explanation of the enhanced slow light in graphene is given. Our results indicate graphene is an excellent platform for slow light applications, promoting various future slow light devices based on graphene. PMID:26478563

  13. Semiconductor Nanocrystals-Based White Light Emitting Diodes

    SciTech Connect

    Dai, Quanqin; Hu, Michael Z.; Duty, Chad E

    2010-01-01

    In response to the demands for energy and the concerns of global warming and climate change, energy efficient and environmentally friendly solid state lighting, such as white light emitting diodes (WLEDs), is considered to be the most promising and suitable light source. Because of their small size, high efficiency, and long lifetime, WLEDs based on colloidal semiconductor nanocrystals (or quantum dots) are emerging as a completely new technology platform for the development of flat-panel displays and solid state lighting, exhibiting the potential to replace the conventionally used incandescent and fluorescent lamps. This replacement could cut the ever-increasing energy consumption, solve the problem of rapidly depleting fossil fuel reserves, and improve the quality of the global environment. In this review, we highlight the recent progress in semiconductor nanocrystals-based WLEDs, compare different approaches for generating white light, and discuss the benefits and challenges of the solid state lighting technology.

  14. Fiber based generation of azimuthally polarized light

    NASA Astrophysics Data System (ADS)

    Jocher, Christoph; Jauregui, Cesar; Voigtländer, Christian; Stutzki, Fabian; Nolte, Stefan; Limpert, Jens; Tünnermann, Andreas

    2012-02-01

    We report on a novel approach for the generation of radially and azimuthally polarized light employing a fiber mode filter. The mode filter consists of a Fiber Bragg Grating written in a strongly guiding fiber with lifted modal degeneracy. These kinds of fibers guide radially and azimuthally polarized modes with non-degenerated, i.e. distinct, effective refractive indexes. The Fiber Bragg Grating reflects light only if the Bragg condition is fulfilled. In case of strongly guiding fibers the radially and azimuthally polarized modes are guided with different effective refractive indices and, consequently, the Bragg condition is fulfilled at different wavelengths. If the reflection bandwidth of the Fiber Bragg Grating is narrow enough, the radially and azimuthally polarized modes are spectrally separated. Thus, with such a mode filter it is possible to filter the radially or azimuthally polarized mode. This filter is suitable for its integration in a resonator for stable, compact and high polarization purity azimuthally and radially polarized all-fiber oscillators. In a first experiment an azimuthally polarized mode filter consisting of a commercially available step index fiber and a femtosecond written Fiber Bragg Grating was fabricated. The experimental results are presented and discussed.

  15. Optical bidirectional beacon based visible light communications.

    PubMed

    Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon Ho

    2015-10-01

    In an indoor bidirectional visible light communications (VLC), a line-of-sight (LOS) transmission plays a major role in obtaining adequate performance of a VLC system. Signals are often obstructed in the LOS transmission path, causing an effect called optical shadowing. In the absence of LOS, the performance of the VLC system degrades significantly and, in particular, at uplink transmission this degradation becomes severe due to design constraints and limited power at uplink devices. In this paper, a novel concept and design of an optical bidirectional beacon (OBB) is presented as an efficient model to counter the performance degradation in a non-line-of-sight (NLOS) VLC system. OBB is an independent operating bidirectional transceiver unit installed on walls, composed of red, green, and blue (RGB) light emitting diodes (LEDs), photodetectors (PDs) and color filters. OBB improves the coverage area in the form of providing additional or alternate paths for transmission and enhances the performance of the VLC system in terms of bit error rate (BER). To verify the effectiveness of the proposed system, simulations were carried out under optical shadowing conditions at various locations in an indoor environment. The simulation results and analysis show that the implementation of OBB improves the performance of the VLC system significantly, especially when the LOS bidirectional transmission paths are completely or partially obstructed. PMID:26480168

  16. A lighting assembly based on red and blue light-emitting diodes as a lighting source for space agriculture

    NASA Astrophysics Data System (ADS)

    Avercheva, Olga; Berkovich, Yuliy A.; Smolyanina, Svetlana; Bassarskaya, Elizaveta; Zhigalova, Tatiana; Ptushenko, Vasiliy; Erokhin, Alexei

    Light-emitting diodes (LEDs) are a promising lighting source for space agriculture due to their high efficiency, longevity, safety, and other factors. Assemblies based on red and blue LEDs have been recommended in literature, although not all plants show sufficient productivity in such lighting conditions. Adding of green LEDs proposed in some works was aimed at psychological support for the crew, and not at the improvement of plant growth. We studied the growth and the state of the photosynthetic apparatus in Chinese cabbage (Brassica chinensis L.) plants grown under red (650 nm) and blue (470 nm) light-emitting diodes (LEDs). Plants grown under a high-pressure sodium lamp (HPS lamp) were used as a control. The plants were illuminated with two photosynthetic photon flux levels: nearly 400 µE and about 100 µE. Plants grown under LEDs with 400 µE level, as compared to control plants, showed lower fresh weight, edible biomass, growth rate, and sugar content. The difference in fresh weight and edible biomass was even more pronounced in plants grown with 100 µE level; the data indicate that the adaptability of the test plants to insufficient lighting decreased. Under LEDs, we observed the decreasing of root growth and the absence of transition to the flowering stage, which points to a change in the hormonal balance in plants grown in such lighting conditions. We also found differences in the functioning of the photosynthetic apparatus and its reaction to a low lighting level. We have concluded that a lighting assembly with red and blue LEDs only is insufficient for the plant growth and productivity, and can bring about alterations in their adaptive and regulatory mechanisms. Further studies are needed to optimize the lighting spectrum for space agriculture, taking into account the photosynthetic, phototropic and regulatory roles of light. Using white LEDs or adding far-red and green LEDs might be a promising approach.

  17. Filter selection based on light source for multispectral imaging

    NASA Astrophysics Data System (ADS)

    Xu, Peng; Xu, Haisong

    2016-07-01

    In multispectral imaging, it is necessary to select a reduced number of filters to balance the imaging efficiency and spectral reflectance recovery accuracy. Due to the combined effect of filters and light source on reflectance recovery, the optimal filters are influenced by the employed light source in the multispectral imaging system. By casting the filter selection as an optimization issue, the selection of optimal filters corresponding to the employed light source proceeds with respect to a set of target samples utilizing one kind of genetic algorithms, regardless of the detailed spectral characteristics of the light source, filters, and sensor. Under three light sources with distinct spectral power distributions, the proposed filter selection method was evaluated on a filter-wheel based multispectral device with a set of interference filters. It was verified that the filters derived by the proposed method achieve better spectral and colorimetric accuracy of reflectance recovery than the conventional one under different light sources.

  18. Beacon system based on light-emitting diode sources for runways lighting

    NASA Astrophysics Data System (ADS)

    Montes, Mario González; Vázquez, Daniel; Fernandez-Balbuena, Antonio A.; Bernabeu, Eusebio

    2014-06-01

    New aeronautical ground lighting techniques are becoming increasingly important to ensure the safety and reduce the maintenance costs of the plane's tracks. Until recently, tracks had embedded lighting systems whose sources were based on incandescent lamps. But incandescent lamps have several disadvantages: high energy consumption and frequent breakdowns that result in high maintenance costs (lamp average life-time is ˜1500 operating hours) and the lamp's technology has a lack of new lighting functions, such as signal handling and modification. To solve these problems, the industry has developed systems based on light-emitting diode (LED) technology with improved features: (1) LED lighting consumes one tenth the power, (2) it improves preventive maintenance (an LED's lifetime range is between 25,000 and 100,000 hours), and (3) LED lighting technology can be controlled remotely according to the needs of the track configuration. LEDs have been in use for more than three decades, but only recently, around 2002, have they begun to be used as visual aids, representing the greatest potential change for airport lighting since their inception in the 1920s. Currently, embedded LED systems are not being broadly used due to the specific constraints of the rules and regulations of airports (beacon dimensions, power system technology, etc.). The fundamental requirements applied to embedded lighting systems are to be hosted on a volume where the dimensions are usually critical and also to integrate all the essential components for operation. An embedded architecture that meets the lighting regulations for airport runways is presented. The present work is divided into three main tasks: development of an optical system to optimize lighting according to International Civil Aviation Organization, manufacturing prototype, and model validation.

  19. Spectral matching research for light-emitting diode-based neonatal jaundice therapeutic device light source

    NASA Astrophysics Data System (ADS)

    Gan, Ruting; Guo, Zhenning; Lin, Jieben

    2015-09-01

    To decrease the risk of bilirubin encephalopathy and minimize the need for exchange transfusions, we report a novel design for light source of light-emitting diode (LED)-based neonatal jaundice therapeutic device (NJTD). The bilirubin absorption spectrum in vivo was regarded as target. Based on spectral constructing theory, we used commercially available LEDs with different peak wavelengths and full width at half maximum as matching light sources. Simple genetic algorithm was first proposed as the spectral matching method. The required LEDs number at each peak wavelength was calculated, and then, the commercial light source sample model of the device was fabricated to confirm the spectral matching technology. In addition, the corresponding spectrum was measured and the effect was analyzed finally. The results showed that fitted spectrum was very similar to the target spectrum with 98.86 % matching degree, and the actual device model has a spectrum close to the target with 96.02 % matching degree. With higher fitting degree and efficiency, this matching algorithm is very suitable for light source matching technology of LED-based spectral distribution, and bilirubin absorption spectrum in vivo will be auspicious candidate for the target spectrum of new LED-based NJTD light source.

  20. Berkeley Accelerator Space Effects (BASE) Light Ion FacilityUpgrade

    SciTech Connect

    Johnson, Michael B.; McMahan, Margaret A.; Gimpel, Thomas L.; Tiffany, William S.

    2006-07-07

    The BASE Light Ion Facility upgrades have been completed. All proton beams are now delivered to Cave 4A. New control software, a larger diameter beam window, and improved quality assurance measures have been added.

  1. What future for quantum dot-based light emitters?

    NASA Astrophysics Data System (ADS)

    Nurmikko, Arto

    2015-12-01

    Synthesis of semiconductor colloidal quantum dots by low-cost, solution-based methods has produced an abundance of basic science. Can these materials be transformed to high-performance light emitters to disrupt established photonics technologies, particularly semiconductor lasers?

  2. Context-based presets for lighting setup in residential space.

    PubMed

    Choi, Kyungah; Lee, Jeongmin; Suk, Hyeon-Jeong

    2016-01-01

    This study aims to derive context-based lighting setup presets in residential space by exploring the multilateral relationships among household activities, affects, and lighting setups. Three procedures were involved: First, sixty affective words were evaluated through which seven affect factors were extracted to facilitate the evaluation of colored illumination in the subsequent experiment. Second, in the user study, seven affect factors and thirty household activities were used to evaluate 147 lighting setups extracted from combinations of twelve hues, six illuminance levels, and three purity levels. As a result, twenty lighting setup presets were derived that were not only activity-based, but affect-based as well. Lastly, the twenty presets were prototyped as a set of testbed to further explore potentials and limitations. This study demonstrates that intuitive, context-based presets can help users explore the effects of colored illumination in creating a diverse range of user experiences. PMID:26360214

  3. Semiconductor-Nanocrystals-Based White Light-Emitting Diodes

    SciTech Connect

    Dai, Quanqin; Duty, Chad E; Hu, Michael Z.

    2010-01-01

    In response to the demands for energy and the concerns of global warming and climate change, energy efficient and environmentally friendly solid-state lighting, such as white lightemitting diodes (WLEDs), is considered to be the most promising and suitable light source. Because of their small size, high efficiency, and long lifetime, WLEDs based on colloidal semiconductor nanocrystals (or quantum dots) are emerging as a completely new technology platform for the development of flat-panel displays and solid-state lighting, exhibiting the potential to replace the conventionally used incandescent and fluorescent lamps. This replacement can cut the ever-increasing level of energy consumption, solve the problem of rapidly depleting fossil fuel reserves, and improve the quality of the global environment. In this review, the recent progress in semiconductor-nanocrystals-based WLEDs is highlighted, the different approaches for generating white light are compared, and the benefits and challenges of the solid-state lighting technology are discussed.

  4. Cherenkov Light-based Beam Profiling for Ultrarelativistic Electron Beams

    SciTech Connect

    Adli, E.; Gessner, S. J.; Corde, S.; Hogan, M. J.; Bjerke, H. H.

    2015-02-09

    We describe a beam profile monitor design based on Cherenkov light emitted from a charged particle beam in an air gap. The main components of the profile monitor are silicon wafers used to reflect Cherenkov light onto a camera lens system. The design allows for measuring large beam sizes, with large photon yield per beam charge and excellent signal linearity with beam charge. Furthermore, the profile monitor signal is independent of the particle energy for ultrarelativistic particles. Different design and parameter considerations are discussed. A Cherenkov light-based profile monitor has been installed at the FACET User Facility at SLAC. Finally, we report on the measured performance of this profile monitor.

  5. A ratiometric fluorescent probe based on boron dipyrromethene and rhodamine Förster resonance energy transfer platform for hypochlorous acid and its application in living cells.

    PubMed

    Liu, Ying; Zhao, Zhi-Min; Miao, Jun-Ying; Zhao, Bao-Xiang

    2016-05-19

    We have developed a ratiometric fluorescent probe BRT based on boron dipyrromethene (BODIPY) and rhodamine-thiohydrazide Förster resonance energy transfer (FRET) platform for sensing hypochlorous acid (HOCl) with high selectivity and sensitivity. The probe can detect HOCl in 15 s with the detection limit of 38 nM. Upon mixing with HOCl the fluorescence colour of probe BRT changed from green to orange. Moreover, probe BRT was applied to successfully monitor HOCl in living RAW 264.7 cells. PMID:27126792

  6. A review on visible light active perovskite-based photocatalysts.

    PubMed

    Kanhere, Pushkar; Chen, Zhong

    2014-01-01

    Perovskite-based photocatalysts are of significant interest in the field of photocatalysis. To date, several perovskite material systems have been developed and their applications in visible light photocatalysis studied. This article provides a review of the visible light (λ > 400 nm) active perovskite-based photocatalyst systems. The materials systems are classified by the B site cations and their crystal structure, optical properties, electronic structure, and photocatalytic performance are reviewed in detail. Titanates, tantalates, niobates, vanadates, and ferrites form important photocatalysts which show promise in visible light-driven photoreactions. Along with simple perovskite (ABO3) structures, development of double/complex perovskites that are active under visible light is also reviewed. Various strategies employed for enhancing the photocatalytic performance have been discussed, emphasizing the specific advantages and challenges offered by perovskite-based photocatalysts. This review provides a broad overview of the perovskite photocatalysts, summarizing the current state of the work and offering useful insights for their future development. PMID:25532834

  7. Light weight cellular structures based on aluminium

    SciTech Connect

    Prakash, O.; Embury, J.D.; Sinclair, C.; Sang, H.; Silvetti, P.

    1997-02-01

    An interesting form of lightweight material which has emerged in the past 2 decades is metallic foam. This paper deals with the basic concepts of making metallic foams and a detailed study of foams produced from Al-SiC. In addition, some aspects of cellular solids based on honeycomb structures are outlined including the concept of producing both two-phase foams and foams with composite walls.

  8. Improved spring model-based collaborative indoor visible light positioning

    NASA Astrophysics Data System (ADS)

    Luo, Zhijie; Zhang, WeiNan; Zhou, GuoFu

    2016-03-01

    Gaining accuracy with indoor positioning of individuals is important as many location-based services rely on the user's current position to provide them with useful services. Many researchers have studied indoor positioning techniques based on WiFi and Bluetooth. However, they have disadvantages such as low accuracy or high cost. In this paper, we propose an indoor positioning system in which visible light radiated from light-emitting diodes is used to locate the position of receivers. Compared with existing methods using light-emitting diode light, we present a high-precision and simple implementation collaborative indoor visible light positioning system based on an improved spring model. We first estimate coordinate position information using the visible light positioning system, and then use the spring model to correct positioning errors. The system can be employed easily because it does not require additional sensors and the occlusion problem of visible light would be alleviated. We also describe simulation experiments, which confirm the feasibility of our proposed method.

  9. Improved spring model-based collaborative indoor visible light positioning

    NASA Astrophysics Data System (ADS)

    Luo, Zhijie; Zhang, WeiNan; Zhou, GuoFu

    2016-06-01

    Gaining accuracy with indoor positioning of individuals is important as many location-based services rely on the user's current position to provide them with useful services. Many researchers have studied indoor positioning techniques based on WiFi and Bluetooth. However, they have disadvantages such as low accuracy or high cost. In this paper, we propose an indoor positioning system in which visible light radiated from light-emitting diodes is used to locate the position of receivers. Compared with existing methods using light-emitting diode light, we present a high-precision and simple implementation collaborative indoor visible light positioning system based on an improved spring model. We first estimate coordinate position information using the visible light positioning system, and then use the spring model to correct positioning errors. The system can be employed easily because it does not require additional sensors and the occlusion problem of visible light would be alleviated. We also describe simulation experiments, which confirm the feasibility of our proposed method.

  10. Broadband visible light source based on AllnGaN light emitting diodes

    DOEpatents

    Crawford, Mary H.; Nelson, Jeffrey S.

    2003-12-16

    A visible light source device is described based on a light emitting diode and a nanocluster-based film. The light emitting diode utilizes a semiconductor quantum well structure between n-type and p-type semiconductor materials on the top surface a substrate such as sapphire. The nanocluster-based film is deposited on the bottom surface of the substrate and can be derived from a solution of MoS.sub.2, MoSe.sub.2, WS.sub.2, and WSe.sub.2 particles of size greater than approximately 2 nm in diameter and less than approximately 15 nm in diameter, having an absorption wavelength greater than approximately 300 nm and less than approximately 650 nm.

  11. Optical characterization of nitride-based light-emitting diodes for solid-state lighting applications

    NASA Astrophysics Data System (ADS)

    Masui, Hisashi

    This dissertation describes research dedicated to the solid-state lighting technology based on III-nitride light-emitting diodes (LEDs). Nitride semiconductors are rather an immature material system compared to conventional III-V semiconductors. As the solid-state lighting technology based on nitride optoelectronic devices becomes widely accepted in the market, solid-state technology is required to compete with the conventional vacuum lighting technology, especially in energy efficiency. In addition to such energy-efficiency requirements, solid-state optoelectronic devices have the potential to explore new applications based on their unique properties. The research was conducted as a way of optical characterization of LEDs with a strong emphasis on electroluminescence. Device-packaging techniques were introduced in the early stage of the research to evaluate performances of discrete LEDs including phosphor-combined white-light emitting devices. Light extraction and white-LED fabrication were of direct interest in terms of solid-state lighting, which occupies a large part of the present dissertation. The suspended-LED technique was introduced to improve light extraction and the sphere package was invented as a result of the technique. A phosphor-combined sphere LED achieved as high as 117 lm/W of luminous efficacy. Low-temperature characterization is important to evaluate light-emission efficiency of LEDs, especially the internal quantum efficiency. It was a generally known problem that electroluminescence efficiency deteriorates drastically at low temperature where photoluminescence efficiency remains high. High-quality LEDs prepared on GaN bulk substrates that became available during the present project contributed to the low-temperature study, largely to address the problem. Electroluminescence is related to carrier generation processes via low-temperature measurements on such high-quality LEDs. This study produced a model to explain electroluminescence

  12. Overview of Light Hydrogen-Based Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Miley, George H.; Shrestha, Prajakti J.

    This paper reviews light water and hydrogen-based low-energy nuclear reactions (LENRs) including the different methodologies used to study these reactions and the results obtained. Reports of excess heat production, transmutation reactions, and nuclear radiation emission are cited. An aim of this review is to present a summary of the present status of light water LENR research and provide some insight into where this research is heading.

  13. Advances and prospects in nitrides based light-emitting-diodes

    NASA Astrophysics Data System (ADS)

    Jinmin, Li; Zhe, Liu; Zhiqiang, Liu; Jianchang, Yan; Tongbo, Wei; Xiaoyan, Yi; Junxi, Wang

    2016-06-01

    Due to their low power consumption, long lifetime and high efficiency, nitrides based white light-emitting-diodes (LEDs) have long been considered to be a promising technology for next generation illumination. In this work, we provide a brief review of the development of GaN based LEDs. Some pioneering and significant experiment results of our group and the overview of the recent progress in this field are presented. We hope it can provide some meaningful information for the development of high efficiency GaN based LEDs and solid-state-lighting. Project supported by the National High Technology Research and Development Program of China (No. 2013AA03A101).

  14. Lighting.

    SciTech Connect

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  15. Semiconductor-nanocrystals-based white light-emitting diodes.

    PubMed

    Dai, Quanqin; Duty, Chad E; Hu, Michael Z

    2010-08-01

    In response to the demands for energy and the concerns of global warming and climate change, energy efficient and environmentally friendly solid-state lighting, such as white light-emitting diodes (WLEDs), is considered to be the most promising and suitable light source. Because of their small size, high efficiency, and long lifetime, WLEDs based on colloidal semiconductor nanocrystals (or quantum dots) are emerging as a completely new technology platform for the development of flat-panel displays and solid-state lighting, exhibiting the potential to replace the conventionally used incandescent and fluorescent lamps. This replacement can cut the ever-increasing level of energy consumption, solve the problem of rapidly depleting fossil fuel reserves, and improve the quality of the global environment. In this review, the recent progress in semiconductor-nanocrystals-based WLEDs is highlighted, the different approaches for generating white light are compared, and the benefits and challenges of the solid-state lighting technology are discussed. PMID:20602425

  16. Light: an experiments based learning approach with primary school children

    NASA Astrophysics Data System (ADS)

    Abreu, Cátia; Noversa, Silvana; Varela, Paulo; Costa, Manuel F.

    2014-07-01

    A pedagogical intervention project was carried out at a primary school in the municipality of Vila Verde, Braga in Portugal. In a class of the 3rd grade, composed of 16 students, a practice of inquiry-based science teaching was implemented, addressing the curricular topic "Light Experiments". Various experimental activities were planned within this topic, including: What is light? How does light travel? Does light travel through every material? How is light reflected by a mirror? This project adopted an action research methodology and had as its main objectives: a) to promote a practical and experimental approach to the science component of the Environmental Studies curricular area; b) to describe the scientific meaning construction process inherent to the topics addressed in the classroom with the children, c) to assess the learning steps and children' achievements. Class diaries were prepared, based on field notes and audio recordings taken in the classroom. Through the analysis of the class diary concerning the topic "materials that let light travel through them" we intend to illustrate the process of construction of scientific meanings promoted in the classroom with our approach.

  17. Light Field Imaging Based Accurate Image Specular Highlight Removal

    PubMed Central

    Wang, Haoqian; Xu, Chenxue; Wang, Xingzheng; Zhang, Yongbing; Peng, Bo

    2016-01-01

    Specular reflection removal is indispensable to many computer vision tasks. However, most existing methods fail or degrade in complex real scenarios for their individual drawbacks. Benefiting from the light field imaging technology, this paper proposes a novel and accurate approach to remove specularity and improve image quality. We first capture images with specularity by the light field camera (Lytro ILLUM). After accurately estimating the image depth, a simple and concise threshold strategy is adopted to cluster the specular pixels into “unsaturated” and “saturated” category. Finally, a color variance analysis of multiple views and a local color refinement are individually conducted on the two categories to recover diffuse color information. Experimental evaluation by comparison with existed methods based on our light field dataset together with Stanford light field archive verifies the effectiveness of our proposed algorithm. PMID:27253083

  18. Laser and Light-Based Aesthetics in Men.

    PubMed

    Green, Jeremy B; Metelitsa, Andrei I; Kaufman, Joely; Keaney, Terrence

    2015-09-01

    Men represent an important evolving segment of the cosmetic market. With the growing acceptability of cosmetic procedures along with societal and workplace pressure to maintain youthfulness, men increasingly seek the advice of aesthetic practitioners. Despite this so-called "Menaissance," there is a paucity of published literature regarding laser and light treatments of male skin. Herein the differences in male cutaneous physiology are addressed, followed by a review of light-based treatment of conditions largely unique to male skin, pseudofolliculitis barbae, and rhinophyma. Next, the publications related to laser treatment of male skin specifically are examined. We conclude with a discussion of personal observations derived from clinical experience with laser and light-based treatments in men. PMID:26355628

  19. Cherenkov Light-based Beam Profiling for Ultrarelativistic Electron Beams

    DOE PAGESBeta

    Adli, E.; Gessner, S. J.; Corde, S.; Hogan, M. J.; Bjerke, H. H.

    2015-02-09

    We describe a beam profile monitor design based on Cherenkov light emitted from a charged particle beam in an air gap. The main components of the profile monitor are silicon wafers used to reflect Cherenkov light onto a camera lens system. The design allows for measuring large beam sizes, with large photon yield per beam charge and excellent signal linearity with beam charge. Furthermore, the profile monitor signal is independent of the particle energy for ultrarelativistic particles. Different design and parameter considerations are discussed. A Cherenkov light-based profile monitor has been installed at the FACET User Facility at SLAC. Finally,more » we report on the measured performance of this profile monitor.« less

  20. GaN-based light-emitting diodes suitable for white light

    NASA Astrophysics Data System (ADS)

    Mukai, Takashi; Yamada, Motokazu; Mitani, Tomotsugu; Narukawa, Yukio; Shioji, Shuji; Niki, Isamu; Sonobe, Shin-ya; Izuno, Kunihiro; Suenaga, Ryoma

    2003-07-01

    High-efficient light emitting diodes (LEDs) emitting red, amber, green, blue and ultraviolet light have been obtained through the use of an InGaN active layers. The localized energy states caused by In composition fluctuation in the InGaN active layer seem to be related to the high efficiency of the InGaN-based emitting devices in spite of having a large number of threading dislocations (TDs). InGaN single-quantum-well-structure blue LEDs were grown on epitaxially laterally overgrown GaN (ELOG) and sapphire substrates. The characteristics of both LEDs was almost same. These results indicate that the dislocation doesn't affect the efficiency practically. Recently, the development of high-power light source using GaN-based LEDs has become active. In such high-power LEDs, the density of forward current is much higher than that of past LEDs. Therefore, an advantage of carrier localization in InGaN active layer becomes small, because of band filling under high injection level. This means that reducing the density of TDs becomes important, just like GaN-based laser diodes. Also, we show recent results of GaN-based LEDs.

  1. Bright light-emitting diodes based on organometal halide perovskite

    NASA Astrophysics Data System (ADS)

    Tan, Zhi-Kuang; Moghaddam, Reza Saberi; Lai, May Ling; Docampo, Pablo; Higler, Ruben; Deschler, Felix; Price, Michael; Sadhanala, Aditya; Pazos, Luis M.; Credgington, Dan; Hanusch, Fabian; Bein, Thomas; Snaith, Henry J.; Friend, Richard H.

    2014-09-01

    Solid-state light-emitting devices based on direct-bandgap semiconductors have, over the past two decades, been utilized as energy-efficient sources of lighting. However, fabrication of these devices typically relies on expensive high-temperature and high-vacuum processes, rendering them uneconomical for use in large-area displays. Here, we report high-brightness light-emitting diodes based on solution-processed organometal halide perovskites. We demonstrate electroluminescence in the near-infrared, green and red by tuning the halide compositions in the perovskite. In our infrared device, a thin 15 nm layer of CH3NH3PbI3-xClx perovskite emitter is sandwiched between larger-bandgap titanium dioxide (TiO2) and poly(9,9‧-dioctylfluorene) (F8) layers, effectively confining electrons and holes in the perovskite layer for radiative recombination. We report an infrared radiance of 13.2 W sr-1 m-2 at a current density of 363 mA cm-2, with highest external and internal quantum efficiencies of 0.76% and 3.4%, respectively. In our green light-emitting device with an ITO/PEDOT:PSS/CH3NH3PbBr3/F8/Ca/Ag structure, we achieved a luminance of 364 cd m-2 at a current density of 123 mA cm-2, giving external and internal quantum efficiencies of 0.1% and 0.4%, respectively. We show, using photoluminescence studies, that radiative bimolecular recombination is dominant at higher excitation densities. Hence, the quantum efficiencies of the perovskite light-emitting diodes increase at higher current densities. This demonstration of effective perovskite electroluminescence offers scope for developing this unique class of materials into efficient and colour-tunable light emitters for low-cost display, lighting and optical communication applications.

  2. Thermal Performance of III-Nitride Light Emitting Diodes and Developments in Laser Based White Lighting

    NASA Astrophysics Data System (ADS)

    Pfaff, Nathan Andrew

    Light emitting diodes, LEDs, have two distinct reductions in their efficiency. Efficiency droop which is a decrease in efficiency with increasing current density, and thermal droop, a reduction in efficiency with increasing temperature. Although there has been extensive work on efficiency droop and research into both the mitigation and causes of efficiency droop, comparably little research has been done on thermal droop. Since the early years of III-Nitride LEDs, have shown better performance than other materials systems used in visible light emitters when operated at increased temperatures. Due to the push for increased electrical efficiency thermal droop has been largely ignored or dealt with at a packaging level. Now LEDs are increasingly used in general illumination applications requiring high-current and high-flux operation resulting in elevated operating temperatures. In such high power applications LEDs can reach temperatures of over 100 °C where the performance can be significantly degraded. By altering the internal structure both below and within the active region the thermal droop of LEDs was reduced while preserving or enhancing electrical efficiency. Increased high temperature performance was observed on both blue c-plane and m-plane LEDs. Electrical droop which adversely affects LEDs in general illumination applications is difficult to mitigate. As an alternative to high-current, high-luminous flux LEDs for general illumination, phosphor converted laser, pc-LD, based white lighting is demonstrated. pc-LD shows virtually droop free performance over a wide range of high current densities with high luminous flux levels. The ability to achieve efficiencies on par with pc-LEDs, with significantly reduced substrate use and extremely high current operation, suggests that pc-LD white lighting has potential for entry into select white lighting applications in the near future. First demonstrations of pc-LD white lighting with general illumination level fluxes

  3. Absorbance Based Light Emitting Diode Optical Sensors and Sensing Devices

    PubMed Central

    O'Toole, Martina; Diamond, Dermot

    2008-01-01

    The ever increasing demand for in situ monitoring of health, environment and security has created a need for reliable, miniaturised sensing devices. To achieve this, appropriate analytical devices are required that possess operating characteristics of reliability, low power consumption, low cost, autonomous operation capability and compatibility with wireless communications systems. The use of light emitting diodes (LEDs) as light sources is one strategy, which has been successfully applied in chemical sensing. This paper summarises the development and advancement of LED based chemical sensors and sensing devices in terms of their configuration and application, with the focus on transmittance and reflectance absorptiometric measurements.

  4. Laser wakefield accelerator based light sources: potential applications and requirements

    SciTech Connect

    Albert, F.; Thomas, A. G.; Mangles, S. P.D.; Banerjee, S.; Corde, S.; Flacco, A.; Litos, M.; Neely, D.; Viera, J.; Najmudin, Z.; Bingham, R.; Joshi, C.; Katsouleas, T.

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  5. Asynchronous indoor positioning system based on visible light communications

    NASA Astrophysics Data System (ADS)

    Zhang, Weizhi; Chowdhury, M. I. Sakib; Kavehrad, Mohsen

    2014-04-01

    Indoor positioning has become an attractive research topic within the past two decades. However, no satisfying solution has been found with consideration of both accuracy and system complexity. Recently, research on visible light communications (VLC) offer new opportunities in realizing accurate indoor positioning with relatively simple system configuration. An indoor positioning system based on VLC technology is introduced, with no synchronization requirement on the transmitters. Simulation results show that, with over 95% confidence, the target receiver can be located with an accuracy of 5.9 cm, assuming indirect sunlight exposure and proper installation of light-emitting diode bulbs.

  6. Light-pollution model for cloudy and cloudless night skies with ground-based light sources.

    PubMed

    Kocifaj, Miroslav

    2007-05-20

    The scalable theoretical model of light pollution for ground sources is presented. The model is successfully employed for simulation of angular behavior of the spectral and integral sky radiance and/or luminance during nighttime. There is no restriction on the number of ground-based light sources or on the spatial distribution of these sources in the vicinity of the measuring point (i.e., both distances and azimuth angles of the light sources are configurable). The model is applicable for real finite-dimensional surface sources with defined spectral and angular radiating properties contrary to frequently used point-source approximations. The influence of the atmosphere on the transmitted radiation is formulated in terms of aerosol and molecular optical properties. Altitude and spectral reflectance of a cloud layer are the main factors introduced for simulation of cloudy and/or overcast conditions. The derived equations are translated into numerically fast code, and it is possible to repeat the entire set of calculations in real time. The parametric character of the model enables its efficient usage by illuminating engineers and/or astronomers in the study of various light-pollution situations. Some examples of numerical runs in the form of graphical results are presented. PMID:17514252

  7. Wheel pose measurement based on cross structure light

    NASA Astrophysics Data System (ADS)

    Zhao, Qiancheng; Ding, Xun; Wang, Xian; Zhao, Yafeng

    2016-01-01

    It's necessary for automobile to detect and adjust four-wheel alignment parameters regularly, due to the significant effect on improving stability, enhancing security and reducing tire wear of automobiles. In order to measure the parameters that determined by relative position and posture of four wheels to the automobile cab, this paper proposes a method which applies monocular vision of linear structure light to wheel pose measurement. Firstly, space coordinates of feature point cloud are calculated out from the principle of structured light. Then, an algorithm is designed to determine the normal vector of wheel tangent plane and measure the wheel pose. Finally, actual experiments that by evaluation of adjusted wheel angle measurement are carried out to verify the system accuracy. The corresponding studies can be applied in designing and developing 3D four-wheel alignment system that based on structured light.

  8. Laser and light-based treatment options for hidradenitis suppurativa.

    PubMed

    Hamzavi, Iltefat H; Griffith, James L; Riyaz, Farhaad; Hessam, Schapoor; Bechara, Falk G

    2015-11-01

    Hidradenitis suppurativa (HS) is a chronic inflammatory disease that commonly develops painful, deep dermal abscesses and chronic, draining sinus tracts. Classically, pharmacologic and surgical therapies have been effective for reducing lesion activity and inflammation, but provide only modest success in the prevention of future recurrences and disease progression. Adjunctive therapies, such as laser and light-based therapies, have become more commonly used in the management of HS. These therapies work to reduce the occurrence of painful HS flare-ups by decreasing the number of hair follicles, sebaceous glands, and bacteria in affected areas, and by ablatively debulking chronic lesions. The best results are seen when treatment is individualized, taking disease severity into consideration when selecting specific energy-based approaches. This article will discuss various light-based therapies and the evidence supporting their use in the management of HS. PMID:26470622

  9. Performance of light-emitting-diode based on quantum dots

    NASA Astrophysics Data System (ADS)

    Kim, Sungwoo; Im, Sang Hyuk; Kim, Sang-Wook

    2013-05-01

    Light-emitting diodes (LEDs) based on colloidal quantum dots (QDs) have attracted considerable attention due to their potential in applications such as color-saturated displays and white light with high color-rendering index. However, cadmium-based QD-LEDs are strictly regulated in industrial applications because of the high toxicity of cadmium. As an alternative, InP-based cadmium-free QDs are recommended owing to their wide emission range that is comparable to that of CdSe, and their environmentally friendly properties when applied to QD-LEDs and white QD-LEDs. This feature article provides an overview of QDs' merits in display and light-emitting applications as well as a discussion of their color tunability, photo-stability, and high luminescence efficiency. We will include optical down-conversion devices using various QDs, electroluminescent devices based on organic and inorganic charge-transporting layers, and printing methods using cadmium based and cadmium free QDs.

  10. High-Efficiency Nitride-Based Solid-State Lighting

    SciTech Connect

    Paul T. Fini; Shuji Nakamura

    2005-07-30

    In this final technical progress report we summarize research accomplished during Department of Energy contract DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. Two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and the Lighting Research Center at Rensselaer Polytechnic Institute (led by Dr. N. Narendran), pursued the goals of this contract from thin film growth, characterization, and packaging/luminaire design standpoints. The UCSB team initially pursued the development of blue gallium nitride (GaN)-based vertical-cavity surface-emitting lasers, as well as ultraviolet GaN-based light emitting diodes (LEDs). In Year 2, the emphasis shifted to resonant-cavity light emitting diodes, also known as micro-cavity LEDs when extremely thin device cavities are fabricated. These devices have very directional emission and higher light extraction efficiency than conventional LEDs. Via the optimization of thin-film growth and refinement of device processing, we decreased the total cavity thickness to less than 1 {micro}m, such that micro-cavity effects were clearly observed and a light extraction efficiency of over 10% was reached. We also began the development of photonic crystals for increased light extraction, in particular for so-called ''guided modes'' which would otherwise propagate laterally in the device and be re-absorbed. Finally, we pursued the growth of smooth, high-quality nonpolar a-plane and m-plane GaN films, as well as blue light emitting diodes on these novel films. Initial nonpolar LEDs showed the expected behavior of negligible peak wavelength shift with increasing drive current. M-plane LEDs in particular show promise, as unpackaged devices had unsaturated optical output power of {approx} 3 mW at 200 mA drive current. The LRC's tasks were aimed at developing the subcomponents necessary for packaging UCSB's light emitting diodes, and packaging them to produce a white

  11. III V nitride based light-emitting devices

    NASA Astrophysics Data System (ADS)

    Nakamura, Shuji

    1997-04-01

    High brightness InGaN single-quantum-well structure (SQW) blue and green light-emitting diodes (LEDs) with luminous intensities of 2 cd and 10 cd have been achieved and commercialized. By combining these high-power and high-brightness blue InGaN SQW LED, green InGaN SQW LED and red AlInGaP LED, many kinds of applications, such as LED full-color displays and LED white lamps for use in place of incandescent or fluorescent lamps, are now possible with characteristics of high reliability, high durability and low energy consumption. Also, very recently, III-V nitride based laser diodes (LDs) were fabricated for the first time. These LDs emitted coherent light at 390-440 nm from an InGaN based multi-quantum-well structure at room temperature. The emission wavelength is the shortest one ever generated by a semiconductor laser diode.

  12. Versatile multispectral microscope based on light emitting diodes

    NASA Astrophysics Data System (ADS)

    Brydegaard, Mikkel; Merdasa, Aboma; Jayaweera, Hiran; Ålebring, Jens; Svanberg, Sune

    2011-12-01

    We describe the development of a novel multispectral microscope, based on light-emitting diodes, capable of acquiring megapixel images in thirteen spectral bands from the ultraviolet to the near infrared. The system captures images and spectra in transmittance, reflectance, and scattering modes. We present as examples of applications ground truth measurements for remote sensing and parasitology diagnostics. The system is a general purpose scientific instrument that could be used to develop dedicated simplified instruments with optimal bands and mode selection.

  13. Penning plasma based simultaneous light emission source of visible and VUV lights

    NASA Astrophysics Data System (ADS)

    Vyas, G. L.; Prakash, R.; Pal, U. N.; Manchanda, R.; Halder, N.

    2016-06-01

    In this paper, a laboratory-based penning plasma discharge source is reported which has been developed in two anode configurations and is able to produce visible and VUV lights simultaneously. The developed source has simultaneous diagnostics facility using Langmuir probe and optical emission spectroscopy. The two anode configurations, namely, double ring and rectangular configurations, have been studied and compared for optimum use of the geometry for efficient light emissions and recording. The plasma is produced using helium gas and admixture of three noble gases including helium, neon, and argon. The source is capable to produce eight spectral lines for pure helium in the VUV range from 20 to 60 nm and total 24 spectral lines covering the wavelength range 20-106 nm for the admixture of gases. The large range of VUV lines is generated from gaseous admixture rather from the sputtered materials. The recorded spectrum shows that the plasma light radiations in both visible and VUV range are larger in double ring configuration than that of the rectangular configurations at the same discharge operating conditions. To clearly understand the difference, the imaging of the discharge using ICCD camera and particle-in-cell simulation using VORPAL have also been carried out. The effect of ion diffusion, metastable collision with the anode wall and the nonlinear effects are correlated to explain the results.

  14. HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING

    SciTech Connect

    Dr. Paul T. Fini; Prof. Shuji Nakamura

    2002-09-01

    In this annual report we summarize the progress obtained in the first year with the support of DoE contract No.DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has made significant progress in the development of GaN vertical cavity surface-emitting lasers (VCSELs) as well as light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV). The Rensselaer team has developed target specifications for some of the key parameters for the proposed solid-state lighting system, including a luminous flux requirement matrix for various lighting applications, optimal spectral power distributions, and the performance characteristics of currently available commercial LEDs for eventual comparisons to the devices developed in the scope of this project.

  15. Controlled-phase gate for photons based on stationary light

    NASA Astrophysics Data System (ADS)

    Iakoupov, Ivan; Borregaard, Johannes; Sørensen, Anders S.

    We propose a controlled-phase gate for optical photons based on an atomic ensemble coupled to a one-dimensional waveguide. When an ensemble of Λ-type atoms is subject to a standing wave control field, it creates a stationary light effect where the ensemble develops a band gap for light propagation. For frequencies close to the band gap, the light-matter interactions are enhanced due to the reduced group velocity of the light pulses. Changing the internal state of one of the atoms, such that it behaves as an absorbing two-level atom instead of a transparent Λ-type atom, can change the scattering properties of the whole ensemble, switching it from being completely transmissive to being completely reflective. To realize a controlled-phase gate between photons, we store one of the photons inside the atomic ensemble (thereby changing the internal state of one of the atoms), scatter a second photon off the ensemble, and retrieve the first photon. Finally, we consider an application of the proposed controlled-phase gate - a quantum repeater.

  16. Carbon nanotube-based organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Bansal, Malti; Srivastava, Ritu; Lal, C.; Kamalasanan, M. N.; Tanwar, L. S.

    2009-11-01

    Carbon nanotubes; revolutionary and fascinating from the materials point of view and exceedingly sensational from a research point of view; are standing today at the threshold between inorganic electronics and organic electronics and posing a serious challenge to the big daddies of these two domains in electronics i.e., silicon and indium tin oxide (ITO). In the field of inorganic electronics, carbon nanotubes offer advantages such as high current carrying capacity, ballistic transport, absence of dangling bonds, etc. and on the other hand, in the field of organic electronics, carbon nanotubes offer advantages such as high conductivity, high carrier mobility, optical transparency (in visible and IR spectral ranges), flexibility, robustness, environmental resistance, etc. and hence, they are seriously being considered as contenders to silicon and ITO. This review traces the origin of carbon nanotubes in the field of organic electronics (with emphasis on organic light emitting diodes) and moves on to cover the latest advances in the field of carbon nanotube-based organic light emitting diodes. Topics that are covered within include applications of multi-wall nanotubes and single-wall nanotubes in organic light emitting diodes. Applications of carbon nanotubes as hole-transport layers, as electron-transport layers, as transparent electrodes, etc. in organic light emitting diodes are discussed and the daunting challenges facing this progressive field today are brought into the limelight.

  17. HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING

    SciTech Connect

    Dr. Paul T. Fini; Prof. Shuji Nakamura

    2002-04-30

    In this semiannual report we summarize the progress obtained in the first six months with the support of DoE contract No.DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has made significant progress in the development of GaN vertical cavity surface-emitting lasers (VCSELs) as well as light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV). The Rensselaer team has developed target specifications for some of the key parameters for the proposed solid-state lighting system, including a luminous flux requirement matrix for various lighting applications, optimal spectral power distributions, and the performance characteristics of currently available commercial LEDs for eventual comparisons to the devices developed in the scope of this project.

  18. Development of Key Technologies for White Lighting Based on Light-Emitting Diodes (LEDs)

    SciTech Connect

    Werner Goetz; Bill Imler; James Kim; Junko Kobayashi; Andrew Kim; Mike Krames; Rick Mann; Gerd Mueller-Mach; Anneli Munkholm; Jonathan Wierer

    2004-03-31

    This program was organized to focus on materials development issues critical to the acceleration of solid-state lighting, and was split into three major thrust areas: (1) study of dislocation density reduction for GaN grown on sapphire using 'cantilever epitaxy', and the impact of dislocation density on the performance of state-of-the-art high-power LEDs; (2) the evaluation of in situ techniques for monitoring gas phase chemistry and the properties of GaN-based layers during metal-organic vapor phase epitaxy (MOCVD), and (3) feasibility for using semiconductor nanoparticles ('quantum dots') for the down-conversion of blue or ultraviolet light to generate white light. The program included a partnership between Lumileds Lighting (epitaxy and device fabrication for high power LEDs) and Sandia National Laboratories (cantilever epitaxy, gas phase chemistry, and quantum dot synthesis). Key findings included: (1) cantilever epitaxy can provide dislocation density reduction comparable to that of more complicated approaches, but all in one epitaxial growth step; however, further improvements are required to realize significant gains in LED performance at high drive currents, (2) in situ tools can provide detailed knowledge about gas phase chemistry, and can be used to monitor and control epitaxial layer composition and temperature to provide improved yields (e.g., a fivefold increase in color targeting is demonstrated for 540nm LEDs), and (3) quantum efficiency for quantum dots is improved and maintained up to 70% in epoxy thin films, but further work is necessary to increase densification (absorption) and robustness before practical application to LEDs.

  19. Light extraction analysis of GaN-based light-emitting diodes with surface texture and/or patterned substrate.

    PubMed

    Lee, Tsung-Xian; Gao, Ko-Fon; Chien, Wei-Ting; Sun, Ching-Cherng

    2007-05-28

    Light extraction analysis of GaN-based light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high light extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20o to 70o is shown to effectively improve the light extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase light extraction efficiency than the surface texture. PMID:19546977

  20. Novel light emissive yttrium-based nanoparticles and composites

    NASA Astrophysics Data System (ADS)

    Hill, Laura Burka

    Yttrium-based inorganic optical materials generally are of practical interest for three applications: solid state lighting/displays, lasers, and scintillators. Solid-state lighting is particularly desirable commercially for its efficiency and lifetime compared to traditional incandescent alternatives. This type of lighting technology is of increasing interest as incandescent light bulbs are being gradually phased-out due to government regulations on maximum wattage of these devices. Additionally, shortcomings in the current state of the art have driven the need for a more thermally stable material for use in this area. In this dissertation, we develop and characterize a novel composite material consisting of optically active yttrium-based nanoparticles doped into silica sol-gels. For lighting and display applications, low-cost, low-temperature synthesis methods for materials that meet or exceed the quality of the materials currently on the market are highly desirable. During the course of this work, we discuss the characterization of yttrium-based nanoparticles with respect to their incorporation in a sol-gel matrix composite. We then prepared these composite materials using a variety of methods and assess their quality according to a set of selection criteria and for lighting/display applications. Novel light-emitting composites consisting of Ce:YAG or Eu:Y2O 3 (yttria) nanoparticles in an inorganic medium were successfully developed and characterized. The optical properties of the nanoparticles were maintained when incorporated into the sol-gel medium and were shown to be comparable with the current state of the art. Comparison was made between the nanoparticle emission and the composite emission and, in the case of the Ce:YAG, the CIE coordinates, showing no change between the emission intensities or peak locations. We successfully demonstrated the conversion of fluoride-based particles into Y2O3 during sol-gel processing and demonstrated that no reaction took

  1. Silicon-based structures for IR light emission

    NASA Astrophysics Data System (ADS)

    Hansson, Göran V.; Ni, Wei-Xin; Joelsson, Kenneth B.; Buyanova, I. A.

    1997-01-01

    There is a lot of interest in obtaining efficient infra-red (IR) light emission from Si-based structures for use in optoelectronics. Although it has been theoretically predicted that Sim/Gen atomic layer superlattices can have a quasi-direct bandgap, the experimental studies have not yet given very high luminescence intensities, particularly at room temperature, from such structures. So far, the most efficient method to have IR light emission at room temperature is to process Si/Si1-xGex superlattices or quantum well structures into narrow (<60nm diameter) columnar structures. After planarization with insulating material it has been possible to fabricate LEDs using these columns. While the results are very promising there are also a number of unsolved problems concerning the mechanism allowing for efficient light emission and concerning the passivation of the surfaces of the columns to have a long-term stability of the emission. Another way to have IR light emission at room temperature and possibly obtain a Si-based laser is to use Er-doped material. For Er-doped LEDs, most of the work has been done on ion-implanted structures. It has been found that to have the Er-related emission at 1.54 μm it is necessary to also have co-dopants like O or F to activate the Er. Since a high temperature step is necessary to anneal out implantation damage it has been difficult to have high concentrations of Er/O without precipitation, as the required concentration for useful devices is far above the solid solubility of Er in Si. Low temperature growth using MBE is a promising method to achieve high Er/O or Er/F concentrations without precipitation and intense room-temperature electroluminescence has very recently been reported from a reverse biased Er/O-doped LED grown by MBE.

  2. Integrated LED-based luminare for general lighting

    DOEpatents

    Dowling, Kevin J.; Lys, Ihor A.; Roberge, Brian; Williamson, Ryan C.; Roberts, Ron; Datta, Michael; Mollnow, Tomas; Morgan, Frederick M.

    2013-03-05

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  3. Integrated LED-based luminaire for general lighting

    DOEpatents

    Dowling, Kevin J.; Lys, Ihor A.; Williamson, Ryan C.; Roberge, Brian; Roberts, Ron; Morgan, Frederick; Datta, Michael Jay; Mollnow, Tomas Jonathan

    2016-08-30

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  4. A structured light-based system for human heads

    NASA Astrophysics Data System (ADS)

    Wu, XianFeng; Li, Dehua; Gang, Jin; Zhou, Zhu

    2004-07-01

    The 3-D modeling of heads by using optical triangulation techniques is of great interest in the context of virtual reality, telecommunication and computer animation. This paper presents a structured light-based system mainly for human heads. It is named "3-D Laser Color Scanner" (3DLCS). A 3-D model is obtained with a cylindrical scan. The laser beam is switched on and off using a "light valve" and two successive CCD frames are captured, one with the laser line showing and one without. We can simplify the laser line extracting by subtracting these two images. In this system, two CCD cameras are used to avoid occlusion problems. Color information is read from the CCD when the laser light is absent. Since traditional laser scanner will miss the range data in the low-reflectance areas such as the hair area of human head, a shape from silhouette algorithm is presented to overcome this problem. Finally, we give some results using our system. The resulting model is suitable for many applications.

  5. Quantum repeater based on cavity QED evolutions and coherent light

    NASA Astrophysics Data System (ADS)

    Gonţa, Denis; van Loock, Peter

    2016-05-01

    In the framework of cavity QED, we propose a quantum repeater scheme that uses coherent light and chains of atoms coupled to optical cavities. In contrast to conventional repeater schemes, in our scheme there is no need for an explicit use of two-qubit quantum logical gates by exploiting solely the cavity QED evolution. In our previous work (Gonta and van Loock in Phys Rev A 88:052308, 2013), we already proposed a quantum repeater in which the entanglement between two neighboring repeater nodes was distributed using controlled displacements of input coherent light, while the produced low-fidelity entangled pairs were purified using ancillary (four-partite) entangled states. In the present work, the entanglement distribution is realized using a sequence of controlled phase shifts and displacements of input coherent light. Compared to previous coherent-state-based distribution schemes for two-qubit entanglement, our scheme here relies only upon a simple discrimination of two coherent states with opposite signs, which can be performed in a quantum mechanically optimal fashion via a beam splitter and two on-off detectors. For the entanglement purification, we employ a method that avoids the use of extra entangled ancilla states. Our repeater scheme exhibits reasonable fidelities and repeater rates providing an attractive platform for long-distance quantum communication.

  6. Light-responsive viscoelastic fluids based on anionic wormlike micelles.

    PubMed

    Lu, Yechang; Zhou, Tengfei; Fan, Qing; Dong, Jinfeng; Li, Xuefeng

    2013-12-15

    A new class of light-responsive viscoelastic fluids based on anionic wormlike micelles is reported. The key components are sodium oleate (NaOA) and a cationic azobenzene dye, 1-[2-(4-phenylazo-phenoxy)-ethyl]-3-methylimidazolium bromide (C0AZOC2IMB). These binary systems are gel-like fluids at certain concentration ratios of [C0AZOC2IMB]/[NaOA], e.g. 35/100, owing to the formation of long, entangled wormlike micelles. The viscosity of these fluids can be controlled reversibly by light due to photo isomerization between trans-C0AZOC2IMB and cis-C0AZOC2IMB. For example, the zero-shear viscosity (η0) of an originally gel-like sample is high up to ~1300 Pa s when C0AZOC2IMB is in its trans from, whereas the mixture becomes a Newtonian fluid with η0 about 0.01 Pa s after UV light irradiation. For the post-irradiated cis-C0AZOC2IMB, short cylindrical micelles form, hence accounting for the lower viscosity. Evidence for the structural transition is provided by UV-vis spectra, rheology, (1)H NMR and cryo-transmission electronic microscopy measurements. PMID:24144381

  7. High-Efficiency Nitride-Base Photonic Crystal Light Sources

    SciTech Connect

    James Speck; Evelyn Hu; Claude Weisbuch; Yong-Seok Choi; Kelly McGroddy; Gregor Koblmuller; Elison Matioli; Elizabeth Rangel; Fabian Rol; Dobri Simeonov

    2010-01-31

    The research activities performed in the framework of this project represent a major breakthrough in the demonstration of Photonic Crystals (PhC) as a competitive technology for LEDs with high light extraction efficiency. The goals of the project were to explore the viable approaches to manufacturability of PhC LEDS through proven standard industrial processes, establish the limits of light extraction by various concepts of PhC LEDs, and determine the possible advantages of PhC LEDs over current and forthcoming LED extraction concepts. We have developed three very different geometries for PhC light extraction in LEDs. In addition, we have demonstrated reliable methods for their in-depth analysis allowing the extraction of important parameters such as light extraction efficiency, modal extraction length, directionality, internal and external quantum efficiency. The information gained allows better understanding of the physical processes and the effect of the design parameters on the light directionality and extraction efficiency. As a result, we produced LEDs with controllable emission directionality and a state of the art extraction efficiency that goes up to 94%. Those devices are based on embedded air-gap PhC - a novel technology concept developed in the framework of this project. They rely on a simple and planar fabrication process that is very interesting for industrial implementation due to its robustness and scalability. In fact, besides the additional patterning and regrowth steps, the process is identical as that for standard industrially used p-side-up LEDs. The final devices exhibit the same good electrical characteristics and high process yield as a series of test standard LEDs obtained in comparable conditions. Finally, the technology of embedded air-gap patterns (PhC) has significant potential in other related fields such as: increasing the optical mode interaction with the active region in semiconductor lasers; increasing the coupling of the incident

  8. Light programmable organic transistor memory device based on hybrid dielectric

    NASA Astrophysics Data System (ADS)

    Ren, Xiaochen; Chan, Paddy K. L.

    2013-09-01

    We have fabricated the transistor memory devices based on SiO2 and polystyrene (PS) hybrid dielectric. The trap states densities with different semiconductors have been investigated and a maximum 160V memory window between programming and erasing is realized. For DNTT based transistor, the trapped electron density is limited by the number of mobile electrons in semiconductor. The charge transport mechanism is verified by light induced Vth shift effect. Furthermore, in order to meet the low operating power requirement of portable electronic devices, we fabricated the organic memory transistor based on AlOx/self-assembly monolayer (SAM)/PS hybrid dielectric, the effective capacitance of hybrid dielectric is 210 nF cm-2 and the transistor can reach saturation state at -3V gate bias. The memory window in transfer I-V curve is around 1V under +/-5V programming and erasing bias.

  9. Determination of impurities in crude light pyridine bases

    SciTech Connect

    Novikov, E.G.; Tsaur, A.G.; Lisina, L.A.; Dybkin, P.A.

    1981-01-01

    Hydrogen cyanide, hydrogen sulfide, ammonia and phenols are always products of coal pyrolysis. In addition the coke oven gas contains carbon disulfide. The simultaneous presence of ammonia and carbon disulfide leads inevitably to the formation of thiocyanates in the entire recovery system before the saturator, and particularly in the ammonia liquor. All these compounds may be expected to be present in the crude light pyridine bases (CLPB). This causes corrosion of the equipment and reduces the photostability of the final process products. The ability of the phenols to form high boiling point azeotropes with the bases reduces the ..beta..-picoline fraction yield. For these reasons the presence of the stated impurities in the CLPB is undesirable. In the present work an estimate has been made of the average annual concentration of phenols, cyanides, thiocyanates and chlorides in the crude light pyridine bases of all the plants supplying this material in the Eastern USSR. The table shows only the mean values of the concentrations for each component in the samples of the individual plants, and also those for water.

  10. Virtual reality 3D headset based on DMD light modulators

    SciTech Connect

    Bernacki, Bruce E.; Evans, Allan; Tang, Edward

    2014-06-13

    We present the design of an immersion-type 3D headset suitable for virtual reality applications based upon digital micro-mirror devices (DMD). Our approach leverages silicon micro mirrors offering 720p resolution displays in a small form-factor. Supporting chip sets allow rapid integration of these devices into wearable displays with high resolution and low power consumption. Applications include night driving, piloting of UAVs, fusion of multiple sensors for pilots, training, vision diagnostics and consumer gaming. Our design is described in which light from the DMD is imaged to infinity and the user’s own eye lens forms a real image on the user’s retina.

  11. Cellular Bases of Light-regulated Gravity Responses

    NASA Technical Reports Server (NTRS)

    Roux, Stanley J.

    2003-01-01

    This report summarizes the most significant research accomplished in our NAG2-1347 project on the cellular bases of light-regulated gravity responses, It elaborates mainly on our discovery of the role of calcium currents in gravity-directed polar development in single germinating spore cells of the fern Ceratopteris, our development of RNA silencing as a viable method of suppressing the expression of specific genes in Ceratopteris, and on the structure, expression and distribution of members of the annexin family in flowering plants, especially Arabidopsis.

  12. Fast and accurate line scanner based on white light interferometry

    NASA Astrophysics Data System (ADS)

    Lambelet, Patrick; Moosburger, Rudolf

    2013-04-01

    White-light interferometry is a highly accurate technology for 3D measurements. The principle is widely utilized in surface metrology instruments but rarely adopted for in-line inspection systems. The main challenges for rolling out inspection systems based on white-light interferometry to the production floor are its sensitivity to environmental vibrations and relatively long measurement times: a large quantity of data needs to be acquired and processed in order to obtain a single topographic measurement. Heliotis developed a smart-pixel CMOS camera (lock-in camera) which is specially suited for white-light interferometry. The demodulation of the interference signal is treated at the level of the pixel which typically reduces the acquisition data by one orders of magnitude. Along with the high bandwidth of the dedicated lock-in camera, vertical scan-speeds of more than 40mm/s are reachable. The high scan speed allows for the realization of inspection systems that are rugged against external vibrations as present on the production floor. For many industrial applications such as the inspection of wafer-bumps, surface of mechanical parts and solar-panel, large areas need to be measured. In this case either the instrument or the sample are displaced laterally and several measurements are stitched together. The cycle time of such a system is mostly limited by the stepping time for multiple lateral displacements. A line-scanner based on white light interferometry would eliminate most of the stepping time while maintaining robustness and accuracy. A. Olszak proposed a simple geometry to realize such a lateral scanning interferometer. We demonstrate that such inclined interferometers can benefit significantly from the fast in-pixel demodulation capabilities of the lock-in camera. One drawback of an inclined observation perspective is that its application is limited to objects with scattering surfaces. We therefore propose an alternate geometry where the incident light is

  13. MOCVD growth of GaN nanopyramid and nanopillar LED with emission in green to orange color

    NASA Astrophysics Data System (ADS)

    Kuo, Hao-Chung; Cheng, Yuh-Jen

    2012-10-01

    We report the fabrication and demonstration of electrically driven green, yellow-green, and amber color nanopyramid LEDs. The quantum wells were grown on nanopyramid facets, which have low polarization field and allow high In incorporation.

  14. Invisibility Cloaking Based on Geometrical Optics for Visible Light

    NASA Astrophysics Data System (ADS)

    Ichikawa, H.; Oura, M.; Taoda, T.

    2013-06-01

    Optical cloaking has been one of unattainable dreams and just a subject in fiction until recently. Several different approaches to cloaking have been proposed and demonstrated: stealth technology, active camouflage and transformation optics. The last one would be the most formal approach modifying electromagnetic field around an object to be cloaked with metamaterials. While cloaking based on transformation optics, though valid only at single frequency, is experimentally demonstrated in microwave region, its operation in visible spectrum is still distant from realisation mainly owing to difficulty in fabricating metamaterial structure whose elements are much smaller than wavelength of light. Here we show that achromatic optical cloaking in visible spectrum is possible with the mere principle based on geometrical optics. In combining a pair of polarising beam splitters and right-angled prisms, rays of light to be obstructed by an object can make a detour to an observer, while unobstructed rays go straight through two polarising beam splitters. What is observed eventually through the device is simply background image as if nothing exists in between.

  15. Virtual reality 3D headset based on DMD light modulators

    NASA Astrophysics Data System (ADS)

    Bernacki, Bruce E.; Evans, Allan; Tang, Edward

    2014-06-01

    We present the design of an immersion-type 3D headset suitable for virtual reality applications based upon digital micromirror devices (DMD). Current methods for presenting information for virtual reality are focused on either polarizationbased modulators such as liquid crystal on silicon (LCoS) devices, or miniature LCD or LED displays often using lenses to place the image at infinity. LCoS modulators are an area of active research and development, and reduce the amount of viewing light by 50% due to the use of polarization. Viewable LCD or LED screens may suffer low resolution, cause eye fatigue, and exhibit a "screen door" or pixelation effect due to the low pixel fill factor. Our approach leverages a mature technology based on silicon micro mirrors delivering 720p resolution displays in a small form-factor with high fill factor. Supporting chip sets allow rapid integration of these devices into wearable displays with high-definition resolution and low power consumption, and many of the design methods developed for DMD projector applications can be adapted to display use. Potential applications include night driving with natural depth perception, piloting of UAVs, fusion of multiple sensors for pilots, training, vision diagnostics and consumer gaming. Our design concept is described in which light from the DMD is imaged to infinity and the user's own eye lens forms a real image on the user's retina resulting in a virtual retinal display.

  16. Autofocusing system for spatial light modulator-based maskless lithography.

    PubMed

    Schlangen, Sebastian; Ihme, Maximilian; Rahlves, Maik; Roth, Bernhard

    2016-03-10

    To produce diffractive or holographic structures in a photolithographic process, an optical projection system enabling structure resolution in the submicrometer range is highly desirable. To ensure that the optical focus of such a system lies on the substrate surface during the whole lithographic fabrication process, an autofocus system able to focus on a depth of field of a few hundred nanometers is usually required. In this work, we developed an autofocus system for spatial light modulator (SLM)-based maskless photolithographic applications. The system is capable of high-precision focusing without affecting the photoresist performance. It is based on contrast measurement combined with focus-pattern illumination to ensure high contrast at the substrate surface. In addition, we evaluated various autofocus algorithms with respect to time efficiency and accuracy to determine suitable focus-pattern and focus-algorithm combinations. PMID:26974774

  17. Continuous-wave optical fiber based supercontinuum light source

    NASA Astrophysics Data System (ADS)

    Lu, Z. G.; Song, Y.; Liu, J. R.; Zhang, X. P.

    2007-11-01

    We have demonstrated a continuum-wave (CW) supercontinuum (SC) fiber light source with over 1000 nm bandwidth based on a low-cost erbium/ytterbium co-doped double-cladding fiber ring cavity laser. Based on the observation to the SC evolvement, we have experimentally analyzed the detailed contributions of several nonlinear effects within highly nonlinear dispersion-shifted fiber (HNLF). Our experimental results have clearly indicated that four-wave mixing (FWM) and stimulated Raman scattering (SRS) play key roles in CW-pumped SC generation. At the same time, self-phase modulation (SPM) mainly contributes to generate new frequency components near the peaks that appear in the form of the spectra broadening while cross-phase modulation (XPM) enhances the broadening of peaks.

  18. Performance characterization of structured light-based fingerprint scanner

    NASA Astrophysics Data System (ADS)

    Hassebrook, Laurence G.; Wang, Minghao; Daley, Raymond C.

    2013-05-01

    Our group believes that the evolution of fingerprint capture technology is in transition to include 3-D non-contact fingerprint capture. More specifically we believe that systems based on structured light illumination provide the highest level of depth measurement accuracy. However, for these new technologies to be fully accepted by the biometric community, they must be compliant with federal standards of performance. At present these standards do not exist for this new biometric technology. We propose and define a set of test procedures to be used to verify compliance with the Federal Bureau of Investigation's image quality specification for Personal Identity Verification single fingerprint capture devices. The proposed test procedures include: geometric accuracy, lateral resolution based on intensity or depth, gray level uniformity and flattened fingerprint image quality. Several 2-D contact analogies, performance tradeoffs and optimization dilemmas are evaluated and proposed solutions are presented.

  19. Hemithioindigo-based photoswitches as ultrafast light trigger in chromopeptides

    NASA Astrophysics Data System (ADS)

    Cordes, T.; Weinrich, D.; Kempa, S.; Riesselmann, K.; Herre, S.; Hoppmann, C.; Rück-Braun, K.; Zinth, W.

    2006-09-01

    The spectroscopy and dynamics of a novel hemithioindigo-based photoswitch forming a ω-amino acid derivative are presented. Light absorption in the visible spectral range induces photoisomerization between Z and E configurations with quantum yields in the 10% range. The Z isomer is thermally stable, while the E isomer relaxes back to the Z form within several hours. The E isomers provides a distinct spectral range, where the photoisomerization process can be initiated selectively. Both directions of the photoisomerization are investigated by transient absorption spectroscopy and time constants for the formation of the photoproduct in the 10-30 ps range are observed. The ability of the hemithioindigo-based photoswitch to drive structural dynamics in peptides and proteins is tested for two ω-amino acid derivatives forming linear and cyclic structures.

  20. Future Synchrotron Light Sources Based on Ultimate Storage Rings

    SciTech Connect

    Cai, Yunhai; /SLAC

    2012-04-09

    The main purpose of this talk is to describe how far one might push the state of the art in storage ring design. The talk will start with an overview of the latest developments and advances in the design of synchrotron light sources based on the concept of an 'ultimate' storage ring. The review will establish how bright a ring based light source might be, where the frontier of technological challenges are, and what the limits of accelerator physics are. Emphasis will be given to possible improvements in accelerator design and developments in technology toward the goal of achieving an ultimate storage ring. An ultimate storage ring (USR), defined as an electron ring-based light source having an emittance in both transverse planes at the diffraction limit for the range of X-ray wavelengths of interest for a scientific community, would provide very high brightness photons having high transverse coherence that would extend the capabilities of X-ray imaging and probe techniques beyond today's performance. It would be a cost-effective, high-coherence 4th generation light source, competitive with one based on energy recovery linac (ERL) technology, serving a large number of users studying material, chemical, and biological sciences. Furthermore, because of the experience accumulated over many decades of ring operation, it would have the great advantage of stability and reliability. In this paper we consider the design of an USR having 10-pm-rad emittance. It is a tremendous challenge to design a storage ring having such an extremely low emittance, a factor of 100 smaller than those in existing light sources, especially such that it has adequate dynamic aperture and beam lifetime. In many ultra-low emittance designs, the injection acceptances are not large enough for accumulation of the electron beam, necessitating on-axis injection where stored electron bunches are completely replaced with newly injected ones. Recently, starting with the MAX-IV 7-bend achromatic cell, we

  1. A novel amblyopia treatment system based on LED light source

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqing; Chen, Qingshan; Wang, Xiaoling

    2011-05-01

    A novel LED (light emitting diode) light source of five different colors (white, red, green, blue and yellow) is adopted instead of conventional incandescent lamps for an amblyopia treatment system and seven training methods for rectifying amblyopia are incorporated so as for achieving an integrated therapy. The LED light source is designed to provide uniform illumination, adjustable light intensity and alterable colors. Experimental tests indicate that the LED light source operates steadily and fulfills the technical demand of amblyopia treatment.

  2. A novel amblyopia treatment system based on LED light source

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqing; Chen, Qingshan; Wang, Xiaoling

    2010-12-01

    A novel LED (light emitting diode) light source of five different colors (white, red, green, blue and yellow) is adopted instead of conventional incandescent lamps for an amblyopia treatment system and seven training methods for rectifying amblyopia are incorporated so as for achieving an integrated therapy. The LED light source is designed to provide uniform illumination, adjustable light intensity and alterable colors. Experimental tests indicate that the LED light source operates steadily and fulfills the technical demand of amblyopia treatment.

  3. Development of ultraviolet nitride-based light emitting diodes

    NASA Astrophysics Data System (ADS)

    Katona, Thomas Matthew

    2003-10-01

    Deep ultraviolet light emitting diodes, with emission wavelengths shorter than 360 nm, have attracted interest due to their potential applications as replacement white light sources, in non-line of sight communication, for chemical and biological weapons detection, medical applications, water purification, and counterfeit detection. Light emitters in this wavelength range require AlGaN based active regions with increasing Al composition as the wavelength is decreased. High Al composition AlGaN based devices have been challenged by difficulty in growth, low electron and hole mobilities, and deep dopant levels resulting in low carrier concentrations. The combination of these factors has resulted in UV optoelectronic devices with quantum efficiency several orders of magnitude lower than their GaN/InGaN based visible counterparts. This work will details studies on alternative selective area growth techniques for dislocation reduction and the development of ultraviolet LEDs ranging from 292--340 nm. Lateral overgrowth of GaN on patterned Si (111) substrates was developed with the hope of developing seed material for bulk GaN growth. The effect of growth conditions on both the crystallographic wing tilt and crack density in the AlN/GaN films was studied. By controlling the lateral to vertical growth rate at the beginning of lateral overgrowth, the wing tilt can be effectively eliminated. We also demonstrate the first lateral overgrowth of AlN to create low threading dislocation density AlN template layers for optoelectronic device development. Deep UV quantum wells grown on this material were studied with cathodoluminescence to study the effect of dislocations on radiative recombination in deep UV devices. In addition to work on lateral overgrowth of GaN and AlN, 292, 340 nm LEDs were grown on AlN on sapphire and GaN on sapphire respectively. AlN strain relief interlayers were developed to prevent cracking of the 340 nm AlGaN based LEDs that were grown in tension on Ga

  4. High-output LED-based light engine for profile lighting fixtures with high color uniformity using freeform reflectors.

    PubMed

    Gadegaard, Jesper; Jensen, Thøger Kari; Jørgensen, Dennis Thykjær; Kristensen, Peter Kjær; Søndergaard, Thomas; Pedersen, Thomas Garm; Pedersen, Kjeld

    2016-02-20

    In the stage lighting and entertainment market, light engines (LEs) for lighting fixtures are often based on high-intensity discharge (HID) bulbs. Switching to LED-based light engines gives possibilities for fast switching, additive color mixing, a longer lifetime, and potentially, more energy-efficient systems. The lumen output of a single LED is still not sufficient to replace an HID source in high-output profile fixtures, but combining multiple LEDs can create an LE with a similar output, but with added complexity. This paper presents the results of modeling and testing such a light engine. Custom ray-tracing software was used to design a high-output red, green and blue LED-based light engine with twelve CBT-90 LEDs using a dual-reflector principle. The simulated optical system efficiency was 0.626 with a perfect (R=1) reflector coating for light delivered on a target surface through the entire optical system. A profile lighting fixture prototype was created, and provided an output of 6744 lumen and an efficiency of 0.412. The lower efficiency was mainly due to a non-optimal reflector coating, and the optimized design is expected to reach a significantly higher efficiency. PMID:26906589

  5. A Light Scattering Layer for Internal Light Extraction of Organic Light-Emitting Diodes Based on Silver Nanowires.

    PubMed

    Lee, Keunsoo; Shin, Jin-Wook; Park, Jun-Hwan; Lee, Jonghee; Joo, Chul Woong; Lee, Jeong-Ik; Cho, Doo-Hee; Lim, Jong Tae; Oh, Min-Cheol; Ju, Byeong-Kwon; Moon, Jaehyun

    2016-07-13

    We propose and fabricate a random light scattering layer for light extraction in organic light-emitting diodes (OLEDs) with silver nanodots, which were obtained by melting silver nanowires. The OLED with the light scattering layer as an internal light extraction structure was enhanced by 49.1% for the integrated external quantum efficiency (EQE). When a wrinkle structure is simultaneously used for an external light extraction structure, the total enhancement of the integrated EQE was 65.3%. The EQE is maximized to 65.3% at a current level of 2.0 mA/cm(2). By applying an internal light scattering layer and wrinkle structure to an OLED, the variance in the emission spectra was negligible over a broad viewing angle. Power mode analyses with finite difference time domain (FDTD) simulations revealed that the use of a scattering layer effectively reduced the waveguiding mode while introducing non-negligible absorption. Our method offers an effective yet simple approach to achieve both efficiency enhancement and spectral stability for a wide range of OLED applications. PMID:27314500

  6. Experimental Study of Red-, Green-, and Blue-Based Light Emitting Diodes Visible Light Communications for Micro-Projector Application

    NASA Astrophysics Data System (ADS)

    Chou, H.-H.; Liaw, S.-K.; Jiang, J.-S.; Teng, C.

    2016-05-01

    In this research, an experimental short-range visible light communication link using red-, green-, and blue-based light-emitting diodes (LEDs) for portable micro-projector applications is presented. A Reconfigurable design of a post-equalizer aimed to improve the inherent narrow modulation bandwidth of red-, green-, and blue-based LEDs has been experimentally implemented, and its effectiveness with optical filters at the receiver is investigated. Reflective liquid-crystal-on-silicon-based micro-projection architecture, widely used in portable micro-projectors, was set up to evaluate the proposed visible light communication system. The measurement results demonstrated that a significant aggregative bandwidth improvement of 162 MHz as well as an aggregative data transmission rate of nearly 400 Mb/s can be achieved by using a non-return-to-zero-on-off keying (NRZ-OOK) modulation scheme based on only one polarization state of incident light without any offline signal processing.

  7. Ultrafast image-based dynamic light scattering for nanoparticle sizing.

    PubMed

    Zhou, Wu; Zhang, Jie; Liu, Lili; Cai, Xiaoshu

    2015-11-01

    An ultrafast sizing method for nanoparticles is proposed, called as UIDLS (Ultrafast Image-based Dynamic Light Scattering). This method makes use of the intensity fluctuation of scattered light from nanoparticles in Brownian motion, which is similar to the conventional DLS method. The difference in the experimental system is that the scattered light by nanoparticles is received by an image sensor instead of a photomultiplier tube. A novel data processing algorithm is proposed to directly get correlation coefficient between two images at a certain time interval (from microseconds to milliseconds) by employing a two-dimensional image correlation algorithm. This coefficient has been proved to be a monotonic function of the particle diameter. Samples of standard latex particles (79/100/352/482/948 nm) were measured for validation of the proposed method. The measurement accuracy of higher than 90% was found with standard deviations less than 3%. A sample of nanosilver particle with nominal size of 20 ± 2 nm and a sample of polymethyl methacrylate emulsion with unknown size were also tested using UIDLS method. The measured results were 23.2 ± 3.0 nm and 246.1 ± 6.3 nm, respectively, which is substantially consistent with the transmission electron microscope results. Since the time for acquisition of two successive images has been reduced to less than 1 ms and the data processing time in about 10 ms, the total measuring time can be dramatically reduced from hundreds seconds to tens of milliseconds, which provides the potential for real-time and in situ nanoparticle sizing. PMID:26628172

  8. Ultrafast image-based dynamic light scattering for nanoparticle sizing

    NASA Astrophysics Data System (ADS)

    Zhou, Wu; Zhang, Jie; Liu, Lili; Cai, Xiaoshu

    2015-11-01

    An ultrafast sizing method for nanoparticles is proposed, called as UIDLS (Ultrafast Image-based Dynamic Light Scattering). This method makes use of the intensity fluctuation of scattered light from nanoparticles in Brownian motion, which is similar to the conventional DLS method. The difference in the experimental system is that the scattered light by nanoparticles is received by an image sensor instead of a photomultiplier tube. A novel data processing algorithm is proposed to directly get correlation coefficient between two images at a certain time interval (from microseconds to milliseconds) by employing a two-dimensional image correlation algorithm. This coefficient has been proved to be a monotonic function of the particle diameter. Samples of standard latex particles (79/100/352/482/948 nm) were measured for validation of the proposed method. The measurement accuracy of higher than 90% was found with standard deviations less than 3%. A sample of nanosilver particle with nominal size of 20 ± 2 nm and a sample of polymethyl methacrylate emulsion with unknown size were also tested using UIDLS method. The measured results were 23.2 ± 3.0 nm and 246.1 ± 6.3 nm, respectively, which is substantially consistent with the transmission electron microscope results. Since the time for acquisition of two successive images has been reduced to less than 1 ms and the data processing time in about 10 ms, the total measuring time can be dramatically reduced from hundreds seconds to tens of milliseconds, which provides the potential for real-time and in situ nanoparticle sizing.

  9. Ultrafast image-based dynamic light scattering for nanoparticle sizing

    SciTech Connect

    Zhou, Wu; Zhang, Jie; Liu, Lili; Cai, Xiaoshu

    2015-11-15

    An ultrafast sizing method for nanoparticles is proposed, called as UIDLS (Ultrafast Image-based Dynamic Light Scattering). This method makes use of the intensity fluctuation of scattered light from nanoparticles in Brownian motion, which is similar to the conventional DLS method. The difference in the experimental system is that the scattered light by nanoparticles is received by an image sensor instead of a photomultiplier tube. A novel data processing algorithm is proposed to directly get correlation coefficient between two images at a certain time interval (from microseconds to milliseconds) by employing a two-dimensional image correlation algorithm. This coefficient has been proved to be a monotonic function of the particle diameter. Samples of standard latex particles (79/100/352/482/948 nm) were measured for validation of the proposed method. The measurement accuracy of higher than 90% was found with standard deviations less than 3%. A sample of nanosilver particle with nominal size of 20 ± 2 nm and a sample of polymethyl methacrylate emulsion with unknown size were also tested using UIDLS method. The measured results were 23.2 ± 3.0 nm and 246.1 ± 6.3 nm, respectively, which is substantially consistent with the transmission electron microscope results. Since the time for acquisition of two successive images has been reduced to less than 1 ms and the data processing time in about 10 ms, the total measuring time can be dramatically reduced from hundreds seconds to tens of milliseconds, which provides the potential for real-time and in situ nanoparticle sizing.

  10. A low emittance and high efficiency visible light photocathode for high brightness accelerator-based X-ray light sources

    SciTech Connect

    Vecchione, T.; Ben-Zvi, I.; Dowell, D.H.; Feng, J.; Rao, T.; Smedley, J.; Wan, W.; Padmore, H.A.

    2011-07-21

    Free-electron lasers and energy recovery linacs represent a new generation of ultra-high brightness electron accelerator based x-ray sources. Photocathodes are a critical performance-limiting component of these systems. Here, we describe the development of photocathodes based on potassium-cesium-antimonide that satisfy many of the key requirements of future light sources, such as robustness, high quantum efficiency when excited with visible light, and low transverse emittance.

  11. A low emittance and high efficiency visible light photocathode for high brightness accelerator-based X-ray light sources

    SciTech Connect

    Vecchione, T.; Feng, J.; Wan, W.; Padmore, H. A.; Ben-Zvi, I.; Dowell, D. H.; Rao, T.; Smedley, J.

    2011-07-18

    Free-electron lasers and energy recovery linacs represent a new generation of ultra-high brightness electron accelerator based x-ray sources. Photocathodes are a critical performance-limiting component of these systems. Here, we describe the development of photocathodes based on potassium-cesium-antimonide that satisfy many of the key requirements of future light sources, such as robustness, high quantum efficiency when excited with visible light, and low transverse emittance.

  12. HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING

    SciTech Connect

    Paul T. Fini; Shuji Nakamura

    2003-10-30

    In this second annual report we summarize the progress in the second-year period of Department of Energy contract DE-FC26-01NT41203, entitled ''High- Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has recently made significant progress in the development of light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV), resonant-cavity LEDs (RCLEDs), as well as lateral epitaxial overgrowth (LEO) techniques to obtain large-area non-polar GaN films with low average dislocation density. The Rensselaer team has benchmarked the performance of commercially available LED systems and has also conducted efforts to develop an optimized RCLED packaging scheme, including development of advanced epoxy encapsulant chemistries.

  13. Nitride and Oxynitride Based Phosphors for Solid State Lighting

    SciTech Connect

    Tian, Yongchi

    2011-10-15

    The objective of the project is to advance the technology of the Lightscape Materials Inc. (Lightscape) proprietary nitride and oxynitride phosphors for solid state lighting (SSL) from the current level of maturity of applied research to advanced engineering development. This objective will be accomplished by optimizing the novel nitride and oxynitride phosphors, whose formulations are listed in Table 1, and establishing cost-effective preparation processes for the phosphors. The target performances of the phosphors are: • High luminescence efficiency: Quantum Yield = 90%. • Superior thermal stability of luminescence: Thermal Quenching Loss <10% at 150 °C. • Superior environmental stability: Luminescence Maintenance >90% after 5,000 hours at 85 °C and 85% relative humidity. • Scattering loss <10%. • Cost-effective preparation processes. The resulting phosphor materials and their preparation processes are anticipated to be a drop-in component for product development paths undertaken by LED lamp makers in the SSL industry. Upon program completion, Lightscape will target market insertion that enables high efficacy, high color rendering index (CRI), high thermal stability and long lifetime LED-based lighting products for general illumination that realizes substantial energy savings.

  14. Ellipse-based DCO-OFDM for visible light communications

    NASA Astrophysics Data System (ADS)

    Mao, Tianqi; Wang, Zhaocheng; Wang, Qi; Dai, Linglong

    2016-02-01

    Ellipse-based DC-biased optical orthogonal frequency division multiplexing (E-DCO-OFDM) is proposed for visible light communications (VLC), which achieves a significant peak-to-average power ratio (PAPR) reduction, thus enhancing the overall performance when light-emitting diode (LED) nonlinearity is considered. In E-DCO-OFDM, the real-valued output of OFDM is modulated onto an ellipse, whereby only the imaginary part of the complex point on the ellipse is transmitted. Although the PAPR of E-DCO-OFDM decreases as the ratio of major radius to minor radius becomes larger, it may be more vulnerable to the effect of noise, leading to the performance loss. Therefore, the relationship between the system performance and the critical parameters in E-DCO-OFDM, such as the ratio between the major and minor radius of the ellipse, is investigated. Meanwhile, simulations demonstrate that E-DCO-OFDM adopting the optimal parameters achieves a considerable signal-to-noise ratio (SNR) gain over the conventional DCO-OFDM.

  15. Contrasting trends in light pollution across Europe based on satellite observed night time lights.

    PubMed

    Bennie, Jonathan; Davies, Thomas W; Duffy, James P; Inger, Richard; Gaston, Kevin J

    2014-01-01

    Since the 1970s nighttime satellite images of the Earth from space have provided a striking illustration of the extent of artificial light. Meanwhile, growing awareness of adverse impacts of artificial light at night on scientific astronomy, human health, ecological processes and aesthetic enjoyment of the night sky has led to recognition of light pollution as a significant global environmental issue. Links between economic activity, population growth and artificial light are well documented in rapidly developing regions. Applying a novel method to analysis of satellite images of European nighttime lights over 15 years, we show that while the continental trend is towards increasing brightness, some economically developed regions show more complex patterns with large areas decreasing in observed brightness over this period. This highlights that opportunities exist to constrain and even reduce the environmental impact of artificial light pollution while delivering cost and energy-saving benefits. PMID:24445659

  16. Contrasting trends in light pollution across Europe based on satellite observed night time lights

    NASA Astrophysics Data System (ADS)

    Bennie, Jonathan; Davies, Thomas W.; Duffy, James P.; Inger, Richard; Gaston, Kevin J.

    2014-01-01

    Since the 1970s nighttime satellite images of the Earth from space have provided a striking illustration of the extent of artificial light. Meanwhile, growing awareness of adverse impacts of artificial light at night on scientific astronomy, human health, ecological processes and aesthetic enjoyment of the night sky has led to recognition of light pollution as a significant global environmental issue. Links between economic activity, population growth and artificial light are well documented in rapidly developing regions. Applying a novel method to analysis of satellite images of European nighttime lights over 15 years, we show that while the continental trend is towards increasing brightness, some economically developed regions show more complex patterns with large areas decreasing in observed brightness over this period. This highlights that opportunities exist to constrain and even reduce the environmental impact of artificial light pollution while delivering cost and energy-saving benefits.

  17. Contrasting trends in light pollution across Europe based on satellite observed night time lights

    PubMed Central

    Bennie, Jonathan; Davies, Thomas W.; Duffy, James P.; Inger, Richard; Gaston, Kevin J.

    2014-01-01

    Since the 1970s nighttime satellite images of the Earth from space have provided a striking illustration of the extent of artificial light. Meanwhile, growing awareness of adverse impacts of artificial light at night on scientific astronomy, human health, ecological processes and aesthetic enjoyment of the night sky has led to recognition of light pollution as a significant global environmental issue. Links between economic activity, population growth and artificial light are well documented in rapidly developing regions. Applying a novel method to analysis of satellite images of European nighttime lights over 15 years, we show that while the continental trend is towards increasing brightness, some economically developed regions show more complex patterns with large areas decreasing in observed brightness over this period. This highlights that opportunities exist to constrain and even reduce the environmental impact of artificial light pollution while delivering cost and energy-saving benefits. PMID:24445659

  18. Optomechanics based on angular momentum exchange between light and matter

    NASA Astrophysics Data System (ADS)

    Shi, H.; Bhattacharya, M.

    2016-08-01

    The subject of optomechanics involves interactions between optical and mechanical degrees of freedom, and is currently of great interest as an enabler of fundamental investigations in quantum mechanics, as well as a platform for ultrasensitive measurement devices. The majority of optomechanical configurations rely on the exchange of linear momentum between light and matter. We will begin this tutorial with a brief description of such systems. Subsequently, we will introduce optomechanical systems based on angular momentum exchange. In this context, optical fields carrying polarization and orbital angular momentum will be considered, while for the mechanics, torsional and free rotational motion will be of relevance. Our overall aims will be to supply basic analyses of some of the existing theoretical proposals, to provide functional descriptions of some of the experiments conducted thus far, and to consider some directions for future research. We hope this tutorial will be useful to both theorists and experimentalists interested in the subject.

  19. Directed light fabrication of iron-based materials

    SciTech Connect

    Thoma, D.J.; Charbon, C.; Lewis, G.K.; Nemec, R.B.

    1995-01-01

    Directed light fabrication (DLF) is a process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, 3-dimensional metal components. From a computer generated solid model, deposition ``tool paths`` are constructed that command the laser movement to fabricate near net shape parts a layer at a time. Among potential candidate systems to study, iron-based alloys are particularly attractive for rapid prototyping. To evaluate the processing parameters in the DLF process, studies have been performed on the microstructural development in 1-dimensional and 2-dimensional Fe-based components. For example, continuous microstructural features are evident, implying a continuous liquid/solid interface during processing. In addition, solidification cooling rates have been determined based upon secondary dendrite arm spacings in Fe-25wt. % Ni and 316 stainless steel. Cooling rates vary from 10{sup 1}{minus}10{sup 5} K s{sup {minus}1}, and the solidification behavior has been simulated using macroscopic heat transfer analyses.

  20. Light based anti-infectives: ultraviolet C irradiation, photodynamic therapy, blue light, and beyond

    PubMed Central

    Yin, Rui; Dai, Tianhong; Avci, Pinar; Jorge, Ana Elisa Serafim; de Melo, Wanessa CMA; Vecchio, Daniela; Huang, Ying-Ying; Gupta, Asheesh; Hamblin, Michael R

    2013-01-01

    Owing to the worldwide increase in antibiotic resistance, researchers are investigating alternative anti-infective strategies to which it is supposed microorganisms will be unable to develop resistance. Prominent among these strategies, is a group of approaches which rely on light to deliver the killing blow. As is well known, ultraviolet light, particularly UVC (200–280nm), is germicidal, but it has not been much developed as an anti-infective approach until recently, when it was realized that the possible adverse effects to host tissue were relatively minor compared to its high activity in killing pathogens. Photodynamic therapy is the combination of non-toxic photosensitizing dyes with harmless visible light that together produce abundant destructive reactive oxygen species (ROS). Certain cationic dyes or photosensitizers have good specificity for binding to microbial cells while sparing host mammalian cells and can be used for treating many localized infections, both superficial and even deep-seated by using fiber optic delivered light. Many microbial cells are highly sensitive to killing by blue light (400–470 nm) due to accumulation of naturally occurring photosensitizers such as porphyrins and flavins. Near infrared light has also been shown to have antimicrobial effects against certain species. Clinical applications of these technologies include skin, dental, wound, stomach, nasal, toenail and other infections which are amenable to effective light delivery. PMID:24060701

  1. Enabling a blue-hazard free general lighting based on candle light-style OLED.

    PubMed

    Jou, Jwo-Huei; Kumar, Sudhir; An, Chih-Chia; Singh, Meenu; Yu, Huei-Huan; Hsieh, Chun-Yu; Lin, You-Xing; Sung, Chao-Feng; Wang, Ching-Wu

    2015-06-01

    Increasing studies report blue light to possess a potential hazard to the retina of human eyes, secretion of melatonin and artworks. To devise a human- and artwork-friendly light source and to also trigger a "Lighting Renaissance", we demonstrate here how to enable a quality, blue-hazard free general lighting source on the basis of low color-temperature organic light emitting diodes. With the use of multiple candlelight complementary emitters, the sensationally warm candle light-style emission is proven to be also drivable by electricity. To be energy-saving, highly efficient candle-light emission is demanded. The device shows, at 100 cd m-2 for example, an efficacy of 85.4 lm W-1, an external quantum efficiency of 27.4%, with a 79 spectrum resemblance index and 2,279 K color temperature. The high efficiency may be attributed to the candlelight emitting dyes with a high quantum yield, and the host molecules facilitating an effective host-to-guest energy transfer, as well as effective carrier injection balance. PMID:26072882

  2. Light emitting diode-based nanosecond ultraviolet light source for fluorescence lifetime measurements

    NASA Astrophysics Data System (ADS)

    Araki, Tsutomu; Misawa, Hiroaki

    1995-12-01

    A compact pulsed-light source is devised from an InGaN/AlGaN double heterostructure light-emitting diode (LED). The LED emits a 450-nm (blue) light under conventional dc operation below 30 mA. When a current larger than 50 mA is applied, the intensity of the 450-nm light saturates, but that of the 380-nm light due to the InGaN component continues to increase. This phenomenon is utilized to realize a nanosecond ultraviolet (UV) light source. Under repetitive, large current pulsing (frequency=10 kHz, pulse width=4 ns, peak current=2 A), the peak LED emission shifts from 450 to 380 nm. Intense light pulses (peak value=40 mW) of 4-ns duration were generated. To evaluate the potential of the pulsed LED as an excitation source, the fluorescence lifetime of a quinine-sulfate solution was measured. The observed lifetime characteristics agreed well with the generally accepted behavior.

  3. Light scattering in opal-based photonic crystals

    NASA Astrophysics Data System (ADS)

    Limonov, M. F.

    2010-05-01

    We present a new light scattering pattern in low-contrast opal-based photonic crystals (PhCs). The structure of real opals is always imperfect because of the a-SiO2 particles being inherently inhomogeneous and nonuniform in size and average dielectric permittivity. We found that opals possess all predictable properties of multi-component PhCs, which we define as periodic structures consisting of inhomogeneous or multiple (three or more) components. By theory, by properly tuning the permittivity of one of the components in ordered, low-contrast multi-component PhCs (for instance, of the filler ɛf in an opal), one can produce selective disappearance of any non-resonant (hkl) stop band. A study of transmission spectra of opals revealed that stop bands exhibit different (including resonant) behavior under variation of ɛf. Experiment did not, however, substantiate complete disappearance of stop bands predicted by theory for an ordered PhC. In the region of the predicted disappearance, a new effect has been observed, namely flip-over of the Bragg band, i.e., transformation of the Bragg dip into a Bragg rise. The flip-over effect, which has been studied in considerable detail in the particular example of the (111) stop band, originates from the nonuniformity of a-SiO2 particles. This nonuniformity leads to additional broad-band light scattering, the character of which is determined by Mie scattering. Thus, Mie scattering is responsible for two components in opal transmission spectra, more specifically, narrow Bragg bands and broad-band background. Their interference gives rise to formation of the Fano resonance, which in opal spectra becomes manifest, first, in a Bragg band asymmetry, and, second, in the flip-over effect, i.e., transformation of a photonic stop band into a photonic pass band.

  4. Lifelog-based lighting design for biofied building

    NASA Astrophysics Data System (ADS)

    Kake, Fumika; Mita, Akira

    2016-04-01

    A design tool is proposed for lighting control system that reflects histories of residents' past life using a genetic mechanism. There are many previous researches which show the preference of lighting design differs depending on people and their behaviors. And recently, due to the appearance of LED which can change light color easily, the number of lighting scenes have drastically increased. It is difficult for residents to grasp all patterns of lighting and understand what pattern of lighting design fits for their behaviors. So if we can extract lighting preferences and demands of each resident from histories of past life and reflect these information in next lighting control, it's possible to make living space more comfortable. An evolutionally adaptation mechanism learnt from living organisms is proposed in this research to extract the information from lifelog, especially focusing on methylation and mutation. Methylation is one of the epigenetic algorithms making a difference in phenotype without changing DNA sequence. Mutation is one of the genetic algorithms making a difference in phenotype by changing DNA sequence. Those two mechanisms are applied in the system. First, the lifelog of residents and using hysteresis of lighting equipment are collected. Then the lifelog is converted into the genetic information and stored. When the lifelog is stored enough, the superior genes will be picked up from the stored genetic information to be reflected in lighting control in next generation. Simulations to verify the versatility of the system were conducted.

  5. High light extraction efficiency in bulk-GaN based volumetric violet light-emitting diodes

    SciTech Connect

    David, Aurelien Hurni, Christophe A.; Aldaz, Rafael I.; Cich, Michael J.; Ellis, Bryan; Huang, Kevin; Steranka, Frank M.; Krames, Michael R.

    2014-12-08

    We report on the light extraction efficiency of III-Nitride violet light-emitting diodes with a volumetric flip-chip architecture. We introduce an accurate optical model to account for light extraction. We fabricate a series of devices with varying optical configurations and fit their measured performance with our model. We show the importance of second-order optical effects like photon recycling and residual surface roughness to account for data. We conclude that our devices reach an extraction efficiency of 89%.

  6. Beam-based Feedback for the Linac Coherent Light Source

    SciTech Connect

    Fairley, D.; Allison, S.; Chevtsov, S.; Chu, P.; Decker, F.J.; Emma, P.; Frisch, J.; Himel, T.; Kim, K.; Krejcik, P.; Loos, H.; Lahey, T.; Natampalli, P.; Peng, S.; Rogind, D.; Shoaee, H.; Straumann, T.; Williams, E.; White, G.; Wu, J.; Zelazney, M.; /SLAC

    2010-02-11

    Beam-based feedback control loops are required by the Linac Coherent Light Source (LCLS) program in order to provide fast, single-pulse stabilization of beam parameters. Eight transverse feedback loops, a 6 x 6 longitudinal feedback loop, and a loop to maintain the electron bunch charge were successfully prototyped in MATLAB for the LCLS, and have been maintaining stability of the LCLS electron beam at beam rates up to 30Hz. In the final commissioning phase of LCLS the beam will be operating at up to 120Hz. In order to run the feedback loops at beam rate, the feedback loops will be implemented in EPICS IOCs with a dedicated ethernet multi-cast network. This paper will discuss the design of the beam-based Fast Feedback System for LCLS. Topics include MATLAB feedback prototyping, algorithm for 120Hz feedback, network design for fast data transport, actuator and sensor design for single-pulse control and sensor readback, and feedback configuration and runtime control.

  7. Light-Harvesting Antennae Based on Silicon Nanocrystals.

    PubMed

    Romano, Francesco; Yu, Yixuan; Korgel, Brian A; Bergamini, Giacomo; Ceroni, Paola

    2016-08-01

    Silicon (Si) nanocrystals are relatively strong light emitters, but are weak light absorbers as a result of their indirect band gap. One way to enhance light absorption is to functionalize the nanocrystals with chromophores that are strong light absorbers. By designing systems that enable efficient energy transfer from the chromophore to the Si nanocrystal, the brightness of the nanocrystals can be significantly increased. There have now been a few experimental systems in which covalent attachment of chromophores, efficient energy transfer and significantly increased brightness have been demonstrated. This review discusses progress on these systems and the remaining challenges. PMID:27573405

  8. Lighting

    SciTech Connect

    Audin, L.

    1994-12-31

    EPAct covers a vast territory beyond lighting and, like all legislation, also contains numerous {open_quotes}favors,{close_quotes} compromises, and even some sleight-of-hand. Tucked away under Title XIX, for example, is an increase from 20% to 28% tax on gambling winnings, effective January 1, 1993 - apparently as a way to help pay for new spending listed elsewhere in the bill. Overall, it is a landmark piece of legislation, about a decade overdue. It remains to be seen how the Federal Government will enforce upgrading of state (or even their own) energy codes. There is no mention of funding for {open_quotes}energy police{close_quotes} in EPAct. Merely creating such a national standard, however, provides a target for those who sincerely wish to create an energy-efficient future.

  9. Light Pollution: A Threat to Ground-based Astronomy

    NASA Astrophysics Data System (ADS)

    Davis, D. R.

    1999-09-01

    Light pollution that accompanies population growth has reduced the effectiveness of several world class observing sites and threatens most others in the world. Recent decades have seen an activist approach to dealing with light pollution issues, led by a few members of the astronomical community. The principal tool for combating light pollution is the local outdoor lighting ordinance designed to protect dark skies by requiring some combination of: a) shielding outdoor lighting so that none of the light is emitted above the horizontal plane, 2) encouraging the use of "astronomy friendly" light sources such as low pressure sodium, and 3) limiting the total amount of outdoor light that is produced. Such measures have been effective in the past, however, in some areas, development is rapidly moving close to world-class observatories; the Canoa Ranch development near Mt. Hopkins in southern Arizona is the most recent highly visible example. More effective measures are needed to protect existing sites in the future. The astronomical community needs to become more aware of the increasing threat to many prime observing sites and become more active in developing effective programs for preserving the dark sky. This is needed not only for the benefit of our profession but also for preserving the heritage of the night sky for future generations.

  10. Glass-based confined structures enabling light control

    SciTech Connect

    Chiappini, Andrea; Normani, Simone; Chiasera, Alessandro; Vasilchenko, Iustyna; Ristic, Davor; Boulard, Brigitte; Dorosz, Dominik; Scotognella, Francesco; Vaccari, Alessandro; Taccheo, Stefano; Pelli, Stefano; Righini, Giancarlo C.; Conti, Gualtiero Nunzi; Ramponi, Roberta; and others

    2015-04-24

    When a luminescent ion is confined in a system characterized by one or more specific properties such as spatial size, geometrical dimension and shape, refractive index, local crystal field, cut-off vibrational energy and so on, it's possible to control its emission. The control of branching ratios as a function of the composition, the luminescence enhancement induced by a photonic crystal, or the laser action in a microresonator, are well known examples of light control. Photonic glass-based structures are extremely viable systems to exploit the above mentioned properties and in our research team we have successfully fabricated luminescent photonic structures by different techniques, including sol-gel, rf sputtering, drawing, melting, and physical vapour deposition. Here we will discuss some of them with the aim to make the reader aware of the chemical-physical properties related to each specific system. We will demonstrate that glass ceramic waveguides in some cases present superior spectroscopic properties in respect to the parent glass, that compositional properties can play a positive role in reducing luminescence quenching and in developing novel planar waveguides and fibers, that colloids allow to obtain high internal quantum efficiency and that photonic crystals, microcavities and microresonators can enable the handling of the rare earth luminescence. Finally, the pros and cons of the systems and of the different techniques employed for their fabrication will be discussed and some perspectives concerning the glass photonics will be proposed looking at both possible applications and investigation of physical properties.

  11. Scheduling for indoor visible light communication based on graph theory.

    PubMed

    Tao, Yuyang; Liang, Xiao; Wang, Jiaheng; Zhao, Chunming

    2015-02-01

    Visible light communication (VLC) has drawn much attention in the field of high-rate indoor wireless communication. While most existing works focused on point-to-point VLC technologies, few studies have concerned multiuser VLC, where multiple optical access points (APs) transmit data to multiple user receivers. In such scenarios, inter-user interference constitutes the major factor limiting the system performance. Therefore, a proper scheduling scheme has to be proposed to coordinate the interference and optimize the whole system performance. In this work, we aim to maximize the sum rate of the system while taking into account user fairness by appropriately assigning LED lamps to multiple users. The formulated scheduling problem turns out to be a maximum weighted independent set problem. We then propose a novel and efficient resource allocation method based on graph theory to achieve high sum rates. Moreover, we also introduce proportional fairness into our scheduling scheme to ensure the user fairness. Our proposed scheduling scheme can, with low complexity, achieve more multiplexing gains, higher sum rate, and better fairness than the existing works. PMID:25836136

  12. Structured Light-Based 3D Reconstruction System for Plants

    PubMed Central

    Nguyen, Thuy Tuong; Slaughter, David C.; Max, Nelson; Maloof, Julin N.; Sinha, Neelima

    2015-01-01

    Camera-based 3D reconstruction of physical objects is one of the most popular computer vision trends in recent years. Many systems have been built to model different real-world subjects, but there is lack of a completely robust system for plants.This paper presents a full 3D reconstruction system that incorporates both hardware structures (including the proposed structured light system to enhance textures on object surfaces) and software algorithms (including the proposed 3D point cloud registration and plant feature measurement). This paper demonstrates the ability to produce 3D models of whole plants created from multiple pairs of stereo images taken at different viewing angles, without the need to destructively cut away any parts of a plant. The ability to accurately predict phenotyping features, such as the number of leaves, plant height, leaf size and internode distances, is also demonstrated. Experimental results show that, for plants having a range of leaf sizes and a distance between leaves appropriate for the hardware design, the algorithms successfully predict phenotyping features in the target crops, with a recall of 0.97 and a precision of 0.89 for leaf detection and less than a 13-mm error for plant size, leaf size and internode distance. PMID:26230701

  13. GPGPU-based surface inspection from structured white light

    NASA Astrophysics Data System (ADS)

    Bordallo López, Miguel; Niemelä, Karri; Silvén, Olli

    2012-03-01

    Automatic surface inspection has been used in the industry to reliably detect all kinds of surface defects and to measure the overall quality of a produced piece. Structured light systems (SLS) are based on the reconstruction of the 3D information of a selected area by projecting several phase-shifted sinusoidal patterns onto a surface. Due to the high speed of production lines, surface inspection systems require extremely fast imaging methods and lots of computational power. The cost of such systems can easily become considerable. The use of standard PCs and Graphics Processing Units (GPUs) for data processing tasks facilitates the construction of cost-effective systems. We present a parallel implementation of the required algorithms written in C with CUDA extensions. In our contribution, we describe the challenges of the design on a GPU, compared with a traditional CPU implementation. We provide a qualitative evaluation of the results and a comparison of the algorithm speed performance on several platforms. The system is able to compute two megapixels height maps with 100 micrometers spatial resolution in less than 200ms on a mid-budget laptop. Our GPU implementation runs about ten times faster than our previous C code implementation.

  14. Structured Light-Based 3D Reconstruction System for Plants.

    PubMed

    Nguyen, Thuy Tuong; Slaughter, David C; Max, Nelson; Maloof, Julin N; Sinha, Neelima

    2015-01-01

    Camera-based 3D reconstruction of physical objects is one of the most popular computer vision trends in recent years. Many systems have been built to model different real-world subjects, but there is lack of a completely robust system for plants. This paper presents a full 3D reconstruction system that incorporates both hardware structures (including the proposed structured light system to enhance textures on object surfaces) and software algorithms (including the proposed 3D point cloud registration and plant feature measurement). This paper demonstrates the ability to produce 3D models of whole plants created from multiple pairs of stereo images taken at different viewing angles, without the need to destructively cut away any parts of a plant. The ability to accurately predict phenotyping features, such as the number of leaves, plant height, leaf size and internode distances, is also demonstrated. Experimental results show that, for plants having a range of leaf sizes and a distance between leaves appropriate for the hardware design, the algorithms successfully predict phenotyping features in the target crops, with a recall of 0.97 and a precision of 0.89 for leaf detection and less than a 13-mm error for plant size, leaf size and internode distance. PMID:26230701

  15. Glass-based confined structures enabling light control

    NASA Astrophysics Data System (ADS)

    Chiappini, Andrea; Lukowiak, Anna; Vasilchenko, Iustyna; Ristic, Davor; Normani, Simone; Chiasera, Alessandro; Boulard, Brigitte; Dorosz, Dominik; Scotognella, Francesco; Vaccari, Alessandro; Taccheo, Stefano; Pelli, Stefano; Conti, Gualtiero Nunzi; Ramponi, Roberta; Righini, Giancarlo C.; Gonçalves, Rogeria R.; Rahman, M. Kamil Abd; Ferrari, Maurizio

    2015-04-01

    When a luminescent ion is confined in a system characterized by one or more specific properties such as spatial size, geometrical dimension and shape, refractive index, local crystal field, cut-off vibrational energy and so on, it's possible to control its emission. The control of branching ratios as a function of the composition, the luminescence enhancement induced by a photonic crystal, or the laser action in a microresonator, are well known examples of light control. Photonic glass-based structures are extremely viable systems to exploit the above mentioned properties and in our research team we have successfully fabricated luminescent photonic structures by different techniques, including sol-gel, rf sputtering, drawing, melting, and physical vapour deposition. Here we will discuss some of them with the aim to make the reader aware of the chemical-physical properties related to each specific system. We will demonstrate that glass ceramic waveguides in some cases present superior spectroscopic properties in respect to the parent glass, that compositional properties can play a positive role in reducing luminescence quenching and in developing novel planar waveguides and fibers, that colloids allow to obtain high internal quantum efficiency and that photonic crystals, microcavities and microresonators can enable the handling of the rare earth luminescence. Finally, the pros and cons of the systems and of the different techniques employed for their fabrication will be discussed and some perspectives concerning the glass photonics will be proposed looking at both possible applications and investigation of physical properties.

  16. Dynamic Light Scattering Based Microelectrophoresis: Main Prospects and Limitations

    PubMed Central

    Uskoković, Vuk

    2013-01-01

    Microelectrophoresis based on the dynamic light scattering (DLS) effect has been a major tool for assessing and controlling the conditions for stability of colloidal systems. However, both the DLS methods for characterization of the hydrodynamic size of dispersed submicron particles and the theory behind the electrokinetic phenomena are associated with fundamental and practical approximations that limit their sensitivity and information output. Some of these fundamental limitations, including the spherical approximation of DLS measurements and an inability of microelectrophoretic analyses of colloidal systems to detect discrete charges and differ between differently charged particle surfaces due to rotational diffusion and particle orientation averaging, are revisited in this work. Along with that, the main prospects of these two analytical methods are mentioned. A detailed review of the role of zeta potential in processes of biochemical nature is given too. It is argued that although zeta potential has been used as one of the main parameters in controlling the stability of colloidal dispersions, its application potentials are much broader. Manipulating surface charges of interacting species in designing complex soft matter morphologies using the concept of zeta potential, intensively investigated recently, is given as one of the examples. Branching out from the field of colloid chemistry, DLS and zeta potential analyses are now increasingly finding application in drug delivery, biotechnologies, physical chemistry of nanoscale phenomena and other research fields that stand on the frontier of the contemporary science. Coupling the DLS-based microelectrophoretic systems with complementary characterization methods is mentioned as one of the prosperous paths for increasing the information output of these two analytical techniques. PMID:23904690

  17. A low-cost low-maintenance ultraviolet lithography light source based on light-emitting diodes.

    PubMed

    Erickstad, M; Gutierrez, E; Groisman, A

    2015-01-01

    A source of collimated ultraviolet (UV) light is a central piece of equipment needed for lithographic fabrication of microfluidic devices. Conventional UV light sources based on high-pressure mercury lamps require considerable maintenance and provide broad-band illumination with intensity that often changes with time. Here we present a source of narrow-band UV light based on an array of nine 365 nm light-emitting diodes (LEDs). Each LED has two dedicated converging lenses, reducing the divergence of light emanating from it to 5.4°. Partial overlap of the areas illuminated by individual LEDs provides UV illumination with a mean intensity of ~1.7 mW cm(-2) and coefficient of variation <3% over a 90 × 90 mm target area. The light source was used to lithographically fabricate micro-reliefs with thicknesses from ~25 to 311 μm with SU8 photoresists. A cumulative irradiation of 370 mJ cm(-2) (4 min exposure) produced reliefs of good quality for all SU8 thicknesses. Polydimethylsiloxane (PDMS) replicas of the SU8 reliefs had microchannels with nearly rectangular cross-sections that were highly consistent over the entire target area, and partitions between the channels had depth to width ratios up to 5. The UV light source has also been successfully used for photolithography with positive photoresists, AZ40XT and SPR-220. The proposed light source is built with a total cost of <$1000, consumes a minimal amount of power, is expected to last for ~50,000 exposures, is maintenance-free, and is particularly appealing for small research-and-development microfluidic fabrication. PMID:25322205

  18. Modulation based cells distribution for visible light communication.

    PubMed

    Wu, Yongsheng; Yang, Aiying; Feng, Lihui; Zuo, Lin; Sun, Yu-Nan

    2012-10-22

    Cells distribution for visible light communication can enhance the capacity of the data transmission by the reuse of optical spectrum. In this paper, we adopt three modulation formats as OOK, PPM and PWM for neighboring cells A, B and C respectively. The prototype experiment results demonstrate the error free transmission of 1.0 Mbit/s and 6.25 Mbit/s visible light communication system with our scheme. With the available LED, we can expect that the data rate of a visible light communication system with seamless connectivity can be up to 71.4 Mbit/s. PMID:23187182

  19. Carbonitride based phosphors and light emitting devices using the same

    DOEpatents

    Li, Yuanqiang; Tian, Yongchi; Romanelli, Michael Dennis

    2013-08-20

    Disclosed herein is a novel group of carbidonitride phosphors and light emitting devices which utilize these phosphors. In certain embodiments, the present invention is directed to a novel family of carbidonitride-based phosphors expressed as follows: Ca.sub.1-xAl.sub.x-xySi.sub.1-x+xyN.sub.2-x-xyC.sub.xy:A; (1) Ca.sub.1-x-zNa.sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xyC.sub.xy:- A; (2) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x- -xyC.sub.xy:A; (3) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w/- 3C.sub.xyO.sub.w-v/2H.sub.v:A; and (4) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w/- 3-v/3C.sub.xyO.sub.wH.sub.v:A, (4a) wherein 0xy+z, and 0

  20. Three-dimension reconstruction based on spatial light modulator

    NASA Astrophysics Data System (ADS)

    Deng, Xuejiao; Zhang, Nanyang; Zeng, Yanan; Yin, Shiliang; Wang, Weiyu

    2011-02-01

    Three-dimension reconstruction, known as an important research direction of computer graphics, is widely used in the related field such as industrial design and manufacture, construction, aerospace, biology and so on. Via such technology we can obtain three-dimension digital point cloud from a two-dimension image, and then simulate the three-dimensional structure of the physical object for further study. At present, the obtaining of three-dimension digital point cloud data is mainly based on the adaptive optics system with Shack-Hartmann sensor and phase-shifting digital holography. Referring to surface fitting, there are also many available methods such as iterated discrete fourier transform, convolution and image interpolation, linear phase retrieval. The main problems we came across in three-dimension reconstruction are the extraction of feature points and arithmetic of curve fitting. To solve such problems, we can, first of all, calculate the relevant surface normal vector information of each pixel in the light source coordinate system, then these vectors are to be converted to the coordinates of image through the coordinate conversion, so the expectant 3D point cloud get arise. Secondly, after the following procedures of de-noising, repairing, the feature points can later be selected and fitted to get the fitting function of the surface topography by means of Zernike polynomial, so as to reconstruct the determinand's three-dimensional topography. In this paper, a new kind of three-dimension reconstruction algorithm is proposed, with the assistance of which, the topography can be estimated from its grayscale at different sample points. Moreover, the previous stimulation and the experimental results prove that the new algorithm has a strong capability to fit, especially for large-scale objects .

  1. LED-based endoscopic light source for spectral imaging

    NASA Astrophysics Data System (ADS)

    Browning, Craig M.; Mayes, Samuel; Favreau, Peter; Rich, Thomas C.; Leavesley, Silas J.

    2016-03-01

    Colorectal cancer is the United States 3rd leading cancer in death rates.1 The current screening for colorectal cancer is an endoscopic procedure using white light endoscopy (WLE). There are multiple new methods testing to replace WLE, for example narrow band imaging and autofluorescence imaging.2 However, these methods do not meet the need for a higher specificity or sensitivity. The goal for this project is to modify the presently used endoscope light source to house 16 narrow wavelength LEDs for spectral imaging in real time while increasing sensitivity and specificity. The process to do such was to take an Olympus CLK-4 light source, replace the light and electronics with 16 LEDs and new circuitry. This allows control of the power and intensity of the LEDs. This required a larger enclosure to house a bracket system for the solid light guide (lightpipe), three new circuit boards, a power source and National Instruments hardware/software for computer control. The results were a successfully designed retrofit with all the new features. The LED testing resulted in the ability to control each wavelength's intensity. The measured intensity over the voltage range will provide the information needed to couple the camera for imaging. Overall the project was successful; the modifications to the light source added the controllable LEDs. This brings the research one step closer to the main goal of spectral imaging for early detection of colorectal cancer. Future goals will be to connect the camera and test the imaging process.

  2. Yttrium oxide based three dimensional metamaterials for visible light cloaking

    NASA Astrophysics Data System (ADS)

    Rai, Pratyush; Kumar, Prashanth S.; Varadan, Vijay K.; Ruffin, Paul; Brantley, Christina; Edwards, Eugene

    2014-04-01

    Metamaterial with negative refractive index is the key phenomenon behind the concept of a cloaking device to hide an object from light in visible spectrum. Metamaterials made of two and three dimensional lattices of periodically placed electromagnetic resonant cells can achieve absorption and propagation of incident electromagnetic radiation as confined electromagnetic fields confined to a waveguide as surface plasmon polaritons, which can be used for shielding an object from in-tune electromagnetic radiation. The periodicity and dimensions of resonant cavity determine the frequency, which are very small as compared to the wavelength of incident light. Till now the phenomena have been demonstrated only for lights in near infrared spectrum. Recent advancements in fabrication techniques have made it possible to fabricate array of three dimensional nanostructures with cross-sections as small as 25 nm that are required for negative refractive index for wavelengths in visible light spectrum of 400-700 nm and for wider view angle. Two types of metamaterial designs, three dimensional concentric split ring and fishnet, are considered. Three dimensional structures consisted of metal-dielectric-metal stacks. The metal is silver and dielectric is yttrium oxide, other than conventional materials such as FR4 and Duroid. High κ dielectric and high refractive index as well as large crystal symmetry of Yttrium oxide has been investigated as encapsulating medium. Dependence of refractive index on wavelength and bandwidth of negative refractive index region are analyzed for application towards cloaking from light in visible spectrum.

  3. Gold Nanorods Based Platforms for Light-Mediated Theranostics

    PubMed Central

    Zhang, Zhenjiang; Wang, Jing; Chen, Chunying

    2013-01-01

    Due to their tunable surface plasmon and photothermal effects, gold nanorods (AuNRs) have proved to be promising in a wide range of biomedical applications such as imaging, hyperthermia therapy and drug delivery. All these applications can be remotely controlled by near infrared (NIR) light which can penetrate deep into human tissues with minimal lateral invasion. AuNRs thus hold the potential to combine both imaging diagnosis and therapeutic treatment into one single system and function as a NIR light-mediated theranostic platform. Herein we review recent progress in diagnostic and therapeutic applications of AuNRs with a highlight on combined applications for theranostic purposes. PMID:23471510

  4. Photo-actuating waveguiding fibers based on light responsive hydrogels

    NASA Astrophysics Data System (ADS)

    Zhou, Ying; Hauser, Adam; Rasmussen, Nathan; Kuzyk, Mark; Hayward, Ryan

    2015-03-01

    The combination of light-absorbing nanoparticles with thermally sensitive hydrogels has been widely explored as a strategy for photo-thermal actuation. Here, we employ a system of photo-crosslinkable copolymers containing pendent benzophenone units to prepare planar waveguiding polymethylmethacrylate(PMMA) fibers patterned with poly(N-isopropyl acrylamide) (PNIPAM) copolymer hydrogels containing Au nanoparticles. These structures show both thermally- and photo-actuated bending behavior due to swelling stresses developed in the PNIPAM gel layer. Further, we establish that light can be successfully guided into micro-patterned fibers, yielding a route to remotely controlled micro-actuators.

  5. Preliminary study for improving the VIIRS DNB low light calibration accuracy with ground based active light source

    NASA Astrophysics Data System (ADS)

    Cao, Changyong; Zong, Yuqing; Bai, Yan; Shao, Xi

    2015-09-01

    There is a growing interest in the science and user community in the Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) low light detection capabilities at night for quantitative applications such as airglow, geophysical retrievals under lunar illumination, light power estimation, search and rescue, energy use, urban expansion and other human activities. Given the growing interest in the use of the DNB data, a pressing need arises for improving the calibration stability and absolute accuracy of the DNB at low radiances. Currently the low light calibration accuracy was estimated at a moderate 15%-100% while the long-term stability has yet to be characterized. This study investigates selected existing night light point sources from Suomi NPP DNB observations and evaluates the feasibility of SI traceable nightlight source at radiance levels near 3 nW·cm-2·sr-1, that potentially can be installed at selected sites for VIIRS DNB calibration/validation. The illumination geometry, surrounding environment, as well as atmospheric effects are also discussed. The uncertainties of the ground based light source are estimated. This study will contribute to the understanding of how the Earth's atmosphere and surface variability contribute to the stability of the DNB measured radiances, and how to separate them from instrument calibration stability. It presents the need for SI traceable active light sources to monitor the calibration stability, radiometric and geolocation accuracy, and point spread functions of the DNB. Finally, it is also hoped to address whether or not active light sources can be used for detecting environmental changes, such as aerosols.

  6. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2016-07-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  7. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2015-11-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  8. Photonic crystal fibre-based light source for STED lithography

    SciTech Connect

    Glubokov, D A; Sychev, V V; Vitukhnovsky, Alexey G; Korol'kov, A E

    2013-06-30

    A light source having a relative noise level in the order of 10{sup -6} and sufficient stability for application in STED lithography has been obtained using the generation of Cherenkov peaks in a supercontinuum spectrum. (laser applications and other topics in quantum electronics)

  9. Nanocluster-based white-light-emitting material employing surface tuning

    DOEpatents

    Wilcoxon, Jess P.; Abrams, Billie L.; Thoma, Steven G.

    2007-06-26

    A method for making a nanocrystal-based material capable of emitting light over a sufficiently broad spectral range to appear white. Surface-modifying ligands are used to shift and broaden the emission of semiconductor nanocrystals to produce nanoparticle-based materials that emit white light.

  10. Using an ethernet based relay to remotely control lights at CFHT

    NASA Astrophysics Data System (ADS)

    Barrick, Gregory

    2011-03-01

    Prior to observatory automation, all the lights at the summit were controlled using local light switches. Lights that were inadvertently left on during the day that impact observing can previously could be turned off by the night staff. Likewise, the night staff could turn on lights as needed for troubleshooting. Remote observing will make this impossible. The use of WebRelays provided a means for remotely turning on or off critical lights as needed. WebRelays are an Ethernet based relay that can be controlled either using network commands or by supplying voltage to an optically isolated input on the WebRelay.

  11. Cell light scattering characteristic research based on FDTD algorithm

    NASA Astrophysics Data System (ADS)

    Lin, Xiaogang; Zhu, Hao; Li, Wenchao; Ye, Changbin

    2015-10-01

    As with the number of cancer increases year by year, so it is important to be found and treated earlier. With biological cells and tissues are sensitive to infrared and visible light, cell morphology and physical structure of the optical properties can easily obtain, we can provide theoretical basis for the early diagnosis of cancer by observing the difference of optical properties between normal and cancerous cells. Compared with Mie scattering theory, finite difference time domain (FDTD) algorithm can analyze any complex structure model. In this paper we use mathematical modeling method to establish the single cell mathematical model and with finite difference time domain algorithm to simulate the propagation and scattering of light in the biological cells, you can calculate the scattering of electromagnetic field distribution at anytime and anywhere. With radar cross section (RCS) to measure the results of the scattering characteristics. Due to the difference between normal cells and cancerous cells are embodied in cell shape, size and the refractive index, through the simulation we can get different cell parameters of light scattering information, Find out the cell parameters change the changing rule of the influence on the scattering characteristics and find out change regularity of scattering characteristics. These data can judge very accurate of the cells is normal or cancerous cells.

  12. White organic light-emitting diodes based on tandem structures

    NASA Astrophysics Data System (ADS)

    Guo, Fawen; Ma, Dongge

    2005-10-01

    White organic light-emitting diodes made of two electroluminescent (EL) units connected by a charge generation layer were fabricated. Thus, with a tandem structure of indium tin oxide/N ,N'-di(naphthalene-1-yl)-N ,N'-diphenyl-benzidine (NPB)/9,10-bis-(β-naphthyl)-anthrene (ADN)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(8-hydroxyquinoline) aluminum (Alq3)/BCP:Li/V2O5/NPB/Alq3:4-(dicyanomethylene)-2-t-butyle-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)4H-pyran (DCJTB)/Alq3/LiF/Al, a stable white light with Commission Internationale De L'Eclairage chromaticity coordinates from (0.35, 0.32) at 18V to (0.36, 0.36) at 50V was generated. It was clearly seen that the EL spectra consist of red band at 600nm due to DCJTB, green band at 505nm due to Alq3, and blue band at 435nm due to ADN, and the current efficiency and brightness equal basically to the sum of the two EL units. As a result, the tandem devices showed white light emission with a maximum brightness of 10200cd /m2 at a bias of 40V and a maximum current efficiency of 10.7cd/A at a current density of 3.5mA/cm2.

  13. LiteVis: Integrated Visualization for Simulation-Based Decision Support in Lighting Design.

    PubMed

    Sorger, Johannes; Ortner, Thomas; Luksch, Christian; Schwärzler, Michael; Gröller, Eduard; Piringer, Harald

    2016-01-01

    State-of-the-art lighting design is based on physically accurate lighting simulations of scenes such as offices. The simulation results support lighting designers in the creation of lighting configurations, which must meet contradicting customer objectives regarding quality and price while conforming to industry standards. However, current tools for lighting design impede rapid feedback cycles. On the one side, they decouple analysis and simulation specification. On the other side, they lack capabilities for a detailed comparison of multiple configurations. The primary contribution of this paper is a design study of LiteVis, a system for efficient decision support in lighting design. LiteVis tightly integrates global illumination-based lighting simulation, a spatial representation of the scene, and non-spatial visualizations of parameters and result indicators. This enables an efficient iterative cycle of simulation parametrization and analysis. Specifically, a novel visualization supports decision making by ranking simulated lighting configurations with regard to a weight-based prioritization of objectives that considers both spatial and non-spatial characteristics. In the spatial domain, novel concepts support a detailed comparison of illumination scenarios. We demonstrate LiteVis using a real-world use case and report qualitative feedback of lighting designers. This feedback indicates that LiteVis successfully supports lighting designers to achieve key tasks more efficiently and with greater certainty. PMID:26529708

  14. Multifocal multiphoton microscopy based on a spatial light modulator

    PubMed Central

    Shao, Y.; Qin, W.; Liu, H.; Peng, X.; Niu, H.

    2013-01-01

    We present a new multifocal multiphoton microscope that employs a programmable spatial light modulator to generate dynamic multifocus arrays which can be rapidly scanned by changing the incident angle of the laser beam using a pair of galvo scanners. Using this microscope, we can rapidly select the number and the spatial density of focal points in a multifocus array, as well as the locations and shapes of arrays according to the features of the areas of interest in the field of view without any change to the hardware. PMID:23894222

  15. Metal Organic Vapor Phase Epitaxy of Monolithic Two-Color Light-Emitting Diodes Using an InGaN-Based Light Converter

    NASA Astrophysics Data System (ADS)

    Damilano, Benjamin; Kim-Chauveau, Hyonju; Frayssinet, Eric; Brault, Julien; Hussain, Sakhawat; Lekhal, Kaddour; Vennéguès, Philippe; De Mierry, Philippe; Massies, Jean

    2013-09-01

    Monolithic InGaN-based light-emitting diodes (LEDs) using a light converter fully grown by metal organic vapor phase epitaxy are demonstrated. The light converter, consisting of 10-40 InGaN/GaN quantum wells, is grown first, followed by a violet pump LED. The structure and growth conditions of the pump LED are specifically adapted to avoid thermal degradation of the light converter. Electroluminescence analysis shows that part of the pump light is absorbed by the light converter and reemitted at longer wavelength. Depending on the emission wavelength of the light converter, different LED colors are achieved. In particular, for red-emitting light converters, a color temperature of 2100 K corresponding to a tint between warm white and candle light is demonstrated.

  16. Ejecta from Hypervelocity Dust Impacts Based on Light Flash Measurements

    NASA Astrophysics Data System (ADS)

    Drake, Keith; Sternovsky, Z.; Horányi, M.; Kempf, S.; Srama, R.

    2013-10-01

    Ejecta from hypervelocity dust impacts have been shown to depend on the impinging particles’ velocity, mass, composition, etc. (J. Friichtenicht 1965, G. Eichhorn 1976). Ejecta is thought to be responsible for developing rings and dusty atmospheres of moons throughout the solar system. In order for rings to be produced, dust velocities must be greater than the moon’s escape speed. To understand the dust impact yield; impact ejecta parameters (velocities, masses, angular distributions) must be well understood. Laboratory experiments provide direct information about the ejecta production rates and impactor fluxes. Using hypervelocity (1-60km/s) iron dust at the University of Colorado dust accelerator in Boulder, Colorado we measured the time characteristics and intensities of light flashes produced on a quartz disc from primary and secondary impacts. The flashes were measured with a photomultiplier tube at varying distances and angles. By analyzing the light flashes produced by such impacts we show that this method is a viable technique for measuring these parameters. These measurements provide detailed information about the secondary mass and velocity profiles, leading to insights into the formation of dusty rings and atmospheres.

  17. Light-triggered thermoelectric conversion based on a carbon nanotube-polymer hybrid gel.

    PubMed

    Miyako, Eijiro; Nagata, Hideya; Funahashi, Ryoji; Hirano, Ken; Hirotsu, Takahiro

    2009-01-01

    Lights? Nanotubes? Action! A hydrogel comprising lysozymes, poly(ethylene glycol), phospholipids, and functionalized single-walled carbon nanotubes is employed for light-driven thermoelectric conversion. A photoinduced thermoelectric conversion module based on the hydrogel functions as a novel electric power generator (see image). This concept may find application in various industries, such as robotics and aerospace engineering. PMID:19455558

  18. Visible light responsive systems based on metastable-state photoacids

    NASA Astrophysics Data System (ADS)

    Liao, Yi

    2015-09-01

    Proton transfer is one of the most fundamental processes in nature. Metastable-state photoacids can reversibly generate a large proton concentration under visible light with moderate intensity. which provides a general approach to control various proton transfer processes. Several applications of mPAHs have been demonstrated recently including control of acid-catalyzed reactions, volume-change of hydrogels, polymer conductivity, bacteria killing, odorant release, and color change of materials. They have also been utilized to control supramolecular assemblies, molecular switches, microbial fuel cells and cationic sensors. In this talk, the mechanism, structure design, and applications of metastable-state photoacids are introduced. Recent development of different types of metastable-state photoacids is presented. Challenges and future work are also discussed.

  19. Multilayer light emitting diodes using a PPV based copolymer

    NASA Astrophysics Data System (ADS)

    Nguyen, T. P.; Chen, L. C.; Wang, X.; Huang, Z.

    1998-01-01

    We have investigated the electrical and optical properties of poly((2,5-(dimethoxy) p-phenylene vinylene)- p-phenylene vinylene) (PDMeOPV/PPV) copolymer used as an emitting layer in light emitting diodes. With p-phenylene vinylene (PPV) used as a hole transport layer and polyphenylquinoxaline (PPQ) as an electron transport layer, the emission intensity of the devices has substantially increased without alteration of the transport property. The different conduction mechanisms in the diodes were examined and discussed in terms of the energy band diagrams of the polymer layers. A balance of the injected charge carriers confined in the copolymer could explain the enhancement of the performance of the multilayer diodes.

  20. Automultiscopic displays based on orbital angular momentum of light

    NASA Astrophysics Data System (ADS)

    Li, Xuefeng; Chu, Jiaqi; Smithwick, Quinn; Chu, Daping

    2016-08-01

    Orbital angular momentum (OAM) of light has drawn increasing attention due to its intriguingly rich physics and potential for a variety of applications. Having an unbounded set of orthogonal states, OAM has been used to enhance the channel capacity of data transmission. We propose and demonstrate the viability of using OAM to create an automultiscopic 3D display. Multi-view image information is encoded using an OAM beam array, then sorted into different view directions using coordinate transformation elements. A three-view demonstration was achieved to encode and decode 9 × 9 pixel images. These demonstrations suggest that OAM could potentially serve as an additional platform for future 3D display systems.

  1. Synthesis of quinoline based heterocyclic compounds for blue lighting application

    NASA Astrophysics Data System (ADS)

    Kumar, Vinod; Gohain, Mukut; Van Tonder, Johannes H.; Ponra, S.; Bezuindenhoudt, B. C. B.; Ntwaeaborwa, O. M.; Swart, H. C.

    2015-12-01

    2,4-Diphenylquinoline (DPQ), derivatives 6-chloro-2,4-diphenylquinoline (DPQ-Cl) and 4‧,6-dichloro-2,4-diphenylquinoline (DPQ-Cl2) were synthesized using a three-component domino reaction. The DPQ, DPQ-Cl and DPQ-Cl2 were characterized by nuclear magnetic resonance spectroscopy, scanning electron microscopy, thermogravimetric analysis (TGA). Fourier transformed infra-red spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy. The TGA results showed that the DPQ was more thermally stable with respect to the DPQ-Cl and DPQ-Cl2. The synthesized organic phosphors showed bright emission in the blue region under an UV excitation wavelength of 325 nm with the power of 18 mW. These organic phosphors were found to be efficient candidate and may be used in organic blue light emitting devices.

  2. Characterizing Scitillation and Cherenkov Light Yield in Water-Based Liquid Scintillators

    NASA Astrophysics Data System (ADS)

    Land, B. J.; Caravaca, J.; Descamps, F. B.; Orebi Gann, G. D.

    2016-03-01

    The recent development of Water-based Liquid Scintillator (WbLS) has made it possible to produce scintillating materials with highly tunable light yields and excellent optical clarity. This allows for a straightforward combination of the directional properties of Cherenkov light with the greater energy resolution afforded by the typically brighter scintillation light, which lends itself well to a broad program of neutrino physics. Here we explore the light yields and optical properties of WbLS materials in development for Theia (formerly ASDC) as measured in our benchtop Theia R&D at Berkeley Lab and extrapolate to larger detectors.

  3. Catalytic oxidation of light alkanes in presence of a base

    DOEpatents

    Bhinde, Manoj V.; Bierl, Thomas W.

    1998-01-01

    The presence of a base in the reaction mixture in a metal-ligand catalyzed partial oxidation of alkanes results in sustained catalyst activity, and in greater percent conversion as compared with oxidation in the absence of base, while maintaining satisfactory selectivity for the desired oxidation, for example the oxidation of isobutane to isobutanol.

  4. Catalytic oxidation of light alkanes in presence of a base

    DOEpatents

    Bhinde, M.V.; Bierl, T.W.

    1998-03-03

    The presence of a base in the reaction mixture in a metal-ligand catalyzed partial oxidation of alkanes results in sustained catalyst activity, and in greater percent conversion as compared with oxidation in the absence of base, while maintaining satisfactory selectivity for the desired oxidation, for example the oxidation of isobutane to isobutanol. 1 fig.

  5. Design and implementation of green intelligent lights based on the ZigBee

    NASA Astrophysics Data System (ADS)

    Gan, Yong; Jia, Chunli; Zou, Dongyao; Yang, Jiajia; Guo, Qianqian

    2013-03-01

    By analysis of the low degree of intelligence of the traditional lighting control methods, the paper uses the singlechip microcomputer for the control core, and uses a pyroelectric infrared technology to detect the existence of the human body, light sensors to sense the light intensity; the interface uses infrared sensor module, photosensitive sensor module, relay module to transmit the signal, which based on ZigBee wireless network. The main function of the design is to realize that the lighting can intelligently adjust the brightness according to the indoor light intensity when people in door, and it can turn off the light when people left. The circuit and program design of this system is flexible, and the system achieves the effect of intelligent energy saving control.

  6. Influences of colorful LED emissions on spectrophotometric properties of a LED based white light source

    NASA Astrophysics Data System (ADS)

    Sametoglu, F.; Celikel, O.

    2011-05-01

    A LED based white light source (WLS) is designed and constructed to determine the color characteristics of the samples having specular and diffuse reflectance properties at the standard measurement conditions of 0/45 and d/8. The light source is composed of high power cool white and ultraviolet light emitting diodes (LEDs) which are operable in adjustable current levels. In order to combine the light beams emerging from two LED sources, a 1x2 fiber optic combiner is used. Optical characterizations of the light source designed and influences of several colorful LEDs called Royal-Blue, Blue, Cyan, Green, Amber, Red-Orange and Red on spectrophotometric properties of the light source are investigated.

  7. Smell sensing and visualizing based on multi-quantum wells spatial light modulator

    NASA Astrophysics Data System (ADS)

    Tian, Fengchun; Zhao, Zhenzhen; Jia, Pengfei; Liao, Hailin; Chen, Danyu; Liu, Shouqiong

    2014-09-01

    For the existing drawbacks of traditional detecting methods which use gratings or prisms to detect light intensity distribution at each wavelength of polychromatic light, a novel method based on multi-quantum wells spatial light modulator (MQWs-SLM) has been proposed in this paper. In the proposed method, MQWs-SLM serves as a distribution features detector of the signal light. It is on the basis of quantum-confine Stark effect (QCSE) that the vertical applied voltage can change the absorption features of exciton in multi-quantum wells, and further change the distribution features of the readout polychromatic light of MQWs-SLM. It can be not only an universal detecting method, but also especially recommended to use in the Electronic nose system for features detecting of signal light so as to realize smell sensing and visualizing. The feasibility of the proposed method has been confirmed by mathematical modeling and analysis, simulation experiments and research status analysis.

  8. Controlling the light distribution through turbid media with wavefront shaping based on volumetric optoacoustic feedback

    NASA Astrophysics Data System (ADS)

    Deán-Ben, X. Luís.; Estrada, Héctor; Özbek, Ali; Razansky, Daniel

    2016-03-01

    Wavefront shaping based on optoacoustic (photoacoustic) feedback has recently emerged as a promising tool to control the light distribution in optically-scattering media. In this approach, the phase of a short-pulsed light beam is spatially-modulated to create constructive light interference (focusing) at specific locations in the speckle pattern of the scattered wavefield. The optoacoustic signals generated by light absorption provide a convenient feedback mechanism to optimize the phase mask of the spatial light modulator in order to achieve the desired light intensity distribution. The optimization procedure can be done by directly considering the acquired signals or the reconstructed images of the light absorption distribution. Recently, our group has introduced a volumetric (three-dimensional) optoacoustic wavefront shaping platform that enables monitoring the distribution of light absorption in an entire volume with frame rates of tens of Hz. With this approach, it is possible to simultaneously control the volumetric light distribution through turbid media. Experiments performed with absorbing microparticles distributed in a three-dimensional region showcase the feasibility of enhancing the light intensity at specific points, where the size of particles is also essential to maximize the signal enhancement. The advantages provided by optoacoustic imaging in terms of spatial and temporal resolution anticipate new capabilities of wavefront shaping techniques in biomedical optics.

  9. Dynamic light scattering (DLS)-based immunoassay for ultra-sensitive detection of tumor marker protein.

    PubMed

    Li, Chao; Ma, Jiehua; Fan, Qiongxuan; Tao, Yaqin; Li, Genxi

    2016-06-14

    A novel dynamic light scattering (DLS)-based immunoassay that utilizes manganese dioxide nanosheet-modified gold nanoparticles (MnO2-GNPs) as an activatable nanoprobe has been developed to detect tumor markers down to femtomolar levels. PMID:27247980

  10. DNA-Based Oligochromophores as Light-Harvesting Systems.

    PubMed

    Ensslen, Philipp; Brandl, Fabian; Sezi, Sabrina; Varghese, Reji; Kutta, Roger-Jan; Dick, Bernhard; Wagenknecht, Hans-Achim

    2015-06-22

    The chromophores ethynyl pyrene as blue, ethynyl perylene as green and ethynyl Nile red as red emitter were conjugated to the 5-position of 2'-deoxyuridine via an acetylene bridge. Using phosphoramidite chemistry on solid phase labelled DNA duplexes were prepared that bear single chromophore modifications, and binary and ternary combinations of these chromophore modifications. The steady-state and time-resolved fluorescence spectra of all three chromophores were studied in these modified DNA duplexes. An energy-transfer cascade occurs from ethynyl pyrene over ethynyl perylene to ethynyl Nile red and subsequently an electron-transfer cascade in the opposite direction (from ethynyl Nile red to ethynyl perylene or ethynyl pyrene, but not from ethynyl perylene to ethynyl pyrene). The electron-transfer processes finally provide charge separation. The efficiencies by these energy and electron-transfer processes can be tuned by the distances between the chromophores and the sequences. Most importantly, excitation at any wavelength between 350 and 700 nm finally leads to charge separated states which make these DNA samples promising candidates for light-harvesting systems. PMID:26069203

  11. Optoelectrofluidic field separation based on light-intensity gradients

    PubMed Central

    Lee, Sanghyun; Park, Hyun Jin; Yoon, Jin Sung; Kang, Kwan Hyoung

    2010-01-01

    Optoelectrofluidic field separation (OEFS) of particles under light -intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. In the OEFS system, the codirectional illumination and observation induce the levitation effect, compensating the attenuation of the DEP force under LIG illumination by slightly floating particles from the surface. Results of the field separation and concentration of diverse particle pairs (0.82–16 μm) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. The OEFS with codirectional LIG strategy could be a promising particle manipulation method in many applications where a rapid manipulation of biological cells and particles over the entire working area are of interest. PMID:20697461

  12. Toward user mobility for OFDM-based visible light communications.

    PubMed

    Hong, Yang; Chen, Lian-Kuan

    2016-08-15

    We propose and experimentally demonstrate a mobile visible light communications (mobi-VLC) transmission system. The impact of user mobility on the performance of the mobi-VLC system is characterized, and we propose the use of the channel-independent orthogonal circulant matrix transform (OCT) precoding to combat the packet loss performance degradation induced by mobility. A mobile user terminal is used to detect the signal from a blue laser placed at 1 m away from the moving track. Various moving speeds (20, 40, 60, and 80  cm/s) and lateral moving distances (30, 40, and 50 cm) of the user terminal are investigated. The effectiveness of the OCT precoding is evaluated by the comparison with the conventional orthogonal frequency division multiplexing (OFDM) scheme and the adaptive-loaded discrete multi-tone (DMT) scheme. Experimental results show that the system performance degrades with the increase in user mobility speed and in moving distance. Furthermore, the OCT precoding provides performance improvement that is superior over that of conventional OFDM schemes, and it exhibits lower packet loss rate than that of adaptive-loaded DMT. No packet loss for 300  Mb/s transmission is achieved with a 30 cm lateral moving distance at 20  cm/s. PMID:27519083

  13. Research on spaceborne low light detection based on EMCCD and CMOS

    NASA Astrophysics Data System (ADS)

    Wu, Xingxing; Liu, Jinguo; Zhou, Huaide; Zhang, Boyan

    2015-10-01

    Electron Multiplying Charge Coupled Device(EMCCD) can realize read out noise of less than 1e- by promoting gain of charges with the charge multiplication principle and is suitable for low light imaging. With the development of back Illuminated CMOS technology CMOS with high quantum efficiency and less than 1.5e- read noise has been developed by Changchun Institute of Optics, Fine Mechanics and Physics(CIOMP). Spaceborne low light detection cameras based on EMCCD CCD201 and based on CMOS were respectively established and system noise models were founded. Low light detection performance as well as principle of spaceborne camera based on EMCCD and spaceborne camera based on CMOS were compared and analyzed. Results of analysis indicated that signal to noise(SNR) of spaceborne low light detection camera based on EMCCD would be 23.78 as radiance at entrance pupil of the camera was as low as 10-9 W/cm2/sr/μm at the focal plane temperature of 20°C. Spaceborne low light detection camera worked in starring mode and the integration time was 2 second. SNR of low light detection camera based on CMOS would be 27.42 under the same conditions. If cooling systems were used and the temperature was lowered from 20°C to -20°C, SNR of low light detection camera based on EMCCD would be improved to 27.533 while SNR of low light detection camera based on CMOS would be improved to 27.79.

  14. Graphene-Based Ultra-Light Batteries for Aircraft

    NASA Technical Reports Server (NTRS)

    Calle, Carlos I.; Kaner, Richard B.

    2014-01-01

    Develop a graphene-based ultracapacitor prototype that is flexible, thin, lightweight, durable, low cost, and safe and that will demonstrate the feasibility for use in aircraft center dot These graphene-based devices store charge on graphene sheets and take advantage of the large accessible surface area of graphene (2,600 m2/g) to increase the electrical energy that can be stored. center dot The proposed devices should have the electrical storage capacity of thin-film-ion batteries but with much shorter charge/discharge cycle times as well as longer lives center dot The proposed devices will be carbon-based and so will not have the same issues with flammability or toxicity as the standard lithium-based storage cells There are two main established methods for the storage and delivery of electrical energy: center dot Batteries - Store energy with electrochemical reactions - High energy densities - Slow charge/discharge cycles - Used in applications requiring large amounts of energy ? aircraft center dot Electrochemical capacitors - Store energy in electrochemical double layers - Fast charge/discharge cycles - Low energy densities - Used in electronics devices - Large capacitors are used in truck engine cranking

  15. GENERIC, COMPONENT FAILURE DATA BASE FOR LIGHT WATER AND LIQUID SODIUM REACTOR PRAs

    SciTech Connect

    S. A. Eide; S. V. Chmielewski; T. D. Swantz

    1990-02-01

    A comprehensive generic component failure data base has been developed for light water and liquid sodium reactor probabilistic risk assessments (PRAs) . The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) and the Centralized Reliability Data Organization (CREDO) data bases were used to generate component failure rates . Using this approach, most of the failure rates are based on actual plant data rather than existing estimates .

  16. Stray light correction for diode-array-based spectrometers using a monochromator.

    PubMed

    Salim, Saber G R; Fox, Nigel P; Hartree, William S; Woolliams, Emma R; Sun, Tong; Grattan, Kenneth T V

    2011-09-10

    Photodiode-array-based spectrometers are increasingly being used in a wide variety of applications. However, the signal measured by this type of instrument often is not what is anticipated by the user and is often subject to contamination from stray light. This paper describes an efficient and low-cost stray light correction approach based on a relatively simple system using a monochromator-based source. The paper further discusses the limitations of using a monochromator instead of a laser, as used by previous researchers, and its impact on the quality of the stray light correction. The reliability and robustness of the stray light correction matrix generated have been studied and are also reported. PMID:21946995

  17. Enhancing the light extraction efficiency of GaN-based LEDs

    NASA Astrophysics Data System (ADS)

    Niu, Pingjuan; Li, Yanling; Li, Xiaoyun; Liu, Hongwei; Tian, Haitao; Gao, Tiecheng; Yang, Guanghua

    2007-11-01

    GaN-based light-emitting diode (LED) has been widely used in recent years, and tremendous progress has been achieved in GaN-based semiconductor materials and relevant process. However, owing to the large refractive index contrast between GaN-based semiconductor materials and air, light can be easily totally internally reflected at the semiconductor/air interface, and the critical angle for light to escape from the semiconductor is small. Therefore, the light extraction efficiency for GaN-based LED is still low and needs improving. Some of the leading approaches to enhance light extraction efficiency of GaN-based LED such as surface texturing or roughening, omnidirectional reflectors, photonic crystals, laser liftoff, transparent electrode, patterned substrate and so on are introduced in detail. For each approach, how the variation in device structure or material improves the light extraction efficiency is analyzed thoroughly. At last, some of mentioned approaches that are promising are evaluated and viewed briefly.

  18. VLC-based indoor location awareness using LED light and image sensors

    NASA Astrophysics Data System (ADS)

    Lee, Seok-Ju; Yoo, Jong-Ho; Jung, Sung-Yoon

    2012-11-01

    Recently, indoor LED lighting can be considered for constructing green infra with energy saving and additionally providing LED-IT convergence services such as visible light communication (VLC) based location awareness and navigation services. For example, in case of large complex shopping mall, location awareness to navigate the destination is very important issue. However, the conventional navigation using GPS is not working indoors. Alternative location service based on WLAN has a problem that the position accuracy is low. For example, it is difficult to estimate the height exactly. If the position error of the height is greater than the height between floors, it may cause big problem. Therefore, conventional navigation is inappropriate for indoor navigation. Alternative possible solution for indoor navigation is VLC based location awareness scheme. Because indoor LED infra will be definitely equipped for providing lighting functionality, indoor LED lighting has a possibility to provide relatively high accuracy of position estimation combined with VLC technology. In this paper, we provide a new VLC based positioning system using visible LED lights and image sensors. Our system uses location of image sensor lens and location of reception plane. By using more than two image sensor, we can determine transmitter position less than 1m position error. Through simulation, we verify the validity of the proposed VLC based new positioning system using visible LED light and image sensors.

  19. Recognition of Banknote Fitness Based on a Fuzzy System Using Visible Light Reflection and Near-infrared Light Transmission Images

    PubMed Central

    Kwon, Seung Yong; Pham, Tuyen Danh; Park, Kang Ryoung; Jeong, Dae Sik; Yoon, Sungsoo

    2016-01-01

    Fitness classification is a technique to assess the quality of banknotes in order to determine whether they are usable. Banknote classification techniques are useful in preventing problems that arise from the circulation of substandard banknotes (such as recognition failures, or bill jams in automated teller machines (ATMs) or bank counting machines). By and large, fitness classification continues to be carried out by humans, and this can cause the problem of varying fitness classifications for the same bill by different evaluators, and requires a lot of time. To address these problems, this study proposes a fuzzy system-based method that can reduce the processing time needed for fitness classification, and can determine the fitness of banknotes through an objective, systematic method rather than subjective judgment. Our algorithm was an implementation to actual banknote counting machine. Based on the results of tests on 3856 banknotes in United States currency (USD), 3956 in Korean currency (KRW), and 2300 banknotes in Indian currency (INR) using visible light reflection (VR) and near-infrared light transmission (NIRT) imaging, the proposed method was found to yield higher accuracy than prevalent banknote fitness classification methods. Moreover, it was confirmed that the proposed algorithm can operate in real time, not only in a normal PC environment, but also in an embedded system environment of a banknote counting machine. PMID:27294940

  20. Recognition of Banknote Fitness Based on a Fuzzy System Using Visible Light Reflection and Near-infrared Light Transmission Images.

    PubMed

    Kwon, Seung Yong; Pham, Tuyen Danh; Park, Kang Ryoung; Jeong, Dae Sik; Yoon, Sungsoo

    2016-01-01

    Fitness classification is a technique to assess the quality of banknotes in order to determine whether they are usable. Banknote classification techniques are useful in preventing problems that arise from the circulation of substandard banknotes (such as recognition failures, or bill jams in automated teller machines (ATMs) or bank counting machines). By and large, fitness classification continues to be carried out by humans, and this can cause the problem of varying fitness classifications for the same bill by different evaluators, and requires a lot of time. To address these problems, this study proposes a fuzzy system-based method that can reduce the processing time needed for fitness classification, and can determine the fitness of banknotes through an objective, systematic method rather than subjective judgment. Our algorithm was an implementation to actual banknote counting machine. Based on the results of tests on 3856 banknotes in United States currency (USD), 3956 in Korean currency (KRW), and 2300 banknotes in Indian currency (INR) using visible light reflection (VR) and near-infrared light transmission (NIRT) imaging, the proposed method was found to yield higher accuracy than prevalent banknote fitness classification methods. Moreover, it was confirmed that the proposed algorithm can operate in real time, not only in a normal PC environment, but also in an embedded system environment of a banknote counting machine. PMID:27294940

  1. Reflected-light-source-based three-dimensional display with high brightness.

    PubMed

    Lv, Guo-Jiao; Wu, Fei; Zhao, Wu-Xiang; Fan, Jun; Zhao, Bai-Chuan; Wang, Qiong-Hua

    2016-05-01

    A reflected-light-source (RLS)-based 3D display is proposed. This display consists of an RLS and a 2D display panel. The 2D display panel is located in front of the RLS. The RLS consists of a light source, a light guide plate (LGP), and a reflection cavity. The light source and the LGP are located in the reflection cavity. Light from the light source can enter into the LGP and reflect continuously in the reflection cavity. The reflection cavity has a series of slits, and light can exit only from these slits. These slits can work as a postpositional parallax barrier, so when they modulate the parallax images on the 2D display, 3D images are formed. Different from the conventional 3D display based on a parallax barrier, this RLS has less optical loss, so it can provide higher brightness. A prototype of this display is developed. Experimental results show that this RLS-based 3D display can provide higher brightness than the conventional one. PMID:27140355

  2. Exploring the performance of indoor localization systems based on VLC-RSSI, including the effect of NLOS components using two light-emitting diode lighting systems

    NASA Astrophysics Data System (ADS)

    Elkarim, Mohammed Abd; Mohammed, Nazmi A.; Aly, Moustafa H.

    2015-10-01

    We analyze the effect of diffuse reflection on indoor localization systems based on visible light communication. The target position is estimated using a received signal strength indication technique. Two lighting systems are considered: distinct and uniform lighting systems. Each utilizes commercially available light-emitting diodes and photodiodes with an illumination level conforming to standards. We introduce a comparative study between the two lighting systems through different transmitter (Tx) and receiver (Rx) essential parameters. The results show that the uniform lighting system achieves less localization error (≤20.43 cm) than a distinct lighting system (≤45.9 cm). The uniform lighting system is well adapted to low-Rx field of view (FOV) and narrow radiation angle (error=1 mm when semiradiation angle=5 deg). In the case of a distinct lighting system, low-Rx FOV is also required, while the Tx semiradiation angle needs to be determined carefully (error≤3.08 cm when semiradiation angle=20 deg). Finally, the uniform lighting system shows flexibility in the process of Tx and Rx designs. A uniform lighting system can utilize Rxs with narrow FOVs (≥8.6 deg), while a distinct lighting system is limited to Rx with a wide FOV (≥53.96 deg).

  3. Comparison of atom interferometers and light interferometers as space-based gravitational wave detectors.

    PubMed

    Baker, John G; Thorpe, J I

    2012-05-25

    We consider a class of proposed gravitational-wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, noninertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g., multiple-arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and, in principle, favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe. PMID:23003235

  4. Comparative Sensitivities of Gravitational Wave Detectors Based on Atom Interferometers and Light Interferometers

    NASA Technical Reports Server (NTRS)

    Baker, John G.; Thorpe, J. I.

    2012-01-01

    We consider a class of proposed gravitational wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, non-inertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g. multiple arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe. Whether this potential advantage outweighs the additional complexity associated with including atom interferometers will require further study.

  5. Comparison of Atom Interferometers and Light Interferometers as Space-Based Gravitational Wave Detectors

    NASA Technical Reports Server (NTRS)

    Baker, John G.

    2012-01-01

    We consider a class of proposed gravitational wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, non-inertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g. multiple arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe.

  6. Light-curing considerations for resin-based composite materials: a review. Part I.

    PubMed

    Malhotra, Neeraj; Mala, Kundabala

    2010-09-01

    There has been a continual advent of improved technologies in dentistry. Among these are the material sciences of resin-based composites (RBCs). Since the introduction of light-cured RBCs, the problem of polymerization shrinkage and the methods used to overcome this have concerned clinicians and researchers. Types of curing light and modes of curing have been shown to affect the degree of polymerization and related shrinkage of RBCs. This review, which is divided into two parts, discusses the contemporary light-curing units. Part I explores the evolution in light-curing units and different curing modes. Part II highlights the clinical considerations regarding light curing of RBCs that are important for achieving optimal curing and maximum polymerization of RBCs in a clinical setting. PMID:20879203

  7. A Red-Light Running Prevention System Based on Artificial Neural Network and Vehicle Trajectory Data

    PubMed Central

    Li, Pengfei; Li, Yan; Guo, Xiucheng

    2014-01-01

    The high frequency of red-light running and complex driving behaviors at the yellow onset at intersections cannot be explained solely by the dilemma zone and vehicle kinematics. In this paper, the author presented a red-light running prevention system which was based on artificial neural networks (ANNs) to approximate the complex driver behaviors during yellow and all-red clearance and serve as the basis of an innovative red-light running prevention system. The artificial neural network and vehicle trajectory are applied to identify the potential red-light runners. The ANN training time was also acceptable and its predicting accurate rate was over 80%. Lastly, a prototype red-light running prevention system with the trained ANN model was described. This new system can be directly retrofitted into the existing traffic signal systems. PMID:25435870

  8. Space-based visible all-reflective stray light telescope

    NASA Astrophysics Data System (ADS)

    Wang, Dexter; Gardner, Leo R.; Wong, Wallace K.; Hadfield, Peter

    1991-08-01

    A 6-inch diameter aperture space-based visible telescope has been optimized to perform surveillance against the space background with earth albedo as a primary source of straylight. A three mirror off-axis anastigmat has been designed to cover a 1.4 degree(s) by 6.6 degree(s) field- of-view with 60 (mu) radian spatial resolution. The telescope body and optics are constructed of 6061-T6 aluminum to provide a thermally stable optical system. The optical elements are 'superfinished' to minimize scatter. Extensive baffles and stops are utilized to further reduce straylight. The telescope will be used on the Midcourse Space Experiment platform.

  9. Massively parallel spatial light modulation-based optical signal processing

    NASA Astrophysics Data System (ADS)

    Li, Yao

    1993-03-01

    A new optical parallel arithmetic processing scheme using a nonholographic optoelectronic content-addressable memory (CAM) was proposed. The design of a four-bit CAM-based optical carry look-ahead adder was studied. Compared with existing optoelectronic binary addition approaches, this nonholographic CAM Scheme offers a number of practical advantages, such as faster processing speed and ease of optical implementation and alignment. For an addition of numbers longer than four bits, by incorporating the previous stage's carry, a number of four-bit CLA's can be cascaded. Experimental results were also demonstrated. One paper to the Optics Letters was published.

  10. IC-BASED CONTROLS FOR ENERGY-EFFICIENT LIGHTING

    SciTech Connect

    Richard Zhang

    2005-03-01

    A new approach for driving high frequency energy saving ballasts is developed and documented in this report. The developed approach utilizes an IC-based platform that provides the benefits of reduced system cost, reduced ballast size, and universal application to a wide range of lamp technologies, such as linear fluorescent lamps (LFL), compact fluorescent lamps (CFL) and high intensity discharge lamps (HID). The control IC chip set developed for the platform includes dual low voltage (LV) IC gate drive that provides gate drive for high and low side power switches in typical ballast circuits, and ballast controller IC that provides control functionalities optimal for different lamps and digital interface for future extension to more sophisticated control and communication.

  11. Classification and thermal history of petroleum based on light hydrocarbons

    NASA Astrophysics Data System (ADS)

    Thompson, K. F. M.

    1983-02-01

    Classifications of oils and kerogens are described. Two indices are employed, termed the Heptane and IsoheptaneValues, based on analyses of gasoline-range hydrocarbons. The indices assess degree of paraffinicity. and allow the definition of four types of oil: normal, mature, supermature, and biodegraded. The values of these indices measured in sediment extracts are a function of maximum attained temperature and of kerogen type. Aliphatic and aromatic kerogens are definable. Only the extracts of sediments bearing aliphatic kerogens having a specific thermal history are identical to the normal oils which form the largest group (41%) in the sample set. This group was evidently generated at subsurface temperatures of the order of 138°-149°C, (280°-300°F) defined under specific conditions of burial history. It is suggested that all other petroleums are transformation products of normal oils.

  12. Automatic illumination compensation device based on a photoelectrochemical biofuel cell driven by visible light.

    PubMed

    Yu, You; Han, Yanchao; Xu, Miao; Zhang, Lingling; Dong, Shaojun

    2016-04-28

    Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm(-2) and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications. PMID:27076202

  13. Three-visible-light wave combiner based on photonic crystal waveguides.

    PubMed

    Liu, Dingwen; Sun, Yiling; Ouyang, Zhengbiao

    2014-07-20

    We present a three-visible-light wave combiner based on two-dimensional photonic crystal waveguides whose widths are not integral multiples of the lattice period. The proposed device consists of two cascaded directional couplers. It combines three visible light waves with different wavelengths from three input ports into a single output port. As an example, a combiner for combining light waves of 635, 532, and 488 nm, which are commonly used as the three primary colors in laser display systems, is designed and demonstrated through the finite-difference time-domain method. The results show that the proposed device can perform efficient synthesis for three visible light waves with transmittance exceeding 89% for each wavelength and high ability in preventing the backward coupling of waves from different waveguides. The method for designing the combiner is useful for designing other waveguide couplers based on photonic crystals made of dispersion materials. PMID:25090219

  14. Light controlled drug delivery containers based on spiropyran doped liquid crystal micro spheres

    PubMed Central

    Petriashvili, Gia; Devadze, Lali; Zurabishvili, Tsisana; Sepashvili, Nino; Chubinidze, Ketevan

    2016-01-01

    We have developed a novel, light activated drug delivery containers, based on spiropyran doped liquid crystal micro spheres. Upon exposure to UV/violet light, the spiropyran molecules entrapped inside the nematic liquid crystal micro spheres, interconvert from the hydrophobic, oil soluble form, to the hydrophilic, water soluble merocyanine one, which stimulates the translocation of the merocyanine molecules across the nematic liquid crystal-water barrier and results their homogeneous distribution throughout in an aqueous environment. Light controllable switching property and extremely high solubility of spiropyran in the nematic liquid crystal, promise to elaborate a novel and reliable vehicles for the drug delivery systems. PMID:26977353

  15. Light controlled drug delivery containers based on spiropyran doped liquid crystal micro spheres.

    PubMed

    Petriashvili, Gia; Devadze, Lali; Zurabishvili, Tsisana; Sepashvili, Nino; Chubinidze, Ketevan

    2016-02-01

    We have developed a novel, light activated drug delivery containers, based on spiropyran doped liquid crystal micro spheres. Upon exposure to UV/violet light, the spiropyran molecules entrapped inside the nematic liquid crystal micro spheres, interconvert from the hydrophobic, oil soluble form, to the hydrophilic, water soluble merocyanine one, which stimulates the translocation of the merocyanine molecules across the nematic liquid crystal-water barrier and results their homogeneous distribution throughout in an aqueous environment. Light controllable switching property and extremely high solubility of spiropyran in the nematic liquid crystal, promise to elaborate a novel and reliable vehicles for the drug delivery systems. PMID:26977353

  16. Multilayered Organic Light Emitting Diodes Based on Polyfluorenes

    NASA Astrophysics Data System (ADS)

    Bozano, Luisa; Marsitzky, Dirk; Carter, Kenneth; Swanson, Sally; Lee, Victor; Salem, Jesse; Miller, Robert; Scott, Campbell; Carter, Sue

    2001-03-01

    The electroluminescence of polyfluorene homopolymers and various arylene copolymers is in the deep blue, with peak emission wavelengths as small as 420 nm. These materials are therefore of great interest for use in full-color OLED displays both as emitters for blue subpixels and as hosts for red and green emitting dopants or comonomers. In this work, we compare the properties of single and multilayer diode structures based on dihexyl and di(2-ethylexyl) substituted polyfluorenes. A cross-linkable polymeric arylamine hole transport polymer and/or a polyquinoline electron transport layer are introduced to better balance the charge injection from the electrodes and optimize the recombination in the fluorene emitter layer. External quantum efficiencies increase from about 0.1layer devices to well over 1The electrical and optical response is determined by steady state and transient measurements. The effects on efficiency, emission spectrum and electrical response resulting from the introduction of dopant dyes into the emitter layer are also presented.

  17. SPIM-fluid: open source light-sheet based platform for high-throughput imaging

    PubMed Central

    Gualda, Emilio J.; Pereira, Hugo; Vale, Tiago; Estrada, Marta Falcão; Brito, Catarina; Moreno, Nuno

    2015-01-01

    Light sheet fluorescence microscopy has recently emerged as the technique of choice for obtaining high quality 3D images of whole organisms/embryos with low photodamage and fast acquisition rates. Here we present an open source unified implementation based on Arduino and Micromanager, which is capable of operating Light Sheet Microscopes for automatized 3D high-throughput imaging on three-dimensional cell cultures and model organisms like zebrafish, oriented to massive drug screening. PMID:26601007

  18. SPIM-fluid: open source light-sheet based platform for high-throughput imaging.

    PubMed

    Gualda, Emilio J; Pereira, Hugo; Vale, Tiago; Estrada, Marta Falcão; Brito, Catarina; Moreno, Nuno

    2015-11-01

    Light sheet fluorescence microscopy has recently emerged as the technique of choice for obtaining high quality 3D images of whole organisms/embryos with low photodamage and fast acquisition rates. Here we present an open source unified implementation based on Arduino and Micromanager, which is capable of operating Light Sheet Microscopes for automatized 3D high-throughput imaging on three-dimensional cell cultures and model organisms like zebrafish, oriented to massive drug screening. PMID:26601007

  19. Automatic illumination compensation device based on a photoelectrochemical biofuel cell driven by visible light

    NASA Astrophysics Data System (ADS)

    Yu, You; Han, Yanchao; Xu, Miao; Zhang, Lingling; Dong, Shaojun

    2016-04-01

    Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm-2 and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications.Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm-2 and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00759g

  20. Quantum memory for nonstationary light fields based on controlled reversible inhomogeneous broadening

    SciTech Connect

    Kraus, B.; Tittel, W.; Gisin, N.; Nilsson, M.; Kroell, S.; Cirac, J. I.

    2006-02-15

    We propose a method for efficient storage and recall of arbitrary nonstationary light fields, such as, for instance, single photon time-bin qubits or intense fields, in optically dense atomic ensembles. Our approach to quantum memory is based on controlled, reversible, inhomogeneous broadening and relies on a hidden time-reversal symmetry of the optical Bloch equations describing the propagation of the light field. We briefly discuss experimental realizations of our proposal.

  1. Structurally Integrated Photoluminescence-Based Lactate Sensor Using Organic Light Emitting Devices (OLEDs) as the Light Source

    SciTech Connect

    Chengliang Qian

    2006-08-09

    Multianalyte bio(chemical) sensors are extensively researched for monitoring analytes in complex systems, such as blood serum. As a step towards developing such multianalyte sensors, we studied a novel, structurally integrated, organic light emitting device (OLED)-based sensing platform for detection of lactate. Lactate biosensors have attracted numerous research efforts, due to their wide applications in clinical diagnosis, athletic training and food industry. The OLED-based sensor is based on monitoring the oxidation reaction of lactate, which is catalyzed by the lactate oxidase (LOX) enzyme. The sensing component is based on an oxygen-sensitive dye, Platinum octaethyl porphyrin (PtOEP), whose photoluminescence (PL) lifetime {tau} decreases as the oxygen level increases. The PtOEP dye was embedded in a thin film polystyrene (PS) matrix; the LOX was dissolved in solution or immobilized in a sol-gel matrix. {tau} was measured as a function of the lactate concentration; as the lactate concentration increases, {tau} increases due to increased oxygen consumption. The sensors performance is discussed in terms of the detection sensitivity, dynamic range, and response time. A response time of {approx}32 sec was achieved when the LOX was dissolved in solution and kept in a closed cell. Steps towards development of a multianalyte sensor array using an array of individually addressable OLED pixels were also presented.

  2. AlGaInN-based light emitting diodes with a transparent p-contact based on thin ITO films

    SciTech Connect

    Smirnova, I. P. Markov, L. K.; Pavlyuchenko, A. S.; Kukushkin, M. V.

    2012-03-15

    A method for obtaining transparent conductive ITO (indium-tin oxide) films aimed for use in light emitting diodes of the blue spectral range is developed. The peak external quantum efficiency of light-emitting diodes with a p-contact based on the obtained films reaches 25%, while for similar light-emitting diodes with a standard semitransparent metal contact, it is <10%. An observed increase in the direct voltage drop from 3.15 to 3.37 V does not significantly affect the possibility of applying these films in light-emitting diodes since the optical power of light-emitting diodes with a transparent p-contact based on ITO films exceeds that of chips with metal semitransparent p-contacts with a working current of 20 mA by a factor of almost 2.5. Light-emitting diodes with p-contacts based on ITO films successfully withstand a pumping current that exceeds their calculated working current by a factor of 5 without the appearance of any signs of degradation.

  3. Development of Advanced LED Phosphors by Spray-based Processes for Solid State Lighting

    SciTech Connect

    Cabot Corporation

    2007-09-30

    The overarching goal of the project was to develop luminescent materials using aerosol processes for making improved LED devices for solid state lighting. In essence this means improving white light emitting phosphor based LEDs by improvement of the phosphor and phosphor layer. The structure of these types of light sources, displayed in Figure 1, comprises of a blue or UV LED under a phosphor layer that converts the blue or UV light to a broad visible (white) light. Traditionally, this is done with a blue emitting diode combined with a blue absorbing, broadly yellow emitting phosphor such as Y{sub 3}Al{sub 5}O{sub 12}:Ce (YAG). A similar result may be achieved by combining a UV emitting diode and at least three different UV absorbing phosphors: red, green, and blue emitting. These emitted colors mix to make white light. The efficiency of these LEDs is based on the combined efficiency of the LED, phosphor, and the interaction between the two. The Cabot SSL project attempted to improve the over all efficiency of the LED light source be improving the efficiency of the phosphor and the interaction between the LED light and the phosphor. Cabot's spray based process for producing phosphor powders is able to improve the brightness of the powder itself by increasing the activator (the species that emits the light) concentration without adverse quenching effects compared to conventional synthesis. This will allow less phosphor powder to be used, and will decrease the cost of the light source; thus lowering the barrier of entry to the lighting market. Cabot's process also allows for chemical flexibility of the phosphor particles, which may result in tunable emission spectra and so light sources with improved color rendering. Another benefit of Cabot's process is the resulting spherical morphology of the particles. Less light scattering results when spherical particles are used in the phosphor layer (Figure 1) compared to when conventional, irregular shaped phosphor particles

  4. Light interaction in sapphire/MgF2/Al triple-layer omnidirectional reflectors in AlGaN-based near ultraviolet light-emitting diodes

    PubMed Central

    Lee, Keon Hwa; Moon, Yong-Tae; Song, June-O; Kwak, Joon Seop

    2015-01-01

    This study examined systematically the mechanism of light interaction in the sapphire/MgF2/Al triple-layer omnidirectional reflectors (ODR) and its effects on the light output power in near ultraviolet light emitting diodes (NUV-LEDs) with the ODR. The light output power of NUV-LEDs with the triple-layer ODR structure increased with decreasing surface roughness of the sapphire backside in the ODR. Theoretical modeling of the roughened surface suggests that the dependence of the reflectance of the triple-layer ODR structure on the surface roughness can be attributed mainly to light absorption by the Al nano-structures and the trapping of scattered light in the MgF2 layer. Furthermore, the ray tracing simulation based upon the theoretical modeling showed good agreement with the measured reflectance of the ODR structure in diffuse mode. PMID:26010378

  5. A Light Switch Based on Protein S-Nitrosylation Fine-Tunes Photosynthetic Light Harvesting in Chlamydomonas.

    PubMed

    Berger, Hanna; De Mia, Marcello; Morisse, Samuel; Marchand, Christophe H; Lemaire, Stéphane D; Wobbe, Lutz; Kruse, Olaf

    2016-06-01

    Photosynthetic eukaryotes are challenged by a fluctuating light supply, demanding for a modulated expression of nucleus-encoded light-harvesting proteins associated with photosystem II (LHCII) to adjust light-harvesting capacity to the prevailing light conditions. Here, we provide clear evidence for a regulatory circuit that controls cytosolic LHCII translation in response to light quantity changes. In the green unicellular alga Chlamydomonas reinhardtii, the cytosolic RNA-binding protein NAB1 represses translation of certain LHCII isoform mRNAs. Specific nitrosylation of Cys-226 decreases NAB1 activity and could be demonstrated in vitro and in vivo. The less active, nitrosylated form of NAB1 is found in cells acclimated to limiting light supply, which permits accumulation of light-harvesting proteins and efficient light capture. In contrast, elevated light supply causes its denitrosylation, thereby activating the repression of light-harvesting protein synthesis, which is needed to control excitation pressure at photosystem II. Denitrosylation of recombinant NAB1 is efficiently performed by the cytosolic thioredoxin system in vitro. To our knowledge, NAB1 is the first example of stimulus-induced denitrosylation in the context of photosynthetic acclimation. By identifying this novel redox cross-talk pathway between chloroplast and cytosol, we add a new key element required for drawing a precise blue print of the regulatory network of light harvesting. PMID:27208221

  6. Ultra High p-doping Material Research for GaN Based Light Emitters

    SciTech Connect

    Vladimir Dmitriev

    2007-06-30

    The main goal of the Project is to investigate doping mechanisms in p-type GaN and AlGaN and controllably fabricate ultra high doped p-GaN materials and epitaxial structures. Highly doped p-type GaN-based materials with low electrical resistivity and abrupt doping profiles are of great importance for efficient light emitters for solid state lighting (SSL) applications. Cost-effective hydride vapor phase epitaxial (HVPE) technology was proposed to investigate and develop p-GaN materials for SSL. High p-type doping is required to improve (i) carrier injection efficiency in light emitting p-n junctions that will result in increasing of light emitting efficiency, (ii) current spreading in light emitting structures that will improve external quantum efficiency, and (iii) parameters of Ohmic contacts to reduce operating voltage and tolerate higher forward currents needed for the high output power operation of light emitters. Highly doped p-type GaN layers and AlGaN/GaN heterostructures with low electrical resistivity will lead to novel device and contact metallization designs for high-power high efficiency GaN-based light emitters. Overall, highly doped p-GaN is a key element to develop light emitting devices for the DOE SSL program. The project was focused on material research for highly doped p-type GaN materials and device structures for applications in high performance light emitters for general illumination P-GaN and p-AlGaN layers and multi-layer structures were grown by HVPE and investigated in terms of surface morphology and structure, doping concentrations and profiles, optical, electrical, and structural properties. Tasks of the project were successfully accomplished. Highly doped GaN materials with p-type conductivity were fabricated. As-grown GaN layers had concentration N{sub a}-N{sub d} as high as 3 x 10{sup 19} cm{sup -3}. Mechanisms of doping were investigated and results of material studies were reported at several International conferences providing

  7. A novel autonomous real-time position method based on polarized light and geomagnetic field

    PubMed Central

    Wang, Yinlong; Chu, Jinkui; Zhang, Ran; Wang, Lu; Wang, Zhiwen

    2015-01-01

    Many animals exploit polarized light in order to calibrate their magnetic compasses for navigation. For example, some birds are equipped with biological magnetic and celestial compasses enabling them to migrate between the Western and Eastern Hemispheres. The Vikings' ability to derive true direction from polarized light is also widely accepted. However, their amazing navigational capabilities are still not completely clear. Inspired by birds' and Vikings' ancient navigational skills. Here we present a combined real-time position method based on the use of polarized light and geomagnetic field. The new method works independently of any artificial signal source with no accumulation of errors and can obtain the position and the orientation directly. The novel device simply consists of two polarized light sensors, a 3-axis compass and a computer. The field experiments demonstrate device performance. PMID:25851793

  8. A novel autonomous real-time position method based on polarized light and geomagnetic field

    NASA Astrophysics Data System (ADS)

    Wang, Yinlong; Chu, Jinkui; Zhang, Ran; Wang, Lu; Wang, Zhiwen

    2015-04-01

    Many animals exploit polarized light in order to calibrate their magnetic compasses for navigation. For example, some birds are equipped with biological magnetic and celestial compasses enabling them to migrate between the Western and Eastern Hemispheres. The Vikings' ability to derive true direction from polarized light is also widely accepted. However, their amazing navigational capabilities are still not completely clear. Inspired by birds' and Vikings' ancient navigational skills. Here we present a combined real-time position method based on the use of polarized light and geomagnetic field. The new method works independently of any artificial signal source with no accumulation of errors and can obtain the position and the orientation directly. The novel device simply consists of two polarized light sensors, a 3-axis compass and a computer. The field experiments demonstrate device performance.

  9. A novel autonomous real-time position method based on polarized light and geomagnetic field.

    PubMed

    Wang, Yinlong; Chu, Jinkui; Zhang, Ran; Wang, Lu; Wang, Zhiwen

    2015-01-01

    Many animals exploit polarized light in order to calibrate their magnetic compasses for navigation. For example, some birds are equipped with biological magnetic and celestial compasses enabling them to migrate between the Western and Eastern Hemispheres. The Vikings' ability to derive true direction from polarized light is also widely accepted. However, their amazing navigational capabilities are still not completely clear. Inspired by birds' and Vikings' ancient navigational skills. Here we present a combined real-time position method based on the use of polarized light and geomagnetic field. The new method works independently of any artificial signal source with no accumulation of errors and can obtain the position and the orientation directly. The novel device simply consists of two polarized light sensors, a 3-axis compass and a computer. The field experiments demonstrate device performance. PMID:25851793

  10. Reanalysis of the Near-infrared Extragalactic Background Light Based on the IRTS Observations

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Kim, M. G.; Pyo, J.; Tsumura, K.

    2015-07-01

    We reanalyze data of the near-infrared background taken by IRTS using up-to-date observational results of zodiacal light (ZL), integrated star light, and diffuse Galactic light. We confirm the existence of residual isotropic emission, which is slightly lower but almost the same as previously reported. At wavelengths longer than 2 μm, the result is fairly consistent with the recent observation with AKARI. We also perform the same analysis using a different ZL model by Wright and detect residual isotropic emission that is slightly lower than that based on the original Kelsall model. Both models show residual isotropic emission that is significantly brighter than the integrated light of galaxies.

  11. Light-curing considerations for resin-based composite materials: a review. Part II.

    PubMed

    Malhotra, Neeraj; Mala, Kundabala

    2010-10-01

    As discussed in Part I, the type of curing light and curing mode impact the polymerization kinetics of resin-based composite (RBC) materials. Major changes in light-curing units and curing modes have occurred. The type of curing light and mode employed affects the polymerization shrinkage and associated stresses, microhardness, depth of cure, degree of conversion, and color change of RBCs. These factors also may influence the microleakage in an RBC restoration. Apart from the type of unit and mode used, the polymerization of RBCs is also affected by how a light-curing unit is used and handled, as well as the aspects associated with RBCs and the environment. Part II discusses the various clinical issues that should be considered while curing RBC restorations in order to achieve the best possible outcome. PMID:20960988

  12. Comparative efficiency analysis of GaN-based light-emitting diodes and laser diodes

    NASA Astrophysics Data System (ADS)

    Piprek, Joachim

    2016-07-01

    Nobel laureate Shuji Nakamura predicted in 2014 that GaN-based laser diodes are the future of solid state lighting. However, blue GaN-lasers still exhibit less than 40% wall-plug efficiency, while some GaN-based blue light-emitting diodes exceed 80%. This paper investigates non-thermal reasons behind this difference. The inherently poor hole conductivity of the Mg-doped waveguide cladding layer of laser diodes is identified as main reason for their low electrical-to-optical energy conversion efficiency.

  13. Method to produce nanocrystalline powders of oxide-based phosphors for lighting applications

    DOEpatents

    Loureiro, Sergio Paulo Martins; Setlur, Anant Achyut; Williams, Darryl Stephen; Manoharan, Mohan; Srivastava, Alok Mani

    2007-12-25

    Some embodiments of the present invention are directed toward nanocrystalline oxide-based phosphor materials, and methods for making same. Typically, such methods comprise a steric entrapment route for converting precursors into such phosphor material. In some embodiments, the nanocrystalline oxide-based phosphor materials are quantum splitting phosphors. In some or other embodiments, such nanocrystalline oxide based phosphor materials provide reduced scattering, leading to greater efficiency, when used in lighting applications.

  14. Generic component failure data base for light water and liquid sodium reactor PRAs (probabilistic risk assessments)

    SciTech Connect

    Eide, S.A.; Chmielewski, S.V.; Swantz, T.D.

    1990-02-01

    A comprehensive generic component failure data base has been developed for light water and liquid sodium reactor probabilistic risk assessments (PRAs). The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) and the Centralized Reliability Data Organization (CREDO) data bases were used to generate component failure rates. Using this approach, most of the failure rates are based on actual plant data rather than existing estimates. 21 refs., 9 tabs.

  15. Light-based therapy on wound healing : a review

    NASA Astrophysics Data System (ADS)

    Pik Suan, Lau; Bidin, Noriah; Cherng, Chong Jia; Hamid, Asmah

    2014-08-01

    Wound healing is a complex matrix and overlapping process. In order to accelerate the healing process and minimize bacterial infection, light-based therapy was applied to stimulate bio-reaction to improve healing. The aim of this paper is to review the effects induced by light source (laser and incoherent light like LED) on different biological targets. The light-based therapy techniques were categorized according to the wavelength, energy density, type of irradiance and activity of tissues in the healing process. Out of 80 cases, 77% were animal studies, 5% were human studies and 18% were cell studies. Around 75% of light-based therapy has an advantage on tissue interaction and 25% has no effect or inhibition on the healing process. The appropriate dose appears to be between 1 and 5 J cm-2. At shorter wavelength, photobiostimulation would be effective with a high frequently administrated low-energy dose. On the other hand, for longer wavelength it is the reverse, i.e., more effective with a low frequent treated schedule and a high-energy dose.

  16. Laser and Light-based Treatment of Keloids – A Review

    PubMed Central

    Mamalis, A.D.; Lev-Tov, H.; Nguyen, D.H.; Jagdeo, J.R.

    2015-01-01

    Keloids are an overgrowth of fibrotic tissue outside the original boundaries of an injury and occur secondary to defective wound healing. Keloids often have a functional, aesthetic, or psychosocial impact on patients as highlighted by quality-of-life studies. Our goal is to provide clinicians and scientists an overview of the data available on laser and light-based therapies for treatment of keloids, and highlight emerging light-based therapeutic technologies and the evidence available to support their use. We employed the following search strategy to identify the clinical evidence reported in the biomedical literature: in November 2012, we searched PubMed.gov, Ovid MEDLINE, Embase, and Cochrane Reviews (1980-present) for published randomized clinical trials, clinical studies, case series, and case reports related to the treatment of keloids. The search terms we utilized were ‘keloid(s)’ AND ‘laser’ OR ‘light-emitting diode’ OR ‘photodynamic therapy’ OR ‘intense pulsed light’ OR ‘low level light’ OR ‘phototherapy.’ Our search yielded 347 unique articles. Of these, 33 articles met our inclusion and exclusion criteria. We qualitatively conclude that laser and light-based treatment modalities may achieve favorable patient outcomes. Clinical studies using CO2 laser are more prevalent in current literature and a combination regimen may be an adequate ablative approach. Adding light-based treatments, such as LED phototherapy or photodynamic therapy, to laser treatment regimens may enhance patient outcomes. Lasers and other light-based technology have introduced new ways to manage keloids that may result in improved aesthetic and symptomatic outcomes and decreased keloid recurrence. PMID:24033440

  17. Recent Progress in Quantum Dot Based White Light-Emitting Devices.

    PubMed

    Su, Liang; Zhang, Xiaoyu; Zhang, Yu; Rogach, Andrey L

    2016-08-01

    Colloidal semiconductor quantum dots (QDs) have been widely employed as components of white light-emitting diodes (WLEDs) due to their excellent optical properties (highly saturated emission color, high luminescence quantum yield) as well as thermal and chemical stability. Much effort has been devoted to realize efficient QD-based WLEDs, including the synthesis of superior luminescent nanomaterials with excellent stabilities, and the design of advanced devices structures. In this paper, after introducing photometric parameters of the contemporary QD-based WLEDs, we highlight the recent progress in these devices grouped according to three main mechanisms for white light generation: optical excitation, direct charge carrier injection, and Förster resonance energy transfer. The methods to generate white light, the design of QD emitters and QD-based devices, as well as their fabrication techniques are considered, and the key scientific and technological challenges in the QD-based WLEDs are highlighted. Novel light-emitting materials for WLEDs such as carbon-based nanoparticles are also considered. PMID:27573394

  18. Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering

    NASA Astrophysics Data System (ADS)

    Jo, Youngju; Jung, Jaehwang; Lee, Jee Woong; Shin, Della; Park, Hyunjoo; Nam, Ki Tae; Park, Ji-Ho; Park, Yongkeun

    2014-05-01

    Two-dimensional angle-resolved light scattering maps of individual rod-shaped bacteria are measured at the single-cell level. Using quantitative phase imaging and Fourier transform light scattering techniques, the light scattering patterns of individual bacteria in four rod-shaped species (Bacillus subtilis, Lactobacillus casei, Synechococcus elongatus, and Escherichia coli) are measured with unprecedented sensitivity in a broad angular range from -70° to 70°. The measured light scattering patterns are analyzed along the two principal axes of rod-shaped bacteria in order to systematically investigate the species-specific characteristics of anisotropic light scattering. In addition, the cellular dry mass of individual bacteria is calculated and used to demonstrate that the cell-to-cell variations in light scattering within bacterial species is related to the cellular dry mass and growth.

  19. Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering

    PubMed Central

    Jo, YoungJu; Jung, JaeHwang; Lee, Jee Woong; Shin, Della; Park, HyunJoo; Nam, Ki Tae; Park, Ji-Ho; Park, YongKeun

    2014-01-01

    Two-dimensional angle-resolved light scattering maps of individual rod-shaped bacteria are measured at the single-cell level. Using quantitative phase imaging and Fourier transform light scattering techniques, the light scattering patterns of individual bacteria in four rod-shaped species (Bacillus subtilis, Lactobacillus casei, Synechococcus elongatus, and Escherichia coli) are measured with unprecedented sensitivity in a broad angular range from −70° to 70°. The measured light scattering patterns are analyzed along the two principal axes of rod-shaped bacteria in order to systematically investigate the species-specific characteristics of anisotropic light scattering. In addition, the cellular dry mass of individual bacteria is calculated and used to demonstrate that the cell-to-cell variations in light scattering within bacterial species is related to the cellular dry mass and growth. PMID:24867385

  20. Capacity analyze of WDM indoor visible light communication based on LED for standard illumination

    NASA Astrophysics Data System (ADS)

    Huang, Heqing; Tang, Yi; Cui, Lu; Zhu, Qingwei; Luo, Jiabin

    2015-08-01

    For indoor visible light communication (VLC) systems aim to achieve communication and illumination simultaneously, the channel capacity are significantly affected by illumination demands in actual scenarios. To enhance the system performance, the wavelength division multiplex (WDM) technique can be introduced. In this letter, we analyzed the demands of illuminance and chromaticity's influence on indoor WDM visible light communication system based on color light emitting diodes (LED). The spectra distribution, crosstalk and noise of WDM VLC system were analyzed and the relative optimal total channel capacity was obtained by optimizing the number of sub-channels and their intensity at standard illumination scenario. It's shown that by applying WDM technique, the total channel capacity of LED based VLC system can be about 4 times than the situation of single sub-channel, even with indoor illumination constraints. What's more, the system performance can be improved by adjusting appropriate number of sub-channels and their intensity accordingly.

  1. Indoor anti-occlusion visible light positioning systems based on particle filtering

    NASA Astrophysics Data System (ADS)

    Jiang, Meng; Huang, Zhitong; Li, Jianfeng; Zhang, Ruqi; Ji, Yuefeng

    2015-04-01

    As one of the most popular categories of mobile services, a rapid growth of indoor location-based services has been witnessed over the past decades. Indoor positioning methods based on Wi-Fi, radio-frequency identification or Bluetooth are widely commercialized; however, they have disadvantages such as low accuracy or high cost. An emerging method using visible light is under research recently. The existed visible light positioning (VLP) schemes using carrier allocation, time allocation and multiple receivers all have limitations. This paper presents a novel mechanism using particle filtering in VLP system. By this method no additional devices are needed and the occlusion problem in visible light would be alleviated which will effectively enhance the flexibility for indoor positioning.

  2. Detection of UV light based on chemically stimulated luminescence of crystal phosphors

    NASA Astrophysics Data System (ADS)

    Grankin, D. V.; Grankin, V. P.; Martysh, M. A.

    2016-06-01

    High-efficiency accommodation of heterogeneous-reaction energy via an electronic channel and the possibility of using this effect to design an ionizing (UV) radiation detector based on chemically stimulated luminescence have been investigated. Preliminary irradiation of a ZnS sample by UV light is found to cause a luminescence flash under subsequent exposure of the sample surface to a flux of hydrogen atoms. The flash intensity depends on the UV excitation level and increases by several orders of magnitude in comparison with an unirradiated sample. It is shown that a new method for detecting UV light using chemically stimulated luminescence of crystal phosphors accumulating light yield can be developed based on this effect.

  3. Photocapacitive light sensor based on metal-YMnO3-insulator-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Bogusz, A.; Choudhary, O. S.; Skorupa, I.; Bürger, D.; Lawerenz, A.; Lei, Y.; Zeng, H.; Abendroth, B.; Stöcker, H.; Schmidt, O. G.; Schmidt, H.

    2016-02-01

    Technology of light sensors, due to the wide range of applications, is a dynamically developing branch of both science and industry. This work presents concept of photodetectors based on a metal-ferroelectric-insulator-semiconductor, a structure which has not been thoroughly explored in the field of photodetectors. Functionality of the presented light sensor exploits the effects of photocapacitive phenomena, ferroelectric polarization, and charge trapping. This is accomplished by an interplay between polarization alignment, subsequent charge distribution, and charge trapping processes under given illumination condition and gate voltage. Change of capacitance serves as a read out parameter indicating the wavelength and intensity of the illuminating light. The operational principle of the proposed photocapacitive light sensor is demonstrated in terms of capacitance-voltage and capacitance-time characteristics of an Al/YMnO3/SiNx/p-Si structure exposed to green, red, and near infrared light. Obtained results are discussed in terms of optical properties of YMnO3 and SiNx layers contributing to the performance of photodetectors. Presented concept of light sensing might serve as the basis for the development of more advanced photodetectors.

  4. Highly Transparent, Visible-Light Photodetector Based on Oxide Semiconductors and Quantum Dots.

    PubMed

    Shin, Seung Won; Lee, Kwang-Ho; Park, Jin-Seong; Kang, Seong Jun

    2015-09-01

    Highly transparent phototransistors that can detect visible light have been fabricated by combining indium-gallium-zinc oxide (IGZO) and quantum dots (QDs). A wide-band-gap IGZO film was used as a transparent semiconducting channel, while small-band-gap QDs were adopted to absorb and convert visible light to an electrical signal. Typical IGZO thin-film transistors (TFTs) did not show a photocurrent with illumination of visible light. However, IGZO TFTs decorated with QDs showed enhanced photocurrent upon exposure to visible light. The device showed a responsivity of 1.35×10(4) A/W and an external quantum efficiency of 2.59×10(4) under illumination by a 635 nm laser. The origin of the increased photocurrent in the visible light was the small band gap of the QDs combined with the transparent IGZO films. Therefore, transparent phototransistors based on IGZO and QDs were fabricated and characterized in detail. The result is relevant for the development of highly transparent photodetectors that can detect visible light. PMID:26293387

  5. Moisture-insensitive optical fingerprint scanner based on polarization resolved in-finger scattered light.

    PubMed

    Back, Seon-Woo; Lee, Yong-Geon; Lee, Sang-Shin; Son, Geun-Sik

    2016-08-22

    A moisture-insensitive optical fingerprint scanner (FPS) that is based on polarization resolved in-finger light is proposed and realized. Incident visible light, which is selectively fed to a fingerprint sample via a polarization beam splitter (PBS), is deemed to be partially scattered backward by tissues associated with the skin of the finger. The backscattered light is mostly index-guided in the ridge comprising the fingerprint, which has a higher refractive index, and is drastically dispersed in the valley, which is typically filled with water or air and so has a lower index. However, when light reflects directly off the surface of the finger skin, it fundamentally prevents the scanned image from being determined. The proposed FPS produces bright and dark intensity patterns that are alternately created on the surface of the PBS and correspond to the ridges and valleys, respectively. Thus, this method can especially distinguish between a fake synthetic fingerprint and a genuine fingerprint due to its use of in-finger scattered light. The scanner has been rigorously designed by carrying out ray-optic simulations depending on the wavelength, with tissue-induced scattering taken into account. The device was constructed by incorporating a wire-grid type PBS in conjunction with visible LED sources, including blue, green and red. The scanner adopting a blue LED, which exhibits the strongest light scattering, resulted in the best fingerprint image, enabling enhanced fidelity under the wet and dry situations. Finally, a fake synthetic fingerprint could be successfully discriminated. PMID:27557199

  6. Tailoring the chirality of light emission with spherical Si-based antennas.

    PubMed

    Zambrana-Puyalto, Xavier; Bonod, Nicolas

    2016-05-21

    Chirality of light is of fundamental importance in several enabling technologies with growing applications in life sciences, chemistry and photodetection. Recently, some attention has been focused on chiral quantum emitters. Consequently, optical antennas which are able to tailor the chirality of light emission are needed. Spherical nanoresonators such as colloids are of particular interest to design optical antennas since they can be synthesized at a large scale and they exhibit good optical properties. Here, we show that these colloids can be used to tailor the chirality of a chiral emitter. To this purpose, we derive an analytic formalism to model the interaction between a chiral emitter and a spherical resonator. We then compare the performances of metallic and dielectric spherical antennas to tailor the chirality of light emission. It is seen that, due to their strong electric dipolar response, metallic spherical nanoparticles spoil the chirality of light emission by yielding achiral fields. In contrast, thanks to the combined excitation of electric and magnetic modes, dielectric Si-based particles feature the ability to inhibit or to boost the chirality of light emission. Finally, it is shown that dual modes in dielectric antennas preserve the chirality of light emission. PMID:27141982

  7. The numerical simulation and goniometric measurements of cells light scattering based on Mie theory

    NASA Astrophysics Data System (ADS)

    Lin, Xiaogang; Ye, Changbin; Zhu, Hao; Li, Wenchao; Wu, Jie

    2015-10-01

    Optical diagnostic technique, due to its rapid and non-invasive for the diagnosis diseases at the cellular level, can be performed in vivo and allow for real-time diagnosis. While light scattering method is capable of characterizing the structural properties of tissue at the cellular and subcellular scale. In this paper, the spherical models of cells light scattering were established based on Mie, and the distribution curves of scattering intensity in the range of 0~180 degrees were got to explore change rule of cells light scattering information at the molecular level. Also, a platform for experiments used to measure the light scattering information of cells was built to get the change rule of cells light scattering information in wide angular range. And the particle size distribution (PSD) of cells was got by the inversion algorithm. A comparative analysis between numerical simulation and goniometric measurements revealed that the forward-scattering and side-scattering were influenced by the particle size of cells and relative index of refraction between cells and surrounding media. It could also be concluded that it was necessary to get and analyze the light scattering information of larger scattering angle range, which may be related to the intracellular organelles and nucleus.

  8. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials.

    PubMed

    Magalhães Filho, T R; Weig, K M; Costa, M F; Werneck, M M; Barthem, R B; Costa Neto, C A

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8mm diameter and 2mm thickness were produced and polymerized by 20s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. PMID:27040223

  9. Tailoring the chirality of light emission with spherical Si-based antennas

    NASA Astrophysics Data System (ADS)

    Zambrana-Puyalto, Xavier; Bonod, Nicolas

    2016-05-01

    Chirality of light is of fundamental importance in several enabling technologies with growing applications in life sciences, chemistry and photodetection. Recently, some attention has been focused on chiral quantum emitters. Consequently, optical antennas which are able to tailor the chirality of light emission are needed. Spherical nanoresonators such as colloids are of particular interest to design optical antennas since they can be synthesized at a large scale and they exhibit good optical properties. Here, we show that these colloids can be used to tailor the chirality of a chiral emitter. To this purpose, we derive an analytic formalism to model the interaction between a chiral emitter and a spherical resonator. We then compare the performances of metallic and dielectric spherical antennas to tailor the chirality of light emission. It is seen that, due to their strong electric dipolar response, metallic spherical nanoparticles spoil the chirality of light emission by yielding achiral fields. In contrast, thanks to the combined excitation of electric and magnetic modes, dielectric Si-based particles feature the ability to inhibit or to boost the chirality of light emission. Finally, it is shown that dual modes in dielectric antennas preserve the chirality of light emission.

  10. Hybrid light transport model based bioluminescence tomography reconstruction for early gastric cancer detection

    NASA Astrophysics Data System (ADS)

    Chen, Xueli; Liang, Jimin; Hu, Hao; Qu, Xiaochao; Yang, Defu; Chen, Duofang; Zhu, Shouping; Tian, Jie

    2012-03-01

    Gastric cancer is the second cause of cancer-related death in the world, and it remains difficult to cure because it has been in late-stage once that is found. Early gastric cancer detection becomes an effective approach to decrease the gastric cancer mortality. Bioluminescence tomography (BLT) has been applied to detect early liver cancer and prostate cancer metastasis. However, the gastric cancer commonly originates from the gastric mucosa and grows outwards. The bioluminescent light will pass through a non-scattering region constructed by gastric pouch when it transports in tissues. Thus, the current BLT reconstruction algorithms based on the approximation model of radiative transfer equation are not optimal to handle this problem. To address the gastric cancer specific problem, this paper presents a novel reconstruction algorithm that uses a hybrid light transport model to describe the bioluminescent light propagation in tissues. The radiosity theory integrated with the diffusion equation to form the hybrid light transport model is utilized to describe light propagation in the non-scattering region. After the finite element discretization, the hybrid light transport model is converted into a minimization problem which fuses an l1 norm based regularization term to reveal the sparsity of bioluminescent source distribution. The performance of the reconstruction algorithm is first demonstrated with a digital mouse based simulation with the reconstruction error less than 1mm. An in situ gastric cancer-bearing nude mouse based experiment is then conducted. The primary result reveals the ability of the novel BLT reconstruction algorithm in early gastric cancer detection.

  11. Lighting: Green Light.

    ERIC Educational Resources Information Center

    Maniccia, Dorine

    2003-01-01

    Explains that by using sustainable (green) building practices, schools and universities can make their lighting systems more efficient, noting that embracing green design principles can help schools attract students. Discusses lighting-control technologies (occupancy sensing technology, daylighting technology, and scheduling based technologies),…

  12. Influence of light-curing mode on the cytotoxicity of resin-based surface sealants

    PubMed Central

    2014-01-01

    Background Surface sealants have been successfully used in the prevention of erosive tooth wear. However, when multiple tooth surfaces should be sealed, the light-curing procedure is very time-consuming. Therefore, the aim of this study was to investigate whether reduced light-curing time (while maintaining similar energy density) has an influence on resin-based surface sealant cytotoxicity. Methods Bovine dentine discs were treated as follows: group 1: untreated, groups 2–5: Seal&Protect and groups 6–9: experimental sealer. Groups 2 and 6 were light-cured (VALO LED light-curing device) for 40 s (1000 mW/cm2), groups 3 and 7 for 10 s (1000 mW/cm2), groups 4 and 8 for 7 s (1400 mW/cm2) and groups 5 and 9 for 3 s (3200 mW/cm2). Later, materials were extracted in culture medium for 24 h, and released lactate dehydrogenase (LDH) activity as a measure of cytotoxicity was determined photometrically after cells (dental pulp cells and gingival fibroblasts) were exposed to the extracts for 24 h. Three independent experiments, for both sample preparation and cytotoxicity testing, were performed. Results Overall, lowest cytotoxicity was observed for the unsealed control group. No significant influence of light-curing settings on the cytotoxicity was observed (p = 0.537 and 0.838 for pulp cells and gingival fibroblasts, respectively). No significant difference in the cytotoxicity of the two sealants was observed after light-curing with same light-curing settings (group 2 vs. 6, 3 vs. 7, 4 vs. 8 and 5 vs. 9: p > 0.05, respectively). Conclusions Shortening the light-curing time, while maintaining constant energy density, resulted in no higher cytotoxicity of the investigated sealants. PMID:24885810

  13. SearchLight: a freely available web-based quantitative spectral analysis tool (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Prabhat, Prashant; Peet, Michael; Erdogan, Turan

    2016-03-01

    In order to design a fluorescence experiment, typically the spectra of a fluorophore and of a filter set are overlaid on a single graph and the spectral overlap is evaluated intuitively. However, in a typical fluorescence imaging system the fluorophores and optical filters are not the only wavelength dependent variables - even the excitation light sources have been changing. For example, LED Light Engines may have a significantly different spectral response compared to the traditional metal-halide lamps. Therefore, for a more accurate assessment of fluorophore-to-filter-set compatibility, all sources of spectral variation should be taken into account simultaneously. Additionally, intuitive or qualitative evaluation of many spectra does not necessarily provide a realistic assessment of the system performance. "SearchLight" is a freely available web-based spectral plotting and analysis tool that can be used to address the need for accurate, quantitative spectral evaluation of fluorescence measurement systems. This tool is available at: http://searchlight.semrock.com/. Based on a detailed mathematical framework [1], SearchLight calculates signal, noise, and signal-to-noise ratio for multiple combinations of fluorophores, filter sets, light sources and detectors. SearchLight allows for qualitative and quantitative evaluation of the compatibility of filter sets with fluorophores, analysis of bleed-through, identification of optimized spectral edge locations for a set of filters under specific experimental conditions, and guidance regarding labeling protocols in multiplexing imaging assays. Entire SearchLight sessions can be shared with colleagues and collaborators and saved for future reference. [1] Anderson, N., Prabhat, P. and Erdogan, T., Spectral Modeling in Fluorescence Microscopy, http://www.semrock.com (2010).

  14. Exploring light rain in the trades as observed by satellite- and ground-based remote sensing

    NASA Astrophysics Data System (ADS)

    Burdanowitz, Jörg; Nuijens, Louise; Klepp, Christian; Stevens, Bjorn

    2013-04-01

    Satellite climatologies are usually expected to have difficulties to properly capture light rain from shallow marine clouds due to limited spatiotemporal resolution. In order to evaluate this, ground-based radar data from the RICO (Rain in Cumulus clouds over the Ocean) campaign is compared with rainfall estimates of three different satellite climatologies over the subtropical North Atlantic. In particular, these satellite products are the Hamburg Ocean Atmosphere Parameters and fluxes from Satellite data (HOAPS), the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and the Global Precipitation Climatology Project (GPCP). Different footprint sizes and temporal resolutions among the used satellite products require an up-scaling of the data to facilitate a fair comparison. Apart from that, recent micro rain radar data from the Barbados Cloud Observatory (BCO) is analyzed to further explore the nature of light rain over the subtropical ocean at a higher temporal resolution. In the trades, the dominance of light rain, i.e. low rain intensities, is ubiquitous as previously observed in several field studies. However, some of them even seem to be conservative in their estimation of light rain contribution to total rainfall according to recent BCO measurements. For active and passive satellite sensors the light rain detection still remains a challenging task. However, as main result, satellite products showed to be partly able to resolve light rain events from shallow clouds during RICO. HOAPS detects most and GPCP least of them while TMPA performs similarly to HOAPS. But along a mean trade-wind trajectory starting at the Canaries, TMPA detects less light rainfall compared to HOAPS, especially in the Caribbean region. Currently collected ship-based rain data sets will be used to further evaluate the performance of HOAPS and TMPA over larger areas of the subtropical Atlantic.

  15. Simplification of a light-based model for estimating final internode length in greenhouse cucumber canopies

    PubMed Central

    Kahlen, Katrin; Stützel, Hartmut

    2011-01-01

    Background and Aims Light quantity and quality affect internode lengths in cucumber (Cucumis sativus), whereby leaf area and the optical properties of the leaves mainly control light quality within a cucumber plant community. This modelling study aimed at providing a simple, non-destructive method to predict final internode lengths (FILs) using light quantity and leaf area data. Methods Several simplifications of a light quantity and quality sensitive model for estimating FILs in cucumber have been tested. The direct simplifications substitute the term for the red : far-red (R : FR) ratios, by a term for (a) the leaf area index (LAI, m2 m−2) or (b) partial LAI, the cumulative leaf area per m2 ground, where leaf area per m2 ground is accumulated from the top of each plant until a number, n, of leaves per plant is reached. The indirect simplifications estimate the input R : FR ratio based on partial leaf area and plant density. Key Results In all models, simulated FILs were in line with the measured FILs over various canopy architectures and light conditions, but the prediction quality varied. The indirect simplification based on leaf area of ten leaves revealed the best fit with measured data. Its prediction quality was even higher than of the original model. Conclusions This study showed that for vertically trained cucumber plants, leaf area data can substitute local light quality data for estimating FIL data. In unstressed canopies, leaf area over the upper ten ranks seems to represent the feedback of the growing architecture on internode elongation with respect to light quality. This highlights the role of this domain of leaves as the primary source for the specific R : FR signal controlling the final length of an internode and could therefore guide future research on up-scaling local processes to the crop level. PMID:21642233

  16. An azobenzene-based photochromic liquid crystalline amphiphile for a remote-controllable light shutter.

    PubMed

    Kim, Dae-Yoon; Lee, Sang-A; Kim, Huisu; Min Kim, Soo; Kim, Namil; Jeong, Kwang-Un

    2015-07-14

    By considering intramolecular conformations and intermolecular interactions, an azobenzene-based photochromic liquid crystalline amphiphile is synthesized for demonstrating a remote-controllable light shutter by the photo-induced isothermal phase transition between the highly ordered crystal phase and the isotropic liquid phase. PMID:26067781

  17. Light-induced resistive switching in silicon-based metal-insulator-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Tikhov, S. V.; Gorshkov, O. N.; Koryazhkina, M. N.; Antonov, I. N.; Kasatkin, A. P.

    2016-05-01

    We have studied light-induced resistive switching in metal-insulator-semiconductor structures based on silicon covered with a tunneling-thin SiO2 layer and nanometer-thick layer of antimony. The role of an insulator was played by yttria-stabilized zirconia.

  18. Methods for gully characterization in agricultural croplands using ground-based light detection and ranging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gullies constitute an important source of sediment from agricultural fields. In order to properly understand gully formation and evolution over time, as well as, sediment yield, detailed topographic representations of agricultural fields are required. New technologies such as ground-based Light Dete...

  19. Calibration method for line-structured light vision sensor based on a single ball target

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Li, Xiaojing; Li, Fengjiao; Zhang, Guangjun

    2015-06-01

    Profile feature imaging for ball targets is unaffected by the position of the target. On this basis, this study proposes a method for the rapid calibration of a line-structured light system based on a single ball target. The calibration process is as follows: the ball target is placed at least once and is illuminated by the light stripe from the laser projector. The vision sensor captures an image of this target. The laser stripe and profile images of the ball target are then extracted. Based on these extracted features and the optical centre of the camera, the spatial equations of the ball target and a cone profile are calculated. The plane on which the intersection line of the two equations lies is the light plane. Finally, the optimal solution for the light plane equation is obtained through nonlinear optimization under a maximum likelihood criterion. The validity of the proposed method is demonstrated through simulation and physical experiments. In the physical experiment, the field of view of the structured light vision sensor measures 300 mm×250 mm. A calibration accuracy of 0.04 mm can be achieved using the proposed method. This accuracy is comparable to that of the calibration method which utilizes planar targets.

  20. Development of White-Light Emitting Active Layers in Nitride Based Heterostructures for Phosphorless Solid State Lighting

    SciTech Connect

    Jan Talbot; Kailash Mishra

    2007-12-31

    This report provides a summary of research activities carried out at the University of California, San Diego and Central Research of OSRAM SYLVANIA in Beverly, MA partially supported by a research contract from US Department of Energy, DE-FC26-04NT422274. The main objective of this project was to develop III-V nitrides activated by rare earth ions, RE{sup 3+}, which could eliminate the need for phosphors in nitride-based solid state light sources. The main idea was to convert electron-hole pairs injected into the active layer in a LED die to white light directly through transitions within the energy levels of the 4f{sup n}-manifold of RE{sup 3+}. We focused on the following materials: Eu{sup 3+}(red), Tb{sup 3+}(green), Er{sup 3+}(green), Dy{sup 3+}(yellow) and Tm{sup 3+}(blue) in AlN, GaN and alloys of AlN and GaN. Our strategy was to explore candidate materials in powder form first, and then study their behavior in thin films. Thin films of these materials were to be deposited on sapphire substrates using pulsed laser deposition (PLD) and metal organic vapor phase epitaxy (MOVPE). The photo- and cathode-luminescence measurements of these materials were used to investigate their suitability for white light generation. The project proceeded along this route with minor modifications needed to produce better materials and to expedite our progress towards the final goal. The project made the following accomplishments: (1) red emission from Eu{sup 3+}, green from Tb{sup 3+}, yellow from Dy{sup 3+} and blue from Tm{sup 3+} in AlN powders; (2) red emission from Eu{sup 3+} and green emission from Tb{sup 3+} in GaN powder; (3) red emission from Eu{sup 3+} in alloys of GaN and AlN; (4) green emission from Tb{sup 3+} in GaN thin films by PLD; (5) red emission from Eu{sup 3+} and Tb{sup 3+} in GaN thin films deposited by MOVPE; (6) energy transfer from host to RE{sup 3+}; (7) energy transfer from Tb{sup 3+} to Eu{sup 3+} in AlN powders; (8) emission from AlN powder samples

  1. Optical asymmetric cryptography based on elliptical polarized light linear truncation and a numerical reconstruction technique.

    PubMed

    Lin, Chao; Shen, Xueju; Wang, Zhisong; Zhao, Cheng

    2014-06-20

    We demonstrate a novel optical asymmetric cryptosystem based on the principle of elliptical polarized light linear truncation and a numerical reconstruction technique. The device of an array of linear polarizers is introduced to achieve linear truncation on the spatially resolved elliptical polarization distribution during image encryption. This encoding process can be characterized as confusion-based optical cryptography that involves no Fourier lens and diffusion operation. Based on the Jones matrix formalism, the intensity transmittance for this truncation is deduced to perform elliptical polarized light reconstruction based on two intensity measurements. Use of a quick response code makes the proposed cryptosystem practical, with versatile key sensitivity and fault tolerance. Both simulation and preliminary experimental results that support theoretical analysis are presented. An analysis of the resistance of the proposed method on a known public key attack is also provided. PMID:24979424

  2. Enhanced light emission in vertical-structured GaN-based light-emitting diodes with trench etching and arrayed p-electrodes

    NASA Astrophysics Data System (ADS)

    Lin, Tseng-Hsing; Wang, Shui-Jinn; Tu, Yung-Chun; Hung, Chien-Hsiung; Lin, Che-An; Lin, Yung-Cheng; You, Zong-Sian

    2015-05-01

    We investigate the effect of trench etching and arrayed p-electrodes in improving current spreading and the efficiency of light extraction of GaN-based vertical-structured light-emitting diodes (VLEDs). Both simulated and experimental results on the uniformities of current distribution and light emission are presented and discussed. For a 2 × 2 array VLED with a die size of 1020 × 1020 μm2, enhancements in light output power by 0.38% (6.03%) and wall-plug efficiency by 2.79% (2.32%) at 364.4 mA/mm2 (728.9 mA/mm2) as compared with that of regular VLED are achieved experimentally, which are attributed to improved current spreading from the arrayed p-electrode and trench designs as well as enhanced light emission from the trench region.

  3. Phase grating wavefront curvature sensor based on liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Chen, Bo; Li, Xiaoyang; Yang, Xu

    2015-08-01

    The phase grating wavefront curvature sensor based on liquid crystal spatial light modulator is introduced. A close-loop phase retrieval method based on Eigen functions of Laplacian is proposed, and its accuracy and efficiency are analyzed through numerical experiments of atmospheric phase retrieval. The results show that the close-loop phase retrieval method has a high accuracy. Moreover, it is stable regardless of modal cross coupling.

  4. Polarized electroabsorption spectra and light soaking of solar cells based on hydrogenated amorphous silicon

    NASA Astrophysics Data System (ADS)

    Jiang, Lin; Wang, Qi; Schiff, E. A.; Guha, S.; Yang, J.

    1998-03-01

    We present grazing-incidence measurements of polarized electroabsorption spectra in p-i-n solar cells based on hydrogenated amorphous silicon (a-Si:H). We find a significantly stronger polarization dependence in the present measurements compared with earlier work based on electroabsorption detected using coplanar electrodes on a-Si:H thin films. We do not find any significant dependence of the polarized electroabsorption upon light soaking, although this effect was found in previous work with coplanar electrodes.

  5. Study of SBS slow light based on nano-material doped fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Lang, Pei-Lin; Zhang, Ru

    2009-03-01

    A novel optical fiber doped with nano material InP is manufactured by the modified chemical vapor deposition (MCVD). The slow light based on stimulated Brillouin scattering (SBS) in the optical fiber is studied. The results show that a time delay of ˜738 ps is obtained when the input Stokes pulse is 900 ps(FWHM) and the SBS gain is ˜15. It shows that a considerable time delay and an amplification of the input light can be achieved by this novel optical fiber.

  6. Optimal control of light storage in atomic ensemble based on photon echoes

    NASA Astrophysics Data System (ADS)

    Wu, Tingwan; Chen, Qinzhi

    2009-11-01

    This paper presents a simple quantum memory method for efficient storage and retrieve of light. The technique is based on the principle of controlled reversible inhomogeneous broadening for which the information of the quantum state light is imprinted in a two-level atoms ensemble and recalled by flipping the external nonuniform electric field. In present work, the induced Stark shift varied linearly with position, and a numerical analysis for this protocol has been studied. It shows that the storage efficiency can nearly reach 100% with a large enough optical depth, and the optimal broadening for a given pulse width is also analyzed.

  7. Panorama of new generation of accelerator based short wavelength coherent light sources

    NASA Astrophysics Data System (ADS)

    Couprie, M. E.

    2015-12-01

    The newly developed intense short wavelength light sources (from Extreme Ultra-Violet (EUV) to X-rays) have open the path to the exploration of matter for revealing structures and electronic processes and for following their evolution in time. After drawing the panorama of existing accelerator based short wavelength light sources, the new trends of evolution of short wavelengths FEL are described, with some illustrations with the example of the LUNEX5 (free electron Laser a New accelerator for the Exploitation of X-ray radiation of 5th generation) demonstrator project of advanced compact Free Electron Laser.

  8. Shaping of spherical light intensity based on the interference of tightly focused beams with different polarizations

    NASA Astrophysics Data System (ADS)

    Khonina, Svetlana N.; Ustinov, Andrey V.; Volotovsky, Sergey G.

    2014-08-01

    We consider the shaping of spherical intensity distributions based on the interference of counter-propagating tightly focused vortex beams with different polarizations. The formation of 3D distributions is performed using a simple method of optimization of the width and position of the single annular aperture. The optimum parameters for the narrow aperture are calculated analytically. In addition the wide aperture parameters are numerically adjusted. It is shown that depending on the polarization, the additional vortex phase and/or phase shift in the beams allow to form either solid light balls or light spheres of subwavelength radius. They consist of the various electric field components.

  9. Self-Action of Light Fields in Waveguide Photon Structures Based on Electro-Optic Crystals

    NASA Astrophysics Data System (ADS)

    Shandarov, V. M.

    2016-02-01

    Special features of spatial self-action of light fields in nonlinear optical photonic waveguide structures formed in strontium barium niobate and lithium niobate electro-optic crystals are discussed. The main methods of forming such structures including photorefractive waveguide elements and systems are briefly considered. The formation of spatial optical solitons in planar waveguides based on lithium niobate and strontium barium niobate crystals as well as in one-dimensional photonic lattices in lithium niobate is demonstrated experimentally for light beams of microwatt power. In regimes of spatial optical solitons, channel optical waveguides are formed not only in the planar waveguides, but also in the volume of photorefractive lithium niobate.

  10. Physics Holographic Recording Device Based on LCoS Spatial Light Modulator

    NASA Astrophysics Data System (ADS)

    Bulanovs, A.; Tamanis, E.; Mihailova, I.

    2011-01-01

    A PC-controlled holographic recording device has been developed in which a LC-R-2500 Spatial Light Modulator (SLM) based on reflective Liquid Crystal on Silicone (LCoS) display was used. The device allows the amplitude and phase modu-lation of coherent light wave fronts. In the optical scheme, a DPSS (Diode Pumped Solid State) laser with nanosecond pulse duration and wavelength 532 nm was applied. The holographic recording was made and tested in the amplitude and phase wave front modulation modes on a chalcogenide semiconductor photoresist As40S15S45. The experimental results are presented.

  11. 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.

  12. Examination of light distribution from sol-gel based applicators for interstitial laser therapy

    NASA Astrophysics Data System (ADS)

    Hołowacz, I.; Ulatowska-Jarża, A.; Podbielska, H.; Garbaczewska, I.

    2006-02-01

    We describe here the construction of sol-gel based applicators for interstitial thermotheraphy. The silica sol-gel coatings were prepared from silicate precursor TEOS (tetraethylorthosilicate) mixed with ethyl alcohol in acid catalyzed hydrolysis. The matrices were produced with various ratios R=5, 10, 20, 32, 50, whereas R denotes the number of solvent molds (here ethanol) to the number of TEOS moles. The spatial light intensity distribution was examined in order to find out the influence of R factor on the light distribution shape. It was shows that the most homogeneous patterns are observed for sol-gel coatings with R factors equal 10 and 20.

  13. A Planar, Chip-Based, Dual-Beam Refractometer Using an Integrated Organic Light Emitting Diode (OLED) Light Source and Organic Photovoltaic (OPV) Detectors

    PubMed Central

    Ratcliff, Erin L.; Veneman, P. Alex; Simmonds, Adam; Zacher, Brian; Huebner, Daniel

    2010-01-01

    We present a simple chip-based refractometer with a central organic light emitting diode (OLED) light source and two opposed organic photovoltaic (OPV) detectors on an internal reflection element (IRE) substrate, creating a true dual-beam sensor platform. For first-generation platforms, we demonstrate the use of a single heterojunction OLED based on electroluminescence emission from an Alq3/TPD heterojunction (tris-(8-hydroxyquinoline)aluminum/N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine) and light detection with planar heterojunction pentacene/C60 OPVs. The sensor utilizes the considerable fraction of emitted light from conventional thin film OLEDs that is coupled into guided modes in the IRE instead of into the forward (display) direction. A ray-optics description is used to describe light throughput and efficiency-limiting factors for light coupling from the OLED into the substrate modes, light traversing through the IRE substrate, and light coupling into the OPV detectors. The arrangement of the OLED at the center of the chip provides for two sensing regions, a “sample” and “reference” channel, with detection of light by independent OPV detectors. This configuration allows for normalization of the sensor response against fluctuations in OLED light output, stability, and local fluctuations (temperature) which might influence sensor response. The dual beam configuration permits significantly enhanced sensitivity to refractive index changes relative to single-beam protocols, and is easily integrated into a field-portable instrumentation package. Changes in refractive index (ΔR.I.) between 10−2 and 10−3 R.I. units could be detected for single channel operation, with sensitivity increased to ΔR.I. ≈ 10−4 units when the dual beam configuration is employed. PMID:20218580

  14. Improved light extraction of nitride-based flip-chip light-emitting diodes by forming air voids on Ar-implanted sapphire substrate

    NASA Astrophysics Data System (ADS)

    Yeh, Yu-Hsiang; Sheu, Jinn-Kong; Lee, Ming-Lun; Chen, Po-Cheng; Yang, Yu-Chen; Yen, Cheng-Hsiung; Lai, Wei-Chih

    2014-09-01

    GaN-based flip-chip light emitting diodes (FC-LEDs) with embedded air voids grown on a selective-area Arimplanted AlN/sapphire (AIAS) substrate was demonstrated in this study. The proposed FC LED with an embedded light scattering layer can destroy the light interference and thereby increase the LEE of GaN-based flip-chip LEDs. The epitaxial layers grown on Ar-implanted regions exhibited lower growth rates compared with those grown on implantation-free regions. Accordingly, air voids formed over the implanted regions after merging laterally grown GaN facet fronts. The light-output power of LEDs grown on AIAS was greater than that of LEDs grown on implantation free sapphire substrates. At an injection current of 700 mA, the output power of LEDs grown on AIAS was enhanced by 20% compared with those of LEDs without embedded air voids. The increase in output power was mainly attributed to the scattering of light around the air voids, which increased the probability of photons escaping from the LEDs. This study on FC LEDs with embedded light-scattering layer highlights the potential application of these LEDs as an alternative to conventional patterned sapphire substrates for improving the LEE of GaN/sapphire-based LEDs. Based on ray tracing simulation, if the height and the width of bottom of gaps were increased to 3 μm, the Lop could be enhanced over 60%.

  15. Light-emitting diode-based multiwavelength diffuse optical tomography system guided by ultrasound

    PubMed Central

    Yuan, Guangqian; Alqasemi, Umar; Chen, Aaron; Yang, Yi; Zhu, Quing

    2014-01-01

    Abstract. Laser diodes are widely used in diffuse optical tomography (DOT) systems but are typically expensive and fragile, while light-emitting diodes (LEDs) are cheaper and are also available in the near-infrared (NIR) range with adequate output power for imaging deeply seated targets. In this study, we introduce a new low-cost DOT system using LEDs of four wavelengths in the NIR spectrum as light sources. The LEDs were modulated at 20 kHz to avoid ambient light. The LEDs were distributed on a hand-held probe and a printed circuit board was mounted at the back of the probe to separately provide switching and driving current to each LED. Ten optical fibers were used to couple the reflected light to 10 parallel photomultiplier tube detectors. A commercial ultrasound system provided simultaneous images of target location and size to guide the image reconstruction. A frequency-domain (FD) laser-diode-based system with ultrasound guidance was also used to compare the results obtained from those of the LED-based system. Results of absorbers embedded in intralipid and inhomogeneous tissue phantoms have demonstrated that the LED-based system provides a comparable quantification accuracy of targets to the FD system and has the potential to image deep targets such as breast lesions. PMID:25473884

  16. Three-dimensional vision inspection based on structured light projection and neurocalibration

    NASA Astrophysics Data System (ADS)

    Xie, Kai; Liu, Wan Yu; Pu, Zhao-Bang

    2007-02-01

    Structured light three dimensional (3D) vision inspection is an increasing common means for acquiring three dimensional geometry of objects due to its short acquisition time, low cost and its robustness in the presence of ambient light. In this paper, we proposed a method of structure light 3D vision inspection based on neurocalibration. First, the principle of linear structured light 3D vision inspection and Back Propagation (BP) neural network are described. Second, a calibration method based on BP neural network without any knowledge of 3D object and computer vision is proposed, which has the advantage of resolving the system nonlinearity. The feasibility of the approach is based on the fact that multilayer feed-forward networks are capable of approximating an arbitrary continuous nonlinear function and solving least squares problem. The network consists of an input layer and an output layer, with a hidden layer in between. The input neurons denote the coordinates of 2D image pixels and the output neurons denote the corresponding coordinates of 3D world points. At the end, the accuracy and the robustness of the proposed method are tested by experiments. It has been shown that the proposed method is simple, robust and effective.

  17. Light-emitting diode-based multiwavelength diffuse optical tomography system guided by ultrasound.

    PubMed

    Yuan, Guangqian; Alqasemi, Umar; Chen, Aaron; Yang, Yi; Zhu, Quing

    2014-12-01

    Laser diodes are widely used in diffuse optical tomography (DOT) systems but are typically expensive and fragile, while light-emitting diodes (LEDs) are cheaper and are also available in the near-infrared (NIR) range with adequate output power for imaging deeply seated targets. In this study, we introduce a new low-cost DOT system using LEDs of four wavelengths in the NIR spectrum as light sources. The LEDs were modulated at 20 kHz to avoid ambient light. The LEDs were distributed on a hand-held probe and a printed circuit board was mounted at the back of the probe to separately provide switching and driving current to each LED. Ten optical fibers were used to couple the reflected light to 10 parallel photomultiplier tube detectors. A commercial ultrasound system provided simultaneous images of target location and size to guide the image reconstruction. A frequency-domain (FD) laser-diode-based system with ultrasound guidance was also used to compare the results obtained from those of the LED-based system. Results of absorbers embedded in intralipid and inhomogeneous tissue phantoms have demonstrated that the LED-based system provides a comparable quantification accuracy of targets to the FD system and has the potential to image deep targets such as breast lesions. PMID:25473884

  18. A fast multispectral light synthesiser based on LEDs and a diffraction grating

    PubMed Central

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-01-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy. PMID:27558155

  19. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    NASA Astrophysics Data System (ADS)

    Dai, Qi; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-02-01

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330-390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  20. A fast multispectral light synthesiser based on LEDs and a diffraction grating.

    PubMed

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-01-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy. PMID:27558155

  1. Light-Harvesting Systems Based on Organic Nanocrystals To Mimic Chlorosomes.

    PubMed

    Chen, Peng-Zhong; Weng, Yu-Xiang; Niu, Li-Ya; Chen, Yu-Zhe; Wu, Li-Zhu; Tung, Chen-Ho; Yang, Qing-Zheng

    2016-02-18

    We report the first highly efficient artificial light-harvesting systems based on nanocrystals of difluoroboron chromophores to mimic the chlorosomes, one of the most efficient light-harvesting systems found in green photosynthetic bacteria. Uniform nanocrystals with controlled donor/acceptor ratios were prepared by simple coassembly of the donors and acceptors in water. The light-harvesting system funneled the excitation energy collected by a thousand donor chromophores to a single acceptor. The well-defined spatial organization of individual chromophores in the nanocrystals enabled an energy transfer efficiency of 95 %, even at a donor/acceptor ratio as high as 1000:1, and a significant fluorescence of the acceptor was observed up to donor/acceptor ratios of 200 000:1. PMID:26799735

  2. All-optical photochromic spatial light modulators based on photoinduced electron transfer in rigid matrices

    NASA Technical Reports Server (NTRS)

    Beratan, David N. (Inventor); Perry, Joseph W. (Inventor)

    1991-01-01

    A single material (not a multi-element structure) spatial light modulator may be written to, as well as read out from, using light. The device has tailorable rise and hold times dependent on the composition and concentration of the molecular species used as the active components. The spatial resolution of this device is limited only by light diffraction as in volume holograms. The device may function as a two-dimensional mask (transmission or reflection) or as a three-dimensional volume holographic medium. This device, based on optically-induced electron transfer, is able to perform incoherent to coherent image conversion or wavelength conversion over a wide spectral range (ultraviolet, visible, or near-infrared regions).

  3. Mechanisms of ultrasonic modulation of multiply scattered incoherent light based on diffusion theory

    NASA Astrophysics Data System (ADS)

    Zhu, Li-Li; Li, Hui

    2015-01-01

    An analytic equation interpreting the intensity of ultrasound-modulated scattering light is derived, based on diffusion theory and previous explanations of the intensity modulation mechanism. Furthermore, an experiment of ultrasonic modulation of incoherent light in a scattering medium is developed. This analytical model agrees well with experimental results, which confirms the validity of the proposed intensity modulation mechanism. The model supplements the existing research on the ultrasonic modulation mechanism of scattering light. Project supported by the National Natural Science Foundation of China (Grant No. 61178089), the Key Program of Science and Technology of Fujian Province, China (Grant No. 2011Y0019), and the Educational Department of Fujian Province, China (Grant No. JA13074).

  4. Vehicle-mounted real-time digital voice communication system based on visible light communication

    NASA Astrophysics Data System (ADS)

    Yan, Qiurong; Gu, Xiuxiu; Chen, Du; Wang, Hui; Huang, Hua; Chen, Xuxin; Cao, Qingshan; Liu, Hongqing

    2015-11-01

    Based on the phenomenon that more and more cars use LED for lighting and the current rise of visible light communication technology, this paper proposes a vehicle real-time voice communication system with high reliability on the basis of visible light communication for verification. The paper introduces the design of digital audio collection and output module, On-Off Keying (OOK) modulation and demodulation, Reed-Solomon encoding and decoding module, array LEDs emission and the module of PIN receiving signals. The LED lamp frequency response, communication distance, error rate and other parameters are tested and calibrated. The digital audio real-time communication system's receiving speed is 500Kbps when the communication distance is 3.9 meters.

  5. Beam-based model of broad-band impedance of the Diamond Light Source

    NASA Astrophysics Data System (ADS)

    Smaluk, Victor; Martin, Ian; Fielder, Richard; Bartolini, Riccardo

    2015-06-01

    In an electron storage ring, the interaction between a single-bunch beam and a vacuum chamber impedance affects the beam parameters, which can be measured rather precisely. So we can develop beam-based numerical models of longitudinal and transverse impedances. At the Diamond Light Source (DLS) to get the model parameters, a set of measured data has been used including current-dependent shift of betatron tunes and synchronous phase, chromatic damping rates, and bunch lengthening. A matlab code for multiparticle tracking has been developed. The tracking results and analytical estimations are quite consistent with the measured data. Since Diamond has the shortest natural bunch length among all light sources in standard operation, the studies of collective effects with short bunches are relevant to many facilities including next generation of light sources.

  6. Visible Light Image-Based Method for Sugar Content Classification of Citrus

    PubMed Central

    Wang, Xuefeng; Wu, Chunyan; Hirafuji, Masayuki

    2016-01-01

    Visible light imaging of citrus fruit from Mie Prefecture of Japan was performed to determine whether an algorithm could be developed to predict the sugar content. This nondestructive classification showed that the accurate segmentation of different images can be realized by a correlation analysis based on the threshold value of the coefficient of determination. There is an obvious correlation between the sugar content of citrus fruit and certain parameters of the color images. The selected image parameters were connected by addition algorithm. The sugar content of citrus fruit can be predicted by the dummy variable method. The results showed that the small but orange citrus fruits often have a high sugar content. The study shows that it is possible to predict the sugar content of citrus fruit and to perform a classification of the sugar content using light in the visible spectrum and without the need for an additional light source. PMID:26811935

  7. Gap plasmon-based metasurfaces for total control of reflected light

    PubMed Central

    Pors, Anders; Albrektsen, Ole; Radko, Ilya P.; Bozhevolnyi, Sergey I.

    2013-01-01

    In the quest to miniaturise photonics, it is of paramount importance to control light at the nanoscale. We reveal the main physical mechanism responsible for operation of gap plasmon-based gradient metasurfaces, comprising a periodic arrangement of metal nanobricks, and suggest that two degrees of freedom in the nanobrick geometry allow one to independently control the reflection phases of orthogonal light polarisations. We demonstrate, both theoretically and experimentally, how orthogonal linear polarisations of light at wavelengths close to 800 nm can be manipulated independently, efficiently and in a broad wavelength range by realising polarisation beam splitters and polarisation-independent beam steering, showing at the same time the robustness of metasurface designs towards fabrication tolerances. The presented approach establishes a new class of compact optical components, viz., plasmonic metasurfaces with controlled gradient birefringence, with no dielectric counterparts. It can straightforwardly be adapted to realise new optical components with hitherto inaccessible functionalities. PMID:23831621

  8. Visible Light Image-Based Method for Sugar Content Classification of Citrus.

    PubMed

    Wang, Xuefeng; Wu, Chunyan; Hirafuji, Masayuki

    2016-01-01

    Visible light imaging of citrus fruit from Mie Prefecture of Japan was performed to determine whether an algorithm could be developed to predict the sugar content. This nondestructive classification showed that the accurate segmentation of different images can be realized by a correlation analysis based on the threshold value of the coefficient of determination. There is an obvious correlation between the sugar content of citrus fruit and certain parameters of the color images. The selected image parameters were connected by addition algorithm. The sugar content of citrus fruit can be predicted by the dummy variable method. The results showed that the small but orange citrus fruits often have a high sugar content. The study shows that it is possible to predict the sugar content of citrus fruit and to perform a classification of the sugar content using light in the visible spectrum and without the need for an additional light source. PMID:26811935

  9. Nanocellulose-based Translucent Diffuser for Optoelectronic Device Applications with Dramatic Improvement of Light Coupling.

    PubMed

    Wu, Wei; Tassi, Nancy G; Zhu, Hongli; Fang, Zhiqiang; Hu, Liangbing

    2015-12-01

    Nanocellulose is a biogenerated and biorenewable organic material. Using a process based on 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/NaClO/NaBr system, a highly translucent and light-diffusive film consisting of many layers of nanocellulose fibers and wood pulp microfibers was made. The film demonstrates a combination of large optical transmittance of ∼90% and tunable diffuse transmission of up to ∼78% across the visible and near-infrared spectra. The detailed characterizations of the film indicate the combination of high optical transmittance and haze is due to the film's large packing density and microstructured surface. The superior optical properties make the film a translucent light diffuser and applicable for improving the efficiencies of optoelectronic devices such as thin-film silicon solar cells and organic light-emitting devices. PMID:26572592

  10. Tunable broadband light coupler based on two parallel all-fiber acousto-optic tunable filters.

    PubMed

    Zhang, Wending; Huang, Ligang; Gao, Feng; Bo, Fang; Zhang, Guoquan; Xu, Jingjun

    2013-07-15

    Based on the evanescent-field coupling between the cladding modes of two adjacent and parallel all-fiber acousto-optic tunable filters, tunable broadband light coupling with relatively uniform insertion loss of trapping spectrum was achieved. In the experiments, a wide spectral tuning range from 1490 nm to 1610 nm, covering the whole C- and L-band and parts of S-bands, was demonstrated with a wavelength tunability slope of -0.72 nm/kHz. The insertion loss of the trapping spectrum was uniform (around -5.0 dB, which can be improved with a longer evanescent-field coupling length) within the whole tuning spectral range. Such a light coupling structure would be useful in tunable broadband light coupler and broadband optical fiber add/drop multiplexer for applications in coarse wavelength division multiplexing systems. PMID:23938513

  11. Output blue light evaluation for phosphor based smart white LED wafer level packages.

    PubMed

    Kolahdouz, Zahra; Rostamian, Ali; Kolahdouz, Mohammadreza; Ma, Teng; van Zeijl, Henk; Zhang, Kouchi

    2016-02-22

    This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The maximum responsivity at 480 nm is matched with the target blue LED illumination. The designed structure have better responsivity compared to simple photodiode structure due to reducing the effect of dead layer formation close to the surface because of implantation. It has also a two-fold increase in the responsivity and quantum efficiency compared to previously similar published sensors. PMID:26906985

  12. Efficient ZnO-based visible-light-driven photocatalyst for antibacterial applications.

    PubMed

    Kumar, Raju; Anandan, Srinivasan; Hembram, Kaliyan; Rao, Tata Narasinga

    2014-08-13

    Herein, we report the development of a ZnO-based visible-light-driven photocatalyst by interfacial charge transfer process for the inactivation of pathogens under visible-light illumination. Surface modification by a cocatalyst on ZnO, prepared by flame spray pyrolysis process is carried out to induce the visible-light absorption in ZnO. Optical studies showed that surface modification of Cu(2+) induces the visible-light absorption in ZnO by interfacial charge transfer between ZnO and surface Cu(2+) ions upon light irradiation. The photocatalytic efficiency of pure and modified ZnO is evaluated for the inactivation of pathogens and the decomposition of methylene blue under visible-light illumination. The antibacterial activity of Cu(2+)-ZnO is several orders higher than pure ZnO and commercial Degussa-P25 and comparable with Cu(2+)-TiO2. Cu(2+)-ZnO nanorods show better photocatalytic activity than Cu(2+)-ZnO nanosphere, which is attributed to high surface area to volume ratio of former than later. The holes generated in the valence band and the Cu(1+) species generated during the interfacial charge transfer process may attribute for the inactivation of bacteria, whereas the strong oxidation power of hole is responsible for the decomposition of methylene blue. Besides the advantage of Cu(2+)-modified ZnO for visible-light-assisted photocatalytic applications, the method (FSP) used for the synthesis of ZnO in the present study is attractive for commercial application because the process has potential for the production of large quantities (2-3 kg/h) of semiconductors. PMID:25029041

  13. Angular distribution of polarized spontaneous emissions and its effect on light extraction behavior in InGaN-based light emitting diodes

    SciTech Connect

    Yuan, Gangcheng; Chen, Xinjuan; Yu, Tongjun Lu, Huimin; Chen, Zhizhong; Kang, Xiangning; Wu, Jiejun; Zhang, Guoyi

    2014-03-07

    Angular intensity distributions of differently polarized light sources in multiple quantum wells (MQWs) and their effects on extraction behavior of spontaneous emission from light emitting diode (LED) chips have been studied. Theoretical calculation based on k·p approximation, ray tracing simulation and angular electroluminescence measurement were applied in this work. It is found that the electron-hole recombination in the InGaN MQWs produces a spherical distribution of an s-polarized source and a dumbbell-shaped p-polarized source. Light rays from different polarized sources experience different extraction processes, determining the polarization degree of electro-luminescence and extraction efficiency of LEDs.

  14. Portable paper-based device for quantitative colorimetric assays relying on light reflectance principle.

    PubMed

    Li, Bowei; Fu, Longwen; Zhang, Wei; Feng, Weiwei; Chen, Lingxin

    2014-04-01

    This paper presents a novel paper-based analytical device based on the colorimetric paper assays through its light reflectance. The device is portable, low cost (<20 dollars), and lightweight (only 176 g) that is available to assess the cost-effectiveness and appropriateness of the original health care or on-site detection information. Based on the light reflectance principle, the signal can be obtained directly, stably and user-friendly in our device. We demonstrated the utility and broad applicability of this technique with measurements of different biological and pollution target samples (BSA, glucose, Fe, and nitrite). Moreover, the real samples of Fe (II) and nitrite in the local tap water were successfully analyzed, and compared with the standard UV absorption method, the quantitative results showed good performance, reproducibility, and reliability. This device could provide quantitative information very conveniently and show great potential to broad fields of resource-limited analysis, medical diagnostics, and on-site environmental detection. PMID:24375226

  15. Iron-Based Metal-Organic Frameworks as Catalysts for Visible Light-Driven Water Oxidation.

    PubMed

    Chi, Le; Xu, Qian; Liang, Xiaoyu; Wang, Jide; Su, Xintai

    2016-03-01

    The development of earth-abundant, active, and stable catalysts is important for solar energy conversion. Metal-organic frameworks (MOFs) have been viewed as a promising class of porous materials, which may have innovative application in photocatalysis. In this paper, three types of Fe-based MOFs and their aminofunctionalized derivatives have been fabricated and systematically studied as water oxidation catalysts (WOCs) for oxygen evolution under visible light irradiation. MIL-101(Fe) possesses a higher current density and earlier onset potential and exhibits excellent visible light-driven oxygen evolution activity than the other Fe-based catalysts. It speeds up the oxygen evolution reaction rate with the higher initial turnover frequencies value of 0.10 s(-1) . Our study demonstrates that Fe-based MOFs as efficient WOCs are promising candidates for photocatalytic water oxidation process. PMID:26756919

  16. Contrast enhancement based on entropy and reflectance analysis for surgical lighting

    NASA Astrophysics Data System (ADS)

    Shen, Junfei; Wang, Huihui; Wu, Yisi; Li, An; Chen, Chi; Zheng, Zhenrong

    2015-07-01

    Light-emitting diode (LED) is the neotype surgical lighting device as an inexpensive and color-variable illumination. A methodology was designed to value the quality of surgical lighting and used to develop an operation lamp with LEDs enhancing the biological contrast. We assembled a modular array of Phillips LEDs as illumination. In the initial experiment, images of porcine heart were carried out in several LED environments and analyzed quantitatively to assess the function of these LEDs in contrast enhancement. Then we measured the reflectance spectrums of blood, fat and other tissues to obtain the spectral comparison. Based on the result, new illuminations with spectral components which differ most in the comparison was developed. Meanwhile, a new evaluation function combining the entropy analysis and brightness contrast was also built to value the quality of these illuminations. Experiments showed biological features are more visible with treated LED illuminations than the broadband lamps. Thus, the synthesis of LED lighting spectra could be adjusted to provide significant tissue identification. Therefore, we believe the new methodology will contribute to the manufacture of high efficient medical illuminations and act the positive role in coming surgical lighting fields.

  17. Mechanisms of lighting enhancement of Al nanoclusters-embedded Al-doped ZnO film in GaN-based light-emitting diodes

    SciTech Connect

    Lee, Hsin-Ying; Chou, Ying-Hung; Lee, Ching-Ting

    2010-01-15

    Aluminum (Al)-doped ZnO (AZO) films with embedded Al nanoclusters were proposed and utilized to enhance the light output power and maximum operation current of GaN-based light-emitting diodes (LEDs). The AZO films were sputtered using ZnO and Al targets in a magnetron cosputtering system. With Al dc power of 7 W and ZnO 100 W ac power, the electron concentration of 4.1x10{sup 20} cm{sup -3}, electron mobility of 16.2 cm{sup 2}/V s, and resistivity of 7.2x10{sup -4} {Omega} cm were obtained for the deposited AZO film annealed at 600 deg. C for 1 min in a N{sub 2} ambient. As verified by a high resolution transmission electron microscopy, the deposited AZO films with embedded Al nanoclusters were clearly observed. A 35% increase in light output power of the GaN-based LEDs with Al nanoclusters-embedded AZO films was realized compared with the conventional LEDs operated at 500 mA. It was verified experimentally that the various characteristics of GaN-based LEDs including the antireflection, light scattering, current spreading, and the light extraction efficiency in light emission could be significantly enhanced with the use of Al nanoclusters-embedded AZO films.

  18. Enhancement of light extraction based on nanowire hyperbolic metamaterials in a grating structure

    NASA Astrophysics Data System (ADS)

    Kao, Tzu-Hung; Hung, Yu-Chueh

    2016-04-01

    Hyperbolic metamaterial (HMM) has attracted considerable attention owing to several exotic optical properties, including negative refraction, enhanced spontaneous emission, and subwavelength imaging. The hyperbolic dispersion of HMMs increases photonic density of states in a broad bandwidth, leading to enhancement of spontaneous emission. However, the out-coupling of light from HMMs is difficult due to the evanescent character of the high-k modes at the surface. In this study, we implement the full-field numerical calculations based on finite-difference time-domain (FDTD) method to characterize the optical properties of nanowire HMMs embedded in a grating structure. We first examined the power spectrum of the nanowire HMMs. The Purcell factor and the light enhancement are also analyzed. Furthermore, to examine the out-coupling of light by virtue of the periodic structure, the Purcell factor and enhancement of light extraction efficiency of the hybrid structure will be examined and discussed. The analysis result is important toward engineering highly-efficient photonic devices based on HMMs.

  19. Maximum likelihood estimation of vehicle position for outdoor image sensor-based visible light positioning system

    NASA Astrophysics Data System (ADS)

    Zhao, Xiang; Lin, Jiming

    2016-04-01

    Image sensor-based visible light positioning can be applied not only to indoor environments but also to outdoor environments. To determine the performance bounds of the positioning accuracy from the view of statistical optimization for an outdoor image sensor-based visible light positioning system, we analyze and derive the maximum likelihood estimation and corresponding Cramér-Rao lower bounds of vehicle position, under the condition that the observation values of the light-emitting diode (LED) imaging points are affected by white Gaussian noise. For typical parameters of an LED traffic light and in-vehicle camera image sensor, simulation results show that accurate estimates are available, with positioning error generally less than 0.1 m at a communication distance of 30 m between the LED array transmitter and the camera receiver. With the communication distance being constant, the positioning accuracy depends on the number of LEDs used, the focal length of the lens, the pixel size, and the frame rate of the camera receiver.

  20. An electrically driven, ultrahigh-speed, on-chip light emitter based on carbon nanotubes.

    PubMed

    Mori, Tatsuya; Yamauchi, Yohei; Honda, Satoshi; Maki, Hideyuki

    2014-06-11

    The integration of high-speed light emitters on silicon chips is an important issue that must be resolved in order to realize on-chip or interchip optical interconnects. Here, we demonstrate the first electrically driven ultrafast carbon nanotube (CNT) light emitter based on blackbody radiation with a response speed (1-10 Gbps) that is more than 10(6) times higher than that of conventional incandescent emitters and is either higher than or comparable to that of light-emitting diodes or laser diodes. This high-speed response is explained by the extremely fast temperature response of the CNT film, which is dominated by the small heat capacity of the CNT film and its high heat dissipation to the substrate. Moreover, we experimentally demonstrate 140 ps width pulsed light generation and real-time optical communication. This CNT-based emitter with the advantages of ultrafast response speeds, a small footprint, and integration on silicon can enable novel architectures for optical interconnects, photonic, and optoelectronic integrated circuits. PMID:24796644

  1. Design and fabrication of a foldable 3D silicon based package for solid state lighting applications

    NASA Astrophysics Data System (ADS)

    Sokolovskij, R.; Liu, P.; van Zeijl, H. W.; Mimoun, B.; Zhang, G. Q.

    2015-05-01

    Miniaturization of solid state lighting (SSL) luminaires as well as reduction of packaging and assembly costs are of prime interest for the SSL lighting industry. A novel silicon based LED package for lighting applications is presented in this paper. The proposed design consists of 5 rigid Si tiles connected by flexible polyimide hinges with embedded interconnects (ICs). Electrical, optical and thermal characteristics were taken into consideration during design. The fabrication process involved polyimide (PI) application and patterning, aluminium interconnect integration in the flexible hinge, LED reflector cavity formation and metalization followed by through wafer DRIE etching for chip formation and release. A method to connect chip front to backside without TSVs was also integrated into the process. Post-fabrication wafer level assembly included LED mounting and wirebond, phosphor-based colour conversion and silicone encapsulation. The package formation was finalized by vacuum assisted wrapping around an assembly structure to form a 3D geometry, which is beneficial for omnidirectional lighting. Bending tests were performed on the flexible ICs and optical performance at different temperatures was evaluated. It is suggested that 3D packages can be expanded to platforms for miniaturized luminaire applications by combining monolithic silicon integration and system-in-package (SiP) technologies.

  2. One-Dimensional Multichromophor Arrays Based on DNA: From Self-Assembly to Light-Harvesting.

    PubMed

    Ensslen, Philipp; Wagenknecht, Hans-Achim

    2015-10-20

    Light-harvesting complexes collect light energy and deliver it by a cascade of energy and electron transfer processes to the reaction center where charge separation leads to storage as chemical energy. The design of artificial light-harvesting assemblies faces enormous challenges because several antenna chromophores need to be kept in close proximity but self-quenching needs to be avoided. Double stranded DNA as a supramolecular scaffold plays a promising role due to its characteristic structural properties. Automated DNA synthesis allows incorporation of artificial chromophore-modified building blocks, and sequence design allows precise control of the distances and orientations between the chromophores. The helical twist between the chromophores, which is induced by the DNA framework, controls energy and electron transfer and thereby reduces the self-quenching that is typically observed in chromophore aggregates. This Account summarizes covalently multichromophore-modified DNA and describes how such multichromophore arrays were achieved by Watson-Crick-specific and DNA-templated self-assembly. The covalent DNA systems were prepared by incorporation of chromophores as DNA base substitutions (either as C-nucleosides or with acyclic linkers as substitutes for the 2'-deoxyribofuranoside) and as DNA base modifications. Studies with DNA base substitutions revealed that distances but more importantly relative orientations of the chromophores govern the energy transfer efficiencies and thereby the light-harvesting properties. With DNA base substitutions, duplex stabilization was faced and could be overcome, for instance, by zipper-like placement of the chromophores in both strands. For both principal structural approaches, DNA-based light-harvesting antenna could be realized. The major disadvantages, however, for covalent multichromophore DNA conjugates are the poor yields of synthesis and the solubility issues for oligonucleotides with more than 5-10 chromophore

  3. Titanium oxide nanotube arrays for high light extraction efficiency of GaN-based vertical light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Leem, Young-Chul; Seo, Okkyun; Jo, Yong-Ryun; Kim, Joon Heon; Chun, Jaeyi; Kim, Bong-Joong; Noh, Do Young; Lim, Wantae; Kim, Yong-Il; Park, Seong-Ju

    2016-05-01

    TiO2 nanotube (NT) arrays were fabricated on the surface of n-GaN through a liquid-phase conversion process using ZnO nanorods (NRs) as a template for high-efficiency InGaN/GaN multiple quantum well (MQW) vertical light-emitting diodes (VLEDs). The optical output power of the VLEDs with TiO2 NTs was remarkably enhanced by 23% and 189% at an injection current of 350 mA compared to those of VLEDs with ZnO NRs and planar VLEDs, respectively. The large enhancement in optical output is attributed to a synergistic effect of efficient light injection from the n-GaN layer of the VLED to TiO2 NTs because of the well-matched refractive indices and superior light extraction into air at the end of the TiO2 NTs. Light propagation along various configurations of TiO2 NTs on the VLEDs was investigated using finite-difference time domain simulations and the results indicated that the wall thickness of the TiO2 NTs should be maintained close to 20 nm for superior light extraction from the VLEDs.TiO2 nanotube (NT) arrays were fabricated on the surface of n-GaN through a liquid-phase conversion process using ZnO nanorods (NRs) as a template for high-efficiency InGaN/GaN multiple quantum well (MQW) vertical light-emitting diodes (VLEDs). The optical output power of the VLEDs with TiO2 NTs was remarkably enhanced by 23% and 189% at an injection current of 350 mA compared to those of VLEDs with ZnO NRs and planar VLEDs, respectively. The large enhancement in optical output is attributed to a synergistic effect of efficient light injection from the n-GaN layer of the VLED to TiO2 NTs because of the well-matched refractive indices and superior light extraction into air at the end of the TiO2 NTs. Light propagation along various configurations of TiO2 NTs on the VLEDs was investigated using finite-difference time domain simulations and the results indicated that the wall thickness of the TiO2 NTs should be maintained close to 20 nm for superior light extraction from the VLEDs. Electronic

  4. Influence of the Light Intensity on the layers electrophotographic intensity based on As and Sb chalkogenides

    NASA Astrophysics Data System (ADS)

    Andriesh, A. M.; Buzdugan, A. I.; Shutov, S. D.

    1988-10-01

    Based on dependence of the electrographic sensitivity from the intensity of illumination by an integral and monochromatic light one show that the law of intercompatibility in thin layers based on glasses As_2S_3, alloys of As_2S_3 and Sb_2S_3 and heterostructures Sb_2S_3 and As_2S_3 is not more valid. Underlinear dependences of the lux-ampere characteristics are interpreted based on the Rose model which supposes a great density of localized states of the quasicontinuous and an exponential distribution by energy in a forbidden zone of a semiconductor. Tables 1, Bibliography 5, Illustr. 2

  5. Structurally Integrated Photoluminescent Chemical and Biological Sensors: An Organic Light-Emitting Diode-Based Platform

    NASA Astrophysics Data System (ADS)

    Shinar, J.; Shinar, R.

    The chapter describes the development, advantages, challenges, and potential of an emerging, compact photoluminescence-based sensing platform for chemical and biological analytes, including multiple analytes. In this platform, the excitation source is an array of organic light-emitting device (OLED) pixels that is structurally integrated with the sensing component. Steps towards advanced integration with additionally a thin-film-based photodetector are also described. The performance of the OLED-based sensing platform is examined for gas-phase and dissolved oxygen, glucose, lactate, ethanol, hydrazine, and anthrax lethal factor.

  6. Ray tracing based path-length calculations for polarized light tomographic imaging

    NASA Astrophysics Data System (ADS)

    Manjappa, Rakesh; Kanhirodan, Rajan

    2015-09-01

    A ray tracing based path length calculation is investigated for polarized light transport in a pixel space. Tomographic imaging using polarized light transport is promising for applications in optical projection tomography of small animal imaging and turbid media with low scattering. Polarized light transport through a medium can have complex effects due to interactions such as optical rotation of linearly polarized light, birefringence, di-attenuation and interior refraction. Here we investigate the effects of refraction of polarized light in a non-scattering medium. This step is used to obtain the initial absorption estimate. This estimate can be used as prior in Monte Carlo (MC) program that simulates the transport of polarized light through a scattering medium to assist in faster convergence of the final estimate. The reflectance for p-polarized (parallel) and s-polarized (perpendicular) are different and hence there is a difference in the intensities that reach the detector end. The algorithm computes the length of the ray in each pixel along the refracted path and this is used to build the weight matrix. This weight matrix with corrected ray path length and the resultant intensity reaching the detector for each ray is used in the algebraic reconstruction (ART) method. The proposed method is tested with numerical phantoms for various noise levels. The refraction errors due to regions of different refractive index are discussed, the difference in intensities with polarization is considered. The improvements in reconstruction using the correction so applied is presented. This is achieved by tracking the path of the ray as well as the intensity of the ray as it traverses through the medium.

  7. Telemetric light delivery and monitoring system for photodynamic therapy based on solid-state optodes

    NASA Astrophysics Data System (ADS)

    Margallo-Balbás, Eduardo; Kaptein, Johan G.; Sterenborg, Henricus J. C. M.; Pandraud, Grégory; French, Patrick J.; Robinson, Dominic J.

    2008-02-01

    Light delivery and optical monitoring during photodynamic therapy (PDT) is often limited by the need for a physical optical link between the light source and detection devices and the treatment volume. This can be critical when sources need to be implanted within the body for extended periods. We report on the latest developments for a telemetric PDT delivery and monitoring device that can dynamically vary the local illumination parameters based on the in-situ fluence rate within the PDT target volume. Local light delivery and collection is achieved using solid-state optodes, microfabricated on a silicon substrate. Photodiodes have been produced using a standard bipolar process. Chip-form LEDs are then assembled into micro-machined pits adjacent to the light fluence rate detectors. The devices (1.2×1.2mm2) are bonded to a flexible PCB together with the remaining electronics. Power coupling and communications are achieved by means of an inductive link while light delivery and fluence rate monitoring are digitally managed using a microcontroller. These devices are being tested in optical phantoms and in pre-clinical models. Our results show that it is possible to manufacture solid-state optodes of suitable dimensions and that it is feasible to telemetrically deliver and control the local fluence rate using them. It can also be concluded from our work that while the optode is sufficiently small to be useful as a light delivery and monitoring device, digital control, read-out electronics and power coupling can benefit from further optimization and miniaturization.

  8. A design of LED adaptive dimming lighting system based on incremental PID controller

    NASA Astrophysics Data System (ADS)

    He, Xiangyan; Xiao, Zexin; He, Shaojia

    2010-11-01

    As a new generation energy-saving lighting source, LED is applied widely in various technology and industry fields. The requirement of its adaptive lighting technology is more and more rigorous, especially in the automatic on-line detecting system. In this paper, a closed loop feedback LED adaptive dimming lighting system based on incremental PID controller is designed, which consists of MEGA16 chip as a Micro-controller Unit (MCU), the ambient light sensor BH1750 chip with Inter-Integrated Circuit (I2C), and constant-current driving circuit. A given value of light intensity required for the on-line detecting environment need to be saved to the register of MCU. The optical intensity, detected by BH1750 chip in real time, is converted to digital signal by AD converter of the BH1750 chip, and then transmitted to MEGA16 chip through I2C serial bus. Since the variation law of light intensity in the on-line detecting environment is usually not easy to be established, incremental Proportional-Integral-Differential (PID) algorithm is applied in this system. Control variable obtained by the incremental PID determines duty cycle of Pulse-Width Modulation (PWM). Consequently, LED's forward current is adjusted by PWM, and the luminous intensity of the detection environment is stabilized by self-adaptation. The coefficients of incremental PID are obtained respectively after experiments. Compared with the traditional LED dimming system, it has advantages of anti-interference, simple construction, fast response, and high stability by the use of incremental PID algorithm and BH1750 chip with I2C serial bus. Therefore, it is suitable for the adaptive on-line detecting applications.

  9. Titanium oxide nanotube arrays for high light extraction efficiency of GaN-based vertical light-emitting diodes.

    PubMed

    Leem, Young-Chul; Seo, Okkyun; Jo, Yong-Ryun; Kim, Joon Heon; Chun, Jaeyi; Kim, Bong-Joong; Noh, Do Young; Lim, Wantae; Kim, Yong-Il; Park, Seong-Ju

    2016-05-21

    TiO2 nanotube (NT) arrays were fabricated on the surface of n-GaN through a liquid-phase conversion process using ZnO nanorods (NRs) as a template for high-efficiency InGaN/GaN multiple quantum well (MQW) vertical light-emitting diodes (VLEDs). The optical output power of the VLEDs with TiO2 NTs was remarkably enhanced by 23% and 189% at an injection current of 350 mA compared to those of VLEDs with ZnO NRs and planar VLEDs, respectively. The large enhancement in optical output is attributed to a synergistic effect of efficient light injection from the n-GaN layer of the VLED to TiO2 NTs because of the well-matched refractive indices and superior light extraction into air at the end of the TiO2 NTs. Light propagation along various configurations of TiO2 NTs on the VLEDs was investigated using finite-difference time domain simulations and the results indicated that the wall thickness of the TiO2 NTs should be maintained close to 20 nm for superior light extraction from the VLEDs. PMID:27121775

  10. Light collection optimization in scintillator-based gamma-ray spectrometers

    NASA Astrophysics Data System (ADS)

    Hull, G.; Du, S.; Niedermayr, T.; Payne, S.; Cherepy, N.; Drobshoff, A.; Fabris, L.

    2008-04-01

    Scintillator-based gamma-ray detectors are being actively pursued for homeland security applications. A key property of such detectors is their energy resolution which enables faster detection and more precise identification of gamma-ray sources. In order to obtain the best energy resolution with a given scintillator material, it is crucial to collect the largest fraction possible of the light emitted after gamma-ray absorption. Different techniques to maximize the light collection efficiency were investigated and tested experimentally. In particular, the effect of the scintillator geometry has been simulated with Detect2000. Also, a number of wrapping materials have been tested for their reflectivity and their performance in terms of improving the energy resolution in a BGO-based gamma-ray detector. The best results were obtained with a tapered cylinder geometry and the GORE DRP tape.

  11. Physically-based in silico light sheet microscopy for visualizing fluorescent brain models

    PubMed Central

    2015-01-01

    Background We present a physically-based computational model of the light sheet fluorescence microscope (LSFM). Based on Monte Carlo ray tracing and geometric optics, our method simulates the operational aspects and image formation process of the LSFM. This simulated, in silico LSFM creates synthetic images of digital fluorescent specimens that can resemble those generated by a real LSFM, as opposed to established visualization methods producing visually-plausible images. We also propose an accurate fluorescence rendering model which takes into account the intrinsic characteristics of fluorescent dyes to simulate the light interaction with fluorescent biological specimen. Results We demonstrate first results of our visualization pipeline to a simplified brain tissue model reconstructed from the somatosensory cortex of a young rat. The modeling aspects of the LSFM units are qualitatively analysed, and the results of the fluorescence model were quantitatively validated against the fluorescence brightness equation and characteristic emission spectra of different fluorescent dyes. AMS subject classification Modelling and simulation PMID:26329404

  12. Spectral matching technology for light-emitting diode-based jaundice photodynamic therapy device

    NASA Astrophysics Data System (ADS)

    Gan, Ru-ting; Guo, Zhen-ning; Lin, Jie-ben

    2015-02-01

    The objective of this paper is to obtain the spectrum of light-emitting diode (LED)-based jaundice photodynamic therapy device (JPTD), the bilirubin absorption spectrum in vivo was regarded as target spectrum. According to the spectral constructing theory, a simple genetic algorithm as the spectral matching algorithm was first proposed in this study. The optimal combination ratios of LEDs were obtained, and the required LEDs number was then calculated. Meanwhile, the algorithm was compared with the existing spectral matching algorithms. The results show that this algorithm runs faster with higher efficiency, the switching time consumed is 2.06 s, and the fitting spectrum is very similar to the target spectrum with 98.15% matching degree. Thus, blue LED-based JPTD can replace traditional blue fluorescent tube, the spectral matching technology that has been put forward can be applied to the light source spectral matching for jaundice photodynamic therapy and other medical phototherapy.

  13. Dimensional measurement of 3D microstruture based on white light interferometer

    NASA Astrophysics Data System (ADS)

    Thian, S. C. H.; Feng, W.; Wong, Y. S.; Fuh, J. Y. H.; Loh, H. T.; Tee, K. H.; Tang, Y.; Lu, L.

    2007-07-01

    Dimensional metrology for micro/nano structure is crucial for addressing quality issues and understanding the performance of micro-fabricated products and micro-fabrication processes. Most of the established methods are based on optical microscopy for planar dimensions and stylus profilometry for out-of-plane dimensions. Contact profilers suffer from slow speed of measurement for three-dimensional profiles and are not suitable for delicate surfaces and parts. Advanced systems using white light interferometer are equipped with CCD cameras and interfaced with a microscope to conduct an array of measurements ranging from two-dimensional to three-dimensional profiles and surface roughness analysis. This paper presents a methodology based on white light interferometer for the dimensional measurement of 3D micro-structures, demonstrated on micro-gears and moulds produced by UV lithography and vacuum casting, respectively. Physical artifacts, such as gauge blocks, are also utilized to verify and validate the measurements on the microcomponents.

  14. Light-guiding hydrogels for cell-based sensing and optogenetic synthesis in vivo

    NASA Astrophysics Data System (ADS)

    Choi, Myunghwan; Choi, Jin Woo; Kim, Seonghoon; Nizamoglu, Sedat; Hahn, Sei Kwang; Yun, Seok Hyun

    2013-12-01

    Polymer hydrogels are widely used as cell scaffolds for biomedical applications. Although the biochemical and biophysical properties of hydrogels have been investigated extensively, little attention has been paid to their potential photonic functionalities. Here, we report cell-integrated polyethylene glycol-based hydrogels for in vivo optical-sensing and therapy applications. Hydrogel patches containing cells were implanted in awake, freely moving mice for several days and shown to offer long-term transparency, biocompatibility, cell viability and light-guiding properties (loss of <1 dB cm-1). Using optogenetic, glucagon-like peptide-1 secreting cells, we conducted light-controlled therapy using the hydrogel in a mouse model with diabetes and obtained improved glucose homeostasis. Furthermore, real-time optical readout of encapsulated heat-shock-protein-coupled fluorescent reporter cells made it possible to measure the nanotoxicity of cadmium-based bare and shelled quantum dots (CdTe; CdSe/ZnS) in vivo.

  15. 14 CFR 61.327 - Are there specific endorsement requirements to operate a light-sport aircraft based on VH?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... to operate a light-sport aircraft based on VH? 61.327 Section 61.327 Aeronautics and Space FEDERAL... INSTRUCTORS, AND GROUND INSTRUCTORS Sport Pilots § 61.327 Are there specific endorsement requirements to operate a light-sport aircraft based on VH? (a) Except as specified in paragraph (c) of this section,...

  16. 14 CFR 61.327 - Are there specific endorsement requirements to operate a light-sport aircraft based on VH?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... to operate a light-sport aircraft based on VH? 61.327 Section 61.327 Aeronautics and Space FEDERAL... INSTRUCTORS, AND GROUND INSTRUCTORS Sport Pilots § 61.327 Are there specific endorsement requirements to operate a light-sport aircraft based on VH? (a) Except as specified in paragraph (c) of this section,...

  17. 14 CFR 61.327 - Are there specific endorsement requirements to operate a light-sport aircraft based on VH?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... to operate a light-sport aircraft based on VH? 61.327 Section 61.327 Aeronautics and Space FEDERAL... INSTRUCTORS, AND GROUND INSTRUCTORS Sport Pilots § 61.327 Are there specific endorsement requirements to operate a light-sport aircraft based on VH? (a) Except as specified in paragraph (c) of this section,...

  18. 14 CFR 61.327 - Are there specific endorsement requirements to operate a light-sport aircraft based on VH?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... to operate a light-sport aircraft based on VH? 61.327 Section 61.327 Aeronautics and Space FEDERAL... INSTRUCTORS, AND GROUND INSTRUCTORS Sport Pilots § 61.327 Are there specific endorsement requirements to operate a light-sport aircraft based on VH? (a) Except as specified in paragraph (c) of this section,...

  19. Visible-light-driven photocatalytic water oxidation catalysed by iron-based metal-organic frameworks.

    PubMed

    Horiuchi, Yu; Toyao, Takashi; Miyahara, Kenta; Zakary, Lionet; Van, Dang Do; Kamata, Yusuke; Kim, Tae-Ho; Lee, Soo Wohn; Matsuoka, Masaya

    2016-04-14

    An iron-based metal-organic framework, MIL-101(Fe), promotes photocatalytic water oxidation to produce oxygen from aqueous silver nitrate solution under visible-light irradiation. The finely dispersed iron-oxo clusters embedded as nodes of the porous framework would contribute importantly to the efficient promotion of the reaction as compared to bulk hematite (α-Fe2O3). PMID:26996996

  20. Land-based lidar mapping: a new surveying technique to shed light on rapid topographic change

    USGS Publications Warehouse

    Collins, Brian D.; Kayen, Robert

    2006-01-01

    The rate of natural change in such dynamic environments as rivers and coastlines can sometimes overwhelm the monitoring capacity of conventional surveying methods. In response to this limitation, U.S. Geological Survey (USGS) scientists are pioneering new applications of light detection and ranging (lidar), a laser-based scanning technology that promises to greatly increase our ability to track rapid topographic changes and manage their impact on affected communities.

  1. Using specific and adaptive arrangement of grid-type pilot in channel estimation for white-lightLED-based OFDM visible light communication system

    NASA Astrophysics Data System (ADS)

    Lin, Wan-Feng; Chow, Chi-Wai; Yeh, Chien-Hung

    2015-03-01

    Orthogonal frequency division multiplexing (OFDM) is a promising candidate for light emitting diode (LED)-based optical wireless communication (OWC); however, precise channel estimation is required for synchronization and equalization. In this work, we study and discover that the channel response of the white-lightLED-based OWC was smooth and stable. Hence we propose and demonstrate using a specific and adaptive arrangement of grid-type pilot scheme to estimate the LED OWC channel response. Experimental results show that our scheme can achieve better transmission performance and with some transmission capacity enhancement when compared with the method using training-symbol scheme (also called block-type pilot scheme).

  2. Broadband SLED-based light source (BeST-SLEDTM) and spectrometer

    NASA Astrophysics Data System (ADS)

    Yadid-Pecht, Orly; Dattner, Yonathan

    2016-03-01

    A small footprint, low power, cost effective single mode fiber coupled broadband light source and spectrometer is presented. It is based on Super Luminescent Diode (SLED) devices and a compact design enables coverage of the 1250 nm-1750 nm region with a total optical power of 50 mW at the output of the fiber. This Broad Spectrum Tunable Super Luminescent (BeST-SLEDTM) light source can operate at temperatures ranging from -40°C to 60°C, and resides in a custom designed 26-pin package. The fiber is a polarization maintaining fiber with a FC/APC connector at the output. Three variations of the BeST-SLEDTM were developed, BEST-SLED™ Bands, BeST-SLEDTM Tunable and BeST-SLEDTM FTNIR. In the Bands version six SLEDs were packaged allowing for one SLED on at a time or any combination of the SLEDs on. In the Tunable version an Acoustic Optical Tunable Filter (AOTF) was integrated into the package allowing the user to select one wavelength at a time to pass into the fiber with resolution of ~1 nm @1550nm. In the FTNIR version, a Silicon Photonic based interferometer (the Nano-SpecTM) was integrated into the package for a Fourier Transform Near Infrared based Spectrometer and light source. The BeST-SLEDTM is being used in process control applications such as steam quality measurements, oil in water, gas composition and air quality monitoring.

  3. Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes

    PubMed Central

    Lee, Jaeho; Han, Tae-Hee; Park, Min-Ho; Jung, Dae Yool; Seo, Jeongmin; Seo, Hong-Kyu; Cho, Hyunsu; Kim, Eunhye; Chung, Jin; Choi, Sung-Yool; Kim, Taek-Soo; Lee, Tae-Woo; Yoo, Seunghyup

    2016-01-01

    Graphene-based organic light-emitting diodes (OLEDs) have recently emerged as a key element essential in next-generation displays and lighting, mainly due to their promise for highly flexible light sources. However, their efficiency has been, at best, similar to that of conventional, indium tin oxide-based counterparts. We here propose an ideal electrode structure based on a synergetic interplay of high-index TiO2 layers and low-index hole-injection layers sandwiching graphene electrodes, which results in an ideal situation where enhancement by cavity resonance is maximized yet loss to surface plasmon polariton is mitigated. The proposed approach leads to OLEDs exhibiting ultrahigh external quantum efficiency of 40.8 and 62.1% (64.7 and 103% with a half-ball lens) for single- and multi-junction devices, respectively. The OLEDs made on plastics with those electrodes are repeatedly bendable at a radius of 2.3 mm, partly due to the TiO2 layers withstanding flexural strain up to 4% via crack-deflection toughening. PMID:27250743

  4. Buried graphene electrodes on GaN-based ultra-violet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Kim, Byung-Jae; Lee, Chongmin; Mastro, Michael A.; Hite, Jennifer K.; Eddy, Charles R.; Ren, Fan; Pearton, Stephen J.; Kim, Jihyun

    2012-07-01

    We report that the oxidation of graphene-based highly transparent conductive layers to AlGaN/GaN/AlGaN ultra-violet (UV) light-emitting diodes (LEDs) was suppressed by the use of SiNX passivation layers. Although graphene is considered to be an ideal candidate as the transparent conductive layer to UV-LEDs, oxidation of these layers at high operating temperatures has been an issue. The oxidation is initiated at the un-saturated carbon atoms at the edges of the graphene and reduces the UV light intensity and degrades the current-voltage (I-V) characteristics. The oxidation also can occur at defects, including vacancies. However, GaN-based UV-LEDs deposited with SiNX by plasma-enhanced chemical vapor deposition showed minimal degradation of light output intensity and I-V characteristics because the graphene-based UV transparent conductive layers were shielded from the oxygen molecules. This is a simple and effective approach for maintaining the advantages of graphene conducting layers as electrodes on UV-LEDs.

  5. Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes.

    PubMed

    Lee, Jaeho; Han, Tae-Hee; Park, Min-Ho; Jung, Dae Yool; Seo, Jeongmin; Seo, Hong-Kyu; Cho, Hyunsu; Kim, Eunhye; Chung, Jin; Choi, Sung-Yool; Kim, Taek-Soo; Lee, Tae-Woo; Yoo, Seunghyup

    2016-01-01

    Graphene-based organic light-emitting diodes (OLEDs) have recently emerged as a key element essential in next-generation displays and lighting, mainly due to their promise for highly flexible light sources. However, their efficiency has been, at best, similar to that of conventional, indium tin oxide-based counterparts. We here propose an ideal electrode structure based on a synergetic interplay of high-index TiO2 layers and low-index hole-injection layers sandwiching graphene electrodes, which results in an ideal situation where enhancement by cavity resonance is maximized yet loss to surface plasmon polariton is mitigated. The proposed approach leads to OLEDs exhibiting ultrahigh external quantum efficiency of 40.8 and 62.1% (64.7 and 103% with a half-ball lens) for single- and multi-junction devices, respectively. The OLEDs made on plastics with those electrodes are repeatedly bendable at a radius of 2.3 mm, partly due to the TiO2 layers withstanding flexural strain up to 4% via crack-deflection toughening. PMID:27250743

  6. Re-evaluation of model-based light-scattering spectroscopy for tissue spectroscopy

    NASA Astrophysics Data System (ADS)

    Lau, Condon; Šćepanović, Obrad; Mirkovic, Jelena; McGee, Sasha; Yu, Chung-Chieh; Fulghum, Stephen; Wallace, Michael; Tunnell, James; Bechtel, Kate; Feld, Michael

    2009-03-01

    Model-based light scattering spectroscopy (LSS) seemed a promising technique for in-vivo diagnosis of dysplasia in multiple organs. In the studies, the residual spectrum, the difference between the observed and modeled diffuse reflectance spectra, was attributed to single elastic light scattering from epithelial nuclei, and diagnostic information due to nuclear changes was extracted from it. We show that this picture is incorrect. The actual single scattering signal arising from epithelial nuclei is much smaller than the previously computed residual spectrum, and does not have the wavelength dependence characteristic of Mie scattering. Rather, the residual spectrum largely arises from assuming a uniform hemoglobin distribution. In fact, hemoglobin is packaged in blood vessels, which alters the reflectance. When we include vessel packaging, which accounts for an inhomogeneous hemoglobin distribution, in the diffuse reflectance model, the reflectance is modeled more accurately, greatly reducing the amplitude of the residual spectrum. These findings are verified via numerical estimates based on light propagation and Mie theory, tissue phantom experiments, and analysis of published data measured from Barrett's esophagus. In future studies, vessel packaging should be included in the model of diffuse reflectance and use of model-based LSS should be discontinued.

  7. Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Lee, Jaeho; Han, Tae-Hee; Park, Min-Ho; Jung, Dae Yool; Seo, Jeongmin; Seo, Hong-Kyu; Cho, Hyunsu; Kim, Eunhye; Chung, Jin; Choi, Sung-Yool; Kim, Taek-Soo; Lee, Tae-Woo; Yoo, Seunghyup

    2016-06-01

    Graphene-based organic light-emitting diodes (OLEDs) have recently emerged as a key element essential in next-generation displays and lighting, mainly due to their promise for highly flexible light sources. However, their efficiency has been, at best, similar to that of conventional, indium tin oxide-based counterparts. We here propose an ideal electrode structure based on a synergetic interplay of high-index TiO2 layers and low-index hole-injection layers sandwiching graphene electrodes, which results in an ideal situation where enhancement by cavity resonance is maximized yet loss to surface plasmon polariton is mitigated. The proposed approach leads to OLEDs exhibiting ultrahigh external quantum efficiency of 40.8 and 62.1% (64.7 and 103% with a half-ball lens) for single- and multi-junction devices, respectively. The OLEDs made on plastics with those electrodes are repeatedly bendable at a radius of 2.3 mm, partly due to the TiO2 layers withstanding flexural strain up to 4% via crack-deflection toughening.

  8. Simulation of light transport in scintillators based on 3D characterization of crystal surfaces

    PubMed Central

    Cherry, Simon R.

    2013-01-01

    In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte-Carlo simulations play an important role in guiding research in detector designs and popular software such as GATE now include models of light transport in scintillators. Although current simulation toolkits are able to provide accurate models of perfectly polished surfaces, they do not successfully predict light output for other surface finishes, for example those often used in DOI-encoding detectors. The lack of accuracy of those models mainly originates from a simplified description of rough surfaces as an ensemble of micro-facets determined by the distribution of their normal, typically a Gaussian distribution. The user can specify the standard deviation of this distribution, but this parameter does not provide a full description of the surface reflectance properties. We propose a different approach based on 3D measurements of the surface using atomic force microscopy (AFM). Polished and rough (unpolished) crystals were scanned to compute the surface reflectance properties. The angular distributions of reflectance and reflected rays were computed and stored in look-up tables (LUTs). The LUTs account for the effect of incidence angle and were integrated in a light transport model. Crystals of different sizes were simulated with and without reflector. The simulated maximum light output and the light output as a function of DOI showed very good agreement with experimental characterization of the crystals, indicating that our approach provides an accurate model of polished and rough surfaces and could be used to predict light collection in scintillators. This model is based on a true 3D representation of the surface, makes no assumption about the surface and provides insight on the

  9. Absorbance detector based on a deep UV light emitting diode for narrow-column HPLC.

    PubMed

    Bui, Duy Anh; Bomastyk, Benjamin; Hauser, Peter C

    2013-10-01

    A detector for miniaturized HPLC based on deep UV emitting diodes and UV photodiodes was constructed. The measurement is accomplished by the transverse passage of the radiation from the light-emitting diode (LED) through fused-silica tubing with an internal diameter of 250 μm. The optical cell allows flexible alignment of the LED, tubing, and photodiode for optimization of the light throughput and has an aperture to block stray light. A beam splitter was employed to direct part of the emitted light to a reference photodiode and the Lambert-Beer law was emulated with a log-ratio amplifier circuitry. The detector was tested with two LEDs with emission bands at 280 and 255 nm and showed noise levels as low as 0.25 and 0.22 mAU, respectively. The photometric device was employed successfully in separations using a column of 1 mm inner diameter in isocratic as well as gradient elution. Good linearities over three orders of magnitude in concentration were achieved, and the precision of the measurements was better than 1% in all cases. Detection down to the low micromolar range was possible. PMID:23893947

  10. A Near-Infrared Spectrometer Based on Novel Grating Light Modulators

    PubMed Central

    Wei, Wei; Huang, Shanglian; Wang, Ning; Jin, Zhu; Zhang, Jie; Chen, Weimin

    2009-01-01

    A near-infrared spectrometer based on novel MOEMS grating light modulators is proposed. The spectrum detection method that combines a grating light modulator array with a single near-infrared detector has been applied. Firstly, optics theory has been used to analyze the essential principles of the proposed spectroscopic sensor. Secondly, the grating light modulators have been designed and fabricated by micro-machining technology. Finally, the principles of this spectroscopic sensor have been validated and its key parameters have been tested by experiments. The result shows that the spectral resolution is better than 10 nm, the wavelength deviation is less than 1 nm, the deviation of the intensity of peak wavelength is no more than 0.5%, the driving voltage of grating light modulators array device is below 25 V and the response frequency of it is about 5 kHz. With low cost, satisfactory precision, portability and other advantages, the spectrometer should find potential applications in food safety and quality monitoring, pharmaceutical identification and agriculture product quality classification. PMID:22574065

  11. Skyglow: a retrieval of the approximate radiant intensity function of ground-based light sources

    NASA Astrophysics Data System (ADS)

    Kocifaj, M.; Solano Lamphar, H. A.

    2014-04-01

    The angular distribution of the light emitted from a city is an important source of information about public lighting systems and it also plays a key role in modelling the skyglow. Usually, the upwardly directed radiation is characterized through a parametrized emission function - a semi-empirical approach as a reasonable approximation that allows for fast computations. However, theoretical or experimental retrievals of emission characteristics are extremely difficult to obtain because of both the complexity of radiative transfer methods and/or the lack of highly specialized measuring devices. Our research has been conducted with the specific objective to identify an efficient theoretical technique for retrieval of the emission pattern of ground-based light sources in order to determine the optimum values of the scaling parameters of the Garstang function. In particular, the input data involve the zenith luminance or radiance with horizontal illuminance or irradiance. Theoretical ratios of zenith luminance LV(0) to horizontal illuminance DV are calculated for a set of distances d that separate a hypothetical observer from the light source (a city or town). This approach is advantageous because inexpensive traditional equipment can be used to obtain the mean values of the Garstang parameters. Furthermore, it can also be applied to other parametrizable emission functions and to any measuring site, even one with a masked horizon.

  12. The nature of light: a description of photon diffraction based upon virtual particle exchange

    NASA Astrophysics Data System (ADS)

    Mobley, Michael J.

    2005-08-01

    Any discussion of the nature of light must include a reminder that whenever we make the observation of light (photons), we only observe particle-like properties. This paper provides a reiteration that we don"t need wave-like properties to scattered photons to describe phenomena such as diffraction or refraction of light. This paper updates the original ideas of Duane, later revived by Lande, which provided a description of light diffraction without making reference to a wave nature. These are updated using terminology more common to quantum electrodynamics which describes the interaction of particles in terms of the exchange of virtual photons. Diffraction is described in terms of an ensemble of distinct, probability weighted paths for the scattered photons. The scattering associated with each path results from the quantized momentum exchange with the scattering lattice attributed to the exchange or reflection of virtual photons. The probability for virtual particle exchange/reflection is dependent upon the allowed momentum states of the lattice determined by a Fourier analysis of the lattice geometry. Any scattered photon will exhibit an apparent wavelength inversely proportional to its momentum. Simplified, particle-like descriptions are developed for Young"s double slit diffraction, Fraunhofer diffraction and Fresnel diffraction. This description directly accounts for the quantization of momentum transferred to the scattering lattice and the specific eigenvalues of the lattice based upon the constraints to virtual photon exchange set by the Uncertainty Principle, Δπi = h/ζi.

  13. [Choice of plant light status for space greenhouse: results of ground-based experience].

    PubMed

    Berkovich, Iu A

    2000-01-01

    To decide on the light status of plants in space greenhouse, a theoretical study was undertaken to correlate specific productivity of space greenhouse with illumination characteristics including vertical PAR flux density (I), photoperiod (tau), and crop leaf index (L). It was demonstrated that in pace with I the daily productivity per a volume unit tended to monotonously approach maximum at I = Ip, whereas the greenhouse energy efficiency ME peaked at I = IE, IK < IE < IP, where IK is a compensation point of the light curve of crop photosynthesis. Proposed are compromise criteria to optimize illumination as a maximum of linear combination of MV and ME and coefficients which account for the cost of a space station volume unit and a unit of board power supply, and as maximum of product Q = MV.ME. Experimental results serve as the basis for a technique for determination of the best, by the Q criterion, light status parameters for three types of space greenhouses: research growth chamber for synchronous cultivation of leaf mustard, wheat growth chamber with fixed crop density, and green conveyer for cultivation of Brassica pekinensis (Lour Rupor). For the last mentioned Q effective I and tau values differed with the conveyer step. The technique allows design of ground-based experiments aimed at determination of the most effective light status of space-grown crops. PMID:10732194

  14. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    NASA Astrophysics Data System (ADS)

    Kuang, Y.; van Lare, M. C.; Veldhuizen, L. W.; Polman, A.; Rath, J. K.; Schropp, R. E. I.

    2015-11-01

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  15. Speckle-based measurement of the light scattering by red blood cells in vivo

    NASA Astrophysics Data System (ADS)

    Fine, I.; Kaminsky, A.

    2011-03-01

    Optical spectroscopy approach, using non-coherent light sources, has become an important tool for non-invasive analysis in vivo. It is based on the assumption that biochemical characteristics of biological system can be determined through the optical coefficients of blood and tissue particles. Thus, in the framework of this approach, the major concern is to express the obtained optical signals in terms the optical coefficients of the single particle of blood or tissue. However, since the light propagation in tissue is dominated by the multiple-scattering component, a direct measurement of single scattering characteristics turns to be a very difficult task. Practically, only the relative changes of absorption and scattering coefficients are measured. We suggested to adopt the dynamic light scattering (DLS) or speckle technique for the determination of the light scattering coefficients of the red blood cells under stasis conditions in vivo. We assumed that under zero flow conditions the RBC movement is driven mostly by the Brownian motion. It was shown, that under appropriate measurement geometry, the measured optical signal can be decomposed into a few major components. The most dominant components are ascribed to the single backscattering and forward scattering coefficients of the red blood cells. In-vitro and in vivo experimental tests have shown a good correspondence between the theoretically estimated and experientially measured results. The obtained results indicate that the DLS technique can be adopted for the determination of blood particles scattering characteristics in addition to the movement and effective viscosity parameters measurement in vivo.

  16. Azobenzene-based photomechanical monolayers as light-addressable nano-engineered structures.

    NASA Astrophysics Data System (ADS)

    Dahdah, J. M.; Furtak, T. E.; Walba, D. M.; Fang, G.; Yi, Y.; Maclennan, J. E.; Clark, N. A.

    2007-03-01

    Azobenzene-based photomechanical monolayers have received a great deal of attention for their potential as platforms for light-addressable nano-engineered structures in bioscience, photonics, and display technologies. We have developed an aminoazobenzene material (d-MR), derived from methyl red, which forms high-quality, covalently anchored monolayers on glass. These monolayers demonstrate unusually high sensitivity to polarized light, which controls the molecular orientation distribution through optical anisotropy of the trans-cis isomerization. In an effort to understand and optimize this phenomenon we are studying the influence of the two-dimensional molecular field on the dynamics of the light-driven reorganization. We have correlated the behavior of d-MR monolayers, as determined by spectral studies of dichroism and differential reflection ellipsometry, to dilute solutions of d-MR in a variety of solvents, as characterized by absorption cross sections, quantum yields, and characteristic time constants. The resulting information has helped to clarify the details of how these molecules respond to light leading to design strategies for even higher performing monolayers.

  17. Stray light analysis and suppression method of dynamic star simulator based on LCOS splicing technology

    NASA Astrophysics Data System (ADS)

    Meng, Yao; Zhang, Guo-yu

    2015-10-01

    Star simulator acts ground calibration equipment of the star sensor, It testes the related parameters and performance of the star sensor. At present, when the dynamic star simulator based on LCOS splicing is identified by the star sensor, there is a major problem which is the poor LCOS contrast. In this paper, we analysis the cause of LC OS stray light , which is the relation between the incident angle of light and contrast ratio and set up the function relationship between the angle and the irradiance of the stray light. According to this relationship, we propose a scheme that we control the incident angle . It is a popular method to use the compound parabolic concentrator (CPC), although it can control any angle what we want in theory, in fact, we usually use it above +/-15° because of the length and the manufacturing cost. Then I set a telescopic system in front of the CPC , that principle is the same as the laser beam expander. We simulate the CPC with the Tracepro, it simulate the exit surface irradiance. The telescopic system should be designed by the ZEMAX because of the chromatic aberration correction. As a result, we get a collimating light source which the viewing angle is less than +/-5° and the area of uniform irradiation surface is greater than 20mm×20mm.

  18. An in-Depth Survey of Visible Light Communication Based Positioning Systems.

    PubMed

    Do, Trong-Hop; Yoo, Myungsik

    2016-01-01

    While visible light communication (VLC) has become the candidate for the wireless technology of the 21st century due to its inherent advantages, VLC based positioning also has a great chance of becoming the standard approach to positioning. Within the last few years, many studies on VLC based positioning have been published, but there are not many survey works in this field. In this paper, an in-depth survey of VLC based positioning systems is provided. More than 100 papers ranging from pioneering papers to the state-of-the-art in the field were collected and classified based on the positioning algorithms, the types of receivers, and the multiplexing techniques. In addition, current issues and research trends in VLC based positioning are discussed. PMID:27187395

  19. An in-Depth Survey of Visible Light Communication Based Positioning Systems

    PubMed Central

    Do, Trong-Hop; Yoo, Myungsik

    2016-01-01

    While visible light communication (VLC) has become the candidate for the wireless technology of the 21st century due to its inherent advantages, VLC based positioning also has a great chance of becoming the standard approach to positioning. Within the last few years, many studies on VLC based positioning have been published, but there are not many survey works in this field. In this paper, an in-depth survey of VLC based positioning systems is provided. More than 100 papers ranging from pioneering papers to the state-of-the-art in the field were collected and classified based on the positioning algorithms, the types of receivers, and the multiplexing techniques. In addition, current issues and research trends in VLC based positioning are discussed. PMID:27187395

  20. Non-contact detection of cardiac rate based on visible light imaging device

    NASA Astrophysics Data System (ADS)

    Zhu, Huishi; Zhao, Yuejin; Dong, Liquan

    2012-10-01

    We have developed a non-contact method to detect human cardiac rate at a distance. This detection is based on the general lighting condition. Using the video signal of human face region captured by webcam, we acquire the cardiac rate based on the PhotoPlethysmoGraphy theory. In this paper, the cardiac rate detecting method is mainly in view of the blood's different absorptivities of the lights various wavelengths. Firstly, we discompose the video signal into RGB three color signal channels and choose the face region as region of interest to take average gray value. Then, we draw three gray-mean curves on each color channel with time as variable. When the imaging device has good fidelity of color, the green channel signal shows the PhotoPlethysmoGraphy information most clearly. But the red and blue channel signals can provide more other physiological information on the account of their light absorptive characteristics of blood. We divide red channel signal by green channel signal to acquire the pulse wave. With the passband from 0.67Hz to 3Hz as a filter of the pulse wave signal and the frequency spectrum superimposed algorithm, we design frequency extracted algorithm to achieve the cardiac rate. Finally, we experiment with 30 volunteers, containing different genders and different ages. The results of the experiments are all relatively agreeable. The difference is about 2bmp. Through the experiment, we deduce that the PhotoPlethysmoGraphy theory based on visible light can also be used to detect other physiological information.

  1. Post-illumination pupil response after blue light: Reliability of optimized melanopsin-based phototransduction assessment.

    PubMed

    van der Meijden, Wisse P; te Lindert, Bart H W; Bijlenga, Denise; Coppens, Joris E; Gómez-Herrero, Germán; Bruijel, Jessica; Kooij, J J Sandra; Cajochen, Christian; Bourgin, Patrice; Van Someren, Eus J W

    2015-10-01

    ± 3.6 yr) we examined the potential confounding effects of dark adaptation, time of the day (morning vs. afternoon), body posture (upright vs. supine position), and 24-h environmental light history on the PIPR assessment. Mixed effect regression models were used to analyze these possible confounders. A supine position caused larger PIPR-mm (β = 0.29 mm, SE = 0.10, p = 0.01) and PIPR-% (β = 4.34%, SE = 1.69, p = 0.02), which was due to an increase in baseline dark pupil diameter; this finding is of relevance for studies requiring a supine posture, as in functional Magnetic Resonance Imaging, constant routine protocols, and bed-ridden patients. There were no effects of dark adaptation, time of day, and light history. In conclusion, the presented method provides a reliable and robust assessment of the PIPR to allow for studies on individual differences in melanopsin-based phototransduction and effects of interventions. PMID:26209783

  2. Si-based light emitter in an integrated photonic circuit for smart biosensor applications

    NASA Astrophysics Data System (ADS)

    Germer, S.; Cherkouk, C.; Rebohle, L.; Helm, M.; Skorupa, W.

    2013-05-01

    The motivation for integrated Silicon-based optoelectronics is the creation of low-cost photonics for mass-market applications. Especially, the growing demand for sensitive biochemical sensors in the environmental control or medicine leads to the development of integrated high resolution sensors. Here we present initial results in the integration and butt-coupling of a Si-based light emitting device (LED) [1-3] to a waveguide into a photonic circuit. Our first approach deals with the design, fabrication and characterization of the dielectric high contrast waveguide as an important component, beside the LED, for the development of a Si-based biodetection system. In this work we demonstrate design examples of Si3N4/SiO2-waveguides, which were calculated using MATLAB, the effective index method (EIM) and the finite element method (FEM), with a 0.45μm thick and 0.7μm wide core which shows a high confinement factor of ~74% and coupling efficiency of ~66% at 1.55μm, respectively. The fabrication was done by plasma enhanced chemical vapour deposition (PECVD), optical lithography and reactive ion etching (RIE). Additionally, we characterized the deposited layers via ellipsometry and the etched structures by scanning electron microscopy (SEM). The obtained results establish principles for Si-based LED butt-coupling to a powerful optical waveguide-based interconnect with effective light absorption and an adequate coupling efficiency.

  3. Analysis on the effect of amorphous photonic crystals on light extraction efficiency enhancement for GaN-based thin-film-flip-chip light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yue, Qingyang; Li, Kang; Kong, Fanmin; Zhao, Jia; Liu, Meng

    2016-05-01

    This work showed the liquid-like amorphous photonic crystals (PhCs) can effectively enhance the light extraction efficiency of GaN-based thin-film-flip-chip light-emitting diodes (TFFC LEDs) by the light scattering effect. The finite-difference time-domain (FDTD) method was employed to analyze the light scattering characteristics, numerical studies revealed that the amorphous PhCs can provide omnidirectional scattering, and the transmittances of amorphous PhCs is superior to that of triangular lattice PhCs when the incident angle is in the region 20 ° ≤ θ ≤ 35 ° . The influence of p-GaN layer thickness and the amorphous PhCs feature size on the light extraction efficiency was also studied by 3D-FDTD method systematically. For the proposed amorphous PhCs structure in n-GaN layer, the light extraction efficiency is enhanced by a factor of 1.49 as compared to conventional TFFC LEDs, which shows 1.07 times enhancement in comparison to that of triangular lattice PhCs.

  4. Metazoan circadian rhythm: toward an understanding of a light-based zeitgeber in sponges.

    PubMed

    Müller, Werner E G; Schröder, Heinz C; Pisignano, Dario; Markl, Julia S; Wang, Xiaohong

    2013-07-01

    In all eukaryotes, the 24-h periodicity in the environment contributed to the evolution of the molecular circadian clock. We studied some elements of a postulated circadian clock circuit in the lowest metazoans, the siliceous sponges. First, we identified in the demosponge Suberites domuncula the enzyme luciferase that generates photons. Then (most likely), the photons generated by luciferase are transmitted via the biosilica glass skeleton of the sponges and are finally harvested by cryptochrome in the same individual; hence, cryptochrome is acting as a photosensor. This information-transduction system, generation of light (luciferase), photon transmission (through the siliceous spicules), and photon reception (cryptochrome), all occur in the same individual. Therefore, we propose that this photoreception/phototransduction process might function as a nerve-cell-like signal transmitting system. This was corroborated by the fact that S. domuncula reacts to different wavelengths of light, originating from the sponge environment, with a differential gene expression of the transcription factor SOX. Recently, we succeeded in demonstrating that in sponges a light/dark controlled gene is expressed, which encodes for nocturnin, a protein showing poly(A)-specific 3'-exoribonuclease activity. Quantitative real-time polymerase chain reaction analyses revealed that primmorphs, 3D cell aggregates of sponge cells, after transfer from light to dark, show a 10-fold increased expression of the nocturnin gene. In contrast, the expression level of the gene encoding glycogenin decreases in the dark by three- to four-fold. It is concluded that sponges are provided with the molecular circadian clock protein nocturnin which is highly expressed in the dark. This finding together with the proposed light-transduction and spicule-based signaling system strongly supports the view that already the lowest metazoans, the sponges, have elements of a circadian rhythm, characteristic of higher

  5. A light efficiency uniformity detection system for medical rigid endoscope based on image processing

    NASA Astrophysics Data System (ADS)

    Wang, Yakun; Liu, Ming; Liu, Xiaohua; Zhao, Yuejin; Dong, Liquan; Hui, Mei; Zhai, Xiaohao; Li, Yonghui; Zhou, Peng

    2015-08-01

    Light efficiency uniformity is a very important parameter of medical rigid endoscope. This paper introduces a new system based on image processing to test the light efficiency uniformity of medical rigid endoscope. Employing an electric machinery to reduce the human intervention, so that the precision of measuring and automation degree are improved. We collect the image with a digital CCD camera and display it on the screen of a computer, which can avoid visual fatigue from the direct observation through the rigid endoscope. To perform the image processing on a computer, we adopt a self-developed image processing software, by which the test results can be obtained from PC itself. The processes of our self-developed image processing software include: gray-scale transformation, image pretreatment and image binarization; calculate the center and equivalent radius of the field of view (FOV); plot the curve, through which the ratio of edge and center in different field and the center axisymmetric of light efficiency can be both calculated. It concludes that the relative self-effect of illumination light luminosity is the foremost factor affecting the uniformity, and these endoscopes are all qualified with the max deviation of the center axisymmetric less than 20%. The results of our study prove that this system can test the light efficiency uniformity of medical rigid endoscope quickly, expediently and accurately, and it contains more information instead of only reflecting a particular field of the FOV, what's more, it applies to different types, length and angles of view of medical rigid endoscope.

  6. Stochastic modeling of polarized light scattering using a Monte Carlo based stencil method.

    PubMed

    Sormaz, Milos; Stamm, Tobias; Jenny, Patrick

    2010-05-01

    This paper deals with an efficient and accurate simulation algorithm to solve the vector Boltzmann equation for polarized light transport in scattering media. The approach is based on a stencil method, which was previously developed for unpolarized light scattering and proved to be much more efficient (speedup factors of up to 10 were reported) than the classical Monte Carlo while being equally accurate. To validate what we believe to be the new stencil method, a substrate composed of spherical non-absorbing particles embedded in a non-absorbing medium was considered. The corresponding single scattering Mueller matrix, which is required to model scattering of polarized light, was determined based on the Lorenz-Mie theory. From simulations of a reflected polarized laser beam, the Mueller matrix of the substrate was computed and compared with an established reference. The agreement is excellent, and it could be demonstrated that a significant speedup of the simulations is achieved due to the stencil approach compared with the classical Monte Carlo. PMID:20448777

  7. Dynamically tunable slow light based on plasmon induced transparency in disk resonators coupled MDM waveguide system

    NASA Astrophysics Data System (ADS)

    Han, Xu; Wang, Tao; Li, Xiaoming; Liu, Bo; He, Yu; Tang, Jian

    2015-06-01

    Ultrafast and low-power dynamically tunable single channel and multichannel slow light based on plasmon induced transparencies (PITs) in disk resonators coupled to a metal-dielectric-metal (MDM) waveguide system with a nonlinear optical Kerr medium is investigated both numerically and analytically. A coupled-mode theory (CMT) is introduced to analyze this dynamically tunable single channel slow light structure. Multichannel slow light is realized in this plasmonic waveguide structure based on a bright-dark mode coupling mechanism. In order to reduce the pump intensity and obtain ultrafast response time, the traditional nonlinear Kerr material is replaced by monolayer graphene. It is found that the magnitude of the single PIT window can be controlled between 0.08 and 0.48, while the corresponding group index is controlled between 14.5 and 2.0 by dynamically decreasing pump intensity from 11.7 to 4.4 MW cm-2. Moreover, the phase shift multiplication effect is found in this structure. This work paves a new way towards the realization of highly integrated optical circuits and networks, especially for wavelength-selective, all-optical storage and nonlinear devices.

  8. A color fusion method of infrared and low-light-level images based on visual perception

    NASA Astrophysics Data System (ADS)

    Han, Jing; Yan, Minmin; Zhang, Yi; Bai, Lianfa

    2014-11-01

    The color fusion images can be obtained through the fusion of infrared and low-light-level images, which will contain both the information of the two. The fusion images can help observers to understand the multichannel images comprehensively. However, simple fusion may lose the target information due to inconspicuous targets in long-distance infrared and low-light-level images; and if targets extraction is adopted blindly, the perception of the scene information will be affected seriously. To solve this problem, a new fusion method based on visual perception is proposed in this paper. The extraction of the visual targets ("what" information) and parallel processing mechanism are applied in traditional color fusion methods. The infrared and low-light-level color fusion images are achieved based on efficient typical targets learning. Experimental results show the effectiveness of the proposed method. The fusion images achieved by our algorithm can not only improve the detection rate of targets, but also get rich natural information of the scenes.

  9. Evaluating light-based geolocation for estimating demersal fish movements in high latitudes

    USGS Publications Warehouse

    Seitz, Andrew C; Norcross, B.L.; Wilson, D.; Nielsen, Jennifer L.

    2006-01-01

    We evaluated light-based geolocation estimates from pop-up satellite tags in high latitudesbecause some of the largest fisheries in the world are in areas where this technique has not been assessed. Daily longitude and latitude were estimated by using two Wildlife Computers software programs: 1) Argos Message Processor (AMP), which summarizes light intensity data transmitted to satellites, and 2) Time Series Processor (TSP), which uses more detailed data obtained from retrieved tags. Three experiments were conducted in the northern Gulf of Alaska using tags placed on 1) Pacific halibut in outdoor aquaria, 2) a fixed mooring line at various depths and 3) wild Pacific halibut. TSP performed better than AMP because the percentage of days with geolocation estimates was greater and the mean error magnitude and bias were smaller for TSP and increased with depth for both programs; however, latitude errors were much greater than longitude errors at all depths. Light-based geolocation enabled us to discern basin-scale movements and showed that the Pacific halibut in our study remained within the Gulf of Alaska. We conclude that this technique provides a feasible method for inferring large-scale population structure for demersal fishes in high latitudes. 

  10. Confocal microphotoluminescence of InGaN-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Okamoto, Koichi; Kaneta, Akio; Kawakami, Yoichi; Fujita, Shigeo; Choi, Jungkwon; Terazima, Masahide; Mukai, Takashi

    2005-09-01

    Spatially resolved photoluminescence (PL) of InGaN/GaN/AlGaN-based quantum-well-structured light-emitting diodes (LEDs) with a yellow-green light (530 nm) and an amber light (600 nm) was measured by using confocal microscopy. Submicron-scale spatial inhomogeneities of both PL intensities and spectra were found in confocal micro-PL images. We also found clear correlations between PL intensities and peak wavelength for both LEDs. Such correlations for yellow-green and amber LEDs were different from the reported correlations for blue or green LEDs. This discrepancy should be due to different diffusion, localization, and recombination dynamics of electron-hole pairs generated in InGaN active layers, and should be a very important property for influencing the optical properties of LEDs. In order to explain the results, we proposed a possible carrier dynamics model based on the carrier localization and partial reduction of the quantum confinement Stark effect depending on an indium composition in InGaN active layers. By using this model, we also considered the origin of the reduction of the emission efficiencies with a longer emission wavelength of InGaN LEDs with high indium composition.

  11. Biochemical component identification by light scattering techniques in whispering gallery mode optical resonance based sensor

    NASA Astrophysics Data System (ADS)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

    2014-03-01

    Experimental data on detection and identification of variety of biochemical agents, such as proteins (albumin, interferon, C reactive protein), microelements (Na+, Ca+), antibiotic of different generations, in both single and multi component solutions under varied in wide range concentration are represented. Analysis has been performed on the light scattering parameters of whispering gallery mode (WGM) optical resonance based sensor with dielectric microspheres from glass and PMMA as sensitive elements fixed by spin - coating techniques in adhesive layer on the surface of substrate or directly on the coupling element. Sensitive layer was integrated into developed fluidic cell with a digital syringe. Light from tuneable laser strict focusing on and scattered by the single microsphere was detected by a CMOS camera. The image was filtered for noise reduction and integrated on two coordinates for evaluation of integrated energy of a measured signal. As the entrance data following signal parameters were used: relative (to a free spectral range) spectral shift of frequency of WGM optical resonance in microsphere and relative efficiency of WGM excitation obtained within a free spectral range which depended on both type and concentration of investigated agents. Multiplexing on parameters and components has been realized using spatial and spectral parameters of scattered by microsphere light with developed data processing. Biochemical component classification and identification of agents under investigation has been performed by network analysis techniques based on probabilistic network and multilayer perceptron. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis.

  12. Engineering a light-controlled F1 ATPase using structure-based protein design.

    PubMed

    Hoersch, Daniel

    2016-01-01

    The F1 sub-complex of ATP synthase is a biological nanomotor that converts the free energy of ATP hydrolysis into mechanical work with an astonishing efficiency of up to 100% (Kinosita et al., 2000). To probe the principal mechanics of the machine, I re-engineered the active site of E.coli F1 ATPase with a structure-based protein design approach: by incorporation of a site-specific, photoswitchable crosslinker, whose end-to-end distance can be modulated by illumination with light of two different wavelengths, a dynamic constraint was imposed on the inter-atomic distances of the α and β subunits. Crosslinking reduced the ATP hydrolysis activity of four designs tested in vitro and in one case created a synthetic ATPase whose activity can be reversibly modulated by subsequent illumination with near UV and blue light. The work is a first step into the direction of the long-term goal to design nanoscaled machines based on biological parts that can be precisely controlled by light. PMID:27547581

  13. Engineering a light-controlled F1 ATPase using structure-based protein design

    PubMed Central

    2016-01-01

    The F1 sub-complex of ATP synthase is a biological nanomotor that converts the free energy of ATP hydrolysis into mechanical work with an astonishing efficiency of up to 100% (Kinosita et al., 2000). To probe the principal mechanics of the machine, I re-engineered the active site of E.coli F1 ATPase with a structure-based protein design approach: by incorporation of a site-specific, photoswitchable crosslinker, whose end-to-end distance can be modulated by illumination with light of two different wavelengths, a dynamic constraint was imposed on the inter-atomic distances of the α and β subunits. Crosslinking reduced the ATP hydrolysis activity of four designs tested in vitro and in one case created a synthetic ATPase whose activity can be reversibly modulated by subsequent illumination with near UV and blue light. The work is a first step into the direction of the long-term goal to design nanoscaled machines based on biological parts that can be precisely controlled by light. PMID:27547581

  14. A three-dimensional measurement method based on mesh candidates assisted with structured light

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Zhang, Wenming; Li, Haibin; Liu, Bin

    2009-07-01

    Rendering three-dimensional information of a scene from optical measurement is very important for a wide variety of applications such as robot navigation, rapid prototyping, medical imaging, industrial inspection, etc. In this paper, a new 3D measurement method based on mesh candidate with structured light illuminating is proposed. The vision sensor consists of two CCD cameras and a DLP projector. The measurement system combines the technology of binocular stereo vision and structured light, so as to simplify the process of acquiring depth information using mesh candidates. The measurement method is based on mesh candidates which represent the potential depth in the three dimensional scene. First the mesh grid was created along the direction of axes in world coordinate system, and the nodes were considered as depth candidates on the surface of object. Then each group of the mesh nodes varying along z axis were mapped to the captured image planes of both cameras. At last, according to the similarity measure of the corresponding pixel pairs, the depth of the object surface can be obtained. The matching process is between the pixels in both camera planes corresponding to the spatial mesh candidates. Aided by the structured light pattern, the accuracy of measurement system improved. Appending the periodic sawtooth pattern on the scene by structured light made measurement easier, while the computational cost did not increased since the projector had no need to be calibrated. The 3DS MAX and Matlab software were used to simulate measurement system and reconstruct the surface of the object. After the positioned cameras have been calibrated using Matlab calibration toolbox, the projector is used to project structured light pattern on the scene. Indicated by experimental results, the mesh-candidate-based method is obviously superior in computation and accuracy. Compared with traditional methods based on image matching, our method has several advantages: (1) the complex

  15. Vector magnetometry based on electromagnetically induced transparency in linearly polarized light

    SciTech Connect

    Yudin, V. I.; Taichenachev, A. V.; Dudin, Y. O.; Velichansky, V. L.; Zibrov, A. S.; Zibrov, S. A.

    2010-09-15

    We develop a generalized principle of electromagnetically induced transparency (EIT) vector magnetometry based on high-contrast EIT resonances and the symmetry of atom-light interaction in the linearly polarized bichromatic fields. Operation of such vector magnetometer on the D{sub 1} line of {sup 87}Rb has been demonstrated. The proposed compass-magnetometer has an increased immunity to shifts produced by quadratic Zeeman and ac-Stark effects, as well as by atom-buffer gas and atom-atom collisions. In our proof-of-principle experiment the detected angular sensitivity to magnetic field orientation is 10{sup -3} deg/Hz{sup 1/2}, which is limited by laser intensity fluctuations, light polarization quality, and magnitude of the magnetic field.

  16. A proteorhodopsin-based biohybrid light-powering pH sensor.

    PubMed

    Rao, Siyuan; Guo, Zhibin; Liang, Dawei; Chen, Deliang; Wei, Yen; Xiang, Yan

    2013-10-14

    The biohybrid sensor is an emerging technique for multi-functional detection that utilizes the instinctive responses or interactions of biomolecules. We develop a biohybrid pH sensor by taking advantage of the pH-dependent photoelectric characteristics of proteorhodopsin (pR). The transient absorption kinetics study indicates that the photoelectric behavior of pR is attributed to the varying lifetime of the M intermediate at different environmental pH values. This pR-based biohybrid light-powering sensor with microfluidic design can achieve real-time pH detection with quick response and high sensitivity. The results of this work would shed light on pR and its potential applications. PMID:23970242

  17. Simulation of the Recharging Method of Implantable Biosensors Based on a Wearable Incoherent Light Source

    PubMed Central

    Song, Yong; Hao, Qun; Kong, Xianyue; Hu, Lanxin; Cao, Jie; Gao, Tianxin

    2014-01-01

    Recharging implantable electronics from the outside of the human body is very important for applications such as implantable biosensors and other implantable electronics. In this paper, a recharging method for implantable biosensors based on a wearable incoherent light source has been proposed and simulated. Firstly, we develop a model of the incoherent light source and a multi-layer model of skin tissue. Secondly, the recharging processes of the proposed method have been simulated and tested experimentally, whereby some important conclusions have been reached. Our results indicate that the proposed method will offer a convenient, safe and low-cost recharging method for implantable biosensors, which should promote the application of implantable electronics. PMID:25372616

  18. LATEST LASER AND LIGHT-BASED ADVANCES FOR ETHNIC SKIN REJUVENATION

    PubMed Central

    Elsaie, Mohamed Lotfy; Lloyd, Heather Woolery

    2008-01-01

    Background: Advances in nonablative skin rejuvenation technologies have sparked a renewed interest in the cosmetic treatment of aging skin. More options exist now than ever before to reverse cutaneous changes caused by long-term exposure to sunlight. Although Caucasian skin is more prone to ultraviolet light injury, ethnic skin (typically classified as types IV to VI) also exhibits characteristic photoaging changes. Widespread belief that inevitable or irreversible textural changes or dyspigmentation occurs following laser- or light-based treatments, has been challenged in recent years by new classes of devices capable of protecting the epidermis from injury during treatment. Objective: The purpose of this article is to review recent clinical advances in the treatment of photoaging changes in ethnic skin. This article provides a basis for the classification of current advances in nonablative management of ethnic skin. PMID:19881986

  19. The optimization of collimator's light-weighting structure based on MOBIE system of TMT

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Chen, Yi; Hu, Zhongwen; Xu, Mingming; Ji, Hangxin; Wang, Lei

    2015-10-01

    Design a best light-weighting collimator to conform to the requirements of opto-mechanical design. Good surface accuracy is our aim, based on a less mass. The ratio of diameter to thickness, the type, size and thickness of pocket, the thickness of the mirror, the support size and position, the thickness of the wall and so on is concerned. Besides, comparing two kinds material is also discussed. In addition, we consider the situation that the orientation vary in support plane. Use the orthogonal table to analyze these elements, and find the better methods. According to the analysis in ANSYS, the collimator mass can reduce to 103 kg, below 159 kg; the ratio of light-weight can reach 70%; the peak-valley value is below 100 nm, that meets the request of below 200 nm.

  20. Photocatalytic removal of microcystin-LR by advanced WO3-based nanoparticles under simulated solar light.

    PubMed

    Zhao, Chao; Li, Dawei; Liu, Yonggang; Feng, Chuanping; Zhang, Zhenya; Sugiura, Norio; Yang, Yingnan

    2015-01-01

    A series of advanced WO3-based photocatalysts including CuO/WO3, Pd/WO3, and Pt/WO3 were synthesized for the photocatalytic removal of microcystin-LR (MC-LR) under simulated solar light. In the present study, Pt/WO3 exhibited the best performance for the photocatalytic degradation of MC-LR. The MC-LR degradation can be described by pseudo-first-order kinetic model. Chloride ion (Cl-) with proper concentration could enhance the MC-LR degradation. The presence of metal cations (Cu2+ and Fe3+) improved the photocatalytic degradation of MC-LR. This study suggests that Pt/WO3 photocatalytic oxidation under solar light is a promising option for the purification of water containing MC-LR. PMID:25884038

  1. Photocatalytic Removal of Microcystin-LR by Advanced WO3-Based Nanoparticles under Simulated Solar Light

    PubMed Central

    Zhao, Chao; Li, Dawei; Feng, Chuanping; Zhang, Zhenya; Sugiura, Norio; Yang, Yingnan

    2015-01-01

    A series of advanced WO3-based photocatalysts including CuO/WO3, Pd/WO3, and Pt/WO3 were synthesized for the photocatalytic removal of microcystin-LR (MC-LR) under simulated solar light. In the present study, Pt/WO3 exhibited the best performance for the photocatalytic degradation of MC-LR. The MC-LR degradation can be described by pseudo-first-order kinetic model. Chloride ion (Cl−) with proper concentration could enhance the MC-LR degradation. The presence of metal cations (Cu2+ and Fe3+) improved the photocatalytic degradation of MC-LR. This study suggests that Pt/WO3 photocatalytic oxidation under solar light is a promising option for the purification of water containing MC-LR. PMID:25884038

  2. Magnetoluminescence of light-emitting field-effect transistors based on alpha sexithiophene

    NASA Astrophysics Data System (ADS)

    Pham, Song-Toan; Tada, Hirokazu

    2014-03-01

    We demonstrated the effect of a magnetic field on the luminous intensity and electric current of light-emitting field-effect transistors (LEFETs) based on alpha sexithiophene (α-6T). Sublimate-grade α-6T was thermally deposited on an n+-Si/300 nm-SiO2 substrate with patterned asymmetric gold-aluminum electrodes to fabricate a bottom-contact LEFET. We observed an increase in luminous intensity of approximately 1.3% under a magnetic field of 100 mT. A possible explanation for this is that the magnetic field increased the probability of singlet formation at the α-6T/Al interface. While the magneto-electroluminescence (MEL) was reported to be derived from the magneto-conductance (MC) in ordinary light emitting diodes, the MEL in LEFET was independent with MC. This indicates that the luminous efficiency can be improved by optimizing the magnetic field effect.

  3. High-accuracy indoor positioning system based on visible light communication

    NASA Astrophysics Data System (ADS)

    Wei, Ling; Zhang, Hongming; Yu, Bingyan; Guan, Yang

    2015-11-01

    A visible light communication (VLC)-based high-accuracy indoor positioning system is proposed and demonstrated. In this system, the light-emitting diode identification (LED-ID) indicating the position information of the LED can be transmitted to the receiver by the illumination LED through VLC. In the meantime, with the aid of a camera and angular sensors of the mobile device, a coordinate transform can be employed to calculate the relative position between the receiver and the reference LED so that the position of the receiver can be determined. Finally, the experimental results show that 2-cm positioning accuracy can be achieved and the simulation results indicate that the positioning error can be limited within 4.7 cm when the accuracy of angular sensors is 1 deg.

  4. Optical fiber hydrogen sensor based on light reflection and a palladium-sliver thin film

    NASA Astrophysics Data System (ADS)

    Cui, Lu-Jun; Shang, Hui-Chao; Zhang, Gang; Zhao, Ze-Xiang; Zhou, Jun

    2011-07-01

    Thin alloy films of palladium (Pd) and silver (Ag) are deposited onto glass substrates via the direct current (DC) magnetron technique. The hydrogen sensor probe consists of optical fiber bundle and Pd/Ag optical thin film. When the sensor is exposed to hydrogen, the refractive index of Pd/Ag optical thin layer will diminish and cause attenuation changes of the reflective light. It is observed that the thickness of Pd/Ag alloy layer can affect the hydrogen sensor signal. Under different substrate temperatures, several Pd/Ag samples are coated with different thicknesses of Pd/Ag alloy, and the results of a hydrogen sensor based on reflective light from the Pd/Ag alloy thin film are discussed.

  5. Broadband light trapping based on periodically textured ZnO thin films

    NASA Astrophysics Data System (ADS)

    Liu, Bofei; Liang, Xuejiao; Liang, Junhui; Bai, Lisha; Gao, Haibo; Chen, Ze; Zhao, Ying; Zhang, Xiaodan

    2015-05-01

    Transparent conductive front electrodes (TCFEs) deployed in photovoltaic devices have been extensively studied for their significance in transporting carriers, coupling and trapping the incident photons in high-performing solar cells. The trade-off between the light-transmission, electrical, and scattering properties for TCFEs to achieve a broadband improvement in light absorption in solar cells while maintaining a high electrical performance has become the key issue to be tackled. In this paper, we employ self-assembled polystyrene (PS) spheres based on a sauna-like method as a template, followed by a double-layer deposition and then successfully fabricate highly-transparent, well-conductive, and large-scale periodically-textured ZnO TCFEs with broadband light trapping properties. A sheet resistance below 15 Ω sq-1 was achieved for the periodically-textured ZnO TCFEs, with a concomitant average transmission of 81% (including the glass substrate) in the 400-1100 nm spectral range, a haze improvement in a broadband spectral range, and a wider scattering angular domain. The proposed approach affords a promising alternative method to prepare periodically-textured TCFEs, which are essential for many optoelectronic device semiconductors, such as photovoltaic and display applications.Transparent conductive front electrodes (TCFEs) deployed in photovoltaic devices have been extensively studied for their significance in transporting carriers, coupling and trapping the incident photons in high-performing solar cells. The trade-off between the light-transmission, electrical, and scattering properties for TCFEs to achieve a broadband improvement in light absorption in solar cells while maintaining a high electrical performance has become the key issue to be tackled. In this paper, we employ self-assembled polystyrene (PS) spheres based on a sauna-like method as a template, followed by a double-layer deposition and then successfully fabricate highly-transparent, well

  6. Investigation of Trapezoidal Well for Improving the Light Efficiency in AlGaInP-Based Light-Emitting Diodes.

    PubMed

    Oh, Hwa Sub; Song, A Ri; Jung, Sung Hoon; Jung, Tae Hoon; Kim, Young Jin; Lee, Hyung Joo; Cho, Young Dae; Baek, Jong Hyeob

    2016-02-01

    We investigated high-brightness light emitting diodes appropriate for general lighting applications in terms of their optical behaviors and device performances according to the insertion of the sloped barrier between the well and the barrier and changing the sloped barrier thickness. As the sloped barrier thickness was increased from 0 to 5 nm, radiative recombination efficiency and device performances significantly improved, due to the suppression of carrier overflow by the stronger capture of carriers and the shortening of the carrier lifetime in the active region owing to the built-in quasi-electric field. At a further increase in the sloped barrier thickness to 10 nm, however, the optical and device performances started to degrade because of the loosening of the quantum confinement effect in the active region and due to the saturation of the improvement of the carrier capture by the sloped barrier region. PMID:27433690

  7. A coronagraph based on two spatial light modulators for active amplitude apodizing and phase corrections

    NASA Astrophysics Data System (ADS)

    Dou, Jiangpei; Ren, Deqing; Zhang, Xi; Zhu, Yongtian; Zhao, Gang; Wu, Zhen; Chen, Rui; Liu, Chengchao; Yang, Feng; Yang, Chao

    2014-08-01

    Almost all high-contrast imaging coronagraphs proposed until now are based on passive coronagraph optical components. Recently, Ren and Zhu proposed for the first time a coronagraph that integrates a liquid crystal array (LCA) for the active pupil apodizing and a deformable mirror (DM) for the phase corrections. Here, for demonstration purpose, we present the initial test result of a coronagraphic system that is based on two liquid crystal spatial light modulators (SLM). In the system, one SLM is served as active pupil apodizing and amplitude correction to suppress the diffraction light; another SLM is used to correct the speckle noise that is caused by the wave-front distortions. In this way, both amplitude and phase error can be actively and efficiently compensated. In the test, we use the stochastic parallel gradient descent (SPGD) algorithm to control two SLMs, which is based on the point spread function (PSF) sensing and evaluation and optimized for a maximum contrast in the discovery area. Finally, it has demonstrated a contrast of 10-6 at an inner working angular distance of ~6.2 λ/D, which is a promising technique to be used for the direct imaging of young exoplanets on ground-based telescopes.

  8. A framework for validating light fields created using physically based rendering techniques

    NASA Astrophysics Data System (ADS)

    Whittinghill, David M.

    This research study presents a framework for applying physically based global illumination techniques to the creation of software models of light fields that are then validated against actual light fields measured in physical experiments. A prior experiment was performed by horticulture scientists in which the light field of an empty plant growth chamber was measured using quantum sensors at fixed spatial intervals. The result was a light map consisting of a 9 x 45, fixed-width, two-dimensional graph of sensor readings that described the intensity of radiant energy present in the chamber at the chosen locations. A single observation of the growth chamber was made resulting in a single data set consisting of 45 different, location-sensitive irradiance observations. To test this framework a series of simulations were performed in which the physical attributes of the growth chamber were duplicated as closely as possible in a virtual growth chamber software model. Modeled attributes included physical dimensions, wall and light reflectivity, and full-spectrum light characterization. Light transport was modeled using a physically based, global illumination rendering technique called photon mapping. Virtual sensors that recorded the intensity of the light that transmitted through their surface were placed in the virtual chamber at the same position and interval as the ones that were used in the physical experiment. The output of the virtual chamber experiments were represented as a graph in the same configuration as the one in the physical experiment. The experiment was conducted using a modified version of pbrt, a physically based, extensible renderer developed by Matt Pharr and Greg Humphreys [1]. As photon mapping uses a stochastic algorithm, many repetitions of the virtual chamber experiment were performed and the mean and standard deviation were recorded as a global measure for each chamber as well as for each individual sensor location. The global means of the

  9. Sound Velocity and Diffraction Intensity Measurements Based on Raman-Nath Theory of the Interaction of Light and Ultrasound

    ERIC Educational Resources Information Center

    Neeson, John F.; Austin, Stephen

    1975-01-01

    Describes a method for the measurement of the velocity of sound in various liquids based on the Raman-Nath theory of light-sound interaction. Utilizes an analog computer program to calculate the intensity of light scattered into various diffraction orders. (CP)

  10. Improved green-light-emitting pyrotechnic formulations based on tris(2,2,2-trinitroethyl)borate and boron carbide.

    PubMed

    Klapötke, Thomas M; Krumm, Burkhard; Rusan, Magdalena; Sabatini, Jesse J

    2014-08-28

    Green-light-emitting pyrotechnic compositions based on tris(2,2,2-trinitroethyl)borate (TNEB) and boron carbide have been investigated. The best performing formulations were found to be insensitive to various ignition stimuli, and exhibited very high spectral purities and luminosities compared to previously reported green-light-emitting formulations. PMID:25012058

  11. A multiplexed light-matter interface for fibre-based quantum networks

    NASA Astrophysics Data System (ADS)

    Saglamyurek, Erhan; Grimau Puigibert, Marcelli; Zhou, Qiang; Giner, Lambert; Marsili, Francesco; Verma, Varun B.; Woo Nam, Sae; Oesterling, Lee; Nippa, David; Oblak, Daniel; Tittel, Wolfgang

    2016-04-01

    Processing and distributing quantum information using photons through fibre-optic or free-space links are essential for building future quantum networks. The scalability needed for such networks can be achieved by employing photonic quantum states that are multiplexed into time and/or frequency, and light-matter interfaces that are able to store and process such states with large time-bandwidth product and multimode capacities. Despite important progress in developing such devices, the demonstration of these capabilities using non-classical light remains challenging. Here, employing the atomic frequency comb quantum memory protocol in a cryogenically cooled erbium-doped optical fibre, we report the quantum storage of heralded single photons at a telecom-wavelength (1.53 μm) with a time-bandwidth product approaching 800. Furthermore, we demonstrate frequency-multimode storage and memory-based spectral-temporal photon manipulation. Notably, our demonstrations rely on fully integrated quantum technologies operating at telecommunication wavelengths. With improved storage efficiency, our light-matter interface may become a useful tool in future quantum networks.

  12. The research on binocular stereo video imaging and display system based on low-light CMOS

    NASA Astrophysics Data System (ADS)

    Xie, Ruobing; Li, Li; Jin, Weiqi; Guo, Hong

    2015-10-01

    It is prevalent for the low-light night-vision helmet to equip the binocular viewer with image intensifiers. Such equipment can not only acquire night vision ability, but also obtain the sense of stereo vision to achieve better perception and understanding of the visual field. However, since the image intensifier is for direct-observation, it is difficult to apply the modern image processing technology. As a result, developing digital video technology in night vision is of great significance. In this paper, we design a low-light night-vision helmet with digital imaging device. It consists of three parts: a set of two low-illumination CMOS cameras, a binocular OLED micro display and an image processing PCB. Stereopsis is achieved through the binocular OLED micro display. We choose Speed-Up Robust Feature (SURF) algorithm for image registration. Based on the image matching information and the cameras' calibration parameters, disparity can be calculated in real-time. We then elaborately derive the constraints of binocular stereo display. The sense of stereo vision can be obtained by dynamically adjusting the content of the binocular OLED micro display. There is sufficient space for function extensions in our system. The performance of this low-light night-vision helmet can be further enhanced in combination with The HDR technology and image fusion technology, etc.

  13. Visible-light-induced instability in amorphous metal-oxide based TFTs for transparent electronics

    SciTech Connect

    Ha, Tae-Jun

    2014-10-15

    We investigate the origin of visible-light-induced instability in amorphous metal-oxide based thin film transistors (oxide-TFTs) for transparent electronics by exploring the shift in threshold voltage (V{sub th}). A large hysteresis window in amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs possessing large optical band-gap (≈3 eV) was observed in a visible-light illuminated condition whereas no hysteresis window was shown in a dark measuring condition. We also report the instability caused by photo irradiation and prolonged gate bias stress in oxide-TFTs. Larger V{sub th} shift was observed after photo-induced stress combined with a negative gate bias than the sum of that after only illumination stress and only negative gate bias stress. Such results can be explained by trapped charges at the interface of semiconductor/dielectric and/or in the gate dielectric which play a role in a screen effect on the electric field applied by gate voltage, for which we propose that the localized-states-assisted transitions by visible-light absorption can be responsible.

  14. Focused ultrasound-mediated sonochemical internalization: an alternative to light-based therapies

    NASA Astrophysics Data System (ADS)

    Gonzales, Jonathan; Nair, Rohit Kumar; Madsen, Steen J.; Krasieva, Tatiana; Hirschberg, Henry

    2016-07-01

    Activation of sonosensitizers via focused ultrasound (FUS), i.e., sonodynamic therapy has been proposed as an extension to light-activated photodynamic therapy for the treatment of brain as well as other tumors. The use of FUS, as opposed to light, allows treatment to tumor sites buried deep within tissues as well as through the intact skull. We have examined ultrasonic activation of sonosensitizers together with the anticancer agent bleomycin (BLM), i.e., sonochemical internalization (SCI). SCI is a technique that utilizes FUS for the enhanced delivery of endo-lysosomal trapped macromolecules into the cell cytoplasm in a similar manner to light-based photochemical internalization. The released agent can, therefore, exert its full biological activity, in contrast to being degraded by lysosomal hydrolases. Our results indicate that, compared to drug or FUS treatment alone, FUS activation of the sonosensitizer AlPcS2a together with BLM significantly inhibits the ability of treated glioma cells to grow as three-dimensional tumor spheroids in vitro.

  15. Mechanical properties and failure analysis of visible light crosslinked alginate-based tissue sealants.

    PubMed

    Charron, Patrick N; Fenn, Spencer L; Poniz, Alex; Oldinski, Rachael A

    2016-06-01

    Moderate to weak mechanical properties limit the use of naturally-derived tissue sealants for dynamic medical applications, e.g., sealing a lung leak. To overcome these limitations, we developed visible-light crosslinked alginate-based hydrogels, as either non-adhesive methacrylated alginate (Alg-MA) hydrogel controls, or oxidized Alg-MA (Alg-MA-Ox) tissue adhesive tissue sealants, which form covalent bonds with extracellular matrix (ECM) proteins. Our study investigated the potential for visible-light crosslinked Alg-MA-Ox hydrogels to serve as effective surgical tissue sealants for dynamic in vivo systems. The Alg-MA-Ox hydrogels were designed to be an injectable system, curable in situ. Burst pressure experiments were conducted on a custom-fabricated burst pressure device using constant air flow; burst pressure properties and adhesion characteristics correlated with the degrees of methacrylation and oxidation. In summary, visible light crosslinked Alg-MA-Ox hydrogel tissue sealants form effective seals over critically-sized defects, and maintain pressures up to 50mm Hg. PMID:26897093

  16. Bright luminescence from pure DNA-curcumin-based phosphors for bio hybrid light-emitting diodes.

    PubMed

    Reddy, M Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s(-1). Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign. PMID:27572113

  17. Contact light-emitting diodes based on vertical ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Panin, G. N.; Cho, Hak Dong; Lee, Sang Wuk; Kang, Tae Won

    2014-05-01

    We report vertical contact light-emitting diodes (VCLEDs), that are based on heterojunctions formed by using the point contacts of n-ZnO nanorods (NRs) to the p-type semiconductor substrate and that are fabricated using a new approach to the formation of LEDs (Appl. Phys. Lett. 98, 093110 (2011)). A p-type GaN film grown on a sapphire substrate was used to form n-ZnO NRs/p-GaN VCLEDs on a large area of about 4 cm2. The VCLEDs emitted a pure blue electroluminescence with high efficiency. Electroluminescence at 470 nm, which is visible to the naked eye, started at small current of about 50 μA and is attributed to the good optical properties of the structurallyperfect heterojunctions in the point contacts. The VCLED configuration allows the creation of ZnO/p-GaN nano-LEDs of high density and high-quality with a greatly reduced concentration of nonradiative defects in the active regions. The VCLEDs showed the high brightness of light required for active matrix displays and general solid-state lighting.

  18. A multiplexed light-matter interface for fibre-based quantum networks.

    PubMed

    Saglamyurek, Erhan; Grimau Puigibert, Marcelli; Zhou, Qiang; Giner, Lambert; Marsili, Francesco; Verma, Varun B; Woo Nam, Sae; Oesterling, Lee; Nippa, David; Oblak, Daniel; Tittel, Wolfgang

    2016-01-01

    Processing and distributing quantum information using photons through fibre-optic or free-space links are essential for building future quantum networks. The scalability needed for such networks can be achieved by employing photonic quantum states that are multiplexed into time and/or frequency, and light-matter interfaces that are able to store and process such states with large time-bandwidth product and multimode capacities. Despite important progress in developing such devices, the demonstration of these capabilities using non-classical light remains challenging. Here, employing the atomic frequency comb quantum memory protocol in a cryogenically cooled erbium-doped optical fibre, we report the quantum storage of heralded single photons at a telecom-wavelength (1.53 μm) with a time-bandwidth product approaching 800. Furthermore, we demonstrate frequency-multimode storage and memory-based spectral-temporal photon manipulation. Notably, our demonstrations rely on fully integrated quantum technologies operating at telecommunication wavelengths. With improved storage efficiency, our light-matter interface may become a useful tool in future quantum networks. PMID:27046076

  19. A multiplexed light-matter interface for fibre-based quantum networks

    PubMed Central

    Saglamyurek, Erhan; Grimau Puigibert, Marcelli; Zhou, Qiang; Giner, Lambert; Marsili, Francesco; Verma, Varun B.; Woo Nam, Sae; Oesterling, Lee; Nippa, David; Oblak, Daniel; Tittel, Wolfgang

    2016-01-01

    Processing and distributing quantum information using photons through fibre-optic or free-space links are essential for building future quantum networks. The scalability needed for such networks can be achieved by employing photonic quantum states that are multiplexed into time and/or frequency, and light-matter interfaces that are able to store and process such states with large time-bandwidth product and multimode capacities. Despite important progress in developing such devices, the demonstration of these capabilities using non-classical light remains challenging. Here, employing the atomic frequency comb quantum memory protocol in a cryogenically cooled erbium-doped optical fibre, we report the quantum storage of heralded single photons at a telecom-wavelength (1.53 μm) with a time-bandwidth product approaching 800. Furthermore, we demonstrate frequency-multimode storage and memory-based spectral-temporal photon manipulation. Notably, our demonstrations rely on fully integrated quantum technologies operating at telecommunication wavelengths. With improved storage efficiency, our light-matter interface may become a useful tool in future quantum networks. PMID:27046076

  20. Ionogel-based light-actuated valves for controlling liquid flow in micro-fluidic manifolds.

    PubMed

    Benito-Lopez, Fernando; Byrne, Robert; Răduţă, Ana Maria; Vrana, Nihal Engin; McGuinness, Garrett; Diamond, Dermot

    2010-01-21

    We present the fabrication, characterisation and performance of four novel ionic liquid polymer gels (ionogels) as photo-actuated valves incorporated into micro-fluidic manifolds. The ionogels incorporate benzospiropyran units and phosphonium-based ionic liquids. Each ionogel is photo-polymerised in situ in the channels of a poly(methyl methacrylate) micro-fluidic device, generating a manifold incorporating four different micro-valves. The valves are actuated by simply applying localised white light irradiation, meaning that no physical contact between the actuation impulse (light) and the valve structure is required. Through variation of the composition of the ionogels, each of the micro-valves can be tuned to open at different times under similar illumination conditions. Therefore, flows through the manifold can be independently controlled by a single light source. At present, the contraction process to open the channel is relatively rapid (seconds) while the recovery (expansion) process to re-close the channel is relatively slow (minutes), meaning that the valve, in its current form, is better suited for single-actuation events. PMID:20066247

  1. Broadband light trapping based on periodically textured ZnO thin films.

    PubMed

    Liu, Bofei; Liang, Xuejiao; Liang, Junhui; Bai, Lisha; Gao, Haibo; Chen, Ze; Zhao, Ying; Zhang, Xiaodan

    2015-06-01

    Transparent conductive front electrodes (TCFEs) deployed in photovoltaic devices have been extensively studied for their significance in transporting carriers, coupling and trapping the incident photons in high-performing solar cells. The trade-off between the light-transmission, electrical, and scattering properties for TCFEs to achieve a broadband improvement in light absorption in solar cells while maintaining a high electrical performance has become the key issue to be tackled. In this paper, we employ self-assembled polystyrene (PS) spheres based on a sauna-like method as a template, followed by a double-layer deposition and then successfully fabricate highly-transparent, well-conductive, and large-scale periodically-textured ZnO TCFEs with broadband light trapping properties. A sheet resistance below 15 Ω sq(-1) was achieved for the periodically-textured ZnO TCFEs, with a concomitant average transmission of 81% (including the glass substrate) in the 400-1100 nm spectral range, a haze improvement in a broadband spectral range, and a wider scattering angular domain. The proposed approach affords a promising alternative method to prepare periodically-textured TCFEs, which are essential for many optoelectronic device semiconductors, such as photovoltaic and display applications. PMID:25963950

  2. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    PubMed Central

    Reddy, M. Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s−1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign. PMID:27572113

  3. Realizing high visible-light-induced carriers mobility in TiO2-based photoanodes

    NASA Astrophysics Data System (ADS)

    He, Jingfu; Zhang, Shibao; Sun, Zhihu; Cheng, Weiren; Liu, Qinghua; Jiang, Yong; Hu, Fengchun; Pan, Zhiyun; He, Bo; Wu, Ziyu; Yan, Wensheng; Wei, Shiqiang

    2014-04-01

    Increasing the quantum conversion efficiency in visible-light region is a key issue for the efficient usage of solar energy in the process of photoelectrochemical (PEC) water splitting. Here, based on the N anion and S cation codoped TiO2 thin film photoanodes, we find experimentally and theoretically that the transport ability of visible-light-induced carriers can be notably enhanced by engineering the dopant electronic energy states. The hole transport resistivity is decreased from 6.8 × 104 to 1.3 × 104 Ω m via delocalizing the introduced bands, leading to an evident increase of the internal quantum efficiency from 5% to 20% at the visible-light region of 450-550 nm. Further DFT calculations exhibit that the split of the isolated band is induced by a strong N and S hybridization, which favors to decrease the hole effective mass and to improve the hole mobility by three times. The photocurrent of N - S codoped TiO2 thin film is thus twice that of monodoping cases, the best value for doping modified TiO2 thin film photoanodes. This work may provide not only a design principle but also a candidate for tailoring and optimizing TiO2 towards high PEC activity.

  4. Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements.

    PubMed

    Wang, Rongyan; Lu, Guimin; Qiao, Wenming; Yu, Jianguo

    2016-08-30

    The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure. PMID:27482724

  5. Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Chhajed, S.; Xi, Y.; Li, Y.-L.; Gessmann, Th.; Schubert, E. F.

    2005-03-01

    Trichromatic white-light sources based on light-emitting diodes (LEDs) offer a high luminous efficacy of radiation, a broad range of color temperatures and excellent color-rendering properties with color-rendering indices (CRIs) exceeding 85. An analysis of the luminous efficacy and CRI of a trichromatic light source is performed for a very broad range of wavelength combinations. The peak emission wavelength, spectral width, and the output power of LEDs strongly depend on temperature and the dependencies for red, green, and blue LEDs are established. A detailed analysis of the temperature dependence of trichromatic white LED sources reveals that the luminous efficacy decreases, the color temperature increases, the CRI decreases and the chromaticity point shifts towards the blue as the junction temperature increases. A high CRI >80 can be maintained, by adjusting the LED power ratio so that the chromaticity point is conserved.

  6. Development and assessment of a research-based tutorial on light and shadow

    NASA Astrophysics Data System (ADS)

    Wosilait, Karen; Heron, Paula R. L.; Shaffer, Peter S.; McDermott, Lillian C.

    1998-10-01

    This article describes an investigation of student understanding of geometrical optics and illustrates the use of research as a basis for the development of curriculum. Evidence is presented that university students who have studied physics at the introductory level and beyond often cannot apply basic concepts from geometrical optics to account for the pattern produced on a screen when an aperture or obstacle is placed between a light source and the screen. Identification and analysis of student difficulties guided the initial design of a tutorial to supplement instruction in a typical calculus-based or algebra-based course. Development of a laboratory-based, inquiry-oriented curriculum for precollege teachers took place concurrently. Ongoing assessment was an integral part of the curriculum development process. The instructional materials that evolved from this iterative cycle have proved to be effective with the target populations.

  7. Laser-light delivery microtools based on laser technology: design, fabrication, and applications

    NASA Astrophysics Data System (ADS)

    Veiko, Vadim P.; Voznesensky, Nikolay B.

    2001-06-01

    A set of new laser-light delivery microtools (LDM) based on laser technology is investigated and discussed. Wide application of LDM in different fields of science, medicine, biology, industry and information processing is considered. Fiber optical networks in medical diagnostics and technical, civil engineering and other technological areas are discussed. The general approach based on electromagnetic field equations-transformation for all range of dimensions (mini-, micro and nanodomain) is given. Laser-assisted technology for drawing-out and for microstructuring optical tools is investigated, high-speed movie has been applied to study the process and compared with theoretical description. Finally a number of fibers and micropipettes-based medical tools and SNOM-tips has been fabricated and tested. Applications of some tools for medical operations (thermocoagulation), protein rasters preparing, SNOM-microscopy investigation have been demonstrated.

  8. High-power light-emitting diode based facility for plant cultivation

    NASA Astrophysics Data System (ADS)

    Tamulaitis, G.; Duchovskis, P.; Bliznikas, Z.; Breive, K.; Ulinskaite, R.; Brazaityte, A.; Novickovas, A.; Zukauskas, A.

    2005-09-01

    Based on perspectives of the development of semiconductor materials systems for high-power light-emitting diodes (LEDs), an illumination facility for greenhouse plant cultivation was designed with the dominating 640 nm photosynthetically active component delivered by AlGaInP LEDs and supplementary components from AlGaN (photothropic action, 455 nm) and AlGaAs (photosynthetic 660 nm and photomorphogenetic 735 nm) LEDs. Photosynthesis intensity, photosynthetic productivity and growth morphology as well as chlorophyll and phytohormone concentrations were investigated in radish and lettuce grown in phytotron chambers under the LED-based illuminators and under high-pressure sodium (HPS) lamps with an equivalent photon flux density. Advantages of the high-power LED-based illuminators over conventional HPS lamps, applicability of AlGaInP LEDs for photosynthesis and control of plant growth by circadian manipulation of a relatively weak far-red component were demonstrated.

  9. Visible-Light Induced Self-Powered Sensing Platform Based on a Photofuel Cell.

    PubMed

    Yan, Kai; Yang, Yaohua; Okoth, Otieno Kevin; Cheng, Ling; Zhang, Jingdong

    2016-06-21

    A self-powered sensing system possesses the capacity of harvesting energy from the environment and has no requirement for external electrical power supply during the chemical sensing of analytes. Herein, we design an enzyme-free self-powered sensing platform based on a photofuel cell (PFC) driven by visible-light, using glucose as a model analyte. The fabricated PFC consists of a Ni(OH)2/CdS/TiO2 photoanode and a hemin-graphene (HG) nanocomposite coated cathode in separated chambers. Under visible-light irradiation, glucose in the anodic chamber is facilely oxidized on Ni(OH)2/CdS/TiO2 while H2O2 in the cathodic chamber is catalytically reduced by HG, which generates a certain cell output sensitive to the variation of glucose concentration. Thus, a PFC based self-powered sensor is realized for glucose detection. Compared to the existing enzymatic self-powered glucose sensors, our proposed PFC based strategy exhibits much lower detection concentration. Moreover, it avoids the limitation of conventional enzyme immobilized electrodes and has the potential to develop high-performance self-powered sensors with broader analyte species. PMID:27237828

  10. A structured light sensor measuring method based on wMPS global controlling

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Lin, Jiarui; Guo, Yin; Gao, Yang; Yang, Shourui

    2015-10-01

    In large-scale three-dimensional (3D) coordinates measurement, to solve the problem of structured light sensor's measurement data from different measurement stations unifying to the global coordinate system, a method based on workshop Measuring Position System (wMPS) global controlling is researched to concentrate the structured light sensor's measurement data to the global coordinate system automatically. According to the measurement principle, two calibration methods are proposed to calibrate the structural parameters based on a standard ball, one is transferring stations based on common points and the other is fitting ball equation. Finally, a platform for experiment is built to verify the two calibration methods. Experimental results show that the average measurement error on 10 points is 0.127 mm according to the laser tracker of the first method and the other average error is 0.101 mm, both the two calibration methods have a high precision to meet the demands of large-scale 3D coordinates measurement.

  11. Broadband light sources based on InAs/InGaAs metamorphic quantum dots

    NASA Astrophysics Data System (ADS)

    Seravalli, L.; Gioannini, M.; Cappelluti, F.; Sacconi, F.; Trevisi, G.; Frigeri, P.

    2016-04-01

    We propose a design for a semiconductor structure emitting broadband light in the infrared, based on InAs quantum dots (QDs) embedded into a metamorphic step-graded InxGa1-xAs buffer. We developed a model to calculate the metamorphic QD energy levels based on the realistic QD parameters and on the strain-dependent material properties; we validated the results of simulations by comparison with the experimental values. On this basis, we designed a p-i-n heterostructure with a graded index profile toward the realization of an electrically pumped guided wave device. This has been done by adding layers where QDs are embedded in InxAlyGa1-x-yAs layers, to obtain a symmetric structure from a band profile point of view. To assess the room temperature electro-luminescence emission spectrum under realistic electrical injection conditions, we performed device-level simulations based on a coupled drift-diffusion and QD rate equation model. On the basis of the device simulation results, we conclude that the present proposal is a viable option to realize broadband light-emitting devices.

  12. The performance of 2D array detectors for light sheet based fluorescence correlation spectroscopy.

    PubMed

    Singh, Anand Pratap; Krieger, Jan Wolfgang; Buchholz, Jan; Charbon, Edoardo; Langowski, Jörg; Wohland, Thorsten

    2013-04-01

    Single plane illumination microscopy based fluorescence correlation spectroscopy (SPIM-FCS) is a new method for imaging FCS in 3D samples, providing diffusion coefficients, transport, flow velocities and concentrations in an imaging mode. SPIM-FCS records correlation functions over a whole plane in a sample, which requires array detectors for recording the fluorescence signal. Several types of image sensors are suitable for FCS. They differ in properties such as effective area per pixel, quantum efficiency, noise level and read-out speed. Here we compare the performance of several low light array detectors based on three different technologies: (1) Single-photon avalanche diode (SPAD) arrays, (2) passive-pixel electron multiplying charge coupled device (EMCCD) and (3) active-pixel scientific-grade complementary metal oxide semiconductor cameras (sCMOS). We discuss the influence of the detector characteristics on the effective FCS observation volume, and demonstrate that light sheet based SPIM-FCS provides absolute diffusion coefficients. This is verified by parallel measurements with confocal FCS, single particle tracking (SPT), and the determination of concentration gradients in space and time. While EMCCD cameras have a temporal resolution in the millisecond range, sCMOS cameras and SPAD arrays can extend the time resolution of SPIM-FCS down to 10 μs or lower. PMID:23571955

  13. Analytical devices based on light-emitting diodes--a review of the state-of-the-art.

    PubMed

    Bui, Duy Anh; Hauser, Peter C

    2015-01-01

    A general overview of the development of the uses of light-emitting diodes in analytical instrumentation is given. Fundamental aspects of light-emitting diodes, as far as relevant for this usage, are covered in the first part. The measurement of light intensity is also discussed, as this is an essential part of any device based on light-emitting diodes as well. In the second part, applications are discussed, which cover liquid and gas-phase absorbance measurements, flow-through detectors for chromatography and capillary electrophoresis, sensors, as well as some less often reported methods such as photoacoustic spectroscopy. PMID:25467449

  14. Submicrometer photonic structure fabrication by phase spatial-light-modulator-based interference lithography.

    PubMed

    Behera, Saraswati; Kumar, Manish; Joseph, Joby

    2016-04-15

    We present a large-area and single-step fabrication approach based on phase spatial light modulator (SLM)-assisted interference lithography for the realization of submicrometer photonic structures on photoresist. A multimirror beam steering unit is used to reflect the SLM-generated phase-engineered beams leading to a large angle between interfering beams while also preserving the large area of the interfering plane beams. Both translational and rotational periodic submicrometer structures are experimentally realized. This approach increases the flexibility of interference lithography to fabricate more complex submicrometer photonic structures and photonic metamaterial structures for future applications. PMID:27082372

  15. Influence of pulsed-xenon ultraviolet light-based environmental disinfection on surgical site infections.

    PubMed

    Catalanotti, Angela; Abbe, Dudley; Simmons, Sarah; Stibich, Mark

    2016-06-01

    This study evaluates the influence of nightly pulsed-xenon ultraviolet light disinfection and dedicated housekeeping staff on surgical site infection (SSI) rates. SSIs in class I procedures were reduced by 46% (P = .0496), with a potential cost savings of $478,055. SSIs in class II procedures increased by 22.9%, but this was not significant (P = .6973). Based on these results, it appears that the intervention reduces SSI rates in clean (class I), but not clean-contaminated (class II) procedures. PMID:26856467

  16. The variable refractive index correction algorithm based on a stereo light microscope

    NASA Astrophysics Data System (ADS)

    Pei, W.; Zhu, Y. Y.

    2010-02-01

    Refraction occurs at least twice on both the top and the bottom surfaces of the plastic plate covering the micro channel in a microfluidic chip. The refraction and the nonlinear model of a stereo light microscope (SLM) may severely affect measurement accuracy. In this paper, we study the correlation between optical paths of the SLM and present an algorithm to adjust the refractive index based on the SLM. Our algorithm quantizes the influence of cover plate and double optical paths on the measurement accuracy, and realizes non-destructive, non-contact and precise 3D measurement of a hyaloid and closed container.

  17. Spectrum zooming in network topology based on a white light fiber optic Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Li, Song; Ferhati, Mokhtar; Yuan, Li-Bo

    2015-07-01

    A bus line network based on white light fiber-optic Mach-Zehnder interferometer is introduced by consideration of multiplexing capacity and coupler tailoring. The network topology which consists of N rungs sensing elements linked by N-1 couplers has been contrasted with three cases. The optimization formula has been used to couple more sensors, and Zoom-FFT has been used to analyze spectrum. After using these two methods, the multiplexing capability of the structure is enhanced evidently and a unambiguous spectrum is acquired.

  18. Compact solar autoclave based on steam generation using broadband light-harvesting nanoparticles

    PubMed Central

    Neumann, Oara; Feronti, Curtis; Neumann, Albert D.; Dong, Anjie; Schell, Kevin; Lu, Benjamin; Kim, Eric; Quinn, Mary; Thompson, Shea; Grady, Nathaniel; Nordlander, Peter; Oden, Maria; Halas, Naomi J.

    2013-01-01

    The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator. PMID:23836642

  19. Compact solar autoclave based on steam generation using broadband light-harvesting nanoparticles.

    PubMed

    Neumann, Oara; Feronti, Curtis; Neumann, Albert D; Dong, Anjie; Schell, Kevin; Lu, Benjamin; Kim, Eric; Quinn, Mary; Thompson, Shea; Grady, Nathaniel; Nordlander, Peter; Oden, Maria; Halas, Naomi J

    2013-07-16

    The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator. PMID:23836642

  20. Amplified light storage with high fidelity based on electromagnetically induced transparency in rubidium atomic vapor

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Wang, Gang; Tang, Guoyu; Xue, Yan

    2016-06-01

    By using slow and stored light based on electromagnetically induced transparency (EIT), we theoretically realize the storage of optical pulses with enhanced efficiency and high fidelity in ensembles of warm atoms in 85Rb vapor cells. The enhancement of storage efficiency is achieved by introducing a pump field beyond three-level configuration to form a N-type scheme, which simultaneously inhibits the undesirable four-wave mixing effect while preserves its fidelity. It is shown that the typical storage efficiency can be improved from 29% to 53% with the application of pump field. Furthermore, we demonstrate that this efficiency decreases with storage time and increases over unity with optical depth.

  1. Simplified white-light interferometric strain sensor based on HB fiber with automatic temperature compensation

    NASA Astrophysics Data System (ADS)

    Ma, Jianjun; Bock, Wojtek J.; Urbanczyk, Waclaw

    2003-02-01

    A simplified white-light interferometric strain sensor based on HB fibers with automatic temperature compensation is presented. A variety of experiments conducted within this study confirm an adequate temperature compensation could be achieved. Several different sensor structures were investigated during these experiments. One of the most important results shows that the interference contrast could significantly influence the measurement accuracy achievable by the system. Consequently, a 1% or even better absolute accuracy for short sensing fibers is possible if the contrast is enhanced to 0.5. A quasi-distributed cascade containing several discrete sensors with 0.5 contrast is also suggested.

  2. Optimized light sharing for high-resolution TOF PET detector based on digital silicon photomultipliers.

    PubMed

    Marcinkowski, R; España, S; Van Holen, R; Vandenberghe, S

    2014-12-01

    The majority of current whole-body PET scanners are based on pixelated scintillator arrays with a transverse pixel size of 4 mm. However, recent studies have shown that decreasing the pixel size to 2 mm can significantly improve image spatial resolution. In this study, the performance of Digital Photon Counter (DPC) from Philips Digital Photon Counting (PDPC) was evaluated to determine their potential for high-resolution whole-body time of flight (TOF) PET scanners. Two detector configurations were evaluated. First, the DPC3200-44-22 DPC array was coupled to a LYSO block of 15 × 15 2 × 2 × 22 mm(3) pixels through a 1 mm thick light guide. Due to light sharing among the dies neighbour logic of the DPC was used. In a second setup the same DPC was coupled directly to a scalable 4 × 4 LYSO matrix of 1.9 × 1.9 × 22 mm(3) crystals with a dedicated reflector arrangement allowing for controlled light sharing patterns inside the matrix. With the first approach an average energy resolution of 14.5% and an average CRT of 376 ps were achieved. For the second configuration an average energy resolution of 11% and an average CRT of 295 ps were achieved. Our studies show that the DPC is a suitable photosensor for a high-resolution TOF-PET detector. The dedicated reflector arrangement allows one to achieve better performances than the light guide approach. The count loss, caused by dark counts, is overcome by fitting the matrix size to the size of DPC single die. PMID:25365502

  3. Optimized light sharing for high-resolution TOF PET detector based on digital silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Marcinkowski, R.; España, S.; Van Holen, R.; Vandenberghe, S.

    2014-12-01

    The majority of current whole-body PET scanners are based on pixelated scintillator arrays with a transverse pixel size of 4 mm. However, recent studies have shown that decreasing the pixel size to 2 mm can significantly improve image spatial resolution. In this study, the performance of Digital Photon Counter (DPC) from Philips Digital Photon Counting (PDPC) was evaluated to determine their potential for high-resolution whole-body time of flight (TOF) PET scanners. Two detector configurations were evaluated. First, the DPC3200-44-22 DPC array was coupled to a LYSO block of 15  ×  15 2  ×  2 × 22 mm3 pixels through a 1 mm thick light guide. Due to light sharing among the dies neighbour logic of the DPC was used. In a second setup the same DPC was coupled directly to a scalable 4  ×  4 LYSO matrix of 1.9  ×  1.9  ×  22 mm3 crystals with a dedicated reflector arrangement allowing for controlled light sharing patterns inside the matrix. With the first approach an average energy resolution of 14.5% and an average CRT of 376 ps were achieved. For the second configuration an average energy resolution of 11% and an average CRT of 295 ps were achieved. Our studies show that the DPC is a suitable photosensor for a high-resolution TOF-PET detector. The dedicated reflector arrangement allows one to achieve better performances than the light guide approach. The count loss, caused by dark counts, is overcome by fitting the matrix size to the size of DPC single die.

  4. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    SciTech Connect

    Kuang, Y.; Lare, M. C. van; Polman, A.; Veldhuizen, L. W.; Schropp, R. E. I.; Rath, J. K.

    2015-11-14

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  5. Light-output enhancement of GaN-based light-emitting diodes with three-dimensional backside reflectors patterned by microscale cone array.

    PubMed

    Huang, Huamao; Hu, Jinyong; Wang, Hong

    2014-01-01

    Three-dimensional (3D) backside reflector, compared with flat reflectors, can improve the probability of finding the escape cone for reflecting lights and thus enhance the light-extraction efficiency (LEE) for GaN-based light-emitting diode (LED) chips. A triangle-lattice of microscale SiO2 cone array followed by a 16-pair Ti3O5/SiO2 distributed Bragg reflector (16-DBR) was proposed to be attached on the backside of sapphire substrate, and the light-output enhancement was demonstrated by numerical simulation and experiments. The LED chips with flat reflectors or 3D reflectors were simulated using Monte Carlo ray tracing method. It is shown that the LEE increases as the reflectivity of backside reflector increases, and the light-output can be significantly improved by 3D reflectors compared to flat counterparts. It can also be observed that the LEE decreases as the refractive index of the cone material increases. The 3D 16-DBR patterned by microscale SiO2 cone array benefits large enhancement of LEE. This microscale pattern was prepared by standard photolithography and wet-etching technique. Measurement results show that the 3D 16-DBR can provide 12.1% enhancement of wall-plug efficiency, which is consistent with the simulated value of 11.73% for the enhancement of LEE. PMID:25133262

  6. Light-Output Enhancement of GaN-Based Light-Emitting Diodes with Three-Dimensional Backside Reflectors Patterned by Microscale Cone Array

    PubMed Central

    Hu, Jinyong; Wang, Hong

    2014-01-01

    Three-dimensional (3D) backside reflector, compared with flat reflectors, can improve the probability of finding the escape cone for reflecting lights and thus enhance the light-extraction efficiency (LEE) for GaN-based light-emitting diode (LED) chips. A triangle-lattice of microscale SiO2 cone array followed by a 16-pair Ti3O5/SiO2 distributed Bragg reflector (16-DBR) was proposed to be attached on the backside of sapphire substrate, and the light-output enhancement was demonstrated by numerical simulation and experiments. The LED chips with flat reflectors or 3D reflectors were simulated using Monte Carlo ray tracing method. It is shown that the LEE increases as the reflectivity of backside reflector increases, and the light-output can be significantly improved by 3D reflectors compared to flat counterparts. It can also be observed that the LEE decreases as the refractive index of the cone material increases. The 3D 16-DBR patterned by microscale SiO2 cone array benefits large enhancement of LEE. This microscale pattern was prepared by standard photolithography and wet-etching technique. Measurement results show that the 3D 16-DBR can provide 12.1% enhancement of wall-plug efficiency, which is consistent with the simulated value of 11.73% for the enhancement of LEE. PMID:25133262

  7. A portable smart phone-based plasmonic nanosensor readout platform that measures transmitted light intensities of nanosubstrates using an ambient light sensor.

    PubMed

    Fu, Qiangqiang; Wu, Ze; Xu, Fangxiang; Li, Xiuqing; Yao, Cuize; Xu, Meng; Sheng, Liangrong; Yu, Shiting; Tang, Yong

    2016-05-21

    Plasmonic nanosensors may be used as tools for diagnostic testing in the field of medicine. However, quantification of plasmonic nanosensors often requires complex and bulky readout instruments. Here, we report the development of a portable smart phone-based plasmonic nanosensor readout platform (PNRP) for accurate quantification of plasmonic nanosensors. This device operates by transmitting excitation light from a LED through a nanosubstrate and measuring the intensity of the transmitted light using the ambient light sensor of a smart phone. The device is a cylinder with a diameter of 14 mm, a length of 38 mm, and a gross weight of 3.5 g. We demonstrated the utility of this smart phone-based PNRP by measuring two well-established plasmonic nanosensors with this system. In the first experiment, the device measured the morphology changes of triangular silver nanoprisms (AgNPRs) in an immunoassay for the detection of carcinoembryonic antigen (CEA). In the second experiment, the device measured the aggregation of gold nanoparticles (AuNPs) in an aptamer-based assay for the detection of adenosine triphosphate (ATP). The results from the smart phone-based PNRP were consistent with those from commercial spectrophotometers, demonstrating that the smart phone-based PNRP enables accurate quantification of plasmonic nanosensors. PMID:27137512

  8. Robust thermal performance of Sr2Si5N8:Eu2+: An efficient red emitting phosphor for light emitting diode based white lighting

    NASA Astrophysics Data System (ADS)

    Brinkley, Stuart E.; Pfaff, Nathan; Denault, Kristin A.; Zhang, Zhijun; (Bert) Hintzen, H. T.; Seshadri, Ram; Nakamura, Shuji; Denbaars, Steven P.

    2011-12-01

    An important component to the advent of solid state lighting technology is the development of inorganic crystalline phosphors for efficient conversion of photons from blue light emitting diodes (LEDs) to other visible wavelengths for greater color rendering and "warmer" white lighting. We present the results of a recently developed rare earth doped nitride-based red emitting phosphor, Sr2Si5N8:Eu2+, combined with GaN-based blue emitting LEDs and YAG:Ce phosphor for improved white lighting applications. A unique remote phosphor packaging approach was used in all testing to isolate LED performance from phosphor performance. Luminous efficacies were achieved at 94 lm/W with an improved color rendering index (CRI) of 72, mixing red phosphor with YAG:Ce. The Sr2Si5N8:Eu2+ red emitting phosphor was found to have a low temperature sensitivity (only 28% power reduction at 150 °C) and greater luminous performance at low concentrations in the encapsulant by weight relative to other typical red emitting phosphors.

  9. Color influence on accuracy of 3D scanners based on structured light

    NASA Astrophysics Data System (ADS)

    Voisin, Sophie; Page, David L.; Foufou, Sebti; Truchetet, Frédéric; Abidi, Mongi A.

    2006-02-01

    The characterization of commercial 3D scanners allows acquiring precise and useful data. The accuracy of range and, more recently, color for 3D scanners is usually studied separately, but when the 3D scanner is based on structured light with a color coding pattern, color influence on range accuracy should be investigated. The commercial product that we have tested has the particularity that it can acquire data under ambient light instead of a controlled environment as it is with most available scanners. Therefore, based on related work in the literature and on experiments we have done on a variety of standard illuminants, we have designed an interesting setup to control illuminant interference. Basically, the setup consists of acquiring the well-known Macbeth ColorChecker under a controlled environment and also ambient daylight. The results have shown variations with respect to the color. We have performed several statistical studies to show how the range results evolve with respect to the RGB and the HSV channels. In addition, a systematic noise error has also been identified. This noise depends on the object color. A subset of colors shows strong noise errors while other colors have minimal or even no systematic error under the same illuminant.

  10. Dual paraboloid reflector and light pipe based systems for projection displays

    NASA Astrophysics Data System (ADS)

    Li, Kenneth; Sillyman, Sheldon; Inatsugu, Seiji

    2005-04-01

    With the pressure to reduce cost for mass-market introduction of microdisplay-based rear projection television (MD-RPTV), the image panel and the related optical components have to be reduced in size and novel optical arrangements have to be created to achieve the target price. One major issue always had been the need for more light. Traditional reflector systems, including elliptical and parabolic reflectors, perform well in most cases, but are inefficient for smaller etendue values corresponding to smaller image panels. The common remedy is to make lamps with shorter and shorter arcs to increase the coupling efficiency, but the corresponding lifetime of the lamps are reduced and most of the time, these short arc lamps can only operate at low power, thus limiting the total output of the illuminating system. This paper summarizes the progress in the last few years related to the dual Paraboloid reflector (DPR) system and the associated components including polarization recovery systems and light pipe based projection engines.

  11. 3D measurement method based on combined temporal encoding structured light

    NASA Astrophysics Data System (ADS)

    Yu, Xiaoyang; Wang, Yang; Yu, Shuang; Cheng, Hao; Sun, Xiaoming; Yu, Shuchun; Chen, Deyun

    2013-10-01

    Three-dimensional (3D) vision measurement technology based on encoding structured light plays an important role and has become the main development trend in the field of 3D non-contact measurement. However, how to synthetically improve measurement speed, accuracy and sampling density is still a difficult problem. Thus in the present work, a novel 3D measurement method based on temporal encoding structured light by combining trapezoidal phase-shifting pattern and cyclic code pattern is proposed. Due to trapezoidal phase-shifting has the advantages of high sampling density and high-speed, the proposed method can maintain these advantages by using cyclic code to expand the range of trapezoidal phase-shifting. In addition, the correction scheme is designed to solve the problem of cycle dislocation. Finally, simulation experimental platform is built with 3ds max and MATLAB. Experimental analyses and results show that, the maximal error is less than 3 mm in the range from 400 mm to 1100 mm, cycle dislocation correction has a good effect.

  12. Structure-based model for light-harvesting properties of nucleic acid nanostructures

    PubMed Central

    Pan, Keyao; Boulais, Etienne; Yang, Lun; Bathe, Mark

    2014-01-01

    Programmed self-assembly of DNA enables the rational design of megadalton-scale macromolecular assemblies with sub-nanometer scale precision. These assemblies can be programmed to serve as structural scaffolds for secondary chromophore molecules with light-harvesting properties. Like in natural systems, the local and global spatial organization of these synthetic scaffolded chromophore systems plays a crucial role in their emergent excitonic and optical properties. Previously, we introduced a computational model to predict the large-scale 3D solution structure and flexibility of nucleic acid nanostructures programmed using the principle of scaffolded DNA origami. Here, we use Förster resonance energy transfer theory to simulate the temporal dynamics of dye excitation and energy transfer accounting both for overall DNA nanostructure architecture as well as atomic-level DNA and dye chemical structure and composition. Results are used to calculate emergent optical properties including effective absorption cross-section, absorption and emission spectra and total power transferred to a biomimetic reaction center in an existing seven-helix double stranded DNA-based antenna. This structure-based computational framework enables the efficient in silico evaluation of nucleic acid nanostructures for diverse light-harvesting and photonic applications. PMID:24311563

  13. Structure-based model for light-harvesting properties of nucleic acid nanostructures.

    PubMed

    Pan, Keyao; Boulais, Etienne; Yang, Lun; Bathe, Mark

    2014-02-01

    Programmed self-assembly of DNA enables the rational design of megadalton-scale macromolecular assemblies with sub-nanometer scale precision. These assemblies can be programmed to serve as structural scaffolds for secondary chromophore molecules with light-harvesting properties. Like in natural systems, the local and global spatial organization of these synthetic scaffolded chromophore systems plays a crucial role in their emergent excitonic and optical properties. Previously, we introduced a computational model to predict the large-scale 3D solution structure and flexibility of nucleic acid nanostructures programmed using the principle of scaffolded DNA origami. Here, we use Förster resonance energy transfer theory to simulate the temporal dynamics of dye excitation and energy transfer accounting both for overall DNA nanostructure architecture as well as atomic-level DNA and dye chemical structure and composition. Results are used to calculate emergent optical properties including effective absorption cross-section, absorption and emission spectra and total power transferred to a biomimetic reaction center in an existing seven-helix double stranded DNA-based antenna. This structure-based computational framework enables the efficient in silico evaluation of nucleic acid nanostructures for diverse light-harvesting and photonic applications. PMID:24311563

  14. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    NASA Astrophysics Data System (ADS)

    Cheng, Fei; Gao, Jie; Luk, Ting S.; Yang, Xiaodong

    2015-06-01

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage.

  15. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    DOE PAGESBeta

    Cheng, Fei; Gao, Jie; Luk, Ting S.; Yang, Xiaodong

    2015-06-05

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfectmore » light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage.« less

  16. Generating multi-atom entangled W states via light-matter interface based fusion mechanism.

    PubMed

    Zang, Xue-Ping; Yang, Ming; Ozaydin, Fatih; Song, Wei; Cao, Zhuo-Liang

    2015-01-01

    W state is a key resource in quantum communication. Fusion technology has been proven to be a good candidate for preparing a large-size W state from two or more small-size W states in linear optical system. It is of great importance to study how to fuse W states via light-matter interface. Here we show that it is possible to prepare large-size W-state networks using a fusion mechanism in cavity QED system. The detuned interaction between three atoms and a vacuum cavity mode constitute the main fusion mechanism, based on which two or three small-size atomic W states can be fused into a larger-size W state. If no excitation is detected from those three atoms, the remaining atoms are still in the product of two or three new W states, which can be re-fused. The complicated Fredkin gate used in the previous fusion schemes is avoided here. W states of size 2 can be fused as well. The feasibility analysis shows that our fusion processes maybe implementable with the current technology. Our results demonstrate how the light-matter interaction based fusion mechanism can be realized, and may become the starting point for the fusion of multipartite entanglement in cavity QED system. PMID:26548649

  17. Light-guiding hydrogels for cell-based sensing and optogenetic synthesis in vivo

    PubMed Central

    Choi, Myunghwan; Choi, Jin Woo; Kim, Seonghoon; Nizamoglu, Sedat; Hahn, Sei Kwang; Yun, Seok Hyun

    2013-01-01

    Polymer hydrogels are widely used as cell scaffolds for biomedical applications. While the biochemical and biophysical properties of hydrogels have been extensively investigated, little attention has been paid to their potential photonic functionalities. Here, we report cell-integrated polyethylene glycol-based hydrogels for in-vivo optical sensing and therapy applications. Hydrogel patches containing cells were implanted in awake, freely moving mice for several days and shown to offer long-term transparency, biocompatibility, cell-viability, and light-guiding properties (loss: <1 dB/cm). Using optogenetic, glucagon-like peptide-1 (GLP-1) secreting cells, we conducted light-controlled therapy using the hydrogel in a mouse model with type-2 diabetes and attained improved glucose homeostasis. Furthermore, real-time optical readout of encapsulated heat-shock-protein-coupled fluorescent reporter cells made it possible to measure the nanotoxicity of cadmium-based bare and shelled quantum dots (CdTe; CdSe/ZnS) in vivo. PMID:25346777

  18. Improvement of light penetration based silkworm gender identification with confined regions of interest

    NASA Astrophysics Data System (ADS)

    Kamtongdee, Chakkrit; Sumriddetchkajorn, Sarun; Sa-ngiamsak, Chiranut

    2013-06-01

    Based on our previous work on light penetration-based silkworm gender identification, we find that unwanted optical noises scattering from the surrounding area near the silkworm pupa and the transparent support are sometimes analyzed and misinterpreted leading to incorrect silkworm gender identification. To alleviate this issue, we place a small rectangular hole on a transparent support so that it not only helps the user precisely place the silkworm pupa but also functions as a region of interest (ROI) for blocking unwanted optical noises and for roughly locating the abdomen region in the image for ease of image processing. Apart from the external ROI, we also assign a smaller ROI inside the image in order to remove strong scattering light from all edges of the external ROI and at the same time speed up our image processing operations. With only the external ROI in function, our experiment shows a measured 86% total accuracy in identifying gender of 120 silkworm pupae with a measured average processing time of 38 ms. Combining the external ROI and the image ROI together revamps the total accuracy in identifying the silkworm gender to 95% with a measured faster 18 ms processing time.

  19. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    PubMed Central

    Cheng, Fei; Gao, Jie; Luk, Ting S.; Yang, Xiaodong

    2015-01-01

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage. PMID:26047486

  20. Generating multi-atom entangled W states via light-matter interface based fusion mechanism

    PubMed Central

    Zang, Xue-Ping; Yang, Ming; Ozaydin, Fatih; Song, Wei; Cao, Zhuo-Liang

    2015-01-01

    W state is a key resource in quantum communication. Fusion technology has been proven to be a good candidate for preparing a large-size W state from two or more small-size W states in linear optical system. It is of great importance to study how to fuse W states via light-matter interface. Here we show that it is possible to prepare large-size W-state networks using a fusion mechanism in cavity QED system. The detuned interaction between three atoms and a vacuum cavity mode constitute the main fusion mechanism, based on which two or three small-size atomic W states can be fused into a larger-size W state. If no excitation is detected from those three atoms, the remaining atoms are still in the product of two or three new W states, which can be re-fused. The complicated Fredkin gate used in the previous fusion schemes is avoided here. W states of size 2 can be fused as well. The feasibility analysis shows that our fusion processes maybe implementable with the current technology. Our results demonstrate how the light-matter interaction based fusion mechanism can be realized, and may become the starting point for the fusion of multipartite entanglement in cavity QED system. PMID:26548649

  1. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    SciTech Connect

    Cheng, Fei; Gao, Jie; Luk, Ting S.; Yang, Xiaodong

    2015-06-05

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage.

  2. Fiber-Based Lasers as an Option for GRACE Follow-On Light Source

    NASA Technical Reports Server (NTRS)

    Camp, Jordan

    2010-01-01

    Fiber based lasers offer a number of attractive characteristics for space application: state of the art laser technology, leverage of design and reliability from the substantial investments of the telecon industry, and convenient redundancy of higher risk components through fiber splicing. At NASA/Goddard we are currently investigating three GFO fiber-based laser options: a fiber oscillator built in our laboratory; an effort to space qualify a commercial design that uses a proprietary high-gain fiber cavity; and the space qualification of a promising new commercial external cavity laser, notable for its low-mass, compact design. In my talk I will outline these efforts, and suggest that the GFO Project may soon have the option of a US laser vendor for its light source.

  3. Structure-Based Druggability Assessment of the Mammalian Structural Proteome with Inclusion of Light Protein Flexibility

    PubMed Central

    Loving, Kathryn A.; Lin, Andy; Cheng, Alan C.

    2014-01-01

    Advances reported over the last few years and the increasing availability of protein crystal structure data have greatly improved structure-based druggability approaches. However, in practice, nearly all druggability estimation methods are applied to protein crystal structures as rigid proteins, with protein flexibility often not directly addressed. The inclusion of protein flexibility is important in correctly identifying the druggability of pockets that would be missed by methods based solely on the rigid crystal structure. These include cryptic pockets and flexible pockets often found at protein-protein interaction interfaces. Here, we apply an approach that uses protein modeling in concert with druggability estimation to account for light protein backbone movement and protein side-chain flexibility in protein binding sites. We assess the advantages and limitations of this approach on widely-used protein druggability sets. Applying the approach to all mammalian protein crystal structures in the PDB results in identification of 69 proteins with potential druggable cryptic pockets. PMID:25079060

  4. Portable and visual electrochemical sensor based on the bipolar light emitting diode electrode.

    PubMed

    Zhang, Xiaowei; Chen, Chaogui; Yin, Jianyuan; Han, Yanchao; Li, Jing; Wang, Erkang

    2015-01-01

    Here we report a novel sensing strategy based on the closed bipolar system, in which we utilize a light emitting diode (LED) to connect a split bipolar electrode (BPE) and generate the luminescent signal in the presence of the target. With this design, we have constructed a BPE array for the quick and high-throughput determination of various electroactive substances with naked eyes. Due to the ultrahigh current efficiency of the closed bipolar system, the sample concentration can be reported by the luminous intensity of the inserted LED without the expensive luminescent agent and instruments. Besides, the stability of the signal is improved because of the electroluminescent property of the LED. To demonstrate the promising applications of the bipolar LED electrode (BP-LED-E), the rapid quantification of four model targets (H2O2, ascorbic acid (AA), glucose, and blood sugar) has been achieved based on different principles. PMID:25873190

  5. Measurement of free light chains with assays based on monoclonal antibodies.

    PubMed

    Te Velthuis, Henk; Drayson, Mark; Campbell, John P

    2016-06-01

    Recently, serum free light chain (FLC) assays incorporating anti-kappa (κ) and anti-lambda (λ) FLC monoclonal antibodies have become available: N Latex FLC assay (Siemens) and Seralite® (Abingdon Health). The purpose of this review is to provide an overview of these two new monoclonal antibody-based methods. In doing so, the review will outline the performance characteristics of each method, including a summary of: assay principles, antibody specificity, analytical performance and assay performance in disease. Additionally, the review will describe the potential user benefits of adopting these new generation FLC assays, which are designed to overcome the established limitations of existing polyclonal antibody based FLC assays. PMID:27010775

  6. Electro-optic polymer spatial light modulator based on a Fabry-Perot interferometer configuration.

    PubMed

    Greenlee, Charles; Luo, J; Leedy, K; Bayraktaroglu, B; Norwood, R A; Fallahi, M; Jen, A K-Y; Peyghambarian, N

    2011-06-20

    A spatial light modulator (SLM) based on a Fabry-Perot interferometer configuration has been fabricated and tested. The Fabry-Perot spacer layer is a thin film of the SEO100 electro-optic polymer which serves as the nonlinear medium. Measurement results demonstrate the modulation of multiple pixels operating simultaneously at frequencies ranging from 300 kHz to 800 kHz which is significantly faster than SLMs based on liquid crystal and digital micromirror device technology. An average modulation contrast of 50% for all pixels is achieved with a drive voltage of 70 V(rms) at 100 kHz. Microwave speeds and CMOS compatibility are feasible with improved transmission line and cavity design. PMID:21716517

  7. Advances in phosphors based on organic materials for light emitting devices

    NASA Astrophysics Data System (ADS)

    Sharma, Kashma; Kumar, Vijay; Kumar, Vinod; Swart, Hendrik C.

    2016-01-01

    A brief overview is presented in the light emitting diodes (LEDs) based on purely organic materials. Organic LEDs are of great interest to the research community because of their outstanding properties and flexibility. Comparison between devices made using different organic materials and their derivatives with respect to synthetic protocols, characterizations, quantum efficiencies, sensitivity, specificity and their applications in various fields have been discussed. This review also discusses the essential requirement and scientific issues that arise in synthesizing cost-effective and environmental friendly organic LEDs diodes based on purely organic materials. This mini review aims to capture and convey some of the key current developments in phosphors formed by purely organic materials and highlights some possible future applications. Hence, this study comes up with a widespread discussion on the various contents in a single platform. Also, it offers avenues for new researchers for futuristic development in the area.

  8. Bonding dental amalgam to a light-curing glass-ionomer liner/base.

    PubMed

    Aboush, Y E; Elderton, R J

    1991-03-23

    At a time when amalgam is used widely, yet when the criteria for its use are still evolving, the incorporation of an element of adhesive bonding between the amalgam and the base material may come into greater prominence and aid the general move towards more conservative new or replacement cavity preparations. This study assessed the 24-hour tensile bond strength of amalgam (Dispersalloy) to a light-curing glass-ionomer liner/base (Vitrabond), using Scotchbond dual cure, uncured Vitrabond or Vitrabond liquid as intermediaries. Using the Weibull distribution function, it was found that uncured Vitrabond was a better intermediary than Scotchbond or Vitrabond liquid. The bond strengths obtained with uncured Vitrabond intermediary were of the same order as those which can be expected between a glass-ionomer cement and dentine. This suggests scope for developing techniques for bonding amalgam to parts of cavity preparations. PMID:2021495

  9. Whole-body Fluorescent Optical Imaging Based on Power Light Emitting Diode.

    PubMed

    Chen, Yanping; Xiong, Tao; Yu, Li; Zeng, Shaoqun; Luo, Qingming

    2005-01-01

    With complex configuration, the general whole-body fluorescence optical imaging system is power-consuming for it is mainly composed of laser or mercury lamp, filter and fiber-optic cable. In this paper we aimed at setting up a compact imaging system based on power light emitting diode (LED). We first discussed fluorescence excitation efficiency of mercury lamp and LED. Then we developed a compact prototype whole-body fluorescence optical imaging system based on power LED. With the prototype, we monitored the dynamic course of green fluorescence protein (GFP) expressing tumors in the same intact nude mice. We also recorded the temporal behavior of the infectious process of GFP-expressing bacteria from outside intact infected animals. This study puts forward a platform for monitoring tumor growth. The experiment reveals that it is doable to substitute power LED for mercury lamp for whole-body fluorescence optical imaging. PMID:17282471

  10. A novel violet/blue light-emitting device based on Ce2Si2O7

    PubMed Central

    Li, Ling; Wang, Shenwei; Mu, Guangyao; Yin, Xue; Ou, Kai; Yi, Lixin

    2015-01-01

    Rare-earth silicates are highly efficient materials for silicon-based light sources. Here we report a novel light-emitting device based on Ce2Si2O7. Intense violet/blue electroluminescence was observed, with a turn-on voltage of about 13 V. The violet/blue emission is attributed to 4f–5d transitions of the Ce3+ ions in Ce2Si2O7, which are formed by interfacial reaction of CeO2 and Si. Electroluminescence and photoluminescence mechanisms of the Ce2Si2O7 light-emitting device are also discussed. PMID:26564241

  11. Field-programmable gate array based arbitrary signal generator and oscilloscope for use in slow light and storage of light experiments

    NASA Astrophysics Data System (ADS)

    Nikolić, Stanko N.; Batić, Viktor; Panić, Bratimir; Jelenković, Branislav M.

    2013-06-01

    We present a field-programmable gate array (FPGA) based device that simultaneously generates two arbitrary analog voltage signals with the maximum sample rate of 1.25 MHz and acquires two analog voltage signals with the maximum sample rate of 2.5 MHz. All signals are synchronized with internal FPGA clock. The personal computer application developed for controlling and communicating with FPGA chip provides the shaping of the output signals by mathematical expressions and real-time monitoring of the input signals. The main advantages of FPGA based digital-to-analog and analog-to-digital cards are high speed, rapid reconfigurability, friendly user interface, and low cost. We use this module in slow light and storage of light experiments performed in Rb buffer gas cell.

  12. Efficiency droop effects of GaN-based light-emitting diodes on the performance of code division multiple access visible-light communication system

    NASA Astrophysics Data System (ADS)

    Lu, Huimin; Yan, Chaowen; Gao, Wei; Yu, Tongjun; Wang, Jianping

    2016-02-01

    The physical mechanism in efficiency droop of GaN-based light-emitting diodes (LEDs) was investigated using a modified rate equation model considering inhomogeneous carrier distribution and was compared with the measured result. On this basis, the efficiency droop effect on the performance of a code division multiple access (CDMA) visible-light communication (VLC) system using GaN-based LEDs was also analyzed. The results reveal that the obvious transmitted signal error under the effect of LED efficiency droop leads to performance deterioration of multiuser CDMA VLC systems. Also, the performance of CDMA VLC systems is reduced with the user number increase due to LED efficiency droop. The bit error rate of a CDMA VLC system was further calculated for different branch signal levels and bias currents. It is demonstrated that the efficiency droop effect on the performance of CDMA VLC systems can be alleviated by adjusting the branch signal level and the bias current.

  13. Colorimetric Detection of Escherichia coli Based on the Enzyme-Induced Metallization of Gold Nanorods.

    PubMed

    Chen, Juhong; Jackson, Angelyca A; Rotello, Vincent M; Nugen, Sam R

    2016-05-01

    A novel enzyme-induced metallization colorimetric assay is developed to monitor and measure beta-galactosidase (β-gal) activity, and is further employed for colorimetric bacteriophage (phage)-enabled detection of Escherichia coli (E. coli). This assay relies on enzymatic reaction-induced silver deposition on the surface of gold nanorods (AuNRs). In the presence of β-gal, the substrate p-aminophenyl β-d-galactopyranoside is hydrolyzed to produce p-aminophenol (PAP). Reduction of silver ions by PAP generates a silver shell on the surface of AuNRs, resulting in the blue shift of the longitudinal localized surface plasmon resonance peak and multicolor changes of the detection solution from light green to orange-red. Under optimized conditions, the detection limit for β-gal is 128 pM, which is lower than the conventional colorimetric assay. Additionally, the assay has a broader dynamic range for β-gal detection. The specificity of this assay for the detection of β-gal is demonstrated against several protein competitors. Additionally, this technique is successfully applied to detect E. coli bacteria cells in combination with bacteriophage infection. Due to the simplicity and short incubation time of this enzyme-induced metallization colorimetric method, the assay is well suited for the detection of bacteria in low-resource settings. PMID:26997252

  14. High-color rendering indices performance of glass based phosphor-converted white light-emitting diodes for solid state lighting

    NASA Astrophysics Data System (ADS)

    Tsai, Chun-Chin; Cheng, Wei-Chih; Chen, Guan-Hao; Lee, Yu-Chun; Kuo, Cheng Ta; Cheng, Wood-Hi

    2014-02-01

    The high-temperature operation of glass based phosphor-converted warm-white light-emitting diodes (PC-WWLEDs) is demonstrated. The fabrication and characteristics of low-temperature phosphor (Yollow:Ce:3+:YAG, Greed:Tb3+:YAG, Red:CaAlClSiN3:Eu2+) doped glass applied to high color rendering indices warm-white-light-emitting diodes was presented. In this property is color coordinates (x, y) = (0.32, 0.28), quantum yield (QY) = 55%, color rending index (CRI) =85, correlated color temperature (CCT) =3900K. The result showed the PC-WLEDs maintained good thermal stability at the high temperature operation. The QY decay, CRI attenuation and chromaticity shift in glass and silicone based high-power PC-WLEDs under thermal aging at 150°C and 250°C are also presented and compared. The result indicated that the glass based PC-WLEDs exhibited better thermal stability than the silicone. And the color rendering indices (CRI) glass phosphor may have potential used as a phosphor layer for high-performance and low-cost PCWLEDs used in next-generation indoors solid-state lighting applications.

  15. Electroluminescence spectra of ultraviolet light-emitting diodes based on p-n-heterostructures coated with phosphors

    SciTech Connect

    Gal'china, N. A.; Kogan, L. M.; Soshchin, N. P.; Shirokov, S. S.; Yunovich, A. E.

    2007-09-15

    The electroluminescence spectra of light-emitting diodes based on p-n heterostructures of the InGaN/AlGaN/GaN type are studied in the near-ultraviolet spectral region (360-405 nm). The spectra are peaked at the wavelengths 385 and 395 nm, and the intensity of emission falls exponentially with the photon energy in the shorter-wavelength and longer-wavelength regions. The emitters in the green and yellow spectral regions based on these light-emitting diodes coated with silicate phosphors are studied. The luminescence spectra of phosphors have the Gaussian shape and maximums in the range from 525 to 560 nm. The color characteristics of emitters depend on the ratios of intensities of the ultraviolet and yellow-green bands. The possibilities of fabrication of light-emitting diodes of visible luminescence based on ultraviolet light-emitting diodes that excite colored phosphors are discussed.

  16. The high frequency light load fatigue testing machine based on giant magnetostrictive material and stroke multiplier

    NASA Astrophysics Data System (ADS)

    Wang, M. D.; Li, D. S.; Huang, Y.; Zhang, C.; Zhong, K. M.; Sun, L. N.

    2013-08-01

    In the notebook and clamshell mobile phone, data communication wire often requires repeated bending. Generally, communication wire with the actual application conditions, the test data cannot assess bending resistance performance of data communication wire is tested conventionally using wires with weights of 90 degree to test bending number, this test method and device is not fully reflect the fatigue performance in high frequency and light load application condition, at the same time it has a large difference between the test data of the long-term reliability of high frequency and low load conditions. In this paper, high frequency light load fatigue testing machine based on the giant magnetostrictive material and stroke multiplier is put forward, in which internal reflux stroke multiplier is driven by giant magnetostrictive material to realize the rapid movement of light load. This fatigue testing device has the following advantages: (1) When the load is far less than the friction, reducing friction is very effective to improve the device performance. Because the body is symmetrical, the friction loss of radial does not exist in theory, so the stress situation of mechanism is good with high transmission efficiency and long service life. (2) The installation position of the output hydraulic cylinder, can be arranged conveniently as ordinary cylinder. (3) Reciprocating frequency, displacement and speed of high frequency movement can be programmed easily to change with higher position precision. (4)Hydraulic oil in this device is closed to transmit, which does not produce any environment pollution. The device has no hydraulic pump and tank, and less energy conversion processes, so it is with the trend of green manufacturing.

  17. 3D modeling method for computer animate based on modified weak structured light method

    NASA Astrophysics Data System (ADS)

    Xiong, Hanwei; Pan, Ming; Zhang, Xiangwei

    2010-11-01

    A simple and affordable 3D scanner is designed in this paper. Three-dimensional digital models are playing an increasingly important role in many fields, such as computer animate, industrial design, artistic design and heritage conservation. For many complex shapes, optical measurement systems are indispensable to acquiring the 3D information. In the field of computer animate, such an optical measurement device is too expensive to be widely adopted, and on the other hand, the precision is not as critical a factor in that situation. In this paper, a new cheap 3D measurement system is implemented based on modified weak structured light, using only a video camera, a light source and a straight stick rotating on a fixed axis. For an ordinary weak structured light configuration, one or two reference planes are required, and the shadows on these planes must be tracked in the scanning process, which destroy the convenience of this method. In the modified system, reference planes are unnecessary, and size range of the scanned objects is expanded widely. A new calibration procedure is also realized for the proposed method, and points cloud is obtained by analyzing the shadow strips on the object. A two-stage ICP algorithm is used to merge the points cloud from different viewpoints to get a full description of the object, and after a series of operations, a NURBS surface model is generated in the end. A complex toy bear is used to verify the efficiency of the method, and errors range from 0.7783mm to 1.4326mm comparing with the ground truth measurement.

  18. Multi-color colloidal quantum dot based light emitting diodes micropatterned on silicon hole transporting layers

    NASA Astrophysics Data System (ADS)

    Gopal, Ashwini; Hoshino, Kazunori; Kim, Sunmin; Zhang, Xiaojing

    2009-06-01

    We present a colloidal quantum dot based light emitting diode (QD-LED) which utilizes the p-type silicon substrate as the hole transporting layer. A microcontact printing technique was introduced to pattern self-assembled CdSe/ZnS QD films, which allowed creation of an LED with well-defined geometry suitable for monolithic integration on silicon substrates. Our QD-LED consists of multi-layers of inorganic materials: a combination of Au (thickness: 5 nm) and Ag (12 nm) as the cathode, a ZnO:SnO2 mixture (ratio 3:1, 40 nm) as the electron transporting layer, CdSe/ZnS QDs as the light emission layer, 1 nm SiO2 as an energy barrier layer, and p-type silicon as the hole transporting layer. These printed QD-LEDs are capable of multi-color emission peaked at wavelengths of 576 nm, 598 nm, and 622 nm, corresponding to sizes of the embedded QDs with the diameters of 8.4 nm, 9.0 nm, and 9.8 nm respectively. The optimal thickness of the quantum dot layers needed for light emission is characterized using atomic force microscopy: for 8.4 nm QDs, the value is 33 nm (± 5 nm) or ~4 ML (monolayers). Larger turn on voltages were measured (2, 4 and 5 V) for the smaller average particle diameters (9.8 nm, 9.0 nm and 8.4 nm, respectively). The mixture ratio of Zn and Sn was optimized (40% Zn and 25% Sn) to maintain proper hole-electron recombination at the QD layer and avoid the yellowish-white emission from ZnO/SnO2.

  19. Pristine and supported ZnO-based catalysts for phenazopyridine degradation with direct solar light

    NASA Astrophysics Data System (ADS)

    Hilal, Hikmat S.; Al-Nour, Ghazi Y. M.; Zyoud, Ahed; Helal, Muath H.; Saadeddin, Iyad

    2010-04-01

    In search for safe techniques to manage waste pharmaceutical compounds drained in water, solar-driven degradation of phenazopyridine (a model drug) was investigated in aqueous media using different ZnO-based catalyst systems. Naked ZnO, CdS-sensitized ZnO (ZnO/CdS) and activated carbon-supported ZnO (AC/ZnO) have been studied. Both naked ZnO and AC/ZnO were highly efficient in mineralizing phenazopyridine, reaching complete removal in ˜50 min, with AC/ZnO having the higher edge. The ZnO/CdS system showed lower efficiency, due to screening of light by CdS. Moreover, the tendency of CdS to leach out Cd 2+ ions discouraged the use of CdS as sensitizer in this work. In both ZnO and AC/ZnO systems, the photo-degradation reaction was induced by the UV tail of the solar light. The visible region, with wavelength longer than 400 nm, failed to induce photo-degradation. The reaction was faster with higher catalyst loading, until a maximum efficiency was reached at a certain concentration. The rate of reaction increased with higher drug concentrations up to a certain limit. The effect of pH value was studied, and the catalysts showed highest efficiencies at pH close to 7. Stability of ZnO to degradation was studied. Both catalyst systems showed lowered efficiencies on recovery and reuse. The results suggest that complete mineralization of waste drugs, commonly dumped in sewage water, with direct solar light is a potentially feasible strategy using the AC/ZnO catalyst.

  20. Light Source

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Research on food growth for long duration spacecraft has resulted in a light source for growing plants indoors known as Qbeam, a solid state light source consisting of a control unit and lamp. The light source, manufactured by Quantum Devices, Inc., is not very hot, although it generates high intensity radiation. When Ron Ignatius, an industrial partner of WCSAR, realized that terrestrial plant research lighting was not energy efficient enough for space use, he and WCSAR began to experiment with light emitting diodes. A line of LED products was developed, and QDI was formed to market the technology. An LED-based cancer treatment device is currently under development.

  1. A cross-platform solution for light field based 3D telemedicine.

    PubMed

    Wang, Gengkun; Xiang, Wei; Pickering, Mark

    2016-03-01

    Current telehealth services are dominated by conventional 2D video conferencing systems, which are limited in their capabilities in providing a satisfactory communication experience due to the lack of realism. The "immersiveness" provided by 3D technologies has the potential to promote telehealth services to a wider range of applications. However, conventional stereoscopic 3D technologies are deficient in many aspects, including low resolution and the requirement for complicated multi-camera setup and calibration, and special glasses. The advent of light field (LF) photography enables us to record light rays in a single shot and provide glasses-free 3D display with continuous motion parallax in a wide viewing zone, which is ideally suited for 3D telehealth applications. As far as our literature review suggests, there have been no reports of 3D telemedicine systems using LF technology. In this paper, we propose a cross-platform solution for a LF-based 3D telemedicine system. Firstly, a novel system architecture based on LF technology is established, which is able to capture the LF of a patient, and provide an immersive 3D display at the doctor site. For 3D modeling, we further propose an algorithm which is able to convert the captured LF to a 3D model with a high level of detail. For the software implementation on different platforms (i.e., desktop, web-based and mobile phone platforms), a cross-platform solution is proposed. Demo applications have been developed for 2D/3D video conferencing, 3D model display and edit, blood pressure and heart rate monitoring, and patient data viewing functions. The demo software can be extended to multi-discipline telehealth applications, such as tele-dentistry, tele-wound and tele-psychiatry. The proposed 3D telemedicine solution has the potential to revolutionize next-generation telemedicine technologies by providing a high quality immersive tele-consultation experience. PMID:26689324

  2. A biophysical study of clathrin utilizing light scattering, neutron scattering and structure based computer modeling

    NASA Astrophysics Data System (ADS)

    Ferguson, Matthew Lee

    A principal component in the protein coats of certain post-golgi and endocytic vesicles is clathrin, which appears as a three-legged heteropolymer (known as a triskelion) that assembles into polyhedral baskets principally made up of pentagonal and hexagonal faces. In vitro, this assembly depends on the pH, with baskets forming more readily at low pH and less readily at high pH. We have developed procedures, based on static and dynamic light scattering, to determine the radius of gyration, Rg, and hydrodynamic radius, RH, of isolated triskelia under conditions where basket assembly occurs. Calculations based on rigid molecular bead models of a triskelion show that the measured values can be accounted for by bending of the legs and a puckering at the vertex. We also show that the values of Rg and R H measured for clathrin triskelia in solution are qualitatively consistent with the conformation of an individual triskelion that is part of a "D6 barrel" basket assembly measured by cryo-EM tomography. We extended this study by performing small angle neutron scattering (SANS) experiments on isolated triskelia in solution under conditions where baskets do not assemble. SANS experiments were consistent with previous static light scattering experiments but showed a shoulder in the scattering function at intermediate q-values just beyond the central diffraction peak (the Guinier regime). Theoretical calculations based on rigid bead models of a triskelion showed well-defined features in this region different from the experiment. A flexible bead-spring model of a triskelion and Brownian dynamics simulations were used to generate a time averaged scattering function. This model adequately described the experimental data for flexibilities close to previous estimates from the analysis of electron micrographs.

  3. Ground-based Light Curves Two Pluto Days Before the New Horizons Passage

    NASA Astrophysics Data System (ADS)

    Bosh, A. S.; Pasachoff, J. M.; Babcock, B. A.; Durst, R. F.; Seeger, C. H.; Levine, S. E.; Abe, F.; Suzuki, D.; Nagakane, M.; Sickafoose, A. A.; Person, M. J.; Zuluaga, C.; Kosiarek, M. R.

    2015-12-01

    We observed the occultation of a 12th magnitude star, one of the two brightest occultation stars ever in our dozen years of continual monitoring of Pluto's atmosphere through such studies, on 29 June 2015 UTC. At Canterbury University's Mt. John University Observatory on the south island of New Zealand, in clear sky, we used our POETS frame-transfer CCD at 10 Hz with GPS timing on the 1-m McLellan telescope as well as an infrared camera on an 0.6-m telescope and three-color photometry at a slower cadence on a second 0.6-m telescope. The light curves show a central flash, indicating that we were close to the center of the occultation path, and allowing us to explore Pluto's atmosphere lower than usual. The light curves show that Pluto's atmosphere remained robust. Observations from 0.5- and 0.4-m telescopes at the Auckland Observatory gave the first half of the occultation before clouds came in. We coordinated our observations with aircraft observations with NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) and its High Speed Imaging Photometer for Occultations (HIPO). Our ground-based and airborne stellar-occultation effort came only just over two weeks of Earth days and two Pluto days (based on Pluto's rotational period) before the flyby of NASA's New Horizons spacecraft, meaning that the mission's exquisite snapshot of Pluto's atmosphere can be placed in the context of our series of ground-based occultation observations carried out on a regular basis since 2002 following a first Pluto occultation observed in 1988 from aloft. Our observations were supported by NASA Planetary Astronomy grants NNX12AJ29G to Williams College, NNX15AJ82G to Lowell Observatory, and NNX10AB27G to MIT, and by the National Research Foundation of South Africa. We thank Alan Gilmore, Pam Kilmartin, Robert Lucas, Paul Tristam, and Carolle Varughese for assistance at Mt. John.

  4. Self-reported Impacts of LED Lighting Technology Compared to Fuel-based Lighting on Night Market Business Prosperity in Kenya

    SciTech Connect

    Johnstone, Peter; Jacobson, Arne; Mills, Evan; Mumbi, Maina

    2009-02-11

    The notion of"productive use" is often invoked in discussions about whether new technologies improve productivity or otherwise enhance commerce in developing-country contexts. It an elusive concept,especially when quantitative measures are sought. Improved and more energy efficient illumination systems for off-gridapplication--the focus of the Lumina Project--provide a case in which a significant productivity benefit can be imagined, given the importance of light to the successful performance of many tasks, and the very low quality of baseline illumination provided by flame-based source. This Research Note summarizes self-reported quantitative and qualitative impacts of switching to LED lighting technology on the prosperity of night-market business owners and operators. The information was gathered in the context of our 2008 market testing field work in Kenya?s Rift Valley Province, which was performed in the towns of Maai Mahiu and Karagita by Arne Jacobson, Kristen Radecsky, Peter Johnstone, Maina Mumbi, and others. Maai Mahiu is a crossroads town; provision of services to travelers and freight carriers is a primary income source for the residents. In contrast, the primary income for Karagita's residents is from work in the large, factory style flower farms on the eastern shores of Lake Naivasha that specialize in producing cut flowers for export to the European market. According to residents, both towns had populations of 6,000 to 8,000 people in June 2008. We focused on quantifying the economics of fuel-based and LED lighting technology in the context of business use by night market vendors and shop keepers. Our research activities with the business owners and operators included baseline measurement of their fuel-based lighting use, an initial survey, offering for sale data logger equipped rechargeable LED lamps, monitoring the adoption of the LED lamps, and a follow-up survey.

  5. Development of a multi-sensor airborne investigation platform based on an ultra-light aircraft

    NASA Astrophysics Data System (ADS)

    Herd, Rainer; Holst, Jonathan; Lay, Michael

    2013-04-01

    In the year 2012 the chair Raw Material and Natural Resource Management of Brandenburg University of Technology Cottbus, Germany started to develop, construct and assemble a multi-sensor airborne investigation system based on an ultra-light aircraft. The conceptual ideas were born several years before and triggered by the increasing demand of spatial underground information, increasing restrictions to access private property and the lack of affordable commercially operated systems for projects with small budgets. The concept of the presented system comprehends a full composite ultra-light aircraft, the Pipistrel VIRUS which combines a low minimum (65 km/h, a high crusing speed (250 km/h, a long range (1700 km) and a low noise potential. The investigation equipment which can be modified according to the investigation target comprises actually a CsI-y-spectrometer in the fuselage, 2 K-magnetometer at the wing tips and a VLF-EM-receiver underneath the tail. This configuration enables the system to operate for mineral exploration, geological mapping, detection of freshwater resources and brines and different environmental monitoring missions. The development and actual stage of the project will be presented. The first operating flight is scheduled for spring 2013.

  6. Visualization of energy: light dose indicator based on electrochromic gyroid nano-materials.

    PubMed

    Wei, Di; Scherer, Maik R J; Astley, Michael; Steiner, Ullrich

    2015-06-01

    The typical applications of electrochromic devices do not make use of the charge-dependent, gradual optical response due to their slow voltage-sensitive coloration. However, in this paper we present a design for a reusable, self-powered light dose indicator consisting of a solar cell and a gyroid-structured nickel oxide (NiO) electrochromic display that measures the cumulative charge per se, making use of the efficient voltage-sensitive coloration of gyroid materials. To circumvent the stability issues associated with the standard aqueous electrolyte that is typically accompanied by water splitting and gas evolution, we investigate a novel nano-gyroid NiO electrochromic device based on organic solvents of 1,1,1,3,3,3-hexafluoropropan-2-ol, and room temperature ionic liquid (RTIL) triethylsulfonium bis(trifluoromethylsulfonyl) imide ([SET3][TFSI]) containing lithium bis(trifluoromethylsulfonyl) imide. We show that an effective light dose indicator can be enabled by nano-gyroid NiO with RTIL; this proves to be a reliable device since it does not involve solvent degradation or gas generation. PMID:25969409

  7. A Caenorhabditis elegans–based assay recognizes immunoglobulin light chains causing heart amyloidosis

    PubMed Central

    Rognoni, Paola; Lavatelli, Francesca; Romeo, Margherita; del Favero, Elena; Cantù, Laura; Ghibaudi, Elena; di Fonzo, Andrea; Corbelli, Alessandro; Fiordaliso, Fabio; Palladini, Giovanni; Valentini, Veronica; Perfetti, Vittorio; Salmona, Mario; Merlini, Giampaolo

    2014-01-01

    Poor prognosis and limited therapeutic options characterize immunoglobulin light-chain (AL) amyloidosis with major heart involvement. Reliable experimental models are needed to study light-chain (LC)/heart interactions and to explore strategies for prevention of cardiac damage. We have exploited the nematode Caenorhabditis elegans as a novel tool, because its pharynx is evolutionarily related to the vertebrate heart. Our data demonstrate that the pharyngeal pumping of C elegans is significantly and selectively reduced by LCs from AL patients suffering from cardiomyopathy, but not by amyloid LCs with different organ tropism or nonamyloidogenic LCs from multiple myeloma. This functional alteration is dependent on the LC concentration and results in persistent pharyngeal dysfunction and in a significant reduction of the worms’ lifespan. These manifestations are paralleled by an increase of mitochondrial reactive oxygen species and can be prevented by treatment with antioxidant agents. In conclusion, these data indicate that this nematode-based assay is a promising surrogate model for investigating the heart-specific toxicity of amyloidogenic LCs and for a rapid screening of new therapeutic strategies. PMID:24665135

  8. Visible light induced photoelectrochemical biosensing based on oxygen-sensitive quantum dots.

    PubMed

    Wang, Wenjing; Bao, Lei; Lei, Jianping; Tu, Wenwen; Ju, Huangxian

    2012-09-26

    A visible light induced photoelectrochemical biosensing platform based on oxygen-sensitive near-infrared quantum dots (NIR QDs) was developed for detection of glucose. The NIR QDs were synthesized in an aqueous solution, and characterized with scanning electron microscopy and X-ray photoelectron spectroscopy. The as-prepared NIR QDs were employed to construct oxygen-sensitive photoelectrochemical biosensor on a fluorine-doped tin oxide (FTO) electrode. The oxygen dependency of the photocurrent was investigated at as-prepared electrode, which demonstrated the signal of photocurrent is suppressed with the decreasing of oxygen. Coupling with the consumption of oxygen during enzymatic reaction, a photoelectrochemical strategy was proposed for the detection of substrate. Using glucose oxidase (GOx) as a model enzyme, that is, GOx was covalently attached to the surface of CdTe QDs, the resulting biosensor showed the sensitive response to glucose. Under the irradiation of visible light of a wavelength at 505 nm, the proposed photoelectrochemical method could detect glucose ranging from 0.1 mM to 11 mM with a detection limit of 0.04 mM. The photoelectrochemical biosensor showed a good performance with high upper detection limit, acceptable stability and accuracy, providing an alternative method for monitoring biomolecules and extending the application of near-infrared QDs. PMID:22935371

  9. Laser and light-based treatments of venous lakes: a literature review.

    PubMed

    Mlacker, Stephanie; Shah, Vidhi V; Aldahan, Adam S; McNamara, Colin A; Kamath, Preetha; Nouri, Keyvan

    2016-09-01

    Venous lake is a benign vascular malformation commonly seen in elderly patients, typically arising in sun-exposed areas of the body. Patients often seek treatment to prevent recurrent bleeding or because they find the lesion cosmetically unacceptable. Venous lake may negatively affect quality of life, due to the cosmetic disfigurement it can create and the resulting psychological distress. Traditional treatments, such as surgical excision, cryosurgery, sclerotherapy, and electrocoagulation, result in varying degrees of success and can cause discomfort. Laser- and light-based treatment modalities may offer a safe and effective alternative, as numerous studies have shown their benefit in the treatment of venous lakes, particularly with the long-pulsed 1064-nm neodymium-doped yttrium aluminum garnet (Nd:YAG). Although various types of lasers and lights have been studied, there remains a lack of general consensus as to which one is the superior laser modality. Further studies that establish standardized protocols to compare the results of using different types of laser treatments are warranted. PMID:27056704

  10. Game theory-based mode cooperative selection mechanism for device-to-device visible light communication

    NASA Astrophysics Data System (ADS)

    Liu, Yuxin; Huang, Zhitong; Li, Wei; Ji, Yuefeng

    2016-03-01

    Various patterns of device-to-device (D2D) communication, from Bluetooth to Wi-Fi Direct, are emerging due to the increasing requirements of information sharing between mobile terminals. This paper presents an innovative pattern named device-to-device visible light communication (D2D-VLC) to alleviate the growing traffic problem. However, the occlusion problem is a difficulty in D2D-VLC. This paper proposes a game theory-based solution in which the best-response dynamics and best-response strategies are used to realize a mode-cooperative selection mechanism. This mechanism uses system capacity as the utility function to optimize system performance and selects the optimal communication mode for each active user from three candidate modes. Moreover, the simulation and experimental results show that the mechanism can attain a significant improvement in terms of effectiveness and energy saving compared with the cases where the users communicate via only the fixed transceivers (light-emitting diode and photo diode) or via only D2D.

  11. Organic white-light-emitting devices based on a multimode resonant microcavity

    NASA Astrophysics Data System (ADS)

    Zhang, Hongmei; You, Han; Wang, Wei; Shi, Jiawei; Guo, Shuxu; Liu, Mingda; Ma, Dongge

    2006-08-01

    Organic white-light-emitting devices (OLEDs) based on a multimode resonant microcavity defined by a pair of dielectric mirrors and metal mirrors were presented. By selective effects of the quarter-wave dielectric stack mirror on mode, white light emission containing three individual narrow peaks of red, green and blue was achieved, and showed weak dependence on the viewing angle. The Commission Internationale De L'Eclairage (CIE) chromaticity coordinates changed from (0.29, 0.37) at 0° to (0.31, 0.33) at 40°. Furthermore, the brightness and electroluminescence efficiency of the microcavity OLEDs were enhanced compared with noncavity OLEDs. The maximum brightness reached 1940 cd m-2 at a current density of 200 mA cm-2, and the maximum current efficiency and power efficiency are 1.6 cd A-1 at a current density of 12 mA cm-2 and 0.41 lm W-1 at a current density of 1.6 mA cm-2, which are over 1.6 times higher than that of a noncavity OLED.

  12. Light-sheet-based fluorescence microscopy for three-dimensional imaging of biological samples.

    PubMed

    Swoger, Jim; Pampaloni, Francesco; Stelzer, Ernst H K

    2014-01-01

    In modern biology, most optical imaging technologies are applied to two-dimensional cell culture systems; that is, they are used in a cellular context that is defined by hard and flat surfaces. However, a physiological context is not found in single cells cultivated on coverslips. It requires the complex three-dimensional (3D) relationship of cells cultivated in extracellular matrix (ECM) gels, tissue sections, or in naturally developing organisms. In fact, the number of applications of 3D cell cultures in basic research as well as in drug discovery and toxicity testing has been increasing over the past few years. Unfortunately, the imaging of highly scattering multicellular specimens is still challenging. The main issues are the limited optical penetration depth, the phototoxicity, and the fluorophore bleaching. Light-sheet-based fluorescence microscopy (LSFM) overcomes many drawbacks of conventional fluorescence microscopy by using an orthogonal/azimuthal fluorescence arrangement with independent sets of lenses for illumination and detection. The basic idea is to illuminate the specimen from the side with a thin light sheet that overlaps with the focal plane of a wide-field fluorescence microscope. Optical sectioning and minimal phototoxic damage or photobleaching outside a small volume close to the focal plane are intrinsic properties of LSFM. We discuss the basic principles of LSFM and methods for the preparation, embedding, and imaging of 3D specimens used in the life sciences in an implementation of LSFM known as the single (or selective) plane illumination microscope (SPIM). PMID:24371323

  13. Efficient white organic light-emitting devices based on blue, orange, red phosphorescent dyes

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Zhang, Liying; Duan, Yu; Xie, Wenfa; Zhao, Yi; Hou, Jingying; Liu, Shiyong; Li, Bin

    2009-03-01

    We demonstrate efficient white organic light-emitting devices (WOLEDs) based on an orange phosphorescent iridium complex bis(2-(2-fluorphenyl)-1,3-benzothiozolato-N, C2')iridium(acetylacetonate) in combination with blue phosphorescent dye bis[(4, 6-difluorophenyl)-pyridinato-N,C2)](picolinato) Ir(III) and red phosphorescent dye bis[1-(phenyl)isoquinoline] iridium (III) acetylanetonate. By introducing a thin layer of 4, 7-diphenyl-1,10-phenanthroline between blue and red emission layers, the diffusion of excitons is confined and white light can be obtained. WOLEDs with the interlayer all have a higher colour rendering index (>82) than the device without it (76). One device has the maximum current efficiency of 17.6 cd A-1 and a maximum luminance of 39 050 cd m-2. The power efficiency is 8.7 lm W-1 at 100 cd m-2. Furthermore, the device has good colour stability and the CIE coordinates just change from (0.394, 0.425) to (0.390, 0.426) with the luminance increasing from 630 to 4200 cd m-2.

  14. A new photoacoustic method based on the modulation of the light induced absorption coefficient

    NASA Astrophysics Data System (ADS)

    Engel, S.; Wenisch, C.; Müller, F. A.; Gräf, S.

    2016-04-01

    The present study reports on a new photoacoustic (PA) measurement method that is suitable for the investigation of light induced absorption effects including e.g. excited state absorption. Contrary to the modulation of the radiation intensity used in conventional PA-methods, the key principle of this novel setup is based on the modulation of the induced absorption coefficient by light. For this purpose, a pump-probe setup with a pulsed pump laser beam and a continuous probe laser beam is utilized. In this regime, the potential influence of heat on the PA-signal is much smaller when compared to arrangements with pulsed probe beam and continuous pump beam. Beyond that, the negative effect of thermal lenses can be neglected. Thus, the measurement technique is well-suited for materials exhibiting a strong absorption at the pump wavelength. The quantitative analysis of the induced absorption coefficient was achieved by the calibration of the additional PA-signal caused by the continuous probe laser to the PA-signal resulting from the pulsed pump laser using thallium bromoiodide (KRS-5) as sample material.

  15. A Coded Structured Light System Based on Primary Color Stripe Projection and Monochrome Imaging

    PubMed Central

    Barone, Sandro; Paoli, Alessandro; Razionale, Armando Viviano

    2013-01-01

    Coded Structured Light techniques represent one of the most attractive research areas within the field of optical metrology. The coding procedures are typically based on projecting either a single pattern or a temporal sequence of patterns to provide 3D surface data. In this context, multi-slit or stripe colored patterns may be used with the aim of reducing the number of projected images. However, color imaging sensors require the use of calibration procedures to address crosstalk effects between different channels and to reduce the chromatic aberrations. In this paper, a Coded Structured Light system has been developed by integrating a color stripe projector and a monochrome camera. A discrete coding method, which combines spatial and temporal information, is generated by sequentially projecting and acquiring a small set of fringe patterns. The method allows the concurrent measurement of geometrical and chromatic data by exploiting the benefits of using a monochrome camera. The proposed methodology has been validated by measuring nominal primitive geometries and free-form shapes. The experimental results have been compared with those obtained by using a time-multiplexing gray code strategy. PMID:24129018

  16. The Carrying Capacity Under Four-Aspect Color Light Automatic Block Signaling Based on Cellular Automata

    NASA Astrophysics Data System (ADS)

    Xue, Yuan; Qian, Yong-Sheng; Guang, Xiao-Ping; Zeng, Jun-Wei; Jia, Zhi-Long; Wang, Xin

    2013-05-01

    With the application of the dynamic control system, Cellular Automata model has become a valued tool for the simulation of human behavior and traffic flow. As an integrated kind of railway signal-control pattern, the four-aspect color light automatic block signaling has accounted for 50% in the signal-control system in China. Thus, it is extremely important to calculate correctly its carrying capacity under the automatic block signaling. Based on this fact the paper proposes a new kind of "cellular automata model" for the four-aspect color light automatic block signaling under different speed states. It also presents rational rules for the express trains with higher speed overtaking trains with lower speed in a same or adjacent section and the departing rules in some intermediate stations. In it, the state of mixed-speed trains running in the section composed of many stations is simulated with CA model, and the train-running diagram is acquired accordingly. After analyzing the relevant simulation results, the needed data are achieved herewith for the variation of section carrying capacity, the average train delay, the train speed with the change of mixed proportion, as well as the distance between the adjacent stations.

  17. Stress-induced piezoelectric field in GaN-based 450-nm light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Tawfik, Wael Z.; Hyeon, Gil Yong; Lee, June Key

    2014-10-01

    We investigated the influence of the built-in piezoelectric field induced by compressive stress on the characteristics of GaN-based 450-nm light-emitting diodes (LEDs) prepared on sapphire substrates of different thicknesses. As the sapphire substrate thickness was reduced, the compressive stress in the GaN layer was released, resulting in wafer bowing. The wafer bowing-induced mechanical stress altered the piezoelectric field, which in turn reduced the quantum confined Stark effect in the InGaN/GaN active region of the LED. The flat-band voltage was estimated by measuring the applied bias voltage that induced a 180° phase shift in the electro-reflectance (ER) spectrum. The piezoelectric field estimated by the ER spectra changed by ˜110 kV/cm. The electroluminescence spectral peak wavelength was blue-shifted, and the internal quantum efficiency was improved by about 22% at a high injection current of 100 mA. The LED on the 60-μm-thick sapphire substrate exhibited the highest light output power of ˜59 mW at an injection current of 100 mA, with the operating voltage unchanged.

  18. Low temperature solution process-based defect-induced orange-red light emitting diode

    PubMed Central

    Biswas, Pranab; Baek, Sung-Doo; Hoon Lee, Sang; Park, Ji-Hyeon; Jeong Lee, Su; Il Lee, Tae; Myoung, Jae-Min

    2015-01-01

    We report low-temperature solution-processed p-CuO nanorods (NRs)/n-ZnO NRs heterojunction light emitting diode (LED), exploiting the native point defects of ZnO NRs. ZnO NRs were synthesized at 90 °C by using hydrothermal method while CuO NRs were synthesized at 100 °C by using microwave reaction system. The electrical properties of newly synthesized CuO NRs revealed a promising p-type nature with a hole concentration of 9.64 × 1018 cm−3. The current-voltage characteristic of the heterojunction showed a significantly high rectification ratio of 105 at 4 V with a stable current flow. A broad orange-red emission was obtained from the forward biased LED with a major peak at 610 nm which was attributed to the electron transition from interstitial zinc to interstitial oxygen point defects in ZnO. A minor shoulder peak was also observed at 710 nm, corresponding to red emission which was ascribed to the transition from conduction band of ZnO to oxygen vacancies in ZnO lattice. This study demonstrates a significant progress toward oxide materials based, defect-induced light emitting device with low-cost, low-temperature methods. PMID:26648420

  19. Performance study of an OFDM visible light communication system based on white LED array

    NASA Astrophysics Data System (ADS)

    Tian, Chong-Wen; Li, Yan-Ting; Ye, Wei-Lin; Quan, Xiang-Yin; Song, Zhanwei; Zheng, Chuan-Tao

    2011-11-01

    By introducing orthogonal frequency division multiplexing (OFDM) technology, a visible light communication (VLC) system using a 5×5 white LED array is studied in this paper. The OFDM transmitter and receiver are modeled through MATLAB/Simulink tool. The electrical-optical-electrical (EOE) response of the VLC channel, which is also the response of the detector, is derived based on Lambert's lighting model. Then the modeling on the overall OFDM/VLC system is established by combining the above three models together. The effects of the factors which include the digital modulation, Reed-Solomon (RS) coding, pilot form, pilot ratio (PR) and communication distance on the bit error rate (BER) of the system are discussed. The results show that through the use of RS coding, block pilot, quadrate phase shift keying (QPSK) modulation and a suitable pilot ratio about 1/3, under the communication rate about 550 kbit/s, the BER can be dropped to below 10-5, and the communication distance can reach 0.9 m.

  20. Herbivore Recolonization Rate Influences Light and Nutrient Effects on Algal Based Stream Ecosystems

    NASA Astrophysics Data System (ADS)

    Taulbee, K.

    2005-05-01

    The dynamics of algal based ecosystems are influenced by both resource availability and herbivory. Following a disturbance, the relative importance of top down versus bottom up regulation of algal dynamics in a particular system depends on both herbivore immigration rates and local resource availabilities. The effects of herbivore recolonization and resource availability on the recovery dynamics of algal ecosystems following a disturbance were investigated during two field experiments conducted in 24 in situ stream channels in Convict Creek, California. In each experiment, light and nutrients were cross-classified in a 6x2 factorial design, with 2 replicates per treatment. Initial algal and invertebrate densities were low. Using upstream drift nets of different mesh sizes, herbivore immigration was restricted in one experiment and unrestricted in a second experiment. The relative importance of herbivore versus resource regulation of algae was influenced by herbivore immigration. When immigration was restricted, as might occur following a severe disturbance, algae were more closely regulated by resource availability. In contrast, when herbivore immigration was not restricted, algae were regulated by both resource availability and herbivory. Finally, the effects of light and nutrients on algae were interactive when immigration was restricted, but not when immigration was unrestricted.

  1. Photoelectrochemical lab-on-paper device based on an integrated paper supercapacitor and internal light source.

    PubMed

    Ge, Lei; Wang, Panpan; Ge, Shenguang; Li, Nianqiang; Yu, Jinghua; Yan, Mei; Huang, Jiadong

    2013-04-16

    In this work, a photoelectrochemical (PEC) method was introduced into a microfluidic paper-based analytical device (μ-PAD), and thus, a truly low-cost, simple, portable, and disposable microfluidic PEC origami device (μ-PECOD) with an internal chemiluminescence light source and external digital multimeter (DMM) was demonstrated. The PEC responses of this μ-PECOD were investigated, and the enhancements of photocurrents in μ-PECOD were observed under both external and internal light sources compared with that on a traditional flat electrode counterpart. As a further amplification of the generated photocurrents, an all-solid-state paper supercapacitor was constructed and integrated into the μ-PECOD to collect and store the generated photocurrents. The stored electrical energy could be released instantaneously through the DMM to obtain an amplified (∼13-fold) and DMM-detectable current as well as a higher sensitivity than the direct photocurrent measurement, allowing the expensive and sophisticated electrochemical workstation or lock-in amplifier to be abandoned. As a model, sandwich adenosine triphosphate (ATP)-binding aptamers were taken as molecular reorganization elements on this μ-PECOD for the sensitive determination of ATP in human serum samples in the linear range from 1.0 pM to 1.0 nM with a detection limit of 0.2 pM. The specificity, reproducibility, and stability of this μ-PECOD were also investigated. PMID:23472854

  2. Research on field of view of optical receiving antenna based on indoor visible light communication system

    NASA Astrophysics Data System (ADS)

    Gao, Mingguang; Lan, Tian; Zhao, Tao; Zhang, Yilun; Cui, Zhenghua; Ni, Guoqiang

    2015-08-01

    Optical receiving antenna is usually positioned before the detector of an indoor visible light communication (VLC) system in order to collect more optical energy into the detector. Besides optical gain of the antenna, the field of view (FOV) plays also an important role to the performance of a VLC system. In this paper, the signal noise ratio (SNR) and inter-symbol interference (ISI) versus FOV of the antenna are simulated via Line-of-Sight (LOS) and non-Line-of-Sight (NLOS) links within a room with a size of 5m × 5m × 3m. Results show that, the blind area appears while the FOV is less than 40 deg. and the SNR reduces as FOV increases and keeps small when FOV is more than 70 deg.. Furthermore, the average power of ISI rises with the increase of FOV, and the rising trend is relatively moderate when FOV is below 50 deg., while there is a rapid increase between 50 deg. and 70 deg. and finally tends to be stable after 70 deg. Therefore, it is practical to determine the FOV of the optical receiving antenna in the scope of 40 to 50 deg. based on the installment of LED lights on the ceiling here so as to avoid the blind area, attain high SNR, and reduce the influence of ISI. It is also worthwhile in practice to provide an identifiable evidence for the determination of FOV of the optical antenna.

  3. Efficient inverted organic light-emitting devices by amine-based solvent treatment (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Song, Myoung Hoon; Choi, Kyoung-Jin; Jung, Eui Dae

    2015-10-01

    The efficiency of inverted polymer light-emitting diodes (iPLEDs) were remarkably enhanced by introducing spontaneously formed ripple-shaped nanostructure of ZnO (ZnO-R) and amine-based polar solvent treatment using 2-methoxyethanol and ethanolamine (2-ME+EA) co-solvents on ZnO-R. The ripple-shape nanostructure of ZnO layer fabricated by solution process with optimal rate of annealing temperature improves the extraction of wave guide modes inside the device structure, and 2-ME+EA interlayer enhances the electron injection and hole blocking and reduces exciton quenching between polar solvent treated ZnO-R and emissive layer. As a result, our optimized iPLEDs show the luminous efficiency (LE) of 61.6 cd A-1, power efficiency (PE) of 19.4 lm W-1 and external quantum efficiency (EQE) of 17.8 %. This method provides a promising method, and opens new possibilities for not only organic light-emitting diodes (OLEDs) but also other organic optoelectronic devices such as organic photovoltaics, organic thin film transistors, and electrically driven organic diode laser.

  4. Stress-induced piezoelectric field in GaN-based 450-nm light-emitting diodes

    SciTech Connect

    Tawfik, Wael Z.; Hyeon, Gil Yong; Lee, June Key

    2014-10-28

    We investigated the influence of the built-in piezoelectric field induced by compressive stress on the characteristics of GaN-based 450-nm light-emitting diodes (LEDs) prepared on sapphire substrates of different thicknesses. As the sapphire substrate thickness was reduced, the compressive stress in the GaN layer was released, resulting in wafer bowing. The wafer bowing-induced mechanical stress altered the piezoelectric field, which in turn reduced the quantum confined Stark effect in the InGaN/GaN active region of the LED. The flat-band voltage was estimated by measuring the applied bias voltage that induced a 180° phase shift in the electro-reflectance (ER) spectrum. The piezoelectric field estimated by the ER spectra changed by ∼110 kV/cm. The electroluminescence spectral peak wavelength was blue-shifted, and the internal quantum efficiency was improved by about 22% at a high injection current of 100 mA. The LED on the 60-μm-thick sapphire substrate exhibited the highest light output power of ∼59 mW at an injection current of 100 mA, with the operating voltage unchanged.

  5. Patterning Surfaces on Azo-Based Multilayer Films via Surface Wrinkling Combined with Visible Light Irradiation.

    PubMed

    Zong, Chuanyong; Zhao, Yan; Ji, Haipeng; Xie, Jixun; Han, Xue; Wang, Juanjuan; Cao, Yanping; Lu, Conghua; Li, Hongfei; Jiang, Shichun

    2016-08-01

    Here, a simple combined strategy of surface wrinkling with visible light irradiation to fabricate well tunable hierarchical surface patterns on azo-containing multilayer films is reported. The key to tailor surface patterns is to introduce a photosensitive poly(disperse orange 3) intermediate layer into the film/substrate wrinkling system, in which the modulus decrease is induced by the reversible photoisomerization. The existence of a photoinert top layer prevents the photoisomerization-induced stress release in the intermediate layer to some extent. Consequently, the as-formed wrinkling patterns can be modulated over a large area by light irradiation. Interestingly, in the case of selective exposure, the wrinkle wavelength in the exposed region decreases, while the wrinkles in the unexposed region are evolved into highly oriented wrinkles with the orientation perpendicular to the exposed/unexposed boundary. Compared with traditional single layer-based film/substrate systems, the multilayer system consisting of the photosensitive intermediate layer offers unprecedented advantages in the patterning controllability/universality. As demonstrated here, this simple and versatile strategy can be conveniently extended to functional multilayer systems for the creation of prescribed hierarchical surface patterns with optically tailored microstructures. PMID:27336189

  6. Wireless multi-level terahertz amplitude modulator using active metamaterial-based spatial light modulation.

    PubMed

    Rout, Saroj; Sonkusale, Sameer

    2016-06-27

    The ever increasing demand for bandwidth in wireless communication systems will inevitably lead to the extension of operating frequencies toward the terahertz (THz) band known as the 'THz gap'. Towards closing this gap, we present a multi-level amplitude shift keying (ASK) terahertz wireless communication system using terahertz spatial light modulators (SLM) instead of traditional voltage mode modulation, achieving higher spectral efficiency for high speed communication. The fundamental principle behind this higher efficiency is the conversion of a noisy voltage domain signal to a noise-free binary spatial pattern for effective amplitude modulation of a free-space THz carrier wave. Spatial modulation is achieved using an an active metamaterial array embedded with pseudomorphic high-electron mobility (pHEMT) designed in a consumer-grade galium-arsenide (GaAs) integrated circuit process which enables electronic control of its THz transmissivity. Each array is assembled as individually controllable tiles for transmissive terahertz spatial modulation. Using the experimental data from our metamaterial based modulator, we show that a four-level ASK digital communication system has two orders of magnitude improvement in symbol error rate (SER) for a degradation of 20 dB in transmit signal-to-noise ratio (SNR) using spatial light modulation compared to voltage controlled modulation. PMID:27410614

  7. Conventional E-glass fibre light guides: self-sensing composite based on sol gel cladding

    NASA Astrophysics Data System (ADS)

    Wang, L.; Kister, G.; Ralph, B.; Talbot, J. D. R.; Fernando, G. F.

    2004-02-01

    The aim of this study was to modify conventional reinforcing E-glass fibres to enable them to act as optical waveguides and subsequently as sensor devices. This required the glass fibres to be coated with a relatively homogeneous coating with a corresponding refractive index that was lower than the E-glass fibre (1.56). Although a range of coating materials are available, this study focused on using materials that are generally used as sizing agents for glass fibres to improve the adhesion to the matrix. Two different methods based on conventional sol gel processing were used to obtain crack-free coatings. In the first method, tetraethoxysilane (TEOS) and polyvinyl alcohol were used as precursors. In the second method, acid-catalysed solutions of TEOS mixed with 3-glycidoxypropyltrimethoxysilane were used as precursors. UV visible transmission results showed that the films had low absorption and high transparency in the visible range. The refractive indices of the films were found to be a function of the molar fractions of the major chemical components. A simple impregnation procedure was used to apply the coating to the E-glass fibre bundles. The light transmission characteristics of the coated fibres along with their mechanical properties were evaluated. The sol gel coatings were shown to be effective in converting the conventional E-glass fibres into light guides.

  8. Structural details of light activation of the LOV2-based photoswitch PA-Rac1.

    PubMed

    Winkler, Andreas; Barends, Thomas R M; Udvarhelyi, Anikó; Lenherr-Frey, Daniel; Lomb, Lukas; Menzel, Andreas; Schlichting, Ilme

    2015-02-20

    Optical control of cellular processes is an emerging approach for studying biological systems, affording control with high spatial and temporal resolution. Specifically designed artificial photoswitches add an interesting extension to naturally occurring light-regulated functionalities. However, despite a great deal of structural information, the generation of new tools cannot be based fully on rational design yet; in many cases design is limited by our understanding of molecular details of light activation and signal transduction. Our biochemical and biophysical studies on the established optogenetic tool PA-Rac1, the photoactivatable small GTPase Rac1, reveal how unexpected details of the sensor-effector interface, such as metal coordination, significantly affect functionally important structural elements of this photoswitch. Together with solution scattering experiments, our results favor differences in the population of pre-existing conformations as the underlying allosteric activation mechanism of PA-Rac1, rather than the assumed release of the Rac1 domain from the caging photoreceptor domain. These results have implications for the design of new optogenetic tools and highlight the importance of including molecular details of the sensor-effector interface, which is however difficult to assess during the initial design of novel artificial photoswitches. PMID:25368973

  9. Development Of A Supercontinuum Based Photoacoustic Aerosol Light Absorption And Albedo Spectrometer (PALAAS)

    NASA Astrophysics Data System (ADS)

    Arnold, Ian J.

    Aerosols are a major contributor to the global radiation budget because they modify the planetary albedo with their optical properties. These optical properties need to be measured and understood, ideally at multiple wavelengths. This thesis describes the ongoing development of a supercontinuum based multi-wavelength photoacoustic instrument to measure the light absorption and scattering coefficients of aerosols. Collimation techniques for supercontinuum sources using lens-based and off-axis parabolic mirror-based collimators were evaluated and it was determined that the off-axis mirror had superior collimation abilities for multi-spectral beams. A proof of concept supercontinuum-based photoacoustic instrument was developed using sequential measurements at multiple wavelengths. The instrument data were in good agreement with those from a commercial 3-wavelength photoacoustic instrument and the novel instrument had minimum detectable absorption and scattering coefficients of better than 4 Mm-1 and 21 Mm-1, respectively. The instrument however suffered from poor temporal resolution due to the sequential measurement and required the development of an aerosol delivery system to deliver a slowly varying aerosol concentration. In response, a spectral modulator has been developed to frequency encode different wavelength bands for simultaneous measurement with a photoacoustic instrumen.

  10. White light-emitting diodes based on nonpolar and semipolar gallium nitride orientations

    NASA Astrophysics Data System (ADS)

    Demille, Natalie Fellows

    Gallium nitride has become one of the key components when fabricating white light-emitting diodes. Its use as the blue source in conjunction with a wavelength converter such as the yellow emitting phosphor YAG:Ce 3+ is a technology that is commercially available and usable for solid state lighting applications. Currently available white phosphor-based LEDs (pcLEDs) use the basal plane of wurtzite GaN as their source. Although research over the past couple decades has developed this technology into devices with good photometric performance and high reliability, the introduction of nonbasal plane wurtzite GaN orientations have benefits over basal plane GaN that can be incorporated into the white LED. The focus of this research deals with exploring white illumination on nonpolar and semipolar planes of GaN. Light extraction techniques will be described that allowed for high output powers and efficiencies on the c-plane as well as the (1100), (10 11), and (1122) planes of GaN. With higher performing devices, white pcLEDs were fabricated on c-plane, m-plane, and the (1011) semipolar plane. The novelty in the present research is producing white LEDs with nonbasal plane diodes which exhibit optical polarization anisotropy. This feature, absent on the basal plane, allows for tuning photometric quantities both electrically and optically. This is demonstrated on pcLEDs as well as dichromatic LEDs comprised solely of InGaN diodes. As a consequence of these measurements, an apparent optical polarization was seen to be occurring in the luminescence of the YAG:Ce3+ when the system absorbed linearly polarized light. Polarized emission in YAG:Ce3+ was explored by obtaining single crystals of YAG:Ce3+ with different planar orientations. The experiments led to the conclusion that crystal orientation plays no part in the optical polarization. It is suggested that the cause is a result of electric dipole transitions given by various selection rules between the Ce 3+ ion's 4f and 5d

  11. Low frequency noise of gallium nitride-based deep ultraviolet light emitting diodes

    NASA Astrophysics Data System (ADS)

    Sawyer, Shayla Maya Louise

    This study covers the investigation of deep UV GaN-based light emitting diodes using low frequency noise characterization. Using this technique, device improvements were analyzed as feedback to developers and practical parameters were created for system use. AlGaN LEDs emit wavelengths into the deep UV spectral region (lambda < 290 nm). These devices are an integral component for applications including biological hazard detection systems, biological experimentation, food and water sterilization, non-line-of-sight short range communication, counterfeit identification, photolithography, and general white lighting. The current technological trend demonstrates a decrease in material quality and device performance with decreasing wavelength. However, progress has allowed for its commercialization in a relatively short period of time. Characterization of material and device improvements provides feedback for changes in development. Secondly, methods to determine the reliability and stability of these devices are essential to the applications for which they are used. One such method is through optical and current low frequency noise (LFN) measurements in which both system related parameters such as a signal-to-noise ratio for light sources and insight into the fundamental physics within the devices can be determined. The quality of the device can be compared before costly integration into systems that require low noise, high reliability, and optical stability. It not only quantifies performance limiting noise levels, but it is known to be a sensitive, nondestructive measure of material quality and reliability. The research highlighted in this thesis demonstrates a new measurement technique in analyzing the light intensity fluctuations through low frequency optical noise. From this work, a proposed figure-of-merit is presented. Low frequency current noise was performed as a well known indicator of material quality. Each technique compares LEDs grown by SET Inc. LEDs of

  12. Surgical lighting with contrast enhancement based on spectral reflectance comparison and entropy analysis

    NASA Astrophysics Data System (ADS)

    Shen, Junfei; Wang, Huihui; Wu, Yisi; Li, An; Chen, Chi; Zheng, Zhenrong

    2015-10-01

    Surgical light is important for helping the surgeon easily identify specific tissues during an operation. We propose a spectral reflectance comparison model to optimize the light-emitting diode light spectrum in the operating room. An entropy evaluation method, meant specifically for surgical situations, was developed to evaluate images of biological samples. White light was mixed to achieve an optimal spectrum, and images of different tissues under the light were captured and analyzed. Results showed that images obtained with light with an optimal spectrum had a higher contrast than those obtained with a commercial white light of different color temperatures. Optimized surgical light obtained using this simple and effective method could replace the traditional surgical illumination systems.

  13. Dynamic Measurement for the Diameter of A Train Wheel Based on Structured-Light Vision.

    PubMed

    Gong, Zheng; Sun, Junhua; Zhang, Guangjun

    2016-01-01

    Wheels are very important for the safety of a train. The diameter of the wheel is a significant parameter that needs regular inspection. Traditional methods only use the contact points of the wheel tread to fit the rolling round. However, the wheel tread is easily influenced by peeling or scraping. Meanwhile, the circle fitting algorithm is sensitive to noise when only three points are used. This paper proposes a dynamic measurement method based on structured-light vision. The axle of the wheelset and the tread are both employed. The center of the rolling round is determined by the axle rather than the tread only. Then, the diameter is calculated using the center and the contact points together. Simulations are performed to help design the layout of the sensors, and the influences of different noise sources are also analyzed. Static and field experiments are both performed, and the results show it to be quite stable and accurate. PMID:27104543

  14. Colorimetric characterization models based on colorimetric characteristics evaluation for active matrix organic light emitting diode panels.

    PubMed

    Gong, Rui; Xu, Haisong; Tong, Qingfen

    2012-10-20

    The colorimetric characterization of active matrix organic light emitting diode (AMOLED) panels suffers from their poor channel independence. Based on the colorimetric characteristics evaluation of channel independence and chromaticity constancy, an accurate colorimetric characterization method, namely, the polynomial compensation model (PC model) considering channel interactions was proposed for AMOLED panels. In this model, polynomial expressions are employed to calculate the relationship between the prediction errors of XYZ tristimulus values and the digital inputs to compensate the XYZ prediction errors of the conventional piecewise linear interpolation assuming the variable chromaticity coordinates (PLVC) model. The experimental results indicated that the proposed PC model outperformed other typical characterization models for the two tested AMOLED smart-phone displays and for the professional liquid crystal display monitor as well. PMID:23089779

  15. Solid-base loaded WO3 photocatalyst for decomposition of harmful organics under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Kako, Tetsuya; Meng, Xianguang; Ye, Jinhua

    2015-10-01

    Composite of NaBiO3-loaded WO3 with a mixing ratio of 10:100 was prepared for photocatalytic harmful-organic-contaminant decomposition. The composite properties were measured using X-ray diffraction, ultraviolet-visible spectrophotometer (UV-Vis), and valence band-X-ray photoelectron spectroscope (VB-XPS). The results exhibited that the potentials for top of the valence band and bottom of conduction band for NaBiO3 can be estimated, respectively, as +2.5 V and -0.1 to 0 V. Furthermore, WO3, NaBiO3, and the composite showed IPA oxidation properties under visible-light irradiation. Results show that the composite exhibited much higher photocatalytic activity about 2-propanol (IPA) decomposition into CO2 than individual WO3 or NaBiO3 because of charge separation promotion and the base effect of NaBiO3.

  16. Dynamic Measurement for the Diameter of A Train Wheel Based on Structured-Light Vision

    PubMed Central

    Gong, Zheng; Sun, Junhua; Zhang, Guangjun

    2016-01-01

    Wheels are very important for the safety of a train. The diameter of the wheel is a significant parameter that needs regular inspection. Traditional methods only use the contact points of the wheel tread to fit the rolling round. However, the wheel tread is easily influenced by peeling or scraping. Meanwhile, the circle fitting algorithm is sensitive to noise when only three points are used. This paper proposes a dynamic measurement method based on structured-light vision. The axle of the wheelset and the tread are both employed. The center of the rolling round is determined by the axle rather than the tread only. Then, the diameter is calculated using the center and the contact points together. Simulations are performed to help design the layout of the sensors, and the influences of different noise sources are also analyzed. Static and field experiments are both performed, and the results show it to be quite stable and accurate. PMID:27104543

  17. A simple and highly sensitive assay of perfluorooctanoic acid based on resonance light scattering technique.

    PubMed

    Zhang, Fang; Zheng, Yonghong; Liang, Jiaman; Long, Sha; Chen, Xianping; Tan, Kejun

    2016-04-15

    A simple, highly sensitive resonance light scattering (RLS) method for the detection of perfluorooctanoic acid (PFOA) has been developed based on the interaction with crystal violet (CV). It was found that PFOA can form complexes with CV in acid medium resulting in remarkable enhancement of the RLS intensity of the system. And the enhanced RLS intensities are in proportion to the concentration of PFOA in the range of 0.1-25.0μmol/L (R(2)=0.9998), with a detection limit of 11.0nmol/L (S/N=3). In this work, the optimum reaction conditions and the interferences of foreign substances were investigated. The reaction mechanism between CV and PFOA was also studied by the absorption spectrum and scanning electron microscope (SEM). This method is successfully applied to the determination of PFOA in tap water and Jialing river water samples with RSD≤4.04%. PMID:26824483

  18. Over 1000 channel nitride-based micro-light-emitting diode arrays with tunnel junctions

    NASA Astrophysics Data System (ADS)

    Watanabe, Masahiro; Nakajima, Keisuke; Kaga, Mitsuru; Kuwano, Yuka; Minamikawa, Daichi; Suzuki, Tomoyuki; Yamashita, Kouji; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi; Akasaki, Isamu

    2014-01-01

    We fabricated nitride-based micro-LED arrays with a small number of fabrication process steps by using a combination of tunnel junctions and patterned n-GaN cathode lines. A use of the combination enables us to skip a couple of process steps required in standard LED array fabrication. A 10 × 10 channel matrix-addressable LED array with a 10 × 16 µm2 emission regions and a 25 µm pitch lengths showed uniform operating voltages and light output intensities, indicating good yield due to the small number of process steps used. In addition, microdisplay of over 1000 (14 × 72) channels was successfully demonstrated. The new array structure with the tunnel junction and n-GaN cathode line provides a high density and a high yield simultaneously.

  19. Beam propagation ratios measurement based on transmissive liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Li, Dong; Tian, Jindong

    2015-03-01

    A method is presenting for measuring beam propagation ratios (M2) of laser beam utilizing transmissive liquid crystal spatial light modulator (LC-SLM). In this paper, the function of digital zoom lens (DZL) could be obtained by loading a calculated gray-scale of DZL with desired focal length into the LC-SLM and the accurate focal length of DZL could be gotten by a correction method. By comparing with the standard measuring method provided by ISO (International Standard Organization), through using the transmissive LC-SLM, the beam propagation ratios could be calculated by curve fitting based on the beam spot size collected by digital camera versus the focal length of DZL without any movements in the experiments. The experiment and comparison results have shown that it is effective for us to measure the M2 of Gaussian beam using a transmissive LC-SLM whose experimental setups are simple, relatively.

  20. White organic light-emitting diodes based on incomplete energy transfer from perylene to rubrene

    NASA Astrophysics Data System (ADS)

    Ding, Bangdong; Zhu, Wenqing; Jiang, Xueyin; Zhang, Zhilin

    2008-11-01

    This paper presents organic light-emitting diodes which generate white emission based on both perylene and rubrene doped in 9,10-di(2-naphthyl)anthracene (ADN). In this doping system, the blue dopant perylene not only emitted but also assisted the energy transfer from ADN to rubrene, which contributes to a lower doping concentration of rubrene. The optimal configuration of the device is ITO/TPD(50 nm)/ADN:0.5 wt% perylene:0.006 wt% rubrene(40 nm)/Bphen(25 nm)/LiF(1 nm)/Al. The maximum luminance of 11 665 cd/m 2 at 14 V according to a luminance efficiency of 2.9 cd/A was obtained. A CIE color coordinate of (0.30, 0.37) at 4 mA/cm 2 was also achieved.

  1. Chromophore-Based Luminescent Metal-Organic Frameworks as Lighting Phosphors.

    PubMed

    Lustig, William P; Wang, Fangming; Teat, Simon J; Hu, Zhichao; Gong, Qihan; Li, Jing

    2016-08-01

    Energy-efficient solid-state-lighting (SSL) technologies are rapidly developing, but the lack of stable, high-performance rare-earth free phosphors may impede the growth of the SSL market. One possible alternative is organic phosphor materials, but these can suffer from lower quantum yields and thermal instability compared to rare-earth phosphors. However, if luminescent organic chromophores can be built into a rigid metal-organic framework, their quantum yields and thermal stability can be greatly improved. This Forum Article discusses the design of a group of such chromophore-based luminescent metal-organic frameworks with exceptionally high performance and rational control of the important parameters that influence their emission properties, including electronic structures of chromophore, coligands, metal ions, and guest molecules. PMID:27244591

  2. A simple and highly sensitive assay of perfluorooctanoic acid based on resonance light scattering technique

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Zheng, Yonghong; Liang, Jiaman; Long, Sha; Chen, Xianping; Tan, Kejun

    2016-04-01

    A simple, highly sensitive resonance light scattering (RLS) method for the detection of perfluorooctanoic acid (PFOA) has been developed based on the interaction with crystal violet (CV). It was found that PFOA can form complexes with CV in acid medium resulting in remarkable enhancement of the RLS intensity of the system. And the enhanced RLS intensities are in proportion to the concentration of PFOA in the range of 0.1-25.0 μmol/L (R2 = 0.9998), with a detection limit of 11.0 nmol/L (S/N = 3). In this work, the optimum reaction conditions and the interferences of foreign substances were investigated. The reaction mechanism between CV and PFOA was also studied by the absorption spectrum and scanning electron microscope (SEM). This method is successfully applied to the determination of PFOA in tap water and Jialing river water samples with RSD ≤ 4.04%.

  3. A depth estimation method based on geometric transformation for stereo light microscope.

    PubMed

    Fan, Shengli; Yu, Mei; Wang, Yigang; Jiang, Gangyi

    2014-01-01

    Stereo light microscopes (SLM) with narrow vision and shallow depth of field are widely used in micro-domain research. In this paper, we propose a depth estimation method of micro objects based on geometric transformation. By analyzing the optical imaging geometry, the definition of geometric transformation distance is given and the depth-distance relation express is obtained. The parameters of geometric transformation and express are calibrated with calibration board images captured in aid of precise motorized stage. The depth of micro object can be estimated by calculating the geometric transformation distance. The proposed depth-distance relation express is verified using an experiment in which the depth map of an Olanzapine tablet surface is reconstructed. PMID:25226979

  4. Covalent Triazine-Based Frameworks as Visible Light Photocatalysts for the Splitting of Water.

    PubMed

    Bi, Jinhong; Fang, Wei; Li, Liuyi; Wang, Jinyun; Liang, Shijing; He, Yunhui; Liu, Minghua; Wu, Ling

    2015-10-01

    Covalent triazine-based frameworks (CTFs) with a graphene-like layered morphology have been controllably synthesized by the trifluoromethanesulfonic acid-catalyzed nitrile trimerization reactions at room temperature via selecting different monomers. Platinum nanoparticles are well dispersed in CTF-T1, which is ascribed to the synergistic effects of the coordination of triazine moieties and the nanoscale confinement effect of CTFs. CTF-T1 exhibits excellent photocatalytic activity and stability for H2 evolution in the presence of platinum under visible light irradiation (λ ≥ 420 nm). The activity and stability of CTF-T1 are comparable to those of g-C3 N4 . Importantly, as a result of the tailorable electronic and spatial structures of CTFs that can be achieved through the judicial selection of monomers, CTFs not only show great potential as organic semiconductor for photocatalysis but also may provide a molecular-level understanding of the inherent heterogeneous photocatalysis. PMID:26292975

  5. Parametric amplification of orbital angular momentum beams based on light-acoustic interaction

    SciTech Connect

    Gao, Wei E-mail: zhuzhihandd@sina.com; Mu, Chunyuan; Yang, Yuqiang; Li, Hongwei; Zhu, Zhihan E-mail: zhuzhihandd@sina.com

    2015-07-27

    A high fidelity amplification of beams carrying orbital angular momentum (OAM) is very crucial for OAM multiplexing and other OAM-based applications. Here, we report a demonstration of stimulated Brillouin amplification for OAM beams, and the energy conversion efficiency of photon-phonon coupling and the phase structure of amplified signals are investigated in collinear and noncollinear frame systems, respectively. Our results demonstrate that the OAM signals can be efficiently amplified without obvious noise introduced, and the modes of output signal are independent of the pump modes or the geometrical frames. Meanwhile, an OAM state depending on the optical modes and the geometrical frames is loaded into phonons by coherent light-acoustic interaction, which reveals more fundamental significance and a great application potential in OAM-multiplexing.

  6. Note: A flexible light emitting diode-based broadband transient-absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Gottlieb, Sean M.; Corley, Scott C.; Madsen, Dorte; Larsen, Delmar S.

    2012-05-01

    This Note presents a simple and flexible ns-to-ms transient absorption spectrometer based on pulsed light emitting diode (LED) technology that can be incorporated into existing ultrafast transient absorption spectrometers or operate as a stand-alone instrument with fixed-wavelength laser sources. The LED probe pulses from this instrument exhibit excellent stability (˜0.5%) and are capable of producing high signal-to-noise long-time (>100 ns) transient absorption signals either in a broadband multiplexed (spanning 250 nm) or in tunable narrowband (20 ns) operation. The utility of the instrument is demonstrated by measuring the photoinduced ns-to-ms photodynamics of the red/green absorbing fourth GMP phosphodiesterase/adenylyl cyclase/FhlA domain of the NpR6012 locus of the nitrogen-fixing cyanobacterium Nostoc punctiforme.

  7. Glycogen synthase kinase 3 phosphorylates kinesin light chains and negatively regulates kinesin-based motility

    NASA Technical Reports Server (NTRS)

    Morfini, Gerardo; Szebenyi, Gyorgyi; Elluru, Ravindhra; Ratner, Nancy; Brady, Scott T.

    2002-01-01

    Membrane-bounded organelles (MBOs) are delivered to different domains in neurons by fast axonal transport. The importance of kinesin for fast antero grade transport is well established, but mechanisms for regulating kinesin-based motility are largely unknown. In this report, we provide biochemical and in vivo evidence that kinesin light chains (KLCs) interact with and are in vivo substrates for glycogen synthase kinase 3 (GSK3). Active GSK3 inhibited anterograde, but not retrograde, transport in squid axoplasm and reduced the amount of kinesin bound to MBOs. Kinesin microtubule binding and microtubule-stimulated ATPase activities were unaffected by GSK3 phosphorylation of KLCs. Active GSK3 was also localized preferentially to regions known to be sites of membrane delivery. These data suggest that GSK3 can regulate fast anterograde axonal transport and targeting of cargos to specific subcellular domains in neurons.

  8. Fabrication of chalcopyrite light-absorbing layers based on nanoparticle and nanowire networks

    NASA Astrophysics Data System (ADS)

    Ren, Yuhang; Luo, Paifeng; Gao, Bo; Cevher, Zehra; Sun, Chivin

    2013-03-01

    We report on a method of preparing chalcopyrite, CuInGaSe2 (CIGS) light-absorbing layers using low cost air stable ink based on semiconductor nanoparticle and nanowires. The nanoparticles and nanowires are prepared from metal salts such as metal chloride and acetate at room temperature without inert gas protection. A uniform and non-aggregation CIGS precursor layer is fabricated with the formation of nanoparticle and nanowire networks utilizing ultrasonic spaying technique. We obtain a high quality CIGS absorber by cleaning the residue salts and carbon agents at an increased temperature and through selenizing the pretreated CIGS precursors. Our results offer an opportunity for the low-cost deposition of chalcopyrite absorber materials at large scale with high throughput. This work was partially sponsored by Sun Harmonics Ltd. and by NYSTAR through the Photonics Center for Applied Technology at the City University of New York.

  9. Color tunable light-emitting diodes based on copper doped semiconducting nanocrystals

    NASA Astrophysics Data System (ADS)

    Bhaumik, Saikat; Ghosh, Batu; Pal, Amlan J.

    2011-08-01

    We have introduced copper-doped semiconducting nanocrystals in light-emitting diodes (LEDs). Characteristics of the devices show that electroluminescence (EL) emission in these LEDs is color tunable. In copper-doped ZnS nanocrystals in the core and Zn1-xCdxS host as a shell-layer, photoluminescence (PL) arises from a transition from conduction band-edge of the host to 3d-levels of copper-ions. The PL of the nanocrystals and hence the EL of LEDs based on such nanostructures become tunable by varying the Cd-content in Zn-Cd-S alloys, that is, Zn1-xCdxS with different values of x, which changes the conduction band-edge of the host.

  10. High performance GaN based blue flip-chip light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Jin, G. M.; Choi, I. G.; Park, J. C.; Jeon, S. K.; Park, E. H.

    2015-09-01

    In this study, high performance nitride-based flip-chip (FC) light-emitting diodes (LEDs) using optimized distributed bragg reflector (DBR) were fabricated and compared with conventional FC-LED using silver (Ag) reflector. Most of FCLEDs are using the silver (Ag) as reflector due to its superior reflectance at visual spectrum region. However, A silver has detrimental problems such as electro-chemical migration and agglomerations, which resulting in reliability issues such as degradation of power drop, unstable operating voltage and leakage issues. Our DBR structure was designed to have 99% at whole visible spectrum range (400~750nm), which is higher reflectance than silver reflector (90~95%). Optical power is higher than higher than the Ag-LED up to 30% @ 500mA. As the current increases up to 1A, the gap slightly decreased. Reliability test results show stable optical power, operating voltage, and leakage maintenance.

  11. Negative differential resistance phenomena in colloidal quantum dots-based organic light-emitting diodes

    SciTech Connect

    Yang, Shengyi Zhang, Li; Yang, Dan; Zou, Bingsuo; Liu, Peng; Jiang, Yurong; Guo, Sanwei

    2014-01-20

    The influence of ligands on the electrical behavior of CdSe/ZnS core-shell colloidal quantum dots (CQDs)-based organic light-emitting diodes is presented. Negative differential resistance (NDR) phenomena at room temperature are observed from single-layer device ITO/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)/CQDs/Al in which the original capping ligand tri-n-octylphosphine oxide (TOPO) of CQDs is exchanged with oleylamine, as well as in both bilayer device ITO/PEDOT:PSS/CQDs/BCP(10 nm)/Al and trilayer device ITO/PEDOT:PSS/CQDs/BCP(10 nm)/Alq{sub 3}(10 nm)/Al. However, such a kind of NDR phenomenon disappears if TOPO is exchanged with hexadecylamine. Therefore, NDR phenomenon depends greatly on the ligands of the CQDs, and the origin of NDR from these devices is discussed.

  12. Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source.

    PubMed

    Bakeman, M S; van Tilborg, J; Sokollik, T; Baum, D; Ybarrolaza, N; Duarte, R; Toth, C; Leemans, W P

    2010-10-01

    We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range. PMID:21034012

  13. The Peptide Microarray-Based Resonance Light Scattering Assay for Sensitively Detecting Intracellular Kinase Activity.

    PubMed

    Li, Tao; Liu, Xia; Liu, Dianjun; Wang, Zhenxin

    2016-01-01

    The peptide microarray technology is a robust, reliable, and efficient technique for large-scale determination of enzyme activities, and high-throughput profiling of substrate/inhibitor specificities of enzymes. Here, the activities of cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) in different cell lysates have been detected by a peptide microarray-based resonance light scattering (RLS) assay with gold nanoparticle (GNP) probes. Highly sensitive detection of PKA activity in 0.1 μg total cell proteins of SHG-44 (human glioma cell) cell lysate (corresponding to 200 cells) is achieved by a selected peptide substrate. The experimental results also demonstrate that the RLS assay can be employed to evaluate the chemical regulation of intracellular kinase activity. PMID:26490469

  14. Clustering in Water Based Magnetic Nanofluids: Investigations by Light Scattering Methods

    NASA Astrophysics Data System (ADS)

    Socoliuc, Vlad; Taculescu, Alina; Podaru, Camelia; Dobra, Andreea; Daia, Camelia; Marinica, Oana; Turcu, Rodica; Vekas, Ladislau

    2010-12-01

    Nanosized magnetite particles, with mean physical diameter of about 7 nm, obtained by chemical coprecipitation procedure were dispersed in water carrier by applying sterical stabilization of particles in order to prevent their aggregation and to ensure colloidal stability of the systems. Different chain length (C12, C14, C18) carboxylic acids (lauric (LA), myristic (MA) and oleic (OA)) were used for double layer coating of magnetite nanoparticles. Structural and magnetic properties were investigated by electron microscopy (TEM), dynamical and static light scattering (DLS, SLS) and magnetometry (VSM) to evaluate the role of chain length and of the saturated/unsaturated nature of surfactant layers. Also investigated were two water based magnetic nanocomposites obtained by encapsulating the magnetic nanoparticles in polymers with different functional properties.

  15. Orthogonal frequency-division multiplexing access (OFDMA) based wireless visible light communication (VLC) system

    NASA Astrophysics Data System (ADS)

    Sung, Jiun-Yu; Yeh, Chien-Hung; Chow, Chi-Wai; Lin, Wan-Feng; Liu, Yang

    2015-11-01

    An orthogonal frequency-division multiplexing access (OFDMA) based visible light communication (VLC) system is proposed in this paper. The architecture of the proposed system is divided into several VLC cells, which is defined in this paper. The deployment and upgrade of the system involve only simple combination of the VLC cells. Hence it is economically advantageous. To guarantee smooth communication, nearly equal data rate is provided at every location within the system with no concern on the system scale. The user location monitor strategy is also discussed to solve the region division issues. The characteristics of the proposed system are analyzed in detail in this paper. A one-dimensional experiment was demonstrated with 13.6 Mb/s data rate.

  16. Quantum-beat based dissipation for spin squeezing and light entanglement.

    PubMed

    Huang, Chen; Hu, Xiangming; Zhang, Yang; Li, Lingchao; Rao, Shi

    2016-08-22

    We show an engineered dissipation for the spin squeezing and the light entanglement in a quantum beat system, in which two bright fields interact with an ensemble of three-level atoms in V configuration. The dissipation is based on the atom-field nonlinear interaction that is controlled by the atomic coherence between the excited states off two-photon resonance. Physical analysis and numerical verification are presented for the symmetrical parameters by using the dressed atomic states. It is shown that for particular parameters, the engineered dissipation induces almost perfect two-mode squeezing and entanglement both for the bright fields and for the dressed spins. The excited-state spin has squeezing of near 40% below the standard quantum limit although there remains the spontaneous emission from the involved excited states. PMID:27557189

  17. Advances in Light-based Imaging of Three-Dimensional Cellular Ultrastructure

    PubMed Central

    Kanchanawong, Pakorn; Waterman, Clare M.

    2012-01-01

    Visualization methods are key to gaining insights into cellular structure and function. Since diffraction has long confined optical microscopes to a resolution no better than hundreds of nanometers, the observation of ultrastructural features has traditionally been the domain of electron microscopes (EM). In the past decade, however, advances in super-resolution fluorescence microscopy have considerably expanded the capability of light-based imaging techniques. Advantages of fluorescent labeling such as high sensitivity, specificity, and multichannel capability, can now be exploited to dissect ultrastructural features of cells. With recent methods capable of imaging specific proteins with a resolution on the order of a few tens of nanometers in 3-dimensions, this has made it possible to elucidate the molecular organization of many complex cellular structures. PMID:22209239

  18. HB LED color mixture traffic light solution based on EZ-color

    NASA Astrophysics Data System (ADS)

    Hong, Qunhuan; Wang, Weijian; Xiao, Zhihong

    2010-02-01

    This paper introduces a traffic light design solution using HB LED color mixture,namely an implementation method using a set of traffic lights composed of red, green and blue HB LED to replace ordinary red, yellow and green lights. This scheme realizes HB LED color mixture lighting design on the basis of Cypress EZ-Color controller and codeless embedded design software PSoC Express.

  19. Solution-processed, high-performance light-emitting diodes based on quantum dots.

    PubMed

    Dai, Xingliang; Zhang, Zhenxing; Jin, Yizheng; Niu, Yuan; Cao, Hujia; Liang, Xiaoyong; Chen, Liwei; Wang, Jianpu; Peng, Xiaogang

    2014-11-01

    Solution-processed optoelectronic and electronic devices are attractive owing to the potential for low-cost fabrication of large-area devices and the compatibility with lightweight, flexible plastic substrates. Solution-processed light-emitting diodes (LEDs) using conjugated polymers or quantum dots as emitters have attracted great interest over the past two decades. However, the overall performance of solution-processed LEDs--including their efficiency, efficiency roll-off at high current densities, turn-on voltage and lifetime under operational conditions-remains inferior to that of the best vacuum-deposited organic LEDs. Here we report a solution-processed, multilayer quantum-dot-based LED with excellent performance and reproducibility. It exhibits colour-saturated deep-red emission, sub-bandgap turn-on at 1.7 volts, high external quantum efficiencies of up to 20.5 per cent, low efficiency roll-off (up to 15.1 per cent of the external quantum efficiency at 100 mA cm(-2)), and a long operational lifetime of more than 100,000 hours at 100 cd m(-2), making this device the best-performing solution-processed red LED so far, comparable to state-of-the-art vacuum-deposited organic LEDs. This optoelectronic performance is achieved by inserting an insulating layer between the quantum dot layer and the oxide electron-transport layer to optimize charge balance in the device and preserve the superior emissive properties of the quantum dots. We anticipate that our results will be a starting point for further research, leading to high-performance, all-solution-processed quantum-dot-based LEDs ideal for next-generation display and solid-state lighting technologies. PMID:25363773

  20. DNA and RNA "traffic lights": synthetic wavelength-shifting fluorescent probes based on nucleic acid base substitutes for molecular imaging.

    PubMed

    Holzhauser, Carolin; Wagenknecht, Hans-Achim

    2013-08-01

    The DNA base substitute approach by the (S)-3-amino-1,2-propanediol linker allows placing two fluorophores in a precise way inside a given DNA framework. The double helical architecture around the fluorophores, especially the DNA-induced twist, is crucial for the desired photophysical interactions. Excitonic, excimer, and energy transfer interactions yield fluorescent DNA and RNA probes with dual emission color readout. Especially, our DNA and RNA "traffic light" that combines the green emission of TO with the red emission of TR represents an important tool for molecular imaging and can be applied as aptasensors and as probes to monitor the siRNA delivery into cells. The concept can be extended to the synthetically easier to access postsynthetic 2'-modifications and the NIR range. Thereby, the pool of tailor-made fluorescent nucleic acid conjugates can be extended. PMID:23796243

  1. High-nitrogen-based pyrotechnics: perchlorate-free red- and green-light illuminants based on 5-aminotetrazole.

    PubMed

    Sabatini, Jesse J; Moretti, Jared D

    2013-09-16

    Prototype testing of perchlorate-free hand-held signal illuminants for the US Army's M126 A1 red-star and M195 green-star parachute illuminants are described. Although previous perchlorate-free variants for these items have been developed based on high-nitrogen compounds that are not readily available, the new formulations consist of anhydrous 5-aminotetrazole as the suitable perchlorate replacement. Compared to the perchlorate-containing control, the disclosed illuminants exhibited excellent stabilities toward various ignition stimuli and had excellent pyrotechnic performance. The illuminants are important from both military and civil fireworks perspectives, as the perchlorate-free nature of the illuminants adequately address environmental concerns associated with perchlorate-containing red- and green-light-emitting illuminants. PMID:23950104

  2. Beam characteristics of fiber-based supercontinuum light sources with mirror- and lens-based beam collimators.

    PubMed

    Arnold, Ian J; Moosmüller, Hans; Sharma, Noopur; Mazzoleni, Claudio

    2014-06-01

    Commercially available supercontinuum light sources that cover most of the solar spectrum are well suited for instrumentation, where a well-collimated beam with wide spectral coverage is needed. Typically, the optical power is emitted from a single-mode photonic-crystal fiber and the output can either be collimated using a proprietary, permanently integrated, lens-based collimator or with a customer-provided, off-axis parabolic mirror. Here, we evaluate both approaches and conclude that, superior beam quality and collimation over the whole spectral range can be obtained with an off-axis parabolic mirror, however at the price of a more complex and bulky system requiring additional user alignment. PMID:24921577

  3. [Research on Properties of Light Scattering for Non-Spherical Suspended Particles in Water Based on T Matrix Model].

    PubMed

    Vo, Quang Sang; Feng, Peng; Mi, De-ling; Tang, Bin; Wei, Biao

    2015-10-01

    Scattering light properties of suspended particles in water is an important parameter which influences the accuracy of water quality measurement. In this paper, based on T matrix model, the authors study the UV-Visible light irradiation intensity of 3 kinds of non-spherical suspended. particles including ellipsoid, cylinder and generalized Chebyshev in water. The relationship between light scattering intensity and incident light wavelength, shape parameters of suspended particles, complex refractive index and rotation angle has been presented in detail. Simulation results show that when changing the particle size, adjusting the wavelength of incident light, all light scattering intensity of 3 kinds of non-spherical suspended particles show significant changes. In the wavelength range from 200-800 nm, the impact of geometric on the particles size decreases with increasing wavelength and the sattering properites mainly depends on complex refractive index. The scattering intensity becomes stronger and exhibits strong oscillations for ultraviolet and infrared light when the diameter of particles are less than 0.2 μm or approaching 1 μm. However, the scattering intensity is relatively stable and close to zero, shows small disturbances with the change of wavelength of incident light when the particles sizes are within 0.3 to 0.9 μm. PMID:26904801

  4. Freestanding GaN-based light-emitting diode membranes on Y3Al5O12:Ce3+ crystal phosphor plate for efficient white light emission

    NASA Astrophysics Data System (ADS)

    Feng, Lungang; Li, Yufeng; Xiong, Han; Wang, Shuai; Wang, Jiangteng; Ding, Wen; Zhang, Ye; Yun, Feng

    2016-08-01

    GaN-based light-emitting diode (LED) membranes were peeled from the substrate using electrochemical etching of the bottom sacrificial layer. The freestanding membranes were transferred onto a Y3Al5O12:Ce3+ (YAG:Ce3+) crystal phosphor plate to realize a compact white light source. Verified by the Raman test, the initial strain within the original GaN layers was greatly released after the exfoliation process, which induced alleviation of the quantum confined stark effect. The electroluminescence measurement of a blue LED membranes-on-YAG:Ce3+ plate-structured device was conducted exhibiting color coordinates and a correlated color temperature of (0.3367,0.4525) and 5450 K at 10 mA, respectively.

  5. Enhanced external quantum efficiency in GaN-based vertical-type light-emitting diodes by localized surface plasmons

    PubMed Central

    Yao, Yung-Chi; Hwang, Jung-Min; Yang, Zu-Po; Haung, Jing-Yu; Lin, Chia-Ching; Shen, Wei-Chen; Chou, Chun-Yang; Wang, Mei-Tan; Huang, Chun-Ying; Chen, Ching-Yu; Tsai, Meng-Tsan; Lin, Tzu-Neng; Shen, Ji-Lin; Lee, Ya-Ju

    2016-01-01

    Enhancement of the external quantum efficiency of a GaN-based vertical-type light emitting diode (VLED) through the coupling of localized surface plasmon (LSP) resonance with the wave-guided mode light is studied. To achieve this experimentally, Ag nanoparticles (NPs), as the LSP resonant source, are drop-casted on the most top layer of waveguide channel, which is composed of hydrothermally synthesized ZnO nanorods capped on the top of GaN-based VLED. Enhanced light-output power and external quantum efficiency are observed, and the amount of enhancement remains steady with the increase of the injected currents. To understand the observations theoretically, the absorption spectra and the electric field distributions of the VLED with and without Ag NPs decorated on ZnO NRs are determined using the finite-difference time-domain (FDTD) method. The results prove that the observation of enhancement of the external quantum efficiency can be attributed to the creation of an extra escape channel for trapped light due to the coupling of the LSP with wave-guided mode light, by which the energy of wave-guided mode light can be transferred to the efficient light scattering center of the LSP. PMID:26935648

  6. Multimodal Imaging and Lighting Bias Correction for Improved μPAD-based Water Quality Monitoring via Smartphones

    NASA Astrophysics Data System (ADS)

    McCracken, Katherine E.; Angus, Scott V.; Reynolds, Kelly A.; Yoon, Jeong-Yeol

    2016-06-01

    Smartphone image-based sensing of microfluidic paper analytical devices (μPADs) offers low-cost and mobile evaluation of water quality. However, consistent quantification is a challenge due to variable environmental, paper, and lighting conditions, especially across large multi-target μPADs. Compensations must be made for variations between images to achieve reproducible results without a separate lighting enclosure. We thus developed a simple method using triple-reference point normalization and a fast-Fourier transform (FFT)-based pre-processing scheme to quantify consistent reflected light intensity signals under variable lighting and channel conditions. This technique was evaluated using various light sources, lighting angles, imaging backgrounds, and imaging heights. Further testing evaluated its handle of absorbance, quenching, and relative scattering intensity measurements from assays detecting four water contaminants – Cr(VI), total chlorine, caffeine, and E. coli K12 – at similar wavelengths using the green channel of RGB images. Between assays, this algorithm reduced error from μPAD surface inconsistencies and cross-image lighting gradients. Although the algorithm could not completely remove the anomalies arising from point shadows within channels or some non-uniform background reflections, it still afforded order-of-magnitude quantification and stable assay specificity under these conditions, offering one route toward improving smartphone quantification of μPAD assays for in-field water quality monitoring.

  7. Enhanced external quantum efficiency in GaN-based vertical-type light-emitting diodes by localized surface plasmons.

    PubMed

    Yao, Yung-Chi; Hwang, Jung-Min; Yang, Zu-Po; Haung, Jing-Yu; Lin, Chia-Ching; Shen, Wei-Chen; Chou, Chun-Yang; Wang, Mei-Tan; Huang, Chun-Ying; Chen, Ching-Yu; Tsai, Meng-Tsan; Lin, Tzu-Neng; Shen, Ji-Lin; Lee, Ya-Ju

    2016-01-01

    Enhancement of the external quantum efficiency of a GaN-based vertical-type light emitting diode (VLED) through the coupling of localized surface plasmon (LSP) resonance with the wave-guided mode light is studied. To achieve this experimentally, Ag nanoparticles (NPs), as the LSP resonant source, are drop-casted on the most top layer of waveguide channel, which is composed of hydrothermally synthesized ZnO nanorods capped on the top of GaN-based VLED. Enhanced light-output power and external quantum efficiency are observed, and the amount of enhancement remains steady with the increase of the injected currents. To understand the observations theoretically, the absorption spectra and the electric field distributions of the VLED with and without Ag NPs decorated on ZnO NRs are determined using the finite-difference time-domain (FDTD) method. The results prove that the observation of enhancement of the external quantum efficiency can be attributed to the creation of an extra escape channel for trapped light due to the coupling of the LSP with wave-guided mode light, by which the energy of wave-guided mode light can be transferred to the efficient light scattering center of the LSP. PMID:26935648

  8. Enhanced external quantum efficiency in GaN-based vertical-type light-emitting diodes by localized surface plasmons

    NASA Astrophysics Data System (ADS)

    Yao, Yung-Chi; Hwang, Jung-Min; Yang, Zu-Po; Haung, Jing-Yu; Lin, Chia-Ching; Shen, Wei-Chen; Chou, Chun-Yang; Wang, Mei-Tan; Huang, Chun-Ying; Chen, Ching-Yu; Tsai, Meng-Tsan; Lin, Tzu-Neng; Shen, Ji-Lin; Lee, Ya-Ju

    2016-03-01

    Enhancement of the external quantum efficiency of a GaN-based vertical-type light emitting diode (VLED) through the coupling of localized surface plasmon (LSP) resonance with the wave-guided mode light is studied. To achieve this experimentally, Ag nanoparticles (NPs), as the LSP resonant source, are drop-casted on the most top layer of waveguide channel, which is composed of hydrothermally synthesized ZnO nanorods capped on the top of GaN-based VLED. Enhanced light-output power and external quantum efficiency are observed, and the amount of enhancement remains steady with the increase of the injected currents. To understand the observations theoretically, the absorption spectra and the electric field distributions of the VLED with and without Ag NPs decorated on ZnO NRs are determined using the finite-difference time-domain (FDTD) method. The results prove that the observation of enhancement of the external quantum efficiency can be attributed to the creation of an extra escape channel for trapped light due to the coupling of the LSP with wave-guided mode light, by which the energy of wave-guided mode light can be transferred to the efficient light scattering center of the LSP.

  9. Multimodal Imaging and Lighting Bias Correction for Improved μPAD-based Water Quality Monitoring via Smartphones.

    PubMed

    McCracken, Katherine E; Angus, Scott V; Reynolds, Kelly A; Yoon, Jeong-Yeol

    2016-01-01

    Smartphone image-based sensing of microfluidic paper analytical devices (μPADs) offers low-cost and mobile evaluation of water quality. However, consistent quantification is a challenge due to variable environmental, paper, and lighting conditions, especially across large multi-target μPADs. Compensations must be made for variations between images to achieve reproducible results without a separate lighting enclosure. We thus developed a simple method using triple-reference point normalization and a fast-Fourier transform (FFT)-based pre-processing scheme to quantify consistent reflected light intensity signals under variable lighting and channel conditions. This technique was evaluated using various light sources, lighting angles, imaging backgrounds, and imaging heights. Further testing evaluated its handle of absorbance, quenching, and relative scattering intensity measurements from assays detecting four water contaminants - Cr(VI), total chlorine, caffeine, and E. coli K12 - at similar wavelengths using the green channel of RGB images. Between assays, this algorithm reduced error from μPAD surface inconsistencies and cross-image lighting gradients. Although the algorithm could not completely remove the anomalies arising from point shadows within channels or some non-uniform background reflections, it still afforded order-of-magnitude quantification and stable assay specificity under these conditions, offering one route toward improving smartphone quantification of μPAD assays for in-field water quality monitoring. PMID:27283336

  10. Multimodal Imaging and Lighting Bias Correction for Improved μPAD-based Water Quality Monitoring via Smartphones

    PubMed Central

    McCracken, Katherine E.; Angus, Scott V.; Reynolds, Kelly A.; Yoon, Jeong-Yeol

    2016-01-01

    Smartphone image-based sensing of microfluidic paper analytical devices (μPADs) offers low-cost and mobile evaluation of water quality. However, consistent quantification is a challenge due to variable environmental, paper, and lighting conditions, especially across large multi-target μPADs. Compensations must be made for variations between images to achieve reproducible results without a separate lighting enclosure. We thus developed a simple method using triple-reference point normalization and a fast-Fourier transform (FFT)-based pre-processing scheme to quantify consistent reflected light intensity signals under variable lighting and channel conditions. This technique was evaluated using various light sources, lighting angles, imaging backgrounds, and imaging heights. Further testing evaluated its handle of absorbance, quenching, and relative scattering intensity measurements from assays detecting four water contaminants – Cr(VI), total chlorine, caffeine, and E. coli K12 – at similar wavelengths using the green channel of RGB images. Between assays, this algorithm reduced error from μPAD surface inconsistencies and cross-image lighting gradients. Although the algorithm could not completely remove the anomalies arising from point shadows within channels or some non-uniform background reflections, it still afforded order-of-magnitude quantification and stable assay specificity under these conditions, offering one route toward improving smartphone quantification of μPAD assays for in-field water quality monitoring. PMID:27283336

  11. Low-cost structured-light based 3D capture system design

    NASA Astrophysics Data System (ADS)

    Dong, Jing; Bengtson, Kurt R.; Robinson, Barrett F.; Allebach, Jan P.

    2014-03-01

    Most of the 3D capture products currently in the market are high-end and pricey. They are not targeted for consumers, but rather for research, medical, or industrial usage. Very few aim to provide a solution for home and small business applications. Our goal is to fill in this gap by only using low-cost components to build a 3D capture system that can satisfy the needs of this market segment. In this paper, we present a low-cost 3D capture system based on the structured-light method. The system is built around the HP TopShot LaserJet Pro M275. For our capture device, we use the 8.0 Mpixel camera that is part of the M275. We augment this hardware with two 3M MPro 150 VGA (640 × 480) pocket projectors. We also describe an analytical approach to predicting the achievable resolution of the reconstructed 3D object based on differentials and small signal theory, and an experimental procedure for validating that the system under test meets the specifications for reconstructed object resolution that are predicted by our analytical model. By comparing our experimental measurements from the camera-projector system with the simulation results based on the model for this system, we conclude that our prototype system has been correctly configured and calibrated. We also conclude that with the analytical models, we have an effective means for specifying system parameters to achieve a given target resolution for the reconstructed object.

  12. A Sarsa(λ)-based control model for real-time traffic light coordination.

    PubMed

    Zhou, Xiaoke; Zhu, Fei; Liu, Quan; Fu, Yuchen; Huang, Wei

    2014-01-01

    Traffic problems often occur due to the traffic demands by the outnumbered vehicles on road. Maximizing traffic flow and minimizing the average waiting time are the goals of intelligent traffic control. Each junction wants to get larger traffic flow. During the course, junctions form a policy of coordination as well as constraints for adjacent junctions to maximize their own interests. A good traffic signal timing policy is helpful to solve the problem. However, as there are so many factors that can affect the traffic control model, it is difficult to find the optimal solution. The disability of traffic light controllers to learn from past experiences caused them to be unable to adaptively fit dynamic changes of traffic flow. Considering dynamic characteristics of the actual traffic environment, reinforcement learning algorithm based traffic control approach can be applied to get optimal scheduling policy. The proposed Sarsa(λ)-based real-time traffic control optimization model can maintain the traffic signal timing policy more effectively. The Sarsa(λ)-based model gains traffic cost of the vehicle, which considers delay time, the number of waiting vehicles, and the integrated saturation from its experiences to learn and determine the optimal actions. The experiment results show an inspiring improvement in traffic control, indicating the proposed model is capable of facilitating real-time dynamic traffic control. PMID:24592183

  13. Multi Dark Lens Simulations: weak lensing light-cones and data base presentation

    NASA Astrophysics Data System (ADS)

    Giocoli, Carlo; Jullo, Eric; Metcalf, R. Benton; de la Torre, Sylvain; Yepes, Gustavo; Prada, Francisco; Comparat, Johan; Göttlober, Stefan; Kyplin, Anatoly; Kneib, Jean-Paul; Petkova, Margarita; Shan, Huan Yuan; Tessore, Nicolas

    2016-09-01

    In this paper we present a large data base of weak lensing light cones constructed using different snapshots from the Big MultiDark simulation (BigMDPL). The ray-tracing through different multiple plane has been performed with the GLAMER code accounting both for single source redshifts and for sources distributed along the cosmic time. This first paper presents weak lensing forecasts and results according to the geometry of the VIPERS-W1 and VIPERS-W4 field of view. Additional fields will be available on our data base and new ones can be run upon request. Our data base also contains some tools for lensing analysis. In this paper we present results for convergence power spectra, one point and high order weak lensing statistics useful for forecasts and for cosmological studies. Covariance matrices have also been computed for the different realizations of the W1 and W4 fields. In addition we compute also galaxy-shear and projected density contrasts for different halo masses at two lens redshift according to the CFHTLS source redshift distribution both using stacking and cross-correlation techniques, finding very good agreement.

  14. Silver nanowires for transparent conductive electrode to GaN-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Jeong, Gyu-Jae; Lee, Jae-Hwan; Han, Sang-Hyun; Jin, Won-Yong; Kang, Jae-Wook; Lee, Sung-Nam

    2015-01-01

    Transparent, conductive, and uniform Ag nanowires (NWs) were introduced to improve the optical performance of GaN-based light-emitting diodes (LEDs) by a spin-coating technique. The Ag NWs acted as a current spreading layer, exhibiting high transmittance and low sheet resistance, and ultimately leading to high performance GaN-based LEDs with an ultra large size of 5 × 5 mm2. Compared to the transmittance of conventional LEDs without Ag NWs, the relative transmittance of LEDs with Ag NWs was approximately 90% of the overall wavelength region. However, the electroluminescence (EL) intensity of LED with Ag NWs was much higher than that of conventional LEDs without Ag NWs for injection current above 45 mA. In addition, the EL full width at half maximum of LEDs with Ag NWs was much lower than that of conventional LEDs without Ag NWs. Based on these results, we believe that the enhanced optical performance of ultra large LEDs was due to an increase in the current spreading effect.

  15. Silver nanowires for transparent conductive electrode to GaN-based light-emitting diodes

    SciTech Connect

    Jeong, Gyu-Jae; Lee, Jae-Hwan; Han, Sang-Hyun; Lee, Sung-Nam; Jin, Won-Yong; Kang, Jae-Wook

    2015-01-19

    Transparent, conductive, and uniform Ag nanowires (NWs) were introduced to improve the optical performance of GaN-based light-emitting diodes (LEDs) by a spin-coating technique. The Ag NWs acted as a current spreading layer, exhibiting high transmittance and low sheet resistance, and ultimately leading to high performance GaN-based LEDs with an ultra large size of 5 × 5 mm{sup 2}. Compared to the transmittance of conventional LEDs without Ag NWs, the relative transmittance of LEDs with Ag NWs was approximately 90% of the overall wavelength region. However, the electroluminescence (EL) intensity of LED with Ag NWs was much higher than that of conventional LEDs without Ag NWs for injection current above 45 mA. In addition, the EL full width at half maximum of LEDs with Ag NWs was much lower than that of conventional LEDs without Ag NWs. Based on these results, we believe that the enhanced optical performance of ultra large LEDs was due to an increase in the current spreading effect.

  16. CoPt ferromagnetic injector in light-emitting Schottky diodes based on InGaAs/GaAs nanostructures

    SciTech Connect

    Zdoroveyshchev, A. V. Dorokhin, M. V.; Demina, P. B.; Kudrin, A. V.; Vikhrova, O. V.; Ved’, M. V.; Danilov, Yu. A.; Erofeeva, I. V.; Krjukov, R. N.; Nikolichev, D. E.

    2015-12-15

    The possibility of fabricating a ferromagnetic injector based on a near-equiatomic CoPt alloy with pronounced perpendicular magnetization anisotropy in the InGaAs/GaAs spin light-emitting diode is shown. The physical properties of experimental spin light-emitting diode prototypes are comprehensively studied. Circularly polarized electroluminescence of fabricated diodes is obtained in zero magnetic field due to the remanent magnetization of CoPt layers.

  17. SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC.: Study on the characteristics of linac based THz light source

    NASA Astrophysics Data System (ADS)

    Zhu, Xiong-Wei; Wang, Shu-Hong; Chen, Sen-Yu

    2009-10-01

    There are many methods based on linac for THz radiation production. As one of the options for the Beijing Advanced Light, an ERL test facility is proposed for THz radiation. In this test facility, there are 4 kinds of methods to produce THz radiation: coherent synchrotron radiation (CSR), synchrotron radiation (SR), low gain FEL oscillator, and high gain SASE FEL. In this paper, we study the characteristics of the 4 kinds of THz light sources.

  18. Quantum Dot Light-Emitting Diodes Based on Inorganic Perovskite Cesium Lead Halides (CsPbX3 ).

    PubMed

    Song, Jizhong; Li, Jianhai; Li, Xiaoming; Xu, Leimeng; Dong, Yuhui; Zeng, Haibo

    2015-11-25

    Novel quantum-dot light-emitting diodes based on all-inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals are reported. The well-dispersed, single-crystal quantum dots (QDs) exhibit high quantum yields, and tunable light emission wavelength. The demonstration of these novel perovskite QDs opens a new avenue toward designing optoelectronic devices, such as displays, photodetectors, solar cells, and lasers. PMID:26444873

  19. Spatial light modulation based on photoinduced change in the complex refractive index of bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Takei, Hiroyuki; Shimizu, Norio

    1996-04-01

    Bacteriorhodopsin exhibits photoinduced changes in both absorption and refractive index at 633 nm. To explore the possibility of exploiting this property in constructing a photoaddressed spatial light modulator, we investigated the transmission property of a Fabry-Perot interferometer containing a bacteriorhodopsin thin film. Film was formed that had a phase shift of pi /4 and sufficient interference fringe contrast for spatial light modulation. This establishes the possibility of constructing a spatial light modulator that features nonlinear input-output characteristics and can operate at moderate light intensities of the order of tens of milliwatts per centimeter square. spatial light modulation, complex refractive index.

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

    NASA Astrophysics Data System (ADS)

    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.