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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

    NASA Astrophysics Data System (ADS)

    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.

  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).

  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. 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.

  8. 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.

  9. 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.

  10. Light Scattering based detection of food pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The current methods for detecting foodborne pathogens are mostly destructive (i.e., samples need to be pretreated), and require time, personnel, and laboratories for analyses. Optical methods including light scattering based techniques have gained a lot of attention recently due to its their rapid a...

  11. Big Crunch-based omnidirectional light concentrators

    NASA Astrophysics Data System (ADS)

    Smolyaninov, Igor I.; Hung, Yu-Ju

    2014-12-01

    Omnidirectional light concentration remains an unsolved problem despite such important practical applications as the design of efficient mobile photovoltaic cells. Recently developed optical black hole designs offer partial solutions to this problem. However, even these solutions are not truly omnidirectional since they do not exhibit a horizon, and at large enough incidence angles the light may be trapped into quasi-stationary orbits around such imperfect optical black holes. Here, we propose and realize experimentally another gravity-inspired design of a broadband omnidirectional light concentrator based on the cosmological Big Crunch solutions. By mimicking the Big Crunch spacetime via a corresponding effective optical metric, we make sure that every photon world line terminates in a single point.

  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. Thermal light ghost imaging based on morphology

    NASA Astrophysics Data System (ADS)

    Chen, Zhipeng; Shi, Jianhong; Zeng, Guihua

    2016-12-01

    The quality of thermal light ghost imaging could be degraded by undersampling noise. This kind of noise is generated because of finite sampling, which could reduce the signal-to-noise ratio (SNR) of ghost imaging and submerge object information. In order to reduce the undersampling noise, we propose a thermal light ghost imaging scheme based on the morphology (GIM). In this scheme, the average size of the undersampling noise can be obtained by computing the second-order correlation function of the ghost imaging system. According to the average size of the undersampling noise, the corresponding structure element can be designed and used in the morphological filter; then, the GIM reconstructed image can be obtained. The experiment results show that the peak signal-to-noise ratio of the GIM reconstructed image can increased by 80% than that of conventional ghost imaging for the same number of measurements.

  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. 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.

  17. Enhancement of Light Extracting from GaN-BASED Blue Light Emitting Diodes Using Photonic Crystal

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Wu, Fugen; Zhang, Xin; Yao, Yuanwei; Zhong, Huilin; Yan, Shuya; He, Yun

    Photonic crystal (PC) structures on LED have been known to enhance the light extraction significantly. In this paper, we report the light energy of GaN-based blue lighting emitting diode (LED) with perfect area photonic crystal (PPC) structure and defect area photonic crystal (DPC) structure. As a result, the light extracting energy of LEDs with PPC structure enhanced little compared to that of without PC structure. In addition, the light extracting energy of blue LED with DPC structure was remarkably improved.

  18. Mobile-phone based visible light communication using region-grow light source tracking for unstable light source.

    PubMed

    Liang, Kevin; Chow, Chi-Wai; Liu, Yang

    2016-07-25

    In order to increase the data rate of the camera-based visible light communication (VLC) system, using rolling shutter effect has been demonstrated successfully, in which the pixel rows of the complementary-metal-oxide-semiconductor (CMOS) image sensor are activated sequentially. Previous camera-based VLCs focused on using a stable LED light source, and its illumination area is positioned at the center of an image frame. In this work, we investigate the performance of a camera-based VLC with light source at different parts of an image frame. We propose and demonstrate using region-grow algorithm to track the light source. We also evaluate and discuss different scenarios when the light source is moved. Besides, a recorded > 5 kbit/s net data rate can be achieved by using only a single phosphor-based white-light LED source. Here, we demonstrate that 4.502 pixel/bit can be achieved.

  19. 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

  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. 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

  4. Light-guide-based optical engine for light-valve projection

    NASA Astrophysics Data System (ADS)

    Krijn, Marcel C.; Salters, Bart A.; de Vaan, Ad J.

    2004-09-01

    We present a new type of optical engine for projection displays. The optical engine is based on a light guide with embedded color filters. It is intended for three-panel projection displays with micro-display panels of the transmissive type. The light guide serves the purpose of integrating the light and guiding the light to each of the three panels. Proximity illumination is used to illuminate the micro-display panels: the exits of the light guide are in close contact with the entrance of the panel. The optical design considerations underlying the principle of using light guides are discussed. Among these considerations are measures required to prevent light leakage. We also discuss light guide based optical engines relying on the principle of color recycling and polarization recycling. The results of simulations and experiments on a prototype are discussed. It is shown that the use of light guides enables a very compact design. The lumen output of such a projector can be comparable to, or even better than that of conventional systems.

  5. 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.

  6. 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.

  7. Vortex-based all-optical manipulation of stored light at low light levels.

    PubMed

    Zhao, Lu

    2015-11-16

    We exploit the giant cross-Kerr nonlinearity of electromagnetically induced transparency (EIT) system in ultracold atoms to implement vortex-based multimode manipulation of stored light at low light levels. Using image-bearing signal light fields with angular intensity profiles, sinusoidal grating structures with phase-only modulation can be azimuthally imprinted on the stored probe light field, where the nonlinear absorption loss can be ignored. Upon retrieval of the probe light, collinearly superimposed vortex modes can be generated in the far field. Considering the finite size of atomic gas, the Fraunhofer diffraction patterns of the retrieved probe fields and their spiral spectra are numerically investigated, where the diffracted vortex modes can be efficiently controlled by tuning the weak signal fields. Our studies not only exhibit a fundamental diffraction phenomenon with angular grating structures in EIT system, but also provide a fascinating opportunity to realize multidimensional quantum information processing for stored light in an all-optical manner. PMID:26698464

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Analysis of light guiding property in light piped based solar concentrator

    NASA Astrophysics Data System (ADS)

    Whang, Allen J.; Chuang, Chun-Hsien, Jr.; Chen, Yi-Yung

    2008-02-01

    Recently, many researchers have tried to design a system for indoor illumination because the benefits of solar systems. A simple parabolic reflector is often used to collect sunlight but the efficiency is poor when sunlight isn't incident normally. Therefore, an accurate machine to track sun has to be used. In order to get better tolerance, a light pipe based solar concentrator (LPBSC) which comprises a parabolic reflector and a hollow reflective light pipe is proposed. We develop a math model which combines the reflection times of sunlight in light pipe and the candela data of parabolic reflector to analyze the efficiency. And then, straight light pipe is replaced by tapered light pipe to improve the tolerance. Optical simulation software, TracePro, and mathematical software, MATLAB, are used to prove the model is correct and feasible. In the results, LPBSC can improve the tolerance to get good efficiency.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 8. VIEW OF THE LIGHT GREY GRANITE BASE WITH WHITE ...

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

    8. VIEW OF THE LIGHT GREY GRANITE BASE WITH WHITE GLAZED TERRA COTTA FINISH ABOVE. THIS IS THE NORTHEAST CORNER OF THE BUILDING. - Pacific Telephone & Telegraph Company Building, 1519 Franklin Street, Oakland, Alameda County, CA

  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. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Collimating lens for light-emitting-diode light source based on non-imaging optics.

    PubMed

    Wang, Guangzhen; Wang, Lili; Li, Fuli; Zhang, Gongjian

    2012-04-10

    A collimating lens for a light-emitting-diode (LED) light source is an essential device widely used in lighting engineering. Lens surfaces are calculated by geometrical optics and nonimaging optics. This design progress does not rely on any software optimization and any complex iterative process. This method can be used for any type of light source not only Lambertian. The theoretical model is based on point source. But the practical LED source has a certain size. So in the simulation, an LED chip whose size is 1 mm*1 mm is used to verify the feasibility of the model. The mean results show that the lenses have a very compact structure and good collimating performance. Efficiency is defined as the ratio of the flux in the illuminated plane to the flux from LED source without considering the lens material transmission. Just investigating the loss in the designed lens surfaces, the two types of lenses have high efficiencies of more than 90% and 99%, respectively. Most lighting area (possessing 80% flux) radii are no more than 5 m when the illuminated plane is 200 m away from the light source. PMID:22505154

  9. High-definition imaging system based on spatial light modulators with light-scattering mode

    NASA Astrophysics Data System (ADS)

    Kikuchi, Hiroshi; Fujii, Takanori; Kawakita, Masahiro; Hirano, Yoshiyuki; Fujikake, Hideo; Sato, Fumio; Takizawa, Kuniharu

    2004-01-01

    We have developed a prototype high-definition imaging system using polymer-dispersed liquid-crystal (PDLC) light valves, which can modulate unpolarized light with high spatial resolution and exhibit a high optical efficiency, based on the light-scattering effect. We fabricated high-definition light valves with a fine polymer-matrix structure in a PDLC film by controlling the curing conditions used during the photopolymerization-induced phase separation and formation process. This device has excellent characteristics, such as a high resolution, with 50 lp/mm for a limiting resolution and greater than 20 lp/mm at the 50% modulation transfer function point, and a reflectivity of greater than 60%. An optically addressable full-color projection display was designed, consisting of three PDLC light valves, a schlieren optical system based on shift-decentralization optics with a xenon lamp illumination and input-image sources with 1.5 million pixels, including electrical image compensation of the gamma characteristics. We succeeded in displaying pictures on a 110-inch screen with a resolution of 810 TV lines and a luminous flux of 1900-2100 American National Standards Institute lumens.

  10. 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.

  11. Light Field Imaging Based Accurate Image Specular Highlight Removal.

    PubMed

    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

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Problematic failures of aluminum light standards and pedestals (bases)

    NASA Astrophysics Data System (ADS)

    Scancella, Robert J.

    1998-03-01

    During the winter snow storm of January 7 and 8, 1996 failure occurred to a number of the highway lighting assemblies on the adjacent projects of Route 147, Section 1C and Route 147 Section 1E. These projects are located in Cape May County along the shore area. Eight LES-45 expressway poles attached to transfer bases type TB-17 located on the ground blew down on the Route 147, 1E project, while six L8S-40 lighting poles with shoe bases mounted to bridge parapet of Route 147, 1C blew down (14 in total). The poles fell on the roadway. Had it not been for the storm keeping traffic off the roads damage may have occurred to vehicles and vehicle occupants. Visual inspections by the Resident Engineer of the projects revealed that the damage to the poles and bases was general. Wind velocities recorded by the Weather Bureau and the Coast Guard indicated that wind speeds of more than 50 m.p.h. were reached during the storm. The lighting assemblies are expected to withstand 85 m.p.h. sustained winds and 104 m.p.h. gusts. The New Jersey Department of Transportation, Bureau of materials was requested to conduct an investigation to determine the probable cause of the failures to the LES-45 and L8S-40 lighting assemblies. They were further required to determine a means of inspecting non-failing assemblies for future prevention of these assemblies failing.

  1. Vertical GaN based Light Emitting Diodes on Metal Alloy Substrate for Solid State Lighting Application

    NASA Astrophysics Data System (ADS)

    Doan, T.; Chu, C.; Chen, C.; Liu, W.; Chu, J.; Yeh, J.; Chen, H.; Fan, F.; Tran, C.

    2006-02-01

    Vertical GaN based Light Emitting Diodes on metal alloy substrate were realized and characterized for solid state lighting application. An efficiency of more than 70 lumens/watt was achieved. In addition, these LEDs exhibit many advantages over those on sapphire under extreme operation conditions for general lighting application.

  2. 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.

  3. 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.

  4. 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

  5. Compact, fiber-based, fast-light enhanced optical gyroscope

    NASA Astrophysics Data System (ADS)

    Christensen, Caleb A.; Zavriyev, Anton; Bashkansky, Mark; Beal, A. Craig

    2013-05-01

    It has been proposed that fast-light optical phenomena can increase the sensitivity of a Ring Laser Gyroscope (RLG) of a given size by several orders of magnitude. MagiQ is developing a compact fully-fibered fast light RLG using Stimulated Brillouin Scattering (SBS) in commercial optical fiber. We will discuss our experimental results on SBS pumped lasing in commercial fibers and analyze their implications to the fast light generation. Based on these results, we envision a fast light enhanced Ring Laser Gyroscope (RLG) that will use only a few meters of fiber and require moderate pump power (only a few 100's of mW). We will present the design that is based on proven, commercially available technologies. By using photonic integrated circuits and telecom-grade fiber components, we created a design that is appropriate for mass production in the near term. We eliminated all free-space optical elements (such as atomic vapor cells), in order to enable a compact, high sensitivity RLG stable against environmental disturbances. Results of this effort will have benefits in existing applications of RLGs (such as inertial navigation units, gyrocompasses, and stabilization techniques), and will allow wider use of RLGs in spacecraft, unmanned aerial vehicles or sensors, where the current size and weight of optical gyros are prohibitive.

  6. Design of transient light signal simulator based on FPGA

    NASA Astrophysics Data System (ADS)

    Kang, Jing; Chen, Rong-li; Wang, Hong

    2014-11-01

    A design scheme of transient light signal simulator based on Field Programmable gate Array (FPGA) was proposed in this paper. Based on the characteristics of transient light signals and measured feature points of optical intensity signals, a fitted curve was created in MATLAB. And then the wave data was stored in a programmed memory chip AT29C1024 by using SUPERPRO programmer. The control logic was realized inside one EP3C16 FPGA chip. Data readout, data stream cache and a constant current buck regulator for powering high-brightness LEDs were all controlled by FPGA. A 12-Bit multiplying CMOS digital-to-analog converter (DAC) DAC7545 and an amplifier OPA277 were used to convert digital signals to voltage signals. A voltage-controlled current source constituted by a NPN transistor and an operational amplifier controlled LED array diming to achieve simulation of transient light signal. LM3405A, 1A Constant Current Buck Regulator for Powering LEDs, was used to simulate strong background signal in space. Experimental results showed that the scheme as a transient light signal simulator can satisfy the requests of the design stably.

  7. Separations based on the mechanical forces of light.

    PubMed

    Zhao, Bum Suk; Koo, Yoon-Mo; Chung, Doo Soo

    2006-01-18

    A photon as a particle has an energy and a momentum. In a matter-photon interaction, the matter and photons may exchange their momenta observing the momentum conservation law. The consequence of the momentum transfer from a photon to a matter particle is a mechanical force exerted on the particle. Several separation methods based on this force of light are reviewed. Photophoresis separations for micron-sized particles and optical force chromatography for chemical-sized molecules are discussed.

  8. 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.

  9. Optical polarizer based on the mechanical effect of light.

    PubMed

    Xiong, Hao; Kong, Cui; Yang, Xiaoxue; Wu, Ying

    2016-09-15

    Based on the recent experimental progress in chip-scale silicon photonics, a nontrivial polarizing effect arising from the mechanical effect of light is present in an optomechanical crystal, which enables a new nanophotonic polarizer with excellent functionality. Unlike previously reported optical polarizers, the polarizer proposed here can be adjusted rapidly by tuning polarization and intensity of the control field and may enable on-chip optical control of polarization management with remarkable applications, due to the improvement of nanofabrication techniques. PMID:27628386

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Applications of laser wakefield accelerator-based light sources

    NASA Astrophysics Data System (ADS)

    Albert, Félicie; Thomas, Alec G. R.

    2016-11-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. We first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  15. Text Visualization using Light and Shadow based on Topic Relevance

    NASA Astrophysics Data System (ADS)

    Nishihara, Yoko; Sato, Keita; Sunayama, Wataru

    There are so many opportunities to transmit text information on the Web. Since texts on the Web are not always written by professional writers, those may not be coherent or may be hard to be comprehended. Therefore, we should take too much time and energy to grasp topic relevance of a text. This paper describes HINATA system that visualizes texts using light and shadow based on topic relevance. Topic is defined as a set of words such as nouns contained in a title of a text. The light expresses sentences related to a topic, and the shadow expresses sentences unrelated to a topic. This visualization method efficiently supports users for finding the parts related to a topic, and for grasping relations between sentences of a text and a topic. Experimental results showed that the proposed system could support users for understanding how a text was related to a topic.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. A Signcryption based Light Weight Key Exchange Protocol

    NASA Astrophysics Data System (ADS)

    Feng, Yong; Wei, Qian; Zhang, Xing

    Traditional cryptography based authenticated Diffie-Hellman key exchange protocols expose the problems of efficiency and privacy since signature-then-encryption is heavy to wireless communication special for flexible dynamic deployment, i.e., wireless mesh networks, wireless sensor networks, mobile ad hoc networks, etc., in computational cost and communicational overhead and traditional digital signature allows anyone to verify its validity using the corresponding public key. In this paper, we propose a signcryption based light weight key exchange protocol named SLWKE which can provide resistance to traditional attacks, i.e., eavesdropping, deducing, replaying, interleaving, forging and repudiating, and unknown key-share attack and save computational cost by three modular calculations, i.e., one modular inversion, one modular addition and one modular multiplicative, included in a signature s and communicational overhead by secure length of IqI in comparison to signcryption based direct key exchange using a time-stamp protocol termed Dkeuts.

  2. Light-induced color changes of microgel-based etalons.

    PubMed

    Gao, Yongfeng; Serpe, Michael J

    2014-06-11

    Poly(N-isopropylacrylamide) (pNIPAm) microgel-based etalons were used to fabricate systems that change visual color in response to light exposure. These systems were fabricated by adding pH responsive microgel-based etalons to a solution composed of the photoacid o-nitrobenzaldehyde (o-NBA). Upon exposure of this system to ultraviolet (UV) irradiation, the photoacid released a proton, lowering the pH of the solution. Since the pNIPAm microgel-based etalon was responsive to pH, the etalon changed its optical properties and, hence, visual color. We went on to show that patterned etalons could be fabricated, which only contained pH-responsive microgels in specific regions. These etalons only changed color in the pH-responsive regions, to yield patterns that change color upon UV light exposure. Finally, the color of the etalon was shown to be fully reversible and could be switched multiple times. These unique systems could potentially be used for display technologies, and as a controlled/triggered drug delivery system. PMID:24916052

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Design and evaluation of an LED-based light fixture

    NASA Astrophysics Data System (ADS)

    Gu, Yimin; Narendran, Nadarajah

    2004-01-01

    Interior spaces, such as conference rooms, require multiple forms of lighting to meet different task needs. Linear fluorescent lamp fixtures commonly produce the general ambient light, and reflectorized halogen lamp fixtures produce the directional lighting. Current lighting practice uses multiple light source technologies and fixtures to achieve the required illumination for the various tasks. However, many light fixtures can create an unappealing architectural design, especially in a small space, and multiple light source technologies can cause maintenance difficulties. The ideal scenario would be to create one fixture with a single type of light source that could meet a variety of lighting needs. The size, potential energy savings, and reduced maintenance benefits of white light-emitting diodes (LEDs) make them attractive for use in general illumination applications. Therefore, the goal of this study was to investigate whether a light fixture could be designed with white LEDs to provide different beam distributions. A commercially available ray tracing package was utilized to model, analyze, and optimize light fixture concepts created using LEDs and light guides. The fixtures were optimized for light output distribution and efficiency. While a rectangular-shaped light guide with simple diffused reflective surfaces provided the necessary cosine beam distribution, a more sophisticated surface treatment was required on the light extracting surface of the light guide to create the batwing beam distributions. The surface finish structures were in the form of micro-prism arrays. By switching LED arrays on and off to different light guides, various light levels and distributions could be achieved for different occasions. Further analysis showed that, when used in a typical conference room set up the fixture produced acceptable uniformity over the surfaces. Although the system provided the necessary beam distributions, the system efficiency was quite low, only 48%. Most

  11. Hyperspectral scanning white light interferometry based on compressive imaging

    NASA Astrophysics Data System (ADS)

    Azari, Mohammad; Habibi, Nasim; Abolbashari, Mehrdad; Farahi, Faramarz

    2016-02-01

    We have developed a compressive hyperspectral imaging system that is based on single-pixel camera architecture. We have incorporated the developed system in a scanning white-light interferometer (SWLI) and showed that replacing SWLI's CCD-based camera by the compressive hyperspectral imaging system, we have access to high-resolution multispectral images of interferometer's fringes. Using these multi-spectral images, the system is capable of simultaneous spectroscopy of the surface, which can be used, for example, to eliminate the effect of surface contamination and providing new spectral information for fringe signal analysis which could be used to reduce the need for vertical scan, therefore making height measurement more tolerant to object's position.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. GaN based nanorods for solid state lighting

    SciTech Connect

    Li Shunfeng; Waag, Andreas

    2012-04-01

    In recent years, GaN nanorods are emerging as a very promising novel route toward devices for nano-optoelectronics and nano-photonics. In particular, core-shell light emitting devices are thought to be a breakthrough development in solid state lighting, nanorod based LEDs have many potential advantages as compared to their 2 D thin film counterparts. In this paper, we review the recent developments of GaN nanorod growth, characterization, and related device applications based on GaN nanorods. The initial work on GaN nanorod growth focused on catalyst-assisted and catalyst-free statistical growth. The growth condition and growth mechanisms were extensively investigated and discussed. Doping of GaN nanorods, especially p-doping, was found to significantly influence the morphology of GaN nanorods. The large surface of 3 D GaN nanorods induces new optical and electrical properties, which normally can be neglected in layered structures. Recently, more controlled selective area growth of GaN nanorods was realized using patterned substrates both by metalorganic chemical vapor deposition (MOCVD) and by molecular beam epitaxy (MBE). Advanced structures, for example, photonic crystals and DBRs are meanwhile integrated in GaN nanorod structures. Based on the work of growth and characterization of GaN nanorods, GaN nanoLEDs were reported by several groups with different growth and processing methods. Core/shell nanoLED structures were also demonstrated, which could be potentially useful for future high efficient LED structures. In this paper, we will discuss recent developments in GaN nanorod technology, focusing on the potential advantages, but also discussing problems and open questions, which may impose obstacles during the future development of a GaN nanorod based LED technology.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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

    2014-01-21

    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.

  7. 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.

  8. 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.

  9. GaN-based LEDs for light communication

    NASA Astrophysics Data System (ADS)

    Zhao, LiXia; Zhu, ShiChao; Wu, ChunHui; Yang, Chao; Yu, ZhiGuo; Yang, Hua; Liu, Lei

    2016-10-01

    Rapid improvement in the efficiency of GaN-based LEDs not only speed up its applications for general illumination, but offer the possibilities for data transmission. This review is to provide an overview of current progresses of GaN-based LEDs for light communications. The modulation bandwidth of GaN-based LEDs has been first improved by optimizing the LED epilayer structures and the modulation bandwidth of 73 MHz was achieved at the driving current density of 40 A/cm2 by changing the multi-quantum well structures. After that, in order to increase the current density tolerance, different parallel flip-chip micro-LED arrays were fabricated. With a high injected current density of ˜7900 A/cm2, a maximum modulation bandwidth of ˜227 MHz was obtained with optical power greater than 30 mW. Besides the increase of carrier concentrations, the radiative recombination coefficient B was also enhanced by modifying the photon surrounding environment based on some novel nanostructures such as resonant cavity, surface plasmon, and photonic crystals. The optical 3 dB modulation bandwidth of GaN-based nanostructure LEDs with Ag nanoparticles was enhanced by 2 times compared with GaN-based nanostructure LEDs without Ag nanoparticles. Our results demonstrate that using the QW-SP coupling can effectively help to enhance the carrier spontaneous emission rate and also increase the modulation bandwidth for LEDs, especially for LEDs with high intrinsic IQE. In addition, we discuss the progress of the faster color conversion stimulated by GaN-based LEDs.

  10. Light-Emitting Devices Based on New Phenanthroline Derivates

    NASA Astrophysics Data System (ADS)

    Prelipceanu, Marius; Graur, Adrian

    2014-11-01

    An investigation of film forming properties, electrical characteristics, optical and electroluminescence properties of a recently synthesized pyrrolo[1,2-a][1,10]phenanthroline derivatives (RA) has been reported. The results indicate that these new materials can be used for manufacturing organic devices as lightemitting diodes. Various device structure and thickness have been considered in experiments. The poly(pphenylenevinylene)- PPV has been used as transporting layer while the RA as emitting layer. Good rectification behaviour with a switch-on voltage in range of 3 V and 7 V has been exhibited by these devices. Yellow-green light with of 96 cdṡm-2 luminance has been found for the OLED based on the double layer structure 100 nm Indium Tin Oxide(ITO)/50 nm PPV/60 nm RA/100 nm Al

  11. 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.

  12. Progress in III-nitride based white light sources

    NASA Astrophysics Data System (ADS)

    Gaska, Remis; Zukauskas, Arturas; Shur, Michael S.; Khan, Mohamed A.

    2002-11-01

    We review two complementary approaches to the development of white light solid-state sources. The first approach, which involves polychromatic LED modules, is targeted at advanced optimization of spectral power distribution in order to establish an optimal trade-off between luminous efficacy and color rendering. We apply a stochastic method of optimization of a white-light source that relies on additive color mixing of the emissions from colored primary LEDs. We present the results on optimized spectra for all-semiconductor lamps composed of four primary LEDs with the line widths typical of present AlGaInP and AlInGaN technologies. We point out the problem of the lack of efficient yellow-green (570 nm) emitters required for polychromatic lamps with four and more primary LEDs. The second approach is based on the development of AlInGaN-based UV emitters that can be tailored to directly excite different phosphors without sensitizers. AlInGaN materials system demonstrated potential for making UV LEDs with a high power and short wavelengths required for such applications. This has been achieved by using Strain Energy Band Engineering (SEBE) and Pulsed Atomic Epitaxy (PALE) techniques. SEBE relies on quaternary AlGaInN compounds for controlling strain and band offset and for producing UV emitters with improved device performance. PALE allows us to incorporate the required significant amount of indium (few percent) in AlGaN, since it can be performed at lower growth temperatures required for In incorporation. Further improvements in materials quality of AlInGaN layers with a high molar fraction of Al will be achieved by using bulk AlN substrates.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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%.

  19. 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.

  20. 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.

  1. Improved metropolis light transport algorithm based on multiple importance sampling

    NASA Astrophysics Data System (ADS)

    He, Huaiqing; Yang, Jiaqian; Liu, Haohan

    2015-12-01

    Metropolis light transport was an unbiased and robust Monte Carlo method, which could efficiently reduce noise during rendering the realistic graphics to resolve the global illumination problem. The basic Metropolis light transport was improved by combining with multiple importance sampling, which better solved the large correlation and high variance between samples caused by the basic Metropolis light transport. The experiences manifested that the quality of images generated by improved algorithm was better compared with the basic Metropolis light transport in the same scenes settings.

  2. 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

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

    PubMed

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

    2015-07-29

    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.

  4. 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

  5. An endoscopic 3D scanner based on structured light.

    PubMed

    Schmalz, Christoph; Forster, Frank; Schick, Anton; Angelopoulou, Elli

    2012-07-01

    We present a new endoscopic 3D scanning system based on Single Shot Structured Light. The proposed design makes it possible to build an extremely small scanner. The sensor head contains a catadioptric camera and a pattern projection unit. The paper describes the working principle and calibration procedure of the sensor. The prototype sensor head has a diameter of only 3.6mm and a length of 14mm. It is mounted on a flexible shaft. The scanner is designed for tubular cavities and has a cylindrical working volume of about 30mm length and 30mm diameter. It acquires 3D video at 30 frames per second and typically generates approximately 5000 3D points per frame. By design, the resolution varies over the working volume, but is generally better than 200μm. A prototype scanner has been built and is evaluated in experiments with phantoms and biological samples. The recorded average error on a known test object was 92μm.

  6. 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.

  7. 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

  8. Light field image sensors based on the Talbot effect

    PubMed Central

    Wang, Albert; Gill, Patrick; Molnar, Alyosha

    2010-01-01

    We present a pixel-scale sensor that uses the Talbot effect to detect the local intensity and incident angle of light. The sensor comprises two local diffraction gratings stacked above a photodiode. When illuminated by a plane wave, the upper grating generates a self-image at the half Talbot depth. The second grating, placed at this depth, blocks or passes light depending upon incident angle. Several such structures, tuned to different incident angles, are sufficient to extract local incident angle and intensity. Furthermore, arrays of such structures are sufficient to localize light sources in three dimensions without any additional optics. PMID:19881658

  9. 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.

  10. Color reproduction for LED-based general lighting

    NASA Astrophysics Data System (ADS)

    Salters, B. A.; Krijn, M. P. C. M.

    2006-08-01

    Solid State Lighting is becoming increasingly more advanced, both in terms of lumen output as well as energy efficiency. However, implementation in color consumer lighting products, such as the Philips Ambilight television sets, still requires improvements in both color reproduction as well as intensity uniformity. To build a lighting system capable of correctly reproducing a large color spectrum, 3 primary colored LEDs are required. However, this approach causes problems. In particular, the generation of a white color without color fringes is difficult to implement, as the total amount of light from each primary color should ideally be identical at each position within the light bundle. Our paper focuses on systems using a limited number of high power LEDs. The lumen output of these LEDs is such that even a single red, green and blue LED together can deliver the required lumen output for certain applications. To optimize performance for both luminance and color uniformity we investigated several design options. Ray tracing simulations are compared to the performance of real size prototypes, and recommendations are given for the design of color lighting systems.

  11. 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

  12. 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 .

  13. Is blue optical filter necessary in high speed phosphor-based white light LED visible light communications?

    PubMed

    Sung, Jiun-Yu; Chow, Chi-Wai; Yeh, Chien-Hung

    2014-08-25

    Optical blue filter is usually regarded as a critical optical component for high speed phosphor-based white light emitting diode (LED) visible-light-communication (VLC). However, the optical blue filter plays different roles in VLC when using modulations of on-off keying (OOK) or discrete multi-tone (DMT). We show that in the DMT VLC system, the blue optical filter may be unnecessary, and even degrade the transmission performance (by reducing the optical signal-to-noise ratio (SNR)). Analyses and verifications by experiments are performed. To the best of our knowledge, this is the first time the function of blue filters in VLC is explicitly analyzed.

  14. Light extraction efficiency improvement by multiple laser stealth dicing in InGaN-based blue light-emitting diodes.

    PubMed

    Zhang, Yiyun; Xie, Haizhong; Zheng, Haiyang; Wei, Tongbo; Yang, Hua; Li, Jing; Yi, Xiaoyan; Song, Xiangyang; Wang, Guohong; Li, Jinmin

    2012-03-12

    We report a multiple laser stealth dicing (multi-LSD) method to improve the light extraction efficiency (LEE) of InGaN-based light-emitting diodes (LEDs) using a picosecond (Ps) laser. Compared with conventional LEDs scribed by a nanosecond (Ns) laser and single stealth-diced LEDs, the light output power (LOP) of the LEDs using multi-LSD method can be improved by 26.5% and 11.2%, respectively. The enhanced LOP is due to the increased side emission from the large-area roughened sidewalls of the sapphire substrates fabricated in the multi-LSD process. Numerical simulation results show that the multi-LSD process has little thermal damages to the multiple quantum wells (MQWs) of the LEDs.

  15. Light-operated machines based on threaded molecular structures.

    PubMed

    Credi, Alberto; Silvi, Serena; Venturi, Margherita

    2014-01-01

    Rotaxanes and related species represent the most common implementation of the concept of artificial molecular machines, because the supramolecular nature of the interactions between the components and their interlocked architecture allow a precise control on the position and movement of the molecular units. The use of light to power artificial molecular machines is particularly valuable because it can play the dual role of "writing" and "reading" the system. Moreover, light-driven machines can operate without accumulation of waste products, and photons are the ideal inputs to enable autonomous operation mechanisms. In appropriately designed molecular machines, light can be used to control not only the stability of the system, which affects the relative position of the molecular components but also the kinetics of the mechanical processes, thereby enabling control on the direction of the movements. This step forward is necessary in order to make a leap from molecular machines to molecular motors.

  16. 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

  17. 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.

  18. Integrated development of light armored vehicles based on wargaming simulators

    NASA Astrophysics Data System (ADS)

    Palmarini, Marc; Rapanotti, John

    2004-08-01

    Vehicles are evolving into vehicle networks through improved sensors, computers and communications. Unless carefully planned, these complex systems can result in excessive crew workload and difficulty in optimizing the use of the vehicle. To overcome these problems, a war-gaming simulator is being developed as a common platform to integrate contributions from three different groups. The simulator, OneSAF, is used to integrate simplified models of technology and natural phenomena from scientists and engineers with tactics and doctrine from the military and analyzed in detail by operations analysts. This approach ensures the modelling of processes known to be important regardless of the level of information available about the system. Vehicle survivability can be improved as well with better sensors, computers and countermeasures to detect and avoid or destroy threats. To improve threat detection and reliability, Defensive Aids Suite (DAS) designs are based on three complementary sensor technologies including: acoustics, visible and infrared optics and radar. Both active armour and softkill countermeasures are considered. In a typical scenario, a search radar, providing continuous hemispherical coverage, detects and classifies the threat and cues a tracking radar. Data from the tracking radar is processed and an explosive grenade is launched to destroy or deflect the threat. The angle of attack and velocity from the search radar can be used by the soft-kill system to carry out an infrared search and track or an illuminated range-gated scan for the threat platform. Upon detection, obscuration, countermanoeuvres and counterfire can be used against the threat. The sensor suite is completed by acoustic detection of muzzle blast and shock waves. Automation and networking at the platoon level contribute to improved vehicle survivability. Sensor data fusion is essential in avoiding catastrophic failure of the DAS. The modular DAS components can be used with Light Armoured

  19. 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.

  20. Light communication systems. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Reed, W. E.

    1980-09-01

    The design, performance, and application of laser, infrared, and visual communication systems are covered in the cited research reports. Transmission and equipment studies for space, atmospheric, and underwater light communication are presented. Topics covered include lasers, fiber optics, signal processing, transmission links, and data transmission. This updated bibliography contains 87 citations, 59 of which are new entries to the previous edition.

  1. 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.

  2. 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.

  3. 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

  4. Phytochrome mediates red-light-based positive phototropism in Arabidopsis roots

    NASA Astrophysics Data System (ADS)

    Correll, M.; Mullen, J.; Hangarter, R.; Kiss, J.

    Plants rely on sophisticated mechanisms to interpret the constant bombardment of incoming signals so they can adjust their growth accordingly. The environmental cues of gravity and light are particularly important for plant growth and development. While gravitropism has been extensively studied in roots, there has been increased emphasis on understanding the cellular and molecular basis of root phototropism. In addition to the blue-light-based negative phototropism, roots also exhibit a recently discovered positive phototropism in response to red light. In this paper, we characterize this red-light-based phototropism in roots of Arabidopsis.

  5. Elastomer-based opto-thermo-mechanical actuation for autonomous, self-powered light level control.

    PubMed

    Dhakal, Rabin; Kim, Jaeyoun

    2014-09-01

    We present an autonomous, self-powered solar light controller based on functional integration of a flexible cantilever light guide and a paraffin wax-based optothermal actuator. The controller utilizes the optothermally induced volume increase in the elastomer-encapsulated paraffin wax to produce pneumatic force, which subsequently actuates the cantilever light guide to control the level of frustrated total internal reflection. In its linear response regime, it demonstrated 33% reduction in light intensity fluctuation in terms of the root-mean-square value. PMID:25321367

  6. The cinema LED lighting system design based on SCM

    NASA Astrophysics Data System (ADS)

    En, De; Wang, Xiaobin

    2010-11-01

    A LED lighting system in the modern theater and the corresponding control program is introduced. Studies show that moderate and mutative brightness in the space would attract audiences' attention on the screen easily. SCM controls LED dynamically by outputting PWM pulse in different duty cycle. That cinema dome lights' intensity can vary with the plot changed, make people get a better view of experience. This article expounds the architecture of hardware system in the schedule and the control flow of the host of the solution. Besides, it introduces the design of software as well. At last, the system which is proved energy-saving, reliable, good visual effect and having using value by means of producing a small-scale model, which reproduce the whole system and achieves the desired result.

  7. 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.

  8. 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.

  9. Analysis of light emitting diode array lighting system based on human vision: normal and abnormal uniformity condition.

    PubMed

    Qin, Zong; Ji, Chuangang; Wang, Kai; Liu, Sheng

    2012-10-01

    In this paper, condition for uniform lighting generated by light emitting diode (LED) array was systematically studied. To take human vision effect into consideration, contrast sensitivity function (CSF) was novelly adopted as critical criterion for uniform lighting instead of conventionally used Sparrow's Criterion (SC). Through CSF method, design parameters including system thickness, LED pitch, LED's spatial radiation distribution and viewing condition can be analytically combined. In a specific LED array lighting system (LALS) with foursquare LED arrangement, different types of LEDs (Lambertian and Batwing type) and given viewing condition, optimum system thicknesses and LED pitches were calculated and compared with those got through SC method. Results show that CSF method can achieve more appropriate optimum parameters than SC method. Additionally, an abnormal phenomenon that uniformity varies with structural parameters non-monotonically in LALS with non-Lambertian LEDs was found and analyzed. Based on the analysis, a design method of LALS that can bring about better practicability, lower cost and more attractive appearance was summarized.

  10. Effective light absorption and its enhancement factor for silicon nanowire-based solar cell.

    PubMed

    Duan, Zhiqiang; Li, Meicheng; Mwenya, Trevor; Fu, Pengfei; Li, Yingfeng; Song, Dandan

    2016-01-01

    Although nanowire (NW) antireflection coating can enhance light trapping capability, which is generally used in crystal silicon (CS) based solar cells, whether it can improve light absorption in the CS body depends on the NW geometrical shape and their geometrical parameters. In order to conveniently compare with the bare silicon, two enhancement factors E(T) and E(A) are defined and introduced to quantitatively evaluate the efficient light trapping capability of NW antireflective layer and the effective light absorption capability of CS body. Five different shapes (cylindrical, truncated conical, convex conical, conical, and concave conical) of silicon NW arrays arranged in a square are studied, and the theoretical results indicate that excellent light trapping does not mean more light can be absorbed in the CS body. The convex conical NW has the best light trapping, but the concave conical NW has the best effective light absorption. Furthermore, if the cross section of silicon NW is changed into a square, both light trapping and effective light absorption are enhanced, and the Eiffel Tower shaped NW arrays have optimal effective light absorption.

  11. Holographic display with LED illumination based on phase-only spatial light modulator

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Cao, Liangcai; Zhang, Hao; He, Qingsheng

    2012-11-01

    A new holography display technology based on a phase-only spatial light modulator (SLM) is proposed. The normal use of laser diode (LD) light source led to the inevitable speckle noise introduced by the coherence of the laser beam. Algorithms and special diffractive optical elements have been proposed to reduce the speckle noise. In this paper, a selected light-emitted diode (LED) light source was used in the holographic display system to replace the LD light source. The temporal coherence and spatial coherence of the LED were studied. Though the temporal coherence of LED is short, the spatial coherence of the light field can be improved by optimizing the optical paths such as decreasing the emitting area of the light source and so on. A high-power LED with a narrow band-width was selected. An algorithm to generate computer-generated hologram for the SLM was proposed. The phase-only holograms for the display were computed using the coherent light algorithm. Then the phase holograms were uploaded to the SLM. LED was used as the light source to illuminate the SLM uniformly, and the reconstructions can be observed by naked eye. It is demonstrated that LED is an acceptable light source for holographic display. The reconstruction results showed that the speckle noise and multiple reflections were eliminated when LED was used as the light source.

  12. Ultrabright Laser-based MeV-class Light Source

    SciTech Connect

    Albert, F; Anderson, G; Anderson, S; Bayramian, A; Berry, B; Betts, S; Dawson, J; Ebbers, C; Gibson, D; Hagmann, C; Hall, J; Hartemann, F; Hartouni, E; Heebner, J; Hernandez, J; Johnson, M; Messerly, M; McNabb, D; Phan, H; Pruet, J; Semenov, V; Shverdin, M; Sridharan, A; Tremaine, A; Siders, C W; Barty, C J

    2008-04-02

    We report first light from a novel, new source of 10-ps 0.776-MeV gamma-ray pulses known as T-REX (Thomson-Radiated Extreme X-rays). The MeV-class radiation produced by TREX is unique in the world with respect to its brightness, spectral purity, tunability, pulse duration and laser-like beam character. With T-REX, one can use photons to efficiently probe and excite the isotope-dependent resonant structure of atomic nucleus. This ability will be enabling to an entirely new class of isotope-specific, high resolution imaging and detection capabilities.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Large enhancement of light extraction efficiency in AlGaN-based nanorod ultraviolet light-emitting diode structures

    PubMed Central

    2014-01-01

    Light extraction efficiency (LEE) of AlGaN-based nanorod deep ultraviolet (UV) light-emitting diodes (LEDs) is numerically investigated using three-dimensional finite-difference time-domain simulations. LEE of deep UV LEDs is limited by strong light absorption in the p-GaN contact layer and total internal reflection. The nanorod structure is found to be quite effective in increasing LEE of deep UV LEDs especially for the transverse magnetic (TM) mode. In the nanorod LED, strong dependence of LEE on structural parameters such as the diameter of a nanorod and the p-GaN thickness is observed, which can be attributed to the formation of resonant modes inside the nanorod structure. Simulation results show that, when the structural parameters of the nanorod LED are optimized, LEE can be higher than 50% and 60% for the transverse electric (TE) and TM modes, respectively. The nanorod structure is expected to be a good candidate for the application to future high-efficiency deep UV LEDs. PACS 41.20.Jb; 42.72.Bj; 85.60.Jb PMID:24495598

  1. 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

  2. Dye concentration study in PVK based light emitting diodes

    NASA Astrophysics Data System (ADS)

    Gautier-Thianche, E.; Sentein, C.; Nunzi, J.-M.; Lorin, A.; Denis, C.; Raimond, P.

    1998-06-01

    Light emitting diodes made of a single spin-coated layer of poly(9-vinylcarbazole) doped with coumarin-515 dye have been prepared. The influence of dye concentration on emission and electrical characteristics is evidenced. Two different regimes are identified. At low concentrations, hole injection barrier raises, holes are trapped and mobility decreases. External quantum efficiency increases with concentration. At concentrations larger than 10 per electron. Coumarin in a single-layer diode improves electron-hole injection and recombination balance more than an additional hole-blocking layer. Nous avons étudié des DEL constituées d'une monocouche de poly(9-vinylcarbazole) (PVK) dopée avec un colorant laser : la coumarine 515. Le taux de dopage en colorant influe sur les caractéristiques courant - tension et sur le rendement quantique d'électroluminescence. Aux faibles taux de dopage, la hauteur de la barrière d'injection des trous augmente, les trous sont piégés dans la matrice et leur mobilité décroît. Le rendement quantique externe augmente avec la concentration de dopant. Aux concentrations supérieures à 10 photoluminescence chute mais le rendement quantique externe augmente jusqu'à 0.1 recombinaison électron-trou bien mieux qu'une couche supplémentaire bloquant l'injection des trous.

  3. 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

  4. 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 .

  5. Effects of current crowding on light extraction efficiency of conventional GaN-based light-emitting diodes.

    PubMed

    Cao, Bin; Li, Shuiming; Hu, Run; Zhou, Shengjun; Sun, Yi; Gan, Zhiying; Liu, Sheng

    2013-10-21

    Current crowding effects (CCEs) on light extraction efficiency (LEE) of conventional GaN-based light-emitting diodes (LEDs) are analyzed through Monte Carlo ray-tracing simulation. The non-uniform radiative power distribution of the active layer of the Monte Carlo model is obtained based on the current spreading theory and rate equation. The simulation results illustrate that CCE around n-pad (n-CCE) has little effect on LEE, while CCE around p-pad (p-CCE) results in a notable LEE droop due to the significant absorption of photons emitted under p-pad. LEE droop is alleviated by a SiO₂ current blocking layer (CBL) and reflective p-pad. Compared to the conventional LEDs without CBL, the simulated LEE of LEDs with CBL at 20 A/cm² and 70 A/cm² is enhanced by 7.7% and 19.0%, respectively. It is further enhanced by 7.6% and 11.4% after employing a reflective p-pad due to decreased absorption. These enhancements are in accordance with the experimental results. Output power of LEDs with CBL is enhanced by 8.7% and 18.2% at 20 A/cm² and 70 A/cm², respectively. And the reflective p-pad results in a further enhancement of 8.9% and 12.7%.

  6. 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

  7. 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

    2016-06-11

    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.

  8. 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

  9. 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

  10. A Novel GUI Based Interactive Work Flow Application for Exploratory and Batch Processing of Light Curves

    NASA Astrophysics Data System (ADS)

    Morikawa, E.; Dave, R.; Protopapas, P.

    2008-08-01

    Current methodologies for extracting desired data from light curves involves a complicated process that is often not portable to other projects or other disciplines. To create a more generic environment to easily filter, correct, and clean light-curve data from a myriad of sources; we have developed an XML based work-flow application which allows for a standard, yet scalable and flexible way to handle light curve processing. Wrapped in a Python powered interactive GUI, this application offers astronomers an environment to easily experiment with various light curve filtering techniques. Once a favorable filtering process is discovered, the sequence of filters can be stored, reused, and then applied in batch to large set of raw light curves.

  11. 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

  12. 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

  13. A red-light running prevention system based on artificial neural network and vehicle trajectory data.

    PubMed

    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.

  14. 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.

  15. 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.

  16. A novel sensor system for 3D face scanning based on infrared coded light

    NASA Astrophysics Data System (ADS)

    Modrow, Daniel; Laloni, Claudio; Doemens, Guenter; Rigoll, Gerhard

    2008-02-01

    In this paper we present a novel sensor system for three-dimensional face scanning applications. Its operating principle is based on active triangulation with a color coded light approach. As it is implemented in the near infrared band, the used light is invisible for human perception. Though the proposed sensor is primarily designed for face scanning and biometric applications, its performance characteristics are beneficial for technical applications as well. The acquisition of 3d data is real-time capable, provides accurate and high resolution depthmaps and shows high robustness against ambient light. Hence most of the limiting factors of other sensors for 3d and face scanning applications are eliminated, such as blinding and annoying light patterns, motion constraints and highly restricted scenarios due to ambient light constraints.

  17. 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

  18. 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.

  19. [Long optical path gas detection based on MEMS infrared light source].

    PubMed

    Du, Bin-Bin; Zhang, Peng; Gao, Wen-Hong; Shi, Yun-Bo; Zhu, Lin-Quan

    2014-04-01

    According to the requirements of infrared gas sensor for the light source, a broad wavelength, high modulation frequency, low power consumption and small size MEMS infrared light source is chosen as the radiation source, whose performance meets the requirements of infrared sensing system for the light source greatly. However, the infrared light source with the lamberation radiation characteristics is a surface light source, which is still with a large numerical aperture after shaping. It is difficult to increase the detection sensitivity by using a traditional long optical gas cell in a MEMS infrared light source detection system. Based on the dual-wavelength single beam differential detection method, an integrating sphere as the gas cell for long optical path is designed, which is able to realize long optical path for high sensitivity gas detection. The physical dimension is deduced for the equivalent optical path according to the flux conservation principle in the process of light transmission, solving the calculation problem of equivalent optical path of the integrating sphere cell. Using FPGA control chip, the MEMS infrared light source is droved at high frequency modulation and the detector output signal is processed, which makes the external circuit design much simple and flexible. It turns out that 166.7 cm equivalent optical path and the minimum concentration of methane of 0.001 x 10(-6) are achieved by the use of a 5 cm diameter integrating sphere in the research, improving the sensitivity of infrared detection system greatly.

  20. [Long optical path gas detection based on MEMS infrared light source].

    PubMed

    Du, Bin-Bin; Zhang, Peng; Gao, Wen-Hong; Shi, Yun-Bo; Zhu, Lin-Quan

    2014-04-01

    According to the requirements of infrared gas sensor for the light source, a broad wavelength, high modulation frequency, low power consumption and small size MEMS infrared light source is chosen as the radiation source, whose performance meets the requirements of infrared sensing system for the light source greatly. However, the infrared light source with the lamberation radiation characteristics is a surface light source, which is still with a large numerical aperture after shaping. It is difficult to increase the detection sensitivity by using a traditional long optical gas cell in a MEMS infrared light source detection system. Based on the dual-wavelength single beam differential detection method, an integrating sphere as the gas cell for long optical path is designed, which is able to realize long optical path for high sensitivity gas detection. The physical dimension is deduced for the equivalent optical path according to the flux conservation principle in the process of light transmission, solving the calculation problem of equivalent optical path of the integrating sphere cell. Using FPGA control chip, the MEMS infrared light source is droved at high frequency modulation and the detector output signal is processed, which makes the external circuit design much simple and flexible. It turns out that 166.7 cm equivalent optical path and the minimum concentration of methane of 0.001 x 10(-6) are achieved by the use of a 5 cm diameter integrating sphere in the research, improving the sensitivity of infrared detection system greatly. PMID:25007612

  1. Diamond: shedding light on structure-based drug discovery.

    PubMed

    Brown, David G; Shotton, Elizabeth J

    2015-03-01

    Structure-based drug design has become a key tool for the development of novel drugs. The process involves elucidating the three-dimensional structure of the potential drug molecule bound to the target protein that has been identified as playing a key role in the disease state. Using this three-dimensional information facilitates the process of making improvements to the potential drug molecule by highlighting existing and possible new interactions within the binding site. This knowledge is used to inform increases in potency and selectivity of the molecules as well as to help improve other drug-like properties. The speed and numbers of samples that can be studied, combined with the improved resolution of the structures that can be obtained using synchrotron radiation, have had a significant impact on the utilization of crystallography in the drug discovery process. PMID:25624512

  2. 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.

  3. 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

  4. 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.

  5. Watermarking scheme for microlens-array-based four-dimensional light field imaging.

    PubMed

    Lu, Yucheng; You, Suping; Zhang, Wei; Yang, Bo; Peng, Runling; Zhuang, Songlin

    2016-05-01

    This paper proposes a watermark scheme for lenslet-based light field imaging operating on its 4D Fourier domain. In this scheme, the computational light field of the 2D watermark is first obtained. A slice of its frequency spectrum is then generated. After that, the watermark is embedded into the host light field by slice displacement. The experimental simulations show that the proposed scheme is simple in complexity while the robustness is strong. In addition, it does not bring significant artifacts or distortion into the refocused image or the depth map.

  6. 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

  7. Rapidly reconfigurable slow-light system based on off-resonant Raman absorption

    NASA Astrophysics Data System (ADS)

    Vudyasetu, Praveen K.; Camacho, Ryan M.; Howell, John C.

    2010-11-01

    We present a slow-light system based on dual Raman absorption resonances in warm rubidium vapor. Each Raman absorption resonance is produced by a control beam in an off-resonant Λ system. This system combines all optical control of the Raman absorption and the low-dispersion broadening properties of the double Lorentzian absorption slow light. The bandwidth, group delay, and central frequency of the slow-light system can all be tuned dynamically by changing the properties of the control beam. We demonstrate multiple pulse delays with low distortion and show that such a system has fast switching dynamics and thus fast reconfiguration rates.

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

    SciTech Connect

    Qian, Chengliang

    2006-01-01

    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 τ 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. τ was measured as a function of the lactate concentration; as the lactate concentration increases, τ 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 ~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.

  9. 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

  10. All-optical atomic magnetometers based on nonlinear magneto-optical rotation with amplitude modulated light

    NASA Astrophysics Data System (ADS)

    Pustelny, Szymon; Wojciechowski, Adam; Kotyrba, Mateusz; Sycz, Krystian; Zachorowski, Jerzy; Gawlik, Wojciech; Cingoz, Arman; Leefer, Nathan; Higbie, James M.; Corsini, Eric; Ledbetter, Micah P.; Rochester, Simon M.; Sushkov, Alexander O.; Budker, Dmitry

    2007-03-01

    We demonstrate a magnetometric technique based on nonlinear magneto-optical rotation using amplitude modulated light. The magnetometers can be operated in either open-loop (typical nonlinear magneto-optical rotation with amplitude-modulated light) or closed-loop (self-oscillating) modes. The latter mode is particularly well suited for conditions where the magnetic field is changing by large amounts over a relatively short timescale.

  11. 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

  12. 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.

  13. Fast visible light photoelectric switch based on ultralong single crystalline V₂O₅ nanobelt.

    PubMed

    Lu, Jianing; Hu, Ming; Tian, Ye; Guo, Chuanfei; Wang, Chuang; Guo, Shengming; Liu, Qian

    2012-03-26

    A photoelectric switch with fast response to visible light (<200 μs), suitable photosensitivity and excellent repeatability is proposed based on the ultralong single crystalline V₂O₅ nanobelt, which are synthesized by chemical vapor deposition and its photoconductive mechanism can well be explained by small polaron hopping theory. Our results reveal that the switch has a great potential in next generation photodetectors and light-wave communications.

  14. 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

  15. Tetrastyryl-BODIPY-based dendritic light harvester and estimation of energy transfer efficiency.

    PubMed

    Kostereli, Ziya; Ozdemir, Tugba; Buyukcakir, Onur; Akkaya, Engin U

    2012-07-20

    Versatile BODIPY dyes can be transformed into bright near-IR-emitting fluorophores by quadruple styryl substitutions. When clickable functionalities on the styryl moieties are inserted, an efficient synthesis of a light harvester is possible. In addition, clear spectral evidence is presented showing that, in dendritic light harvesters, calculations commonly based on quantum yield or emission lifetime changes of the donor are bound to yield large overestimations of energy transfer efficiency.

  16. 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.

  17. Enhancing light extraction mechanisms of GaN-based light-emitting diodes through the integration of imprinting microstructures, patterned sapphire substrates, and surface roughness.

    PubMed

    Lee, Yeeu-Chang; Ni, Ching-Huai; Chen, Chih-Yeeu

    2010-11-01

    Analysis of the various light extraction efficiency enhancement mechanisms for the GaN-based light emitting diodes (LEDs) was investigated. Experiments utilized the imprinting technique to fabricate pyramid and inverted pyramid microstructures. Roughness treatment was then integrated with these imprinting structures on patterned sapphire substrate (PSS) LEDs. An approximate 33% improvement in light output power was obtained using the pyramid profile when compared with the planar LED. This was nearly 15% higher than that of the inverted pyramid profile. The roughness effect provided an approximate 5% efficiency enhancement. The total light enhanced efficiency increased to 85.9% by integrating the imprinting pyramid structure, PSS, and surface roughness.

  18. 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

  19. 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

  20. 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

  1. Design method of a light emitting diode front fog lamp based on a freeform reflector

    NASA Astrophysics Data System (ADS)

    Wu, Heng; Zhang, Xianmin; Ge, Peng

    2015-09-01

    We propose a method for the design of a light emitting diode front fog lamp based on a freeform reflector. The source-target mapping is used to establish the relationship between the solid angle of the source and the target plane. The reflector is then constructed based on the non-imaging optics theory and Snell's law. A feedback function is deduced from the deviation in the simulated light pattern based on the sampling method. The reflector is then regenerated with feedback modifications and the variance is minimized after several feedbacks. A reflector for the automobile front fog lamp is designed for the OSTAR Headlamp LED source whose emitting surface is 2.8 mm×2.5 mm. Simulation results indicate that the light performance can well meet the standard of the front fog lamps in ECE R19 Revision 7.

  2. Design method of a light-emitting diode front fog lamp based on a freeform reflector

    NASA Astrophysics Data System (ADS)

    Wu, Heng; Zhang, Xianmin; Ge, Peng

    2015-06-01

    We propose a method for the design of a light-emitting diode front fog lamp based on a freeform reflector. The source-target mapping is used to establish the relationship between the solid angle of the source and the target plane. The reflector is then constructed based on the non-imaging optics theory and Snell's Law. A feedback function is deduced from the deviation in the simulated light pattern based on the sampling method. The reflector is then regenerated with feedback modifications and the variance is minimized after several feedbacks. A reflector for the automobile front fog lamp is designed for the OSTAR Headlamp LED source whose emitting surface is 2.8 mm×2.5 mm. Simulation results indicate that the light performance can well meet the standard of the front fog lamps in ECE R19 Revision 7.

  3. 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

  4. 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.

  5. REANALYSIS OF THE NEAR-INFRARED EXTRAGALACTIC BACKGROUND LIGHT BASED ON THE IRTS OBSERVATIONS

    SciTech Connect

    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.

  6. 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

  7. 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

    2015-04-08

    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.

  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. 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

  10. 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.

  11. 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.

  12. 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),…

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. Modeling spectral sensitivity at low light levels based on mesopic visual performance.

    PubMed

    Viikari, Meri; Ekrias, Aleksanteri; Eloholma, Marjukka; Halonen, Liisa

    2008-03-01

    The spectral sensitivity of the eye at low light levels, ie, mesopic conditions, is determined by the rod and cone photoreceptors of the retina operating together in varying degree as adaptation luminance shifts between the scotopic and photopic. Thus mesopic spectral sensitivity is different from photopic, where only cones contribute to vision. There are definite needs for a practical system of mesopic photometry to be used in assessing light at low light levels, especially in road and other outdoor lighting applications. However, neither of the recently proposed systems of mesopic photometry, the MOVE-model or the X-model, is found satisfactory by common consent of the lighting community. The most active debate has considered the upper luminance limit of the mesopic region, which is regarded to be too high for the MOVE-model and too low for the X-model. The present paper proposes a new modified MOVE-model whose upper luminance limit is adjusted to meet the actual road and street lighting luminance values measured in different weather conditions. The paper compares the MOVE-model, X-model, and the proposed modified MOVE-model with three independent visual performance data sets provided by different European universities. Based on the comparison, recommendations are given for future actions towards internationally accepted practice for mesopic photometry.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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).

  11. 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

  12. Light-extraction enhancement in GaN-based light-emitting diodes using grade-refractive-index amorphous titanium oxide films with porous structures

    SciTech Connect

    Liu, D.-S.; Lin, T.-W.; Huang, B.-W.; Juang, F.-S.; Lei, P.-H.; Hu, C.-Z.

    2009-04-06

    Amorphous titanium oxide (a-TiO{sub x}:OH) films prepared by plasma-enhanced chemical-vapor deposition at 200 and 25 deg. C are in turn deposited onto the GaN-based light-emitting diode (LED) to enhance the associated light extraction efficiency. The refractive index, porosity, and photocatalytic effect of the deposited films are correlated strongly with the deposition temperatures. The efficiency is enhanced by a factor of {approx}1.31 over that of the uncoated LEDs and exhibited an excellent photocatalytic property after an external UV light irradiation. The increase in the light extraction is related to the reduction in the Fresnel transmission loss and the enhancement of the light scattering into the escape cone by using the graded-refractive-index a-TiO{sub x}:OH film with porous structures.

  13. 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.

  14. 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.

  15. Investigation of self-adaptive LED surgical lighting based on entropy contrast enhancing method

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Wang, Huihui; Zhang, Yaqin; Shen, Junfei; Wu, Rengmao; Zheng, Zhenrong; Li, Haifeng; Liu, Xu

    2014-05-01

    Investigation was performed to explore the possibility of enhancing contrast by varying the spectral distribution (SPD) of the surgical lighting. The illumination scenes with different SPDs were generated by the combination of a self-adaptive white light optimization method and the LED ceiling system, the images of biological sample are taken by a CCD camera and then processed by an 'Entropy' based contrast evaluation model which is proposed specific for surgery occasion. Compared with the neutral white LED based and traditional algorithm based image enhancing methods, the illumination based enhancing method turns out a better performance in contrast enhancing and improves the average contrast value about 9% and 6%, respectively. This low cost method is simple, practicable, and thus may provide an alternative solution for the expensive visual facility medical instruments.

  16. 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

  17. Enhancing the sensitivity of liquid refractive index sensor based on slow light photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Zhao, Yong; Huang, He; Wang, Qi

    2011-05-01

    This paper designed a high sensitivity refractive index sensor based on two-dimensional square-lattice slow light photonic crystal waveguide. This structure based on Mach-Zehnder interferometer (MZI) which can be widely used in measuring the refractive index of liquid. The resolution of this sample structure can reach 7×10-7 RIU. This kind of sensor can be integrated with electronic systems to measure the refractive index of gas or fluid.

  18. 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.

  19. Design of a bike headlamp based on a power white-light-emitting diode

    NASA Astrophysics Data System (ADS)

    Lo, Yi-Chien; Chen, Cheng-Chien; Chou, Hung-Yu; Yang, Kai-Yu; Sun, Ching-Cherng

    2011-08-01

    In this letter, we present a new design for a light-emitting diode- based bike headlamp. The optical design contains two horizontal reflectors and a light pipe with two horizontal parallel mirrors. The designed illumination pattern in our simulations performs a contrast of 250 in the K-mark regulation, and it was measured to be 21 in the experiment with a not well-finished prototype, which was operated at 1 W. The contrast is higher than 5 as requested in the regulation.

  20. Lightness-difference data set for evaluation of CIELAB-based color-difference formulae

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Ho; Song, Hee-Kang; Kim, Jae-Pil

    2002-06-01

    A new color-difference data set has been produced to evaluate the lightness difference weighting functions of eight CIELAB-based formulae: CIELAB, CMC, CIE94, DCI-95, LCD97, LCD99, BFD-II and CIEDE2000. Glossy polyester fabric was dyed to prepare 220 color-difference pairs, each having mainly lightness-difference. The gray-scale method was used to assess the color-difference of each pair by an average of twenty-five color normal observers. The test results of the visual data are presented.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. [The Performance Analysis for Lighting Sources in Highway Tunnel Based on Visual Function].

    PubMed

    Yang, Yong; Han, Wen-yuan; Yan, Ming; Jiang, Hai-feng; Zhu, Li-wei

    2015-10-01

    Under the condition of mesopic vision, the spectral luminous efficiency function is shown as a series of curves. Its peak wavelength and intensity are affected by light spectrum, background brightness and other aspects. The impact of light source to lighting visibility could not be carried out via a single optical parametric characterization. The reaction time of visual cognition is regard as evaluating indexes in this experiment. Under the condition of different speed and luminous environment, testing visual cognition based on vision function method. The light sources include high pressure sodium, electrodeless fluorescent lamp and white LED with three kinds of color temperature (the range of color temperature is from 1 958 to 5 537 K). The background brightness value is used for basic section of highway tunnel illumination and general outdoor illumination, its range is between 1 and 5 cd x m(-)2. All values are in the scope of mesopic vision. Test results show that: under the same condition of speed and luminance, the reaction time of visual cognition that corresponding to high color temperature of light source is shorter than it corresponding to low color temperature; the reaction time corresponding to visual target in high speed is shorter than it in low speed. At the end moment, however, the visual angle of target in observer's visual field that corresponding to low speed was larger than it corresponding to high speed. Based on MOVE model, calculating the equivalent luminance of human mesopic vision, which is on condition of different emission spectrum and background brightness that formed by test lighting sources. Compared with photopic vision result, the standard deviation (CV) of time-reaction curve corresponding to equivalent brightness of mesopic vision is smaller. Under the condition of mesopic vision, the discrepancy between equivalent brightness of different lighting source and photopic vision, that is one of the main reasons for causing the

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  13. 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

  14. 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.

  15. An adaptive scaling and biasing scheme for OFDM-based visible light communication systems.

    PubMed

    Wang, Zhaocheng; Wang, Qi; Chen, Sheng; Hanzo, Lajos

    2014-05-19

    Orthogonal frequency-division multiplexing (OFDM) has been widely used in visible light communication systems to achieve high-rate data transmission. Due to the nonlinear transfer characteristics of light emitting diodes (LEDs) and owing the high peak-to-average-power ratio of OFDM signals, the transmitted signal has to be scaled and biased before modulating the LEDs. In this contribution, an adaptive scaling and biasing scheme is proposed for OFDM-based visible light communication systems, which fully exploits the dynamic range of the LEDs and improves the achievable system performance. Specifically, the proposed scheme calculates near-optimal scaling and biasing factors for each specific OFDM symbol according to the distribution of the signals, which strikes an attractive trade-off between the effective signal power and the clipping-distortion power. Our simulation results demonstrate that the proposed scheme significantly improves the performance without changing the LED's emitted power, while maintaining the same receiver structure. PMID:24921387

  16. Pipeline inwall 3D measurement system based on the cross structured light

    NASA Astrophysics Data System (ADS)

    Shen, Da; Lin, Zhipeng; Xue, Lei; Zheng, Qiang; Wang, Zichi

    2014-01-01

    In order to accurately realize the defect detection of pipeline inwall, this paper proposes a measurement system made up of cross structured light, single CCD camera and a smart car, etc. Based on structured light measurement technology, this paper mainly introduces the structured light measurement system, the imaging mathematical model, and the parameters and method of camera calibration. Using these measuring principles and methods, the camera in remote control car platform achieves continuous shooting of objects and real-time rebound processing as well as utilizing established model to extract 3D point cloud coordinate to reconstruct pipeline defects, so it is possible to achieve 3D automatic measuring, and verifies the correctness and feasibility of this system. It has been found that this system has great measurement accuracy in practice.

  17. 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).

  18. 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

  19. 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

  20. 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

  1. 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

  2. Global patterns of phytoplankton nutrient and light colimitation inferred from an optimality-based model

    NASA Astrophysics Data System (ADS)

    Arteaga, Lionel; Pahlow, Markus; Oschlies, Andreas

    2014-07-01

    The widely used concept of constant "Redfield" phytoplankton stoichiometry is often applied for estimating which nutrient limits phytoplankton growth in the surface ocean. Culture experiments, in contrast, show strong relations between growth conditions and cellular stoichiometry with often substantial deviations from Redfield stoichiometry. Here we investigate to what extent both views agree by analyzing remote sensing and in situ data with an optimality-based model of nondiazotrophic phytoplankton growth in order to infer seasonally varying patterns of colimitation by light, nitrogen (N), and phosphorus (P) in the global ocean. Our combined model-data analysis suggests strong N and N-P colimitation in the tropical ocean, seasonal light, and N-P colimitation in the Northern Hemisphere, and strong light limitation only during winter in the Southern Ocean. The eastern equatorial Pacific appears as the only ocean area that is essentially not limited by N, P, or light. Even though our optimality-based approach specifically accounts for flexible stoichiometry, inferred patterns of N and P limitation are to some extent consistent with those obtained from an analysis of surface inorganic nutrients with respect to the Redfield N:P ratio. Iron is not part of our analysis, implying that we cannot accurately predict N cell quotas in high-nutrient, low-chlorophyll regions. Elsewhere, we do not expect a major effect of iron on the relative distribution of N, P, and light colimitation areas. The relative importance of N, P, and light in limiting phytoplankton growth diagnosed here by combining observations and an optimal growth model provides a useful constraint for models used to predict future marine biological production under changing environmental conditions. 2014. American Geophysical Union. All Rights Reserved.

  3. 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.

  4. 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.

  5. 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.

  6. Individuality evaluation for paper based artifact-metrics using transmitted light image

    NASA Astrophysics Data System (ADS)

    Yamakoshi, Manabu; Tanaka, Junichi; Furuie, Makoto; Hirabayashi, Masashi; Matsumoto, Tsutomu

    2008-02-01

    Artifact-metrics is an automated method of authenticating artifacts based on a measurable intrinsic characteristic. Intrinsic characters, such as microscopic random-patterns made during the manufacturing process, are very difficult to copy. A transmitted light image of the distribution can be used for artifact-metrics, since the fiber distribution of paper is random. Little is known about the individuality of the transmitted light image although it is an important requirement for intrinsic characteristic artifact-metrics. Measuring individuality requires that the intrinsic characteristic of each artifact significantly differs, so having sufficient individuality can make an artifact-metric system highly resistant to brute force attack. Here we investigate the influence of paper category, matching size of sample, and image-resolution on the individuality of a transmitted light image of paper through a matching test using those images. More concretely, we evaluate FMR/FNMR curves by calculating similarity scores with matches using correlation coefficients between pairs of scanner input images, and the individuality of paper by way of estimated EER with probabilistic measure through a matching method based on line segments, which can localize the influence of rotation gaps of a sample in the case of large matching size. As a result, we found that the transmitted light image of paper has a sufficient individuality.

  7. Three-visible-light wave combiner based on photonic crystal microcavities.

    PubMed

    Zhou, Xiaoyi; Liu, Dingwen; Sun, Yiling; Ouyang, Zhengbiao

    2015-08-01

    We propose a three-visible-light wave combiner based on two-dimensional square-lattice photonic crystal (PhC) microcavities. A coupled-cavity waveguide is introduced to reduce the insertion losses for the three waves in the combiner. The transmission characteristic of light waves in PhCs with point defects is analyzed. As an example, a combiner for combining light waves of 488, 532, and 635 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 three visible light waves of 488, 532, and 635 nm are output at the same output port with transmittances of 97.6%, 98.1%, and 90.0%, respectively. The results show that the proposed device can perform efficient synthesis and the designing method can be applied in building other combiners based on PhCs made of dispersion materials.

  8. 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.

  9. 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.

  10. Imaging camera system of OYGBR-phosphor-based white LED lighting

    NASA Astrophysics Data System (ADS)

    Kobashi, Katsuya; Taguchi, Tsunemasa

    2005-03-01

    The near-ultraviolet (nUV) white LED approach is analogous to three-color fluorescent lamp technology, which is based on the conversion of nUV radiation to visible light via the photoluminescence process in phosphor materials. The nUV light is not included in the white light generation from nUV-based white LED devices. This technology can thus provide a higher quality of white light than the blue and YAG method. A typical device demonstrates white luminescence with Tc=3,700 K, Ra > 93, K > 40 lm/W and chromaticity (x, y) = (0.39, 0.39), respectively. The orange, yellow, green and blue OYGB) or orange, yellow, red, green and blue (OYRGB) device shows a luminescence spectrum broader than of an RGB white LED and a better color rendering index. Such superior luminous characteristics could be useful for the application of several kinds of endoscope. We have shown the excellent pictures of digestive organs in a stomach of a dog due to the strong green component and high Ra.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. Light-extraction efficiency control in AlGaN-based deep-ultraviolet flip-chip light-emitting diodes: a comparison to InGaN-based visible flip-chip light-emitting diodes.

    PubMed

    Lee, Keon Hwa; Park, Hyun Jung; Kim, Seung Hwan; Asadirad, Mojtaba; Moon, Yong-Tae; Kwak, Joon Seop; Ryou, Jae-Hyun

    2015-08-10

    We study light-extraction efficiency (LEE) of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) using flip-chip (FC) devices with varied thickness in remaining sapphire substrate by experimental output power measurement and computational methods using 3-dimensional finite-difference time-domain (3D-FDTD) and Monte Carlo ray-tracing simulations. Light-output power of DUV-FCLEDs compared at a current of 20 mA increases with thicker sapphire, showing higher LEE for an LED with 250-μm-thick sapphire by ~39% than that with 100-μm-thick sapphire. In contrast, LEEs of visible FCLEDs show only marginal improvement with increasing sapphire thickness, that is, ~6% improvement for an LED with 250-μm-thick sapphire. 3D-FDTD simulation reveals a mechanism of enhanced light extraction with various sidewall roughness and thickness in sapphire substrates. Ray tracing simulation examines the light propagation behavior of DUV-FCLED structures. The enhanced output power and higher LEE strongly depends on the sidewall roughness of the sapphire substrate rather than thickness itself. The thickness starts playing a role only when the sapphire sidewalls become rough. The roughened surface of sapphire sidewall during chip-separation process is critical for TM-polarized photons from AlGaN quantum wells to escape in lateral directions before they are absorbed by p-GaN and Au-metal. Furthermore, the ray tracing results show a reasonably good agreement with the experimental result of the LEE.

  16. 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.

  17. Light illumination and detection patterns for fluorescence diffuse optical tomography based on compressive sensing.

    PubMed

    Jin, An; Yazici, Birsen; Ntziachristos, Vasilis

    2014-06-01

    Fluorescence diffuse optical tomography (FDOT) is an emerging molecular imaging modality that uses near infrared light to excite the fluorophore injected into tissue; and to reconstruct the fluorophore concentration from boundary measurements. The FDOT image reconstruction is a highly ill-posed inverse problem due to a large number of unknowns and limited number of measurements. However, the fluorophore distribution is often very sparse in the imaging domain since fluorophores are typically designed to accumulate in relatively small regions. In this paper, we use compressive sensing (CS) framework to design light illumination and detection patterns to improve the reconstruction of sparse fluorophore concentration. Unlike the conventional FDOT imaging where spatially distributed light sources illuminate the imaging domain one at a time and the corresponding boundary measurements are used for image reconstruction, we assume that the light sources illuminate the imaging domain simultaneously several times and the corresponding boundary measurements are linearly filtered prior to image reconstruction. We design a set of optical intensities (illumination patterns) and a linear filter (detection pattern) applied to the boundary measurements to improve the reconstruction of sparse fluorophore concentration maps. We show that the FDOT sensing matrix can be expressed as a columnwise Kronecker product of two matrices determined by the excitation and emission light fields. We derive relationships between the incoherence of the FDOT forward matrix and these two matrices, and use these results to reduce the incoherence of the FDOT forward matrix. We present extensive numerical simulation and the results of a real phantom experiment to demonstrate the improvements in image reconstruction due to the CS-based light illumination and detection patterns in conjunction with relaxation and greedy-type reconstruction algorithms.

  18. 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,...

  19. 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,...

  20. 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,...

  1. 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,...

  2. Live imaging of Tribolium castaneum embryonic development using light-sheet-based fluorescence microscopy.

    PubMed

    Strobl, Frederic; Schmitz, Alexander; Stelzer, Ernst H K

    2015-10-01

    Tribolium castaneum has become an important insect model organism for evolutionary developmental biology, genetics and biotechnology. However, few protocols for live fluorescence imaging of Tribolium have been reported, and little image data is available. Here we provide a protocol for recording the development of Tribolium embryos with light-sheet-based fluorescence microscopy. The protocol can be completed in 4-7 d and provides procedural details for: embryo collection, microscope configuration, embryo preparation and mounting, noninvasive live imaging for up to 120 h along multiple directions, retrieval of the live embryo once imaging is completed, and image data processing, for which exemplary data is provided. Stringent quality control criteria for developmental biology studies are also discussed. Light-sheet-based fluorescence microscopy complements existing toolkits used to study Tribolium development, can be adapted to other insect species, and requires no advanced imaging or sample preparation skills.

  3. 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

  4. Bright Light-Emitting Diodes Based on Organometal Halide Perovskite Nanoplatelets.

    PubMed

    Ling, Yichuan; Yuan, Zhao; Tian, Yu; Wang, Xi; Wang, Jamie C; Xin, Yan; Hanson, Kenneth; Ma, Biwu; Gao, Hanwei

    2016-01-13

    Bright light-emitting diodes based on solution-processable organometal halide perovskite nanoplatelets are demonstrated. The nanoplatelets created using a facile one-pot synthesis exhibit narrow-band emissions at 529 nm and quantum yield up to 85%. Using these nanoparticles as emitters, efficient electroluminescence is achieved with a brightness of 10 590 cd m(-2) . These ligand-capped nanoplatelets appear to be quite stable in moisture, allowing out-of-glovebox device fabrication.

  5. On-chip silicon-based active photonic molecules by complete photonic bandgap light confinement

    NASA Astrophysics Data System (ADS)

    Qian, Bo; Chen, Kunji; Chen, San; Li, Wei; Zhang, Xiangao; Xu, Jun; Huang, Xinfan; Pavesi, Lorenzo; Jiang, Chunping

    2011-07-01

    We demonstrate an on-chip silicon-based active photonic molecule (PM) structures formed by two coupled photonic quantum dots with complete photonic bandgap (PBG) light confinement. The photonic quantum dots are grown by conformal deposition of amorphous silicon nitride multilayers on patterned substrates. A fine structure of the coupled optical modes in PMs has been observed which shows similarity to the electronic bonding (BN) and antibonding (ABN) states in a molecule.

  6. 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.

  7. Three-dimensional indoor light positioning algorithm based on nonlinear estimation

    NASA Astrophysics Data System (ADS)

    Gu, Wenjun; Kavehrad, Mohsen; Aminikashani, Mohammadreza

    2016-02-01

    With the development of location based services (LBS), indoor positioning has been a popular research topic in recent years. Since global positioning system (GPS) signal suffers from severe attenuation when penetrating through solid walls, other alternatives are proposed to realize indoor positioning. Visible light communication (VLC) systems offer a practical solution. Light emitting diode (LED) is able to be modulated in high speed as a transmitter, and a photodiode (PD) is commonly a receiver to detect the optical signal strength. In VLC based indoor positioning system, LEDs are applied for both positioning and illumination purposes so that infrastructure cost and power consumption are decreased. In addition, light positioning system provides other advantages such as no electromagnetic interference and better immunity against multipath reflections. Several methods are proposed to realize indoor positioning, such as triangulation, scene analysis and proximity, which are also applicable for a VLC based system. In prior works, the height of receiver is known so that the coordinates on the horizontal plane can be calculated. In this paper, the proposed method includes two stages: the height is presumed in the prediction stage and nonlinear estimation is applied in the correction stage to realize three dimensional coordinate estimation.

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

    PubMed

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

    2009-01-01

    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. PMID:19405760

  9. 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.

  10. 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.

  11. 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

  12. Light scattering measurement in an arc lamp-based flow cytometer.

    PubMed

    Steen, H B

    1990-01-01

    The epi-illumination optics employed in most arc lamp-based flow cytometers may be modified so as to produce a dark-field configuration which facilitates highly sensitive detection of both forward and large angle light scattering in an instrument with a "jet on open surface" flow chamber. Forward scattering is detected at angles upwards from about 2 degrees, while large angle scattering includes angles above 18 degrees. Theoretical considerations suggest that large angle scattering measured around 20 degrees may be as efficient as that measured at 90 degrees for the purpose of distinguishing cells on the basis of intracellular structure. This was supported by the finding that dual parameter light scattering histograms of leukocyte suspensions obtained with the arc lamp-based instrument were closely similar to such histograms recorded with a laser-based instrument with the large angle detector at 90 degrees. Different species of bacteria could be distinguished by means of the dual parameter light scattering device, as could different species of sea algae. The sensitivity of the device is sufficient to measure 0.2 microns polystyrene particles in both forward and large angle scattering.

  13. 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

  14. 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.

  15. Light-addressable measurements of cellular oxygen consumption rates in microwell arrays based on phase-based phosphorescence lifetime detection

    PubMed Central

    Huang, Shih-Hao; Hsu, Yu-Hsuan; Wu, Chih-Wei; Wu, Chang-Jer

    2012-01-01

    A digital light modulation system that utilizes a modified commercial digital micromirror device (DMD) projector, which is equipped with a UV light-emitting diode as a light modulation source, has been developed to spatially direct excited light toward a microwell array device to detect the oxygen consumption rate (OCR) of single cells via phase-based phosphorescence lifetime detection. The microwell array device is composed of a combination of two components: an array of glass microwells containing Pt(II) octaethylporphine (PtOEP) as the oxygen-sensitive luminescent layer and a microfluidic module with pneumatically actuated glass lids set above the microwells to controllably seal the microwells of interest. By controlling the illumination pattern on the DMD, the modulated excitation light can be spatially projected to only excite the sealed microwell for cellular OCR measurements. The OCR of baby hamster kidney-21 fibroblast cells cultivated on the PtOEP layer within a sealed microwell has been successfully measured at 104 ± 2.96 amol s−1 cell−1. Repeatable and consistent measurements indicate that the oxygen measurements did not adversely affect the physiological state of the measured cells. The OCR of the cells exhibited a good linear relationship with the diameter of the microwells, ranging from 400 to 1000 μm and containing approximately 480 to 1200 cells within a microwell. In addition, the OCR variation of single cells in situ infected by Dengue virus with a different multiplicity of infection was also successfully measured in real-time. This proposed platform provides the potential for a wide range of biological applications in cell-based biosensing, toxicology, and drug discovery. PMID:24348889

  16. 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

  17. Partial gating image intensifier based on liquid crystal auto-controlling light intensity

    NASA Astrophysics Data System (ADS)

    Zhang, Ruixia; Tang, Yuanhe; Liu, Kai; Liu, Hanchen; Yang, Xusan; Gao, Haiyang; Liang, Yuan; Li, Qing; Ye, Na; Zhao, Gaoxiang

    2008-12-01

    In order to enlarge the dynamic range of image intensifier, and CCD can work normally under the strong light (105lx), based on the generation II image intensifier, we have brought forward an novel equipment of double lens optical system including a liquid crystal panel (twisted nematic liquid crystal panel LCX023-CMT) and a photometric CCD which detects the illuminance real-time. The light intensity is controlled by liquid crystal automatically and the partial gating can be realized. The principle of auto-controlling light intensity is introduced detailedly in this paper. And the transmittance of liquid crystal has been simulated. Experimental result displays that the optical transmittance changed from 1.28% to 25.60% with the gray levels from 0 to 250. The high linearity relation of transmittance to gray levels is obtained when the gray levels change from 90 to 220. The feasibility of partial light intensity auto-controlled by liquid crystal has been further proved by the two obvious contrast pictures that one is photographed with the liquid crystal panel and another without.

  18. 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.

  19. 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.

  20. 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.

  1. High Power, Computer-Controlled, LED-Based Light Sources for Fluorescence Imaging and Image-Guided Surgery

    PubMed Central

    Gioux, Sylvain; Kianzad, Vida; Ciocan, Razvan; Gupta, Sunil; Oketokoun, Rafiou; Frangioni, John V.

    2009-01-01

    Optical imaging requires appropriate light sources. For image-guided surgery, and in particular fluorescence-guided surgery, high fluence rate, long working distance, computer control, and precise control of wavelength are required. In this study, we describe the development of light emitting diode (LED)-based light sources that meet these criteria. These light sources are enabled by a compact LED module that includes an integrated linear driver, heat-dissipation technology, and real-time temperature monitoring. Measuring only 27 mm W by 29 mm H, and weighing only 14.7 g, each module provides up to 6500 lx of white (400-650 nm) light and up to 157 mW of filtered fluorescence excitation light, while maintaining an operating temperature ≤ 50°C. We also describe software that can be used to design multi-module light housings, and an embedded processor that permits computer control and temperature monitoring. With these tools, we constructed a 76-module, sterilizable, 3-wavelength surgical light source capable of providing up to 40,000 lx of white light, 4.0 mW/cm2 of 670 nm near-infrared (NIR) fluorescence excitation light, and 14.0 mW/cm2 of 760 nm NIR fluorescence excitation light over a 15-cm diameter field-of-view. Using this light source, we demonstrate NIR fluorescence-guided surgery in a large animal model. PMID:19723473

  2. 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

  3. Broadening-free SBS-based slow and fast light in optical fibers

    NASA Astrophysics Data System (ADS)

    Schneider, Thomas; Wiatrek, Andrzej

    2013-03-01

    To change the group velocity of optical signals has a lot of possible applications in telecommunications, sensing, nonlinear optics and so on. Especially the exploitation of the effect of stimulated Brillouin scattering (SBS) in optical fibers is of special interest since it just requires standard telecom equipment and low to moderate optical power. However, each delay in one single, low-gain SBS based slow-light system is accompanied by pulse broadening. This is a result of the inherent Kramers-Kronig relations between the gain, the phase-change and the accompanied group velocity. For an ideal flat gain the phase-change is non-ideal, and for an ideal phase-change the gain curve leads to a broadening. Furthermore, if the gain bandwidth is broadened in order to adapt it to the signal, the delay will be reduced. Thus, for one single low-gain slow-light system the broadening can be reduced by several methods but it cannot be zero. Here we will show how a zero-broadening SBS based slow-light system can be achieved by two different methods. The basic idea is a reshaping of the original pulse by an adapted gain in a second stage. This adaptation is achieved by the superposition of two Gaussian gain profiles or by a single saturated gain. As will be shown, these systems show an almost ideal over-all gain and phase function over the bandwidth of the pulses. Thus, SBS based slow-light with a delaybandwidth product of more than 1 bit and zero distortion is possible.

  4. STUDY OF GENERIC FRONT-END DESIGNS FOR ERL BASED LIGHT SOURCES

    SciTech Connect

    Guimei Wang; Yu-Chiu Chao; KUI Zhao; Xiangyang Lu; Jiejia Zhuang; Chuyu Liu; Jiaer Chen; George Neil; Pavel Evtushenko

    2007-06-01

    We present work directed at examining the performance of various front end components of an ERL based light source. These include electron source, bunch compression, merger, and accelerating sections, with parameter space dictated by proposed facilities (at FSU and Beijing University). These facilities share enough common structural features to make the study applicable to both to a large extent. In this report we will discuss the 6D phase space evolution through the front end based on simulation, with reliable modeling of magnetic and superconducting RF fields. Discussion will be devoted to relative merits of alternative designs, robustness and operational scenarios.

  5. Low-cost vibration sensor based on dual fiber Bragg gratings and light intensity measurement.

    PubMed

    Gao, Xueqing; Wang, Yongjiao; Yuan, Bo; Yuan, Yinquan; Dai, Yawen; Xu, Gang

    2013-09-20

    A vibration monitoring system based on light intensity measurement has been constructed, and the designed accelerometer is based on steel cantilever frame and dual fiber Bragg gratings (FBGs). By using numerical simulations for the dual FBGs, the dependence relationship of the area of main lobes on the difference of initial central wavelengths is obtained and the most optimal choice for the initial value and the vibration amplitude of the difference of central wavelengths of two FBGs is suggested. The vibration monitoring experiments are finished, and the measured data are identical to the simulated results.

  6. 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

  7. 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.

  8. 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.

  9. Adaptation to Shift Work: Physiologically Based Modeling of the Effects of Lighting and Shifts’ Start Time

    PubMed Central

    Postnova, Svetlana; Robinson, Peter A.; Postnov, Dmitry D.

    2013-01-01

    Shift work has become an integral part of our life with almost 20% of the population being involved in different shift schedules in developed countries. However, the atypical work times, especially the night shifts, are associated with reduced quality and quantity of sleep that leads to increase of sleepiness often culminating in accidents. It has been demonstrated that shift workers’ sleepiness can be improved by a proper scheduling of light exposure and optimizing shifts timing. Here, an integrated physiologically-based model of sleep-wake cycles is used to predict adaptation to shift work in different light conditions and for different shift start times for a schedule of four consecutive days of work. The integrated model combines a model of the ascending arousal system in the brain that controls the sleep-wake switch and a human circadian pacemaker model. To validate the application of the integrated model and demonstrate its utility, its dynamics are adjusted to achieve a fit to published experimental results showing adaptation of night shift workers (n = 8) in conditions of either bright or regular lighting. Further, the model is used to predict the shift workers’ adaptation to the same shift schedule, but for conditions not considered in the experiment. The model demonstrates that the intensity of shift light can be reduced fourfold from that used in the experiment and still produce good adaptation to night work. The model predicts that sleepiness of the workers during night shifts on a protocol with either bright or regular lighting can be significantly improved by starting the shift earlier in the night, e.g.; at 21∶00 instead of 00∶00. Finally, the study predicts that people of the same chronotype, i.e. with identical sleep times in normal conditions, can have drastically different responses to shift work depending on their intrinsic circadian and homeostatic parameters. PMID:23308206

  10. Adaptation to shift work: physiologically based modeling of the effects of lighting and shifts' start time.

    PubMed

    Postnova, Svetlana; Robinson, Peter A; Postnov, Dmitry D

    2013-01-01

    Shift work has become an integral part of our life with almost 20% of the population being involved in different shift schedules in developed countries. However, the atypical work times, especially the night shifts, are associated with reduced quality and quantity of sleep that leads to increase of sleepiness often culminating in accidents. It has been demonstrated that shift workers' sleepiness can be improved by a proper scheduling of light exposure and optimizing shifts timing. Here, an integrated physiologically-based model of sleep-wake cycles is used to predict adaptation to shift work in different light conditions and for different shift start times for a schedule of four consecutive days of work. The integrated model combines a model of the ascending arousal system in the brain that controls the sleep-wake switch and a human circadian pacemaker model. To validate the application of the integrated model and demonstrate its utility, its dynamics are adjusted to achieve a fit to published experimental results showing adaptation of night shift workers (n = 8) in conditions of either bright or regular lighting. Further, the model is used to predict the shift workers' adaptation to the same shift schedule, but for conditions not considered in the experiment. The model demonstrates that the intensity of shift light can be reduced fourfold from that used in the experiment and still produce good adaptation to night work. The model predicts that sleepiness of the workers during night shifts on a protocol with either bright or regular lighting can be significantly improved by starting the shift earlier in the night, e.g.; at 21:00 instead of 00:00. Finally, the study predicts that people of the same chronotype, i.e. with identical sleep times in normal conditions, can have drastically different responses to shift work depending on their intrinsic circadian and homeostatic parameters.

  11. 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

  12. 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. 

  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. 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.

  15. 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

  16. 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.

  17. Surface topography measurement based on color images processing in white light interferometry

    NASA Astrophysics Data System (ADS)

    Guo, Tong; Gu, Yue; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2015-05-01

    Microstructure surface topography is a key aspect of micro-nano measuring research for it has an obvious influence on the performance and quality of micro-nano devices. Scanning white light interferometry is a common method of testing surface profiling. In this paper, a color CCD camera, rather than a black-and-white CCD camera, was utilized to acquire white light interference images, which contain information of RGB channels. Based on acquired color interference images, wavelet transform method was employed to calculate phase value of corresponding channel in each scanning position. Then zero-optical-path-difference positions were accurately determined via a constructed evaluation function and least square method. Surface topography was eventually obtained via linear relationship of relative height and the zero-optical-path-difference position. The proposed method was verified by simulation and experiment of measuring standard step provided by VLSI Standards Incorporated.

  18. 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.

  19. SLM-based off-axis Fourier filtering in microscopy with white light illumination.

    PubMed

    Steiger, Ruth; Bernet, Stefan; Ritsch-Marte, Monika

    2012-07-01

    In various microscopy applications spatial light modulators (SLMs) are used as programmable Fourier filters to realize different optical contrast enhancement methods. It is often advantageous to use the SLM in off-axis configuration, where the filtered image wave is sent into the first diffraction order of a blazed grating superposed to the phase mask on the SLM. Because of dispersion this approach is, however, typically limited to spectrally narrowband illumination. Here we suggest a method involving a grating for pre-compensation, which allows one to use spectrally broadband (even thermal) light in SLM-based Fourier filtering. The proposed approach is demonstrated by multicolor imaging of amplitude and phase objects, such as a resolution target, onion epidermal cells and human epithelial cheek cells. PMID:22772234

  20. 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

  1. 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.

  2. 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

  3. Irradiance Decay in Fluorescent and Light-emitting Diode-based Phototherapy Devices: A Pilot Study.

    PubMed

    Olusanya, Bolajoko O; Osibanjo, Folashade B; Emokpae, Abieyuwa A; Slusher, Tina M

    2016-10-01

    We set out to determine the rate of decline of irradiance for fluorescent tube (FT) and light-emitting diode (LED) phototherapy devices in resource-limited settings where routine irradiance monitoring is uncommon. Irradiance levels (μW/cm(2)/nm) were measured weekly using BiliBlanket(®) II Meter on three FT-based and two LED-based phototherapy devices over a 19 week period. The two LED devices showed stable irradiance levels and did not require any lamp changes. The three FT-based devices showed rapid decline in irradiance, and all required three complete lamp exchanges approximately every 5-6 weeks. FT-based devices are associated with more rapid decline in irradiance to sub-therapeutic levels and require more frequent lamp changes than LED devices. Clinicians should be alert to the maintenance requirements of the phototherapy devices available in their settings to ensure efficacy of treatment.

  4. Irradiance Decay in Fluorescent and Light-emitting Diode-based Phototherapy Devices: A Pilot Study.

    PubMed

    Olusanya, Bolajoko O; Osibanjo, Folashade B; Emokpae, Abieyuwa A; Slusher, Tina M

    2016-10-01

    We set out to determine the rate of decline of irradiance for fluorescent tube (FT) and light-emitting diode (LED) phototherapy devices in resource-limited settings where routine irradiance monitoring is uncommon. Irradiance levels (μW/cm(2)/nm) were measured weekly using BiliBlanket(®) II Meter on three FT-based and two LED-based phototherapy devices over a 19 week period. The two LED devices showed stable irradiance levels and did not require any lamp changes. The three FT-based devices showed rapid decline in irradiance, and all required three complete lamp exchanges approximately every 5-6 weeks. FT-based devices are associated with more rapid decline in irradiance to sub-therapeutic levels and require more frequent lamp changes than LED devices. Clinicians should be alert to the maintenance requirements of the phototherapy devices available in their settings to ensure efficacy of treatment. PMID:27118821

  5. Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates.

    PubMed

    Pan, Jui-Wen; Tsai, Pei-Jung; Chang, Kao-Der; Chang, Yung-Yuan

    2013-03-01

    In this paper, we propose a method to analyze the light extraction efficiency (LEE) enhancement of a nanopatterned sapphire substrates (NPSS) light-emitting diode (LED) by comparing wave optics software with ray optics software. Finite-difference time-domain (FDTD) simulations represent the wave optics software and Light Tools (LTs) simulations represent the ray optics software. First, we find the trends of and an optimal solution for the LEE enhancement when the 2D-FDTD simulations are used to save on simulation time and computational memory. The rigorous coupled-wave analysis method is utilized to explain the trend we get from the 2D-FDTD algorithm. The optimal solution is then applied in 3D-FDTD and LTs simulations. The results are similar and the difference in LEE enhancement between the two simulations does not exceed 8.5% in the small LED chip area. More than 10(4) times computational memory is saved during the LTs simulation in comparison to the 3D-FDTD simulation. Moreover, LEE enhancement from the side of the LED can be obtained in the LTs simulation. An actual-size NPSS LED is simulated using the LTs. The results show a more than 307% improvement in the total LEE enhancement of the NPSS LED with the optimal solution compared to the conventional LED.

  6. Powerful DMD-based light sources with a high throughput virtual slit

    NASA Astrophysics Data System (ADS)

    Hajian, Arsen R.; Gooding, Ed; Gunn, Thomas; Bradbury, Steven

    2016-02-01

    Many DMD-based programmable light sources consist of a white light source and a pair of spectrometers operating in subtractive mode. A DMD between the two spectrometers shapes the delivered spectrum. Since both spectrometers must (1) fit within a small volume, and (2) provide significant spectral resolution, a narrow intermediary slit is required. Another approach is to use a spectrometer designed around a High Throughput Virtual Slit, which enables higher spectral resolution than is achievable with conventional spectroscopy by manipulating the beam profile in pupil space. Conventional imaging spectrograph designs image the entrance slit onto the exit focal plane after dispersing the spectrum. Most often, near 1:1 imaging optics are used in order to optimize both entrance aperture and spectral resolution. This approach limits the spectral resolution to the product of the dispersion and the slit width. Achieving high spectral resolution in a compact instrument necessarily requires a narrow entrance slit, which limits instrumental throughput (étendue). By reshaping the pupil with reflective optics, HTVS-equipped instruments create a tall, narrow image profile at the exit focal plane without altering the NA, typically delivering 5X or better spectral resolution than is achievable with a conventional design. This approach works equally well in DMD-based programmable light sources as in single stage spectrometers. Assuming a 5X improvement in étendue, a 500 W source can be replaced by a 100 W equivalent, creating a cooler, more efficient tunable light source with equal power density over the desired bandwidth without compromising output power.

  7. Hierarchical Bi based nanobundles: an excellent photocatalyst for visible-light degradation of Rhodamine B dye.

    PubMed

    Gao, Fangfang; Zhao, Yan; Li, Yawen; Wu, Gongjuan; Lu, Yan; Song, Yuehong; Huang, Zhifang; Li, Na; Zhao, Jingzhe

    2015-06-15

    Hierarchical Bi based nanobundles were self-assembled via an aqueous reduction approach using hydrazine hydrate as reductive agent, and were used as photocatalysts for the degradation of Rhodamine B (RhB) under visible light. PVP molecules were designed as inducing agent to construct the Bi based nanobundles. The as-obtained samples were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), thermogravimetric-differential thermal analyzer (TG-DTA), infrared spectroscopy (IR) and field emission scanning electron microscopy (FESEM) to get clear information of the crystals. A possible formation mechanism for the interesting architectures was proposed in the paper. The Bi based nanobundles exhibited excellent photocatalytic activity and good cycling performance towards photodegradation of RhB under visible light. The pH-sensitive degradation can reach 96% in degradation rate after 90 min, which indicates potential applications of the Bi based nanobundles on the degradation of organic pollutants. Degradation mechanism is proposed on the combination of Bi and BiOCl crystals.

  8. 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.

  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.

  11. 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.

  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. Measurement of blood coagulation with considering RBC aggregation through a microchip-based light transmission aggregometer.

    PubMed

    Lim, Hyunjung; Nam, Jeonghun; Xue, Shubin; Shin, Sehyun

    2011-01-01

    Even though blood coagulation can be tested by various methods and techniques, the effect of RBC aggregation on blood coagulation is not fully understood. The present study monitored clot formation in a microchip-based light transmission aggregometer. Citrated blood samples with and without the addition of calcium ion solution were initially disaggregated by rotating a stirrer in the microchip. After abrupt stop of the rotating stirrer, the transmitted light intensity over time was recorded. The syllectogram (light intensity vs. time graph) manifested a rapid increase that is associated with RBC aggregation followed by a decrease that is associated with blood coagulation. The time to reach the peak point was used as a new index of coagulation time (CT) and ranged from 200 to 500 seconds in the present measurements. The CT was inversely proportional to the concentration of fibrinogen, which enhances RBC aggregation. In addition, the CT was inversely proportional to the hematocrit, which is similar to the case of the prothrombin time (PT), as measured by a commercial coagulometer. Thus, we carefully concluded that RBC aggregation should be considered in tests of blood coagulation.

  14. 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

  15. Light helicity detection in MOS-based spin-photodiodes: An analytical model

    NASA Astrophysics Data System (ADS)

    Cantoni, M.; Rinaldi, C.

    2016-09-01

    In a metal-oxide-semiconductor-based spin-photodiode, the helicity of an incoming light is efficiently converted into an electrical signal by exploiting (i) the helicity dependence of the degree of optical spin orientation for photogenerated carriers in the semiconductor and (ii) the spin-dependent tunneling transmission of the insulating barrier between the semiconductor and a ferromagnetic metal. Here, we propose a theoretical model for predicting the electrical response of the device to a circularly polarized light, by integrating the Fert-Jaffrès framework [A. Fert and H. Jaffrès, Phys. Rev. B 64, 184420 (2001)] with a helicity-dependent photo-generation term. A figure of merit, related to the variation of the electrical response to the switching of the light helicity from right to left, is defined, and its dependence on the constitutive parameters of the device (barrier resistivity and spin selectivity, semiconductor resistivity and spin diffusion length) is shown. Finally, a simple analytical formula for identifying the optimal resistance barrier leading to the maximum efficiency is found and experimentally validated on Fe/MgO/Ge spin-photodiodes.

  16. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Reddy, M. Siva Pratap; Park, Chinho

    2016-08-01

    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.

  17. 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

  18. 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.

  19. Color-tunable organic light emitting diodes based on exciplex emission

    NASA Astrophysics Data System (ADS)

    Yu, Junsheng; Lou, Shuangling; Wen, Wen; Jiang, Yadong; Zhang, Qing

    2009-05-01

    A fluorene derivative of 2,3-bis(9,9-dihexyl-9H-fluoren-2-yl)quinoxaline (BFLYQ) with blue fluorescence peaking at 425 nm is synthesized. The blend film of BFLYQ and N,N'-di(naphthalen-2-yl)-N,N'-diphenyl-benzine (NPB) exhibited an additional bathochromic shifted and broadbanded emission at 513 nm besides blue light in photoluminescence (PL) spectrum. The bilayer device with a structure of indium-tin-oxide (ITO)/NPB (40 nm)/BFLYQ (40 nm)/Mg : Ag showed a low-energy emission peaking at green area in electroluminescent (EL) spectra, which is due to exciplex emission between NPB and BFLYQ molecules, and the blue emission from BFLYQ increased with the enhancement of bias voltage. Based on exciplex emission, using 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) as red dye, the color-tunable organic light-emitting diodes (OLEDs) are fabricated by conventional thermal vacuum deposition. The devices showed emission from red to white light with increasing the distance of DCJTB and the interface of NPB/BFLYQ. Also, the luminescent mechanism of DCJTB is discussed.

  20. 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.

  1. Shine on: Review of Laser- and Light-Based Therapies for the Treatment of Burn Scars

    PubMed Central

    Hultman, C. Scott; Edkins, Renee E.; Lee, Clara N.; Calvert, Catherine T.; Cairns, Bruce A.

    2012-01-01

    Restoration of form and function after burn injury remains challenging, but emerging laser and pulsed light technologies now offer hope for patients with hypertrophic scars, which may be associated with persistent hyperemia, chronic folliculitis, intense pruritis, and neuropathic pain. In addition to impairing body image, these scars may limit functional recovery, compromise activities of daily living, and prevent return to work. Three different platforms are now poised to alter our reconstructive algorithm: (1) vascular-specific pulsed dye laser (PDL) to reduce hyperemia, (2) ablative fractional CO2 laser to improve texture and pliability of the burn scar, and (3) intense pulsed light (IPL) to correct burn scar dyschromia and alleviate chronic folliculitis. In this paper, we will provide an overview of our work in this area, which includes a systematic review, a retrospective analysis of our preliminary experience, and interim data from our on-going, prospective, before-after cohort trial. We will demonstrate that laser- and light-based therapies can be combined with each other safely to yield superior results, often at lower cost, by reducing the need for reconstructive surgery. Modulating the burn scar, through minimally invasive modalities, may replace conventional methods of burn scar excision and yield outcomes not previously possible or conceivable. PMID:22778719

  2. 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.

  3. 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

  4. 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

  5. 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

    2016-04-05

    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.

  6. 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

  7. 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.

  8. 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

  9. Cellular Trojan horse based polymer nanoreactors with light-sensitive activity.

    PubMed

    Baumann, Patric; Spulber, Mariana; Dinu, Ionel Adrian; Palivan, Cornelia G

    2014-08-01

    Stimulus-sensitive systems at the nanoscale represent ideal candidates for improving therapeutic and diagnostic approaches by producing rapid responses to the presence of specific molecules or conditions either by changing properties or by acting "on demand". Here we introduce an optimized light-sensitive nanoreactor based on encapsulation of a photosensitizer inside polymer vesicles to serve as an efficient source of reactive oxygen species (ROS) "on demand". Two types of amphiphilic block copolymers, poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyloxazoline), PMOXA-PDMS-PMOXA, and poly(N-vinylpyrrolidone)-block-poly(dimethylsiloxane)-block-poly(N-vinylpyrrolidone), PNVP-PDMS-PNVP, were used to encapsulate Rose Bengal-bovine serum albumin (RB-BSA) inside the cavity of vesicles. The difference of copolymers molecular properties (hydrophobic to hydrophilic ratio, different chemical nature of the hydrophilic block) influenced the encapsulation ability, and uptake by cells, allowing therefore a selection of the most efficient polymer system. Nanoreactors were optimized in terms of (i) size, (ii) stability, and (iii) encapsulation efficiency based on a combination of light scattering, TEM, and UV-vis spectroscopy. By illumination, encapsulated RB-BSA conjugates generated in situ ROS, which diffused through the polymer membrane to the environment of the vesicles, as proved by electron spin resonance spectroscopy (ESR). Optimum illumination conditions were obtained based on the effect of the illumination time on the amount of ROS produced in situ by the encapsulated RB-BSA conjugates. ROS diffusion monitored by ESR was dependent on the molecular weight of copolymer that influences the thickness of the polymer membrane. Upon uptake into HeLa cells our nontoxic nanoreactors acted as a Trojan horse: they produced illumination-controlled ROS in sufficient amounts to induce cell death under photodynamic therapy (PDT) conditions. Straightforward

  10. Hybrid light emitting diodes based on solution processed polymers, colloidal quantum dots, and colloidal metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Ma, Xin

    This dissertation focuses on solution-processed light-emitting devices based on polymer, polymer/PbS quantum dot, and polymer/silver nanoparticle hybrid materials. Solution based materials and organic/inorganic hybrid light emitting diodes attracted significant interest recently due to many of their advantages over conventional light emitting diodes (LEDs) including low fabrication cost, flexible, high substrate compatibility, as well as tunable emission wavelength of the quantum dot materials. However, the application of these novel solution processed materials based devices is still limited due to their low performances. Material properties and fabrication parameters need to be carefully examined and understood for further device improvement. This thesis first investigates the impact of solvent property and evaporation rate on the polymer molecular chain morphology and packaging in device structures. Solvent is a key component to make the active material solution for spin coating fabrication process. Their impacts are observed and examined on both polymer blend system and mono-polymer device. Secondly, PbS colloidal quantum dot are introduced to form hybrid device with polymer and to migrate the device emission into near-IR range. As we show, the dithiol molecules used to cross-link quantum dots determine the optical and electrical property of the resulting thin films. By choosing a proper ligand for quantum dot ligand exchange, a high performance polymer/quantum dot hybrid LED is fabricated. In the end, the interaction of polymer exciton with surface plasmon mode in colloidal silver nanoparticles and the use of this effect to enhance solution processed LEDs' performances are investigated.

  11. Differentiating between light and deep sleep stages using an ambulatory device based on peripheral arterial tonometry.

    PubMed

    Bresler, Ma'ayan; Sheffy, Koby; Pillar, Giora; Preiszler, Meir; Herscovici, Sarah

    2008-05-01

    The objective of this study is to develop and assess an automatic algorithm based on the peripheral arterial tone (PAT) signal to differentiate between light and deep sleep stages. The PAT signal is a measure of the pulsatile arterial volume changes at the finger tip reflecting sympathetic tone variations and is recorded by an ambulatory unattended device, the Watch-PAT100, which has been shown to be capable of detecting wake, NREM and REM sleep. An algorithm to differentiate light from deep sleep was developed using a training set of 49 patients and was validated using a separate set of 44 patients. In both patient sets, Watch-PAT100 data were recorded simultaneously with polysomnography during a full night sleep study. The algorithm is based on 14 features extracted from two time series of PAT amplitudes and inter-pulse periods (IPP). Those features were then further processed to yield a prediction function that determines the likelihood of detecting a deep sleep stage epoch during NREM sleep periods. Overall sensitivity, specificity and agreement of the automatic algorithm to identify standard 30 s epochs of light and deep sleep stages were 66%, 89%, 82% and 65%, 87%, 80% for the training and validation sets, respectively. Together with the already existing algorithms for REM and wake detection we propose a close to full stage detection method based solely on the PAT and actigraphy signals. The automatic sleep stages detection algorithm could be very useful for unattended ambulatory sleep monitoring assessing sleep stages when EEG recordings are not available. PMID:18460762

  12. SEMICONDUCTOR DEVICES: Improved light extraction in AlGaInP-based LEDs using a self-assembly metal nanomask

    NASA Astrophysics Data System (ADS)

    Wenjing, Jiang; Chen, Xu; Guangdi, Shen; Rong, Fang; Wei, Gao

    2010-06-01

    This paper reports a new method of fabricating AlGaInP-based nanorod light emitting diodes (LEDs) by using self-assembly metal layer nanomasks and inductively coupled plasma. Light-power measurements indicate that the scattering of photons considerably enhances the probability of escaping from the nanorod LEDs. The light-intensity of the nanorod LED is increased by 34% for a thin GaP window layer, and by 17% for an 8 μm GaP window layer. The light-power of the nanorod LED is increased by 25% and 13%, respectively.

  13. 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

  14. 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.

  15. 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

  16. Chitosan and gelatin based biodegradable packaging films with UV-light protection.

    PubMed

    Ahmed, Shakeel; Ikram, Saiqa

    2016-10-01

    Biopolymers are polymers obtained from biological origins and used for various biological and industrial applications. A biopolymer should be non-toxic, non-antigenic, non-irritant, non-carcinogenic, sterilisable and adequately available for their widespread applications. In this study, chitosan (CS) and gelatin (GL) based films were prepared to be used as biodegradable packaging films. CS was blended with GL to improve various physicochemical properties. The blended CSGL films were crosslinked with boric acid (BA) to improve various properties viz. light barrier properties, Water Vapour Permeability (WVP), moisture content (%), Total Solubility Matter (TSM), most important to improve the strength. The studies of transparency, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and optical microscopy confirms that the synthesized films were found to be transparent and homogenous indicating good compatibility among different components. The synthesized CS and GL based films showed UV-light barrier properties as supported by data. The tensile strength of films increases, decreases water solubility, moisture content (%) and WVP on crosslinking. In order to make the crosslinked films more flexible, Polyethylene glycol was used as plasticizer, making the films more flexible and transparent. This study indicates that these biodegradable CS and GL based films are potent to be used as packing films. PMID:27560490

  17. Chitosan and gelatin based biodegradable packaging films with UV-light protection.

    PubMed

    Ahmed, Shakeel; Ikram, Saiqa

    2016-10-01

    Biopolymers are polymers obtained from biological origins and used for various biological and industrial applications. A biopolymer should be non-toxic, non-antigenic, non-irritant, non-carcinogenic, sterilisable and adequately available for their widespread applications. In this study, chitosan (CS) and gelatin (GL) based films were prepared to be used as biodegradable packaging films. CS was blended with GL to improve various physicochemical properties. The blended CSGL films were crosslinked with boric acid (BA) to improve various properties viz. light barrier properties, Water Vapour Permeability (WVP), moisture content (%), Total Solubility Matter (TSM), most important to improve the strength. The studies of transparency, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and optical microscopy confirms that the synthesized films were found to be transparent and homogenous indicating good compatibility among different components. The synthesized CS and GL based films showed UV-light barrier properties as supported by data. The tensile strength of films increases, decreases water solubility, moisture content (%) and WVP on crosslinking. In order to make the crosslinked films more flexible, Polyethylene glycol was used as plasticizer, making the films more flexible and transparent. This study indicates that these biodegradable CS and GL based films are potent to be used as packing films.

  18. 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.

  19. PKS1 plays a role in red-light-based positive phototropism in roots.

    PubMed

    Molas, Maria Lia; Kiss, John Z

    2008-06-01

    Aerial parts of plants curve towards the light (i.e. positive phototropism), and roots typically grow away from the light (i.e. negative phototropism). In addition, Arabidopsis roots exhibit positive phototropism relative to red light (RL), and this response is mediated by phytochromes A and B (phyA and phyB). Upon light stimulation, phyA and phyB interact with the phytochrome kinase substrate (PKS1) in the cytoplasm. In this study, we investigated the role of PKS1, along with phyA and phyB, in the positive phototropic responses to RL in roots. Using a high-resolution feedback system, we studied the phenotypic responses of roots of phyA, phyB, pks1, phyA pks1 and phyB pks1 null mutants as well as the PKS1-overexpressing line in response to RL. PKS1 emerged as an intermediary in the signalling pathways and appears to promote a negative curvature to RL in roots. In addition, phyA and phyB were both essential for a positive response to RL and act in a complementary fashion. However, either photoreceptor acting without the other results in negative curvature in response to red illumination so that the mode of action differs depending on whether phyA and phyB act independently or together. Our results suggest that PKS1 is part of a signalling pathway independent of phyA and phyB and that PKS1 modulates RL-based root phototropism.

  20. New strategies to improve Eu light emission in SI-based matrices

    NASA Astrophysics Data System (ADS)

    Franzò, G.; Bellocchi, G.; Boninelli, S.; Miritello, M.; Iacona, F.

    2014-05-01

    A promising approach to obtain light emission from Si-based materials is represented by doping with rare earths and in particular with Eu. In this paper the comparison of the performances of SiO2 and SiOC layers as host matrices for optically active Eu ions is presented. A SiO2 matrix allows to observe light emission from both Eu2+ and Eu3+ ions, owing to a proper tuning of the thermal annealing process used to optically activate the rare earth. However the photoluminescence efficiency of both ions remains relatively low and quite far from the requirements for technological applications, mainly due to the extensive formation of Eu-containing precipitates. A detailed study of the structural and optical properties of these layers allowed us to analyze and elucidate the clustering process and to find suitable strategies to minimize it. We found that the substitution of the SiO2 matrix with a SiOC film allows to obtain a very bright light emission at about 440 nm from Eu2+ ions. In fact SiOC is able to efficiently promote the Eu reduction; furthermore, Eu ions are characterized by an enhanced mobility and solubility in this matrix and, as a consequence, Eu precipitation is strongly reduced. Finally, by taking advantage of the dependence of the photoluminescence peak position on the Eu concentration, an intense white emission is obtained at room temperature by combining two layers with different Eu contents. Since SiOC is a material fully compatible with standard Si technology, Eu-doped SiOC layers can be considered a highly interesting candidate for applications in photonics or in solid-state lighting.

  1. 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.

  2. 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.

  3. Fabry-Perot fiber pressure sensor based on white light interferometry and intensity demodulation method

    NASA Astrophysics Data System (ADS)

    Guo, Zhenwu; Li, Weixiang; Zhang, Dapeng; Pan, Yong; Meng, Qingbin; Liu, Guangwei; Ge, Fuwei; Zhang, Xian

    2009-05-01

    We have designed an intensity-demodulated sensing system based on Fabry-Perot interferometer and fiber Bragg grating (FBG) for pressure measurement. The structure of the sensor probe is presented. It is an optical fiber extrinsic Fabry-Perot interferometer(EFPI) composed of silica tube and optical fibers. The variable quantity of cavity length of the EFPI is equal to that of silica tube, which has direct proportion to external pressure. The sensing system is interrogated by broadband light. In order to compensate intensity fluctuation, we use an FBG as a narrow band filter to obtain the sensing signal and reference signal from white-light interference fringe returned from EFPI. The sensing signal is in the reflected beam from FBG, and the reference signal is contained in reflected beam and transmitted beam of FBG simultaneously. Then two output light signals are transformed into current signals by two photodiodes. Subsequently two current signals are processed at the same time. After the signals being treated with circuit, the inherent disadvantage of intensity-demodulated sensor is removed. It is also to say the sensing system has immunity from the drift of light source power and fluctuation in fiber attenuation by using only a FBG. Meanwhile, the system has advantages of fast response, simple circuitry, strong ability of intensity compensation and low cost. Experimental results show that the experimental data are consistent with theoretical analysis. The dynamic range of sensor is from 0 to 500KPa, and the resolution reaches to 0.5KPa. The sensing system can be used to measure pressure in inflammable and explosive circumstance such as oil height of super oil storage tanks.

  4. Spatially coherent white-light interferometer based on a point fluorescent source.

    PubMed

    Liu, H H; Cheng, P H; Wang, J

    1993-05-01

    We developed a point-fluorescent-source-based white-light interferometer for high-resolution reflectometry, range-gating imaging, and group-velocity-dispersion measurement. The laser-pumped point fluorescent source has 9 mW of power and a spatial coherence of 0.97, which allows it to be used like a laser beam. Owing to its 40-nm FWHM spectral width, the width of its temporal autocorrelation is only 19 fs, which corresponds to that of 14-fs Gaussian pulses.

  5. Modified iterative vector similarity measure for particle size analysis based on forward light scattering.

    PubMed

    Wang, Tian'en; Shen, Jianqi; Lin, Chengjun

    2016-08-10

    The vector similarity measure (VSM), originally applied to information retrieval, has been recently introduced to analyze particle size distribution (PSD) based on forward light scattering. The VSM technique can predict the PSD with low sensitivity to the experimental errors. However, the simulations and experiments of multi-modal distributed particle systems were not satisfying. In this paper, a modified inverse algorithm is presented to improve the VSM technique. Simulated results and experimental evidence show that with this modification the VSM technique can reconstruct the PSD more efficiently. PMID:27534458

  6. Fountain code-based error control scheme for dimmable visible light communication systems

    NASA Astrophysics Data System (ADS)

    Feng, Lifang; Hu, Rose Qingyang; Wang, Jianping; Xu, Peng

    2015-07-01

    In this paper, a novel error control scheme using Fountain codes is proposed in on-off keying (OOK) based visible light communications (VLC) systems. By using Fountain codes, feedback information is needed to be sent back to the transmitter only when transmitted messages are successfully recovered. Therefore improved transmission efficiency, reduced protocol complexity and relative little wireless link-layer delay are gained. By employing scrambling techniques and complementing symbols, the least complemented symbols are needed to support arbitrary dimming target values, and the value of entropy of encoded message are increased.

  7. Concepts for ELIC - A High Luminosity CEBAF Based Electron-Light Ion Collider

    SciTech Connect

    Ya. Derbenev, A. Bogacz, G. Krafft, R. Li, L. Merminga, B. Yunn, Y. Zhang

    2006-09-01

    A CEBAF accelerator based electron-light ion collider (ELIC) of rest mass energy from 20 to 65 GeV and luminosity from 10^33 to 10^35 cm6-2s^-1 with both beams polarized is envisioned as a future upgrade to CEBAF. A two step upgrade scenario is under study: CEBAF accelerator-ring-ring scheme (CRR) as the first step, and a multi-turn ERL-ring as the second step, to attain a better electron emittance and maximum luminosity. In this paper we report results of our studies of the CRR version of ELIC.

  8. 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.

  9. 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.

  10. 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

  11. The Pocketscope: a spatial light modulator based epi-fluorescence microscope for optogenetics

    NASA Astrophysics Data System (ADS)

    Linnenberger, Anna; Peterka, Darcy S.; Quirin, Sean; Yuste, Rafael

    2014-09-01

    Microscopy incorporating spatial light modulators (SLMs) enables three dimensional (3D) excitation and monitoring of the activity of neuronal ensembles, enabling studies of neuronal circuit activity both in vitro and in vivo. In this paper we present a portable (22 cm x 42.5 cm x 30 cm), SLM-based epi-fluorescence upright microscope ("Pocketscope") that enables 3D calcium imaging and photoactivation of neurons in brain slices. Here we describe the implementation of the instrument; quantify the volume over which neural activity can be excited; and demonstrate the use of the system for mapping neural circuits in brain slices.

  12. 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

  13. Parallel lensless optical correlator based on two phase-only spatial light modulators.

    PubMed

    Zeng, Xu; Inoue, Takashi; Fukuchi, Norihiro; Bai, Jian

    2011-06-20

    In this paper, we proposed a parallel phase-only lensless optical correlator based on two pieces of Liquid Crystal on Silicon Spatial Light Modulators. Phase Fresnel Lens Array and specialized grating are implemented to realize multi-channel and multiplexed LOC. Experimental results of Chinese characters' recognitions are given as demonstration of proposed technique. High uniformity of processing channels has been verified by autocorrelation process of four same Chinese characters. The technique is programmable and adjustment of optical path could be realized without changing of optical setup. The implementations could be performed on the same configuration as single channel optical correlator without mechanical alternation. PMID:21716500

  14. Polymerization contraction and conversion of light-curing BisGMA-based methacrylate resins.

    PubMed

    Venhoven, B A; de Gee, A J; Davidson, C L

    1993-09-01

    The aim of this study was to investigate the polymerization contraction and the conversion of light-curing methacrylate resins based on bisphenol-A bis(2-hydroxypropyl)methacrylate (BisGMA) diluted with triethylene glycol dimethyacrylate (TEGDMA), methyl methacrylate (MMA), hydroxypropyl methacrylate (HPMA) or (+/-)-2-ethylhexyl methacrylate (EHMA). The contraction measurements were carried out with a linometer, a simple device to determine true linear polymerization contraction of liquid monomers at ambient temperature. The contraction increased with the amount of diluting monomer. The estimated conversion of the BisGMA-TEGDMA, calculated using the contraction, is consistent with literature values. The BisGMA-HPMA mixtures showed high conversions at moderate contraction.

  15. Visible light dynamical diffraction in a 1-D photonic crystal-based interferometer with an extremely thin spacer layer

    NASA Astrophysics Data System (ADS)

    Prudnikov, I. R.

    2016-01-01

    Properties of light diffraction in a Fabry-Pérot-like interferometer composed of two 1-D photonic crystals and a nanometer-thick spacer layer are analytically investigated. It is shown that the resonant enhancement of light wave intensity in such a layer is possible because of light dynamical diffraction from the photonic crystals of the interferometer. Numerical simulations of (i) light reflectivity and transmittance curves of the interferometer having an ultra-thin spacer layer (its thickness changes from less than 1 nm to about 10 nm) and (ii) the resonant distribution of the light wave intensity in the vicinity of the layer are performed. Based on the numerical simulations, potentialities for the determination of the structural parameters (e.g., thicknesses and refraction indexes) of ultra-thin spacer films are discussed. A difference is found to appear in resonant intensity enhancements inside the ultra-thin spacer layers between s- and p-polarized light waves.

  16. Development of a liquid-crystal-based real-time radiation dosimeter based on electro optical light modulation

    NASA Astrophysics Data System (ADS)

    Heo, Ye Ji; Kim, Kyo Tae; Nam, Sang-Hee; Park, Sung-Kwang; Noh, Si Cheul; Kang, Sang Sick; Park, Ji-Koon

    2016-09-01

    This study evaluates the feasibility of a radiation dosimeter that can monitor radiation exposure in real time based on the electro optical modulation of a liquid crystal (LC) cell and the photoconductor cadmium sulfide (CdS). Cadmium sulfide (CdS) is often used in photosensors because of its high reproducibility and sensitivity to light and radiation. As basic research, the electro optical features of a LC cell and a novel CdS photosensor were analyzed from the viewpoint of fabricating a radiation dosimeter. Based on the results, the feasibility of such a detection device was studied by analyzing the efficiency of its electro optical light modulation. The measurement results suggested that the detection system had high resolution and very good reproducibility, with CdS showing excellent X-ray detection efficiency. The results suggest that noise reduction can be achieved by incorporating an LC, given its static electric features. The results of this study could help realize real-time portable radiation dosimeter systems based on optical modulation and using a CdS photosensor.

  17. DNA-Based Sensor Particles Enable Measuring Light Intensity in Single Cells.

    PubMed

    Mikutis, Gediminas; Mora, Carlos A; Puddu, Michela; Paunescu, Daniela; Grass, Robert N; Stark, Wendelin J

    2016-04-13

    "Lab on a particle" architecture is employed in designing a light nanosensor. Light-sensitive protecting groups are installed on DNA, which is encapsulated in silica particles, qualifying as a self-sufficient light sensor. The nanosensors allow measuring light intensity and duration in very small volumes, such as single cells, and store the irradiation information until readout.

  18. Modal analysis of low-level-light aiming sight-glass based on shock testing conditions

    NASA Astrophysics Data System (ADS)

    Gao, Youtang; Ding, Huan; Xue, Xiao; Xu, Yuan; Chang, Benkang

    2010-10-01

    Low-level-light ( LLL ) aiming sight-glass measurement technologies based on multiple circumstances testing conditions are always concerned by military equipments manufacturers. The article puts forward the concrete steps and method of shock circumstances testing measurement according to military optical equipments circumstances testing standard. Using shock theory and mathematical modeling analysis, shock model of LLL aiming sight-glass based on shock testing conditions is constructed and analyzed. Without considering resistances and under instantaneous half-sine shock pulse, the ratio of system response amplitude and half-sine pulse peak value is related to system inherent characteristic (inherent frequency, cycle T, etc.) and shock pulse duration D. The results indicate that given D/T>~ 10.5, / 1 max / A = , half-sine shock pulse is transmitted by 1:1. Testing device response acceleration is equal to shock pulse peak acceleration. Testing device response is more intense under this condition. LLL aiming sight-glass structural performance and reticle zero point moving are influenced. Optical lens offset of LLL aiming sight-glass testing parts is impacted. Optical path parameters change and light transmission is influenced. What is more serious is that objective lens will be broken due to shock pulse transmission.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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

    2015-11-09

    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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. A novel violet/blue light-emitting device based on Ce2Si2O7.

    PubMed

    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 Ce(3+) 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.

    PubMed

    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. 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.

  13. 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.

  14. 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.

  15. 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

  16. Structure-based druggability assessment of the mammalian structural proteome with inclusion of light protein flexibility.

    PubMed

    Loving, Kathryn A; Lin, Andy; Cheng, Alan C

    2014-07-01

    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.

  17. 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.

  18. Relativistic three-body quark model of light baryons based on hypercentral approach

    NASA Astrophysics Data System (ADS)

    Aslanzadeh, M.; Rajabi, A. A.

    2015-05-01

    In this paper, we have treated the light baryons as a relativistic three-body bound system. Inspired by lattice QCD calculations, we treated baryons as a spin-independent three-quark system within a relativistic three-quark model based on the three-particle Klein-Gordon equation. We presented the analytical solution of three-body Klein-Gordon equation with employing the constituent quark model based on a hypercentral approach through which two- and three-body forces are taken into account. Herewith the average energy values of the up, down and strange quarks containing multiplets are reproduced. To describe the hyperfine structure of the baryon, the splittings within the SU(6)-multiplets are produced by the generalized Gürsey Radicati mass formula. The considered SU(6)-invariant potential is popular "Coulomb-plus-linear" potential and the strange and non-strange baryons spectra are in general well reproduced.

  19. Role of defects in the thermal droop of InGaN-based light emitting diodes

    NASA Astrophysics Data System (ADS)

    De Santi, C.; Meneghini, M.; La Grassa, M.; Galler, B.; Zeisel, R.; Goano, M.; Dominici, S.; Mandurrino, M.; Bertazzi, F.; Robidas, D.; Meneghesso, G.; Zanoni, E.

    2016-03-01

    This paper reports an investigation of the physical origin of the thermal droop (the drop of the optical power at high temperatures) in InGaN-based light-emitting diodes. We critically investigate the role of various mechanisms including Shockley-Read-Hall recombination, thermionic escape from the quantum well, phonon-assisted tunneling, and thermionic trap-assisted tunneling; in addition, to explain the thermal droop, we propose a closed-form model which is able to accurately fit the experimental data by using values extracted from measurements and simulations and a limited set of fitting parameters. The model is based on a two-step phonon-assisted tunneling over an intermediate defective state, corrected in order to take into account the pure thermionic component at zero bias and the field-assisted term.

  20. Dentinal shear bond strength, microleakage, and contraction gap of visible light-polymerized liners/bases.

    PubMed

    Cooley, R L; Barkmeier, W W

    1991-06-01

    The bond strength and microleakage patterns of three light-curing glass-ionomer cement liners/bases (Vitrebond, XR Ionomer, and Zionomer) were evaluated and compared to a fluoride-releasing resin (TimeLine) designed for the same use. Bond strength tests were performed at 24 hours and 7 days. At 24 hours Vitrebond, Time-Line, and Zionomer had statistically significantly greater bond strengths than XR Ionomer. At 7 days, Vitrebond had a statistically significantly stronger bond than the others. Microleakage was evaluated after 24 hours of thermocycling. Vitrebond and XR Ionomer had statistically significantly less leakage than the others, while TimeLine had significantly more leakage than the others. Polymerization contraction gaps between the liners/bases and dentin were examined with scanning electron microscopy. Contraction gaps were approximately 10 microns with Vitrebond and XR Ionomer and 5 microns with TimeLine. A contraction gap generally was not observed with Zionomer.

  1. 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.

  2. 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.

  3. Antimicrobial materials for water disinfection based on visible-light photocatalysts

    NASA Astrophysics Data System (ADS)

    Wu, Pinggui

    Since the discovery of photocatalytic water-splitting on TiO2 in 1972, enormous effort has been devoted to the study of TiO2. Since the optical properties of TiO2 and e--h + recombination are essential to the photon-driven applications, these two areas have drawn tremendous research attention in the past few years. But there is no single optimal system to date that has visible-light activity, high photo-efficiency and easy recovery. In this study, chemical co-doping approach was adopted to achieve desirable properties of TiO2-based photocatalyst. Nitrogen and metal ions selected from the transition metal or the rare earth element group were incorporated into TiO2 to induce a red-shift to the visible-light absorption regime and to enhance photocatalytic activity. The anion and cation co-doped TiO2 was made into various forms, including thin film, fiber, and foam that circumvent the problems associated with catalyst recovery. Chemical composition, structure, microstructure, optical, and photocatalytic properties were investigated to characterize each type of the materials. Electronic structure calculation and electron paramagnetic resonance spectroscopy were conducted to understand the role of nitrogen and metal ions. The photocatalytic property of these visible-light-active photocatalysts were studied in the inactivation of bacteria and bacterial spores in water. Fast killing rate was obtained for the inactivation of E. coli, P. aeruginosa, S. aureus and B. subtilis endospores. The results of mechanistic study provided evidence of oxidative damages, and indicated that hydroxyl radicals are one of the key killing species. Atomic force microscopy and electron microscopy showed that the cell walls were attacked by photocatalytic inactivation. The potential application of the photocatalyst in water disinfection was demonstrated by flow-through tests.

  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. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Structure light telecentric stereoscopic vision 3D measurement system based on Scheimpflug condition

    NASA Astrophysics Data System (ADS)

    Mei, Qing; Gao, Jian; Lin, Hui; Chen, Yun; Yunbo, He; Wang, Wei; Zhang, Guanjin; Chen, Xin

    2016-11-01

    We designed a new three-dimensional (3D) measurement system for micro components: a structure light telecentric stereoscopic vision 3D measurement system based on the Scheimpflug condition. This system creatively combines the telecentric imaging model and the Scheimpflug condition on the basis of structure light stereoscopic vision, having benefits of a wide measurement range, high accuracy, fast speed, and low price. The system measurement range is 20 mm×13 mm×6 mm, the lateral resolution is 20 μm, and the practical vertical resolution reaches 2.6 μm, which is close to the theoretical value of 2 μm and well satisfies the 3D measurement needs of micro components such as semiconductor devices, photoelectron elements, and micro-electromechanical systems. In this paper, we first introduce the principle and structure of the system and then present the system calibration and 3D reconstruction. We then present an experiment that was performed for the 3D reconstruction of the surface topography of a wafer, followed by a discussion. Finally, the conclusions are presented.

  12. 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.

  13. Enhancement of light depolarization by random ensembles of titania-based low-dimensional nanoparticles

    NASA Astrophysics Data System (ADS)

    Zimnyakov, D. A.; Zdrajevsky, R. A.; Yuvchenko, S. A.; Ushakova, O. V.; Angelsky, O. V.; Yermolenko, S. B.

    2015-02-01

    Depolarization peculiarities of the light scattered by the random ensembles of titania-based low-dimensional nanoparticles are studied during the experiments with aqueous suspensions of potassium polytitanate nanoplatelets and nanoribbons. The obtained experimental results are compared with the theoretical data obtained for the random systems of oblate and prolate flattened ellipsoidal nanoparticles with various values of the shape factor and dielectric function corresponding the parent material (titanium dioxide). The possibility to recover the effective dielectric function from the depolarization ratio spectra using the ellipsoidal shape model is considered. Ellipsoidal approximation is appropriate for both the nanoplatelets and nanoribbons in the spectral region for which the real part of nanoparticles permittivity is sufficiently negative and the near-resonant excitation of longitudinal mode of charge oscillations in nanoparticles occurs. Also, ellipsoidal approximation is appropriate for nanoplatelets in the region of sufficiently po sitive real part of permittivity but gives remarkably underestimated values of the depolarization ratio for nanoribbons in the region. This is presumably caused by considerable difference in the light-induced charge distributions for nanoribbons and prolate flattened ellipsoidal nanoparticles with the decreasing efficiency in longitudinal mode excitation. The recovered values of nanoparticle permittivity exhibit the red shift with respect to the permittivity values of the parent material due to its modification in the course of nanoparticles synthesis.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. Light extinction and scattering by agarose based resin beads and applications in high-throughput screening.

    PubMed

    Kittelmann, Jörg; Hämmerling, Frank; Ebeler, Moritz; Hubbuch, Jürgen

    2015-06-01

    Optimization of chromatographic processes by high-throughput screening (HTS) methodologies have become a critical part of downstream process development. Nevertheless there are still no non-invasive optical methods to characterize resin as well as protein-resin interaction on liquid-handling platforms available. Several approaches to automated resin screening in microplates are described in literature, yet all those methods involve indirect measurements by removal of, and sample quantification within, supernatant volumes. In this work, we introduce light extinction by light scattering to directly assess resin volume and bead density within microplates. Methods for this novel resin characterization are described for 96 and 384-well microplates. An example application demonstrates ligand concentration measurement in microplates with four commercial SP Sepharose™ Fast Flow batches. Further, direct quantification of adsorbent bound biomolecules is shown in an example with kinetic protein-resin interaction measurement in a batch screening process. This new approach is expected to promote batch-based resin characterization and monitoring on HTS platforms and further miniaturization and increase in throughput of chromatographic HTS processes.

  2. Paper-Based Analytical Devices Relying on Visible-Light-Enhanced Glucose/Air Biofuel Cells.

    PubMed

    Wu, Kaiqing; Zhang, Yan; Wang, Yanhu; Ge, Shenguang; Yan, Mei; Yu, Jinghua; Song, Xianrang

    2015-11-01

    A strategy that combines visible-light-enhanced biofuel cells (BFCs) and electrochemical immunosensor into paper-based analytical devices was proposed for sensitive detection of the carbohydrate antigen 15-3 (CA15-3). The gold nanoparticle modified paper electrode with large surface area and good conductibility was applied as an effective matrix for primary antibodies. The glucose dehydrogenase (GDH) modified gold-silver bimetallic nanoparticles were used as bioanodic biocatalyst and signal magnification label. Poly(terthiophene) (pTTh), a photoresponsive conducting polymer, served as catalyst in cathode for the reduction of oxygen upon illumination by visible light. In the bioanode, electrons were generated through the oxidation of glucose catalyzed by GDH. The amount of electrons is determined by the amount of GDH, which finally depended on the amount of CA15-3. In the cathode, electrons from the bioanode could combine with the generated holes in the HOMO energy level of cathode catalysts pTTh. Meanwhile, the high energy level photoexcited electrons were generated in the LUMO energy level and involved in the oxygen reduction reaction, finally resulting in an increasing current and a decreasing overpotential. According to the current signal, simple and efficient detection of CA15-3 was achieved.

  3. 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

  4. 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.

  5. Visualization of energy: light dose indicator based on electrochromic gyroid nano-materials

    NASA Astrophysics Data System (ADS)

    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.

  6. 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

  7. Neurochip based on light-addressable potentiometric sensor with wavelet transform de-noising*

    PubMed Central

    Liu, Qing-jun; Ye, Wei-wei; Yu, Hui; Hu, Ning; Du, Li-ping; Wang, Ping

    2010-01-01

    Neurochip based on light-addressable potentiometric sensor (LAPS), whose sensing elements are excitable cells, can monitor electrophysiological properties of cultured neuron networks with cellular signals well analyzed. Here we report a kind of neurochip with rat pheochromocytoma (PC12) cells hybrid with LAPS and a method of de-noising signals based on wavelet transform. Cells were cultured on LAPS for several days to form networks, and we then used LAPS system to detect the extracellular potentials with signals de-noised according to decomposition in the time-frequency space. The signal was decomposed into various scales, and coefficients were processed based on the properties of each layer. At last, signal was reconstructed based on the new coefficients. The results show that after de-noising, baseline drift is removed and signal-to-noise ratio is increased. It suggests that the neurochip of PC12 cells coupled to LAPS is stable and suitable for long-term and non-invasive measurement of cell electrophysiological properties with wavelet transform, taking advantage of its time-frequency localization analysis to reduce noise. PMID:20443210

  8. 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.

  9. DNA Bases Thymine and Adenine in Bio-Organic Light Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Gomez, Eliot F.; Venkatraman, Vishak; Grote, James G.; Steckl, Andrew J.

    2014-11-01

    We report on the use of nucleic acid bases (NBs) in organic light emitting diodes (OLEDs). NBs are small molecules that are the basic building blocks of the larger DNA polymer. NBs readily thermally evaporate and integrate well into the vacuum deposited OLED fabrication. Adenine (A) and thymine (T) were deposited as electron-blocking/hole-transport layers (EBL/HTL) that resulted in increases in performance over the reference OLED containing the standard EBL material NPB. A-based OLEDs reached a peak current efficiency and luminance performance of 48 cd/A and 93,000 cd/m2, respectively, while T-based OLEDs had a maximum of 76 cd/A and 132,000 cd/m2. By comparison, the reference OLED yielded 37 cd/A and 113,000 cd/m2. The enhanced performance of T-based devices is attributed to a combination of energy levels and structured surface morphology that causes more efficient and controlled hole current transport to the emitting layer.

  10. Low power proximity electronics for dust analysers based on light scattering

    NASA Astrophysics Data System (ADS)

    Molfese, C.; Esposito, F.; Cortecchia, F.; Cozzolino, F.

    2012-04-01

    The present paper focuses on the development of an optimized version of the Proximity Electronics (PE) for dust analysers based on static light scattering. This kind of instruments, aimed to the systematic measurement of the size of dust grains in Martian atmosphere, was developed by the Cosmic Physics and Planetology Group at the INAF Astronomical Observatory of Capodimonte (OAC) and University Parthenope (LFC group), in Naples, Italy. One of these instruments, the MEDUSA Experiment, was selected for the Humboldt Payload of the ExoMars mission, the first mission to Mars of the ESA Aurora Programme. Thereafter, this mission was revised because of increasing costs and lack of funds and the MEDUSA experiment has been completely re-engineered to meet more demanding constraints of mass and power consumption. The dust analyser under development is named MicroMED, as it is a lighter and more compact version of MEDUSA. MicroMED is provided with an Optical System (OS) based on the same concept of the one present in MEDUSA, but with a low power PE and low power laser source. This paper reports the features and the tests results of three versions of low power PE developed for MicroMED, and also compares two basic approaches, one based on a linear amplifier, derived from the solution implemented in two different MEDUSA breadboards (B/Bs), and the other one based on a logarithmic amplifier, with better performance in terms of compactness and low power consumption.

  11. DNA Bases Thymine and Adenine in Bio-Organic Light Emitting Diodes

    PubMed Central

    Gomez, Eliot F.; Venkatraman, Vishak; Grote, James G.; Steckl, Andrew J.

    2014-01-01

    We report on the use of nucleic acid bases (NBs) in organic light emitting diodes (OLEDs). NBs are small molecules that are the basic building blocks of the larger DNA polymer. NBs readily thermally evaporate and integrate well into the vacuum deposited OLED fabrication. Adenine (A) and thymine (T) were deposited as electron-blocking/hole-transport layers (EBL/HTL) that resulted in increases in performance over the reference OLED containing the standard EBL material NPB. A-based OLEDs reached a peak current efficiency and luminance performance of 48 cd/A and 93,000 cd/m2, respectively, while T-based OLEDs had a maximum of 76 cd/A and 132,000 cd/m2. By comparison, the reference OLED yielded 37 cd/A and 113,000 cd/m2. The enhanced performance of T-based devices is attributed to a combination of energy levels and structured surface morphology that causes more efficient and controlled hole current transport to the emitting layer. PMID:25417819

  12. 3D modeling of light interception in heterogeneous forest canopies using ground-based LiDAR data

    NASA Astrophysics Data System (ADS)

    Van der Zande, Dimitry; Stuckens, Jan; Verstraeten, Willem W.; Mereu, Simone; Muys, Bart; Coppin, Pol

    2011-10-01

    A methodology is presented that describes the direct interaction of a forest canopy with incoming radiation using terrestrial LiDAR based vegetation structure in a radiative transfer model. The proposed 'Voxel-based Light Interception Model' (VLIM) is designed to estimate the Percentage of Above Canopy Light (PACL) at any given point of the forest scene. First a voxel-based representation of trees is derived from terrestrial LiDAR data as structural input to model and analyze the light interception of canopies at near leaf level scale. Nine virtual forest stands of three species (beech, poplar, plantain) were generated by means of stochastic L-systems as tree descriptors. Using ray tracer technology hemispherical LiDAR measurements were simulated inside these virtual forests. The leaf area density (LAD) estimates derived from the LiDAR datasets resulted in a mean absolute error of 32.57% without correction and 16.31% when leaf/beam interactions were taken into account. Next, comparison of PACL estimates, computed with VLIM with fully rendered light distributions throughout the canopy based on the L-systems, yielded a mean absolute error of 5.78%. This work shows the potential of the VLIM to model both instantaneous light interception by a canopy as well as average light distributions for entire seasons.

  13. Surgical lighting with contrast enhancement based on spectral reflectance comparison and entropy analysis.

    PubMed

    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.

  14. 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.

  15. 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.

  16. 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.

  17. Thermal analysis of high intensity organic light-emitting diodes based on a transmission matrix approach

    NASA Astrophysics Data System (ADS)

    Qi, Xiangfei; Forrest, Stephen R.

    2011-12-01

    We use a general transmission matrix formalism to determine the thermal response of organic light-emitting diodes (OLEDs) under high currents normally encountered in ultra-bright illumination conditions. This approach, based on Laplace transforms, facilitates the calculation of transient coupled heat transfer in a multi-layer composite characteristic of OLEDs. Model calculations are compared with experimental data on 5 cm × 5 cm green and red-emitting electrophosphorescent OLEDs under various current drive conditions. This model can be extended to study other complex optoelectronic structures under a wide variety of conditions that include heat removal via conduction, radiation, and convection. We apply the model to understand the effects of using high-thermal- conductivity substrates, and the transient thermal response under pulsed-current operation.

  18. Diamond based light-emitting diode for visible single-photon emission at room temperature

    NASA Astrophysics Data System (ADS)

    Lohrmann, A.; Pezzagna, S.; Dobrinets, I.; Spinicelli, P.; Jacques, V.; Roch, J.-F.; Meijer, J.; Zaitsev, A. M.

    2011-12-01

    Diamond-based p-i-n light-emitting diodes capable of single-photon emission in the visible spectral region at room temperature are discussed. The diodes were fabricated on a high quality single crystal diamond grown by chemical vapor deposition. Implantation of boron and phosphorus ions followed by annealing at a temperature of 1600 °C has been used for doping p-type and n-type areas, respectively. Electrical characterization of the devices demonstrates clear diode behavior. Spectra of electroluminescence generated in the i-area reveal sole emission from the neutral nitrogen-vacancy (NV) defects. Photon antibunching implies single-photon character of this emission when generated by individual NV defects.

  19. 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.

  20. 90-deg splicing error control in polarization maintaining fiber resonator based on white-light interferometry

    NASA Astrophysics Data System (ADS)

    Lin, Huizu; Yao, Qiong; Hu, Yongming; Ma, Lina

    2012-05-01

    Polarization fluctuation in polarization maintaining fiber (PMF) resonator is one of the major noise sources in resonant fiber optic gyroscope (R-FOG). 90-deg polarization-axis rotated splicing in R-FOG is an effective way to suppress the polarization-fluctuation induced noise. 90-deg polarization-axis rotated splicing error influences the noise suppression effect. Here, a polarization-coupling testing system based on white-light interferometry is designed to control 90-deg splicing error in double-coupler PMF resonator first time and a result of 0.37-deg splicing error is obtained for the first time. Then the resonant characteristics of the double-coupler PMF resonator are tested using the saw-tooth waveform scanning method. The finesse of this double-coupler PMF resonator is 24.0 and the phase interval of the two eigenstates of polarization (ESOPs) is π.

  1. Surface plasmon resonance biochemical sensor based on light guiding flexible fused silica capillary tubing

    NASA Astrophysics Data System (ADS)

    Liu, Xiuxin; Liu, Yun; Liu, Qiang; Gao, Xiaotong; Peng, Wei

    2015-12-01

    A fiber optic surface plasmon resonance (SPR) sensor based on light guiding flexible fused silica tubing with its cladding stripped and coated with gold film as SPR sensing area is presented. Theoretical simulate of the proposed sensing structure for different sensing area length and different film thickness of sensors is done to obtain the suitable parameters, and the simulation for different refractive index is carried out. Meanwhile, the experiments for refractive index (RI) measurement have been demonstrated using the developed sensor, 400 μm optical fiber sensor and 125 μm optical fiber sensor. Experimental results have shown the capillary sensor has advantage in terms of sensitivity and resolution. The capillary sensor is also used for detecting and monitoring biochemical binding and dissociation processes of the RNase B and Con A. It is proved that the sensor with chemical modification can be implemented for specific biochemical sensing

  2. Coherent and dynamic beam splitting based on light storage in cold atoms

    NASA Astrophysics Data System (ADS)

    Park, Kwang-Kyoon; Zhao, Tian-Ming; Lee, Jong-Chan; Chough, Young-Tak; Kim, Yoon-Ho

    2016-09-01

    We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the relative phase, and the optical frequencies of the output pulses. With further improvements, the active beam splitter demonstrated in this work might have applications in photonic photonic quantum information and in all-optical information processing.

  3. Computing light statistics in heterogeneous media based on a mass weighted probability density function method.

    PubMed

    Jenny, Patrick; Mourad, Safer; Stamm, Tobias; Vöge, Markus; Simon, Klaus

    2007-08-01

    Based on the transport theory, we present a modeling approach to light scattering in turbid material. It uses an efficient and general statistical description of the material's scattering and absorption behavior. The model estimates the spatial distribution of intensity and the flow direction of radiation, both of which are required, e.g., for adaptable predictions of the appearance of colors in halftone prints. This is achieved by employing a computational particle method, which solves a model equation for the probability density function of photon positions and propagation directions. In this framework, each computational particle represents a finite probability of finding a photon in a corresponding state, including properties like wavelength. Model evaluations and verifications conclude the discussion.

  4. 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

  5. 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%.

  6. Coherent and dynamic beam splitting based on light storage in cold atoms

    PubMed Central

    Park, Kwang-Kyoon; Zhao, Tian-Ming; Lee, Jong-Chan; Chough, Young-Tak; Kim, Yoon-Ho

    2016-01-01

    We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the relative phase, and the optical frequencies of the output pulses. With further improvements, the active beam splitter demonstrated in this work might have applications in photonic photonic quantum information and in all-optical information processing. PMID:27677457

  7. 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

  8. 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.

  9. 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.

  10. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    NASA Astrophysics Data System (ADS)

    Filippi, F.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Zigler, A.

    2016-09-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC_LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 1016-1017 cm-3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  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. Light-driven strong spin valve effects in an azobenzene-based spin optoelectronic device

    NASA Astrophysics Data System (ADS)

    Zeng, Jing; Chen, Ke-Qiu; Deng, Xiaohui; Long, Mengqiu

    2016-10-01

    A photoswitched single-molecule junction, a stable and reversible single-molecule electrical switch, has been successfully prepared by means of molecular engineering (2016 Science 352 1443). In this work we use a first-principles computational approach to investigate the spin valve effect of an azobenzene-based spin optoelectronic device. Our results demonstrate that the magnetoresistive ratio of the spin optoelectronic device is only about 65% when the azobenzene is in cis configuration, which is a low performance for practical applications. However, the magnetoresistive ratio of the device can be enhanced to about 2775% when the cis configuration of the azobenzene is changed into the trans configuration by applying a pulse of light. As a consequence, photoexcitation provides an effective way to obtain a high-performance spin optoelectronic device.

  18. 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

  19. 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.

  20. Solution-processed, high-performance light-emitting diodes based on quantum dots

    NASA Astrophysics Data System (ADS)

    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.

  1. 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

  2. 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.

  3. 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

  4. 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

    2016-06-10

    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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Phospholipid-based self-assembled mesophase systems for light-activated drug delivery.

    PubMed

    Du, Joanne D; Fong, Wye-Khay; Salentinig, Stefan; Caliph, Suzanne M; Hawley, Adrian; Boyd, Ben J

    2015-06-01

    The manipulation of the structure of phospholipid-based mesophases to induce a slow to fast drug release profile has potential for use in therapeutic situations where continuous absorption of drug is not desirable and reduce the frequency of injection for short acting or rapidly cleared drugs in treatments for diseases such as macular degeneration. This study had two aims; firstly to confirm the phase behaviour of 20 mol% cholesterol in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), which was previously reported to transition from lamellar (slow release) to bicontinuous cubic (fast release) phase with increasing temperature. Contrary to the literature, no bicontinuous cubic phase was observed but a transition to the inverse hexagonal phase occurred at all POPE : cholesterol ratios investigated. The second aim was to render these mesophases responsive to near-infrared laser (NIR) irradiation by incorporation of gold nanorods (GNR) incorporated into the POPE system to induce photothermal heating. The inclusion of 3 nM GNR in POPE systems induced reversible disruption of lipid packing equivalent to increasing the temperature to 55 °C when irradiated for 30 s. This study confirmed that although the previously published phase behavior was not correct, GNR and NIR can be used to manipulate the self-assembled mesophases in phospholipid-based systems and highlights the potential for a phospholipid-based light-activated drug delivery system.

  18. 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.

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

    PubMed

    Bor, E; Turduev, M; Kurt, H

    2016-01-01

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

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

    PubMed

    Bor, E; Turduev, M; Kurt, H

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  2. Analysis on light quantity and quality based on diverse cloud conditions

    NASA Astrophysics Data System (ADS)

    Yamashita, M.; Yoshimura, M.

    2014-09-01

    Photosynthetic active radiation (PAR) is the source of incident light energy for the photosynthetic activity of plants. PAR additionally characterizes the light environment on the surface of the Earth. The light environment is an important factor for estimating quantities such as carbon exchange and the productivities of forests and agriculture. The incident PAR on the ground surface has the characteristics of light quantity consists of direct and diffuse components, and of light quality consists of spectral components such blue, green and red lights. These light quantity and quality are also important light environmental factors in the photosynthetic activities of plants under the natural environment. However, the light environment including direct and diffuse components and spectral components is easily affected by cloud conditions especially cloud cover and its movements. In this paper, we focus on the characteristics of the light quantity and quality under diverse cloud conditions, and analyse the observational data, which are the global- and diffuse- spectral irradiances from 400 to 700 nm with quantum and energy units and the cloud conditions derived from whole-sky images taken during summer in Kyoto city. As for the comparisons with light quality and cloud conditions, we use the Normalized Difference PAR Spectral Index (NDPSI) which shows the difference of red- and blue-light components and we use cloud cover and the Sun appearance ratio derived from the wholesky images to define the cloud conditions. As the results of these analyses, we confirmed that there are the clear relationships between cloud cover and diffuse ratio, between the Sun appearance ratio and the normalized global PAR as the light quantity, between cloud cover and NDPSI in diffuse component, and between the Sun appearance ratio and NDPSI in direct component as the light quality.

  3. The Light Attracting Effect of Pyridine Derivatives Based Quasi-Solid Electrolyte in Dye-Sensitized Solar Cell.

    PubMed

    Cai, Molang; Bell, John; Dai, Songyuan

    2016-06-01

    The pyridine derivatives are added into acetonitrile based electrolyte to establish framework, then form the quasi solid electrolyte. The ion diffusion of cetylpyridinium chloride and cetylpyridinium bromide based electrolytes is enhanced comparing with the ion diffusion of reference acetonitrile electrolyte. The ordered structure of cetylpyridinuium chloride quasi solid electrolyte has been observed by SEM images. Light scattering effect of cetylpyridinuium chloride quasi solid electrolyte is evidenced by the larger resulted by transmitted and scattered spectra. The light harvesting efficiency of device based on C16Cl is much higher than acetonitrile based device. The cell efficiency of C16Cl and C16Br based device are 5.72% and 6.02%, which are 41% and 48% higher than acetonitrile liquid electrolyte based device. The C16l based device produces low cell efficiency 2.06%, which is 49% decrease compare to the blank device due to the limitation of iodide-triodide transportation in the iodide framework. PMID:27427629

  4. White Light Emission from Planar Remote Phosphor Based on NHC Cycloplatinated Complexes.

    PubMed

    Fuertes, Sara; Chueca, Andrés J; Perálvarez, Mariano; Borja, Pilar; Torrell, Marc; Carreras, Josep; Sicilia, Violeta

    2016-06-29

    We report on the generation of bright white luminescence through solid-state illumination of remote phosphors based on novel cycloplatinated N-heterocyclic carbene (NHC) compounds. Following a stepwise protocol we got the new NHC compound [{Pt(μ-Cl)(C(∧)C*)}2] (4) (HC(∧)C*-κC* = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazol-2-ylidene), which was used together with the related ones 4a (HC(∧)C*-κC*= 1-(4-cyanophenyl)-3-methyl-1H-imidazol-2-ylidene) and 4b (HC(∧)C*-κC*= 3-methyl-1-(naphthalen-2-yl)-1H-imidazol-2-ylidene) as starting materials for the synthesis of the new ionic derivatives [Pt(R-C(∧)C*) (CNR')2]PF6 (R = -COOEt, R' = t-Bu (5), Xyl (6); R = -CN, R' = t-Bu (7), Xyl (8); R(∧)C = Naph, R' = t-Bu (9), Xyl (10)). The X-ray structures of 6 and 8-10 have been determined. The photophysical properties of these cationic compounds have been studied and supported by the time-dependent-density functional theory (TD-DFT) calculations. The compounds 5, 8, and 9 have been revealed as the most efficient emitters in the solid state with quantum yields of 41%, 21%, and 40%, respectively. White-light remote-phosphors have been prepared just by stacking different combinations of these compounds and [Pt(bzq) (CN) (CN(t)Bu)] (R1) as blue (5, 8), yellow (9), and red (R1) components onto the same substrate. The CCT (correlated color temperature) and the CRI (color rendering index) of the emitted white-light have been tuned by accurately controlling the individual contributions.

  5. Preliminary evaluation of a light based Contact Hearing Device for the hearing impaired

    PubMed Central

    Fay, Jonathan P.; Perkins, Rodney; Levy, Suzanne Carr; Nilsson, Michael; Puria, Sunil

    2013-01-01

    Objective To assess the safety, stability, and performance of the broad spectrum, light based Contact Hearing Device (CHD) on listeners with hearing impairment. Study Design Feasibility study. Setting Single-Site Research and Development Facility. Subjects Thirteen subjects with symmetric mild to severe sensorineural hearing impairment had the CHD placed bilaterally. Intervention A custom-molded light activated Tympanic Contact Actuator (TCA) was placed into each ear by a physician, where it stayed in contact with the umbo and a portion of the medial wall of the ear canal for four months. Each CHD was calibrated and programmed to provide appropriate broad-spectrum amplification. Main Outcome Measures Safety was determined through routine otologic examinations. Aided and pre-TCA-insertion unaided audiometric thresholds, Reception Threshold for Sentences (RTS), and Abbreviated Profile of Hearing Aid Benefit (APHAB) measurements were made to characterize system performance as well as the benefits of amplification via the CHD. Results The TCAs remained on subjects’ ears for an average total of 122 days, without causing signs of inflammation or infection, and there were no serious device-related adverse events. Measured average maximum output of 90–110 dB SPL in the 0.25–10 kHz range, average maximum gain before feedback of 40 dB, and functional gain through 10 kHz show extended bandwidth broad spectrum output and gain. RTS results showed significant aided improvements of up to 2.8 dB, and APHAB results showed clinically significant aided benefits in 11/12 (92%) subjects. Conclusion The safety, stability, and performance demonstrated in this initial 4-month study suggest that the CHD may offer a feasible way of providing broad-spectrum amplification appropriate to treat listeners with mild to severe hearing impairment. PMID:23524632

  6. Steady State Microbunching for High Brilliance and High Repetition Rate Storage Ring-Based Light Sources

    SciTech Connect

    Chao, Alex; Ratner, Daniel; Jiao, Yi; /Beijing, Inst. High Energy Phys.

    2012-09-06

    Electron-based light sources have proven to be effective sources of high brilliance, high frequency radiation. Such sources are typically either linac-Free Electron Laser (FEL) or storage ring types. The linac-FEL type has high brilliance (because the beam is microbunched) but low repetition rate. The storage ring type has high repetition rate (rapid beam circulation) but comparatively low brilliance or coherence. We propose to explore the feasibility of a microbunched beam in a storage ring that promises high repetition rate and high brilliance. The steady-state-micro-bunch (SSMB) beam in storage ring could provide CW sources for THz, EUV, or soft X-rays. Several SSMB mechanisms have been suggested recently, and in this report, we review a number of these SSMB concepts as promising directions for high brilliance, high repetition rate light sources of the future. The trick of SSMB lies in the RF system, together with the associated synchrotron beam dynamics, of the storage ring. Considering various different RF arrangements, there could be considered a number of scenarios of the SSMB. In this report, we arrange these scenarios more or less in order of the envisioned degree of technical challenge to the RF system, and not in the chronological order of their original references. Once the stored beam is steady-state microbunched in a storage ring, it passes through a radiator repeatedly every turn (or few turns). The radiator extracts a small fraction of the beam energy as coherent radiation with a wavelength corresponding to the microbunched period of the beam. In contrast to an FEL, this radiator is not needed to generate the microbunching (as required e.g. by SASE FELs or seeded FELs), so the radiator can be comparatively simple and short.

  7. White Light Emission from Planar Remote Phosphor Based on NHC Cycloplatinated Complexes.

    PubMed

    Fuertes, Sara; Chueca, Andrés J; Perálvarez, Mariano; Borja, Pilar; Torrell, Marc; Carreras, Josep; Sicilia, Violeta

    2016-06-29

    We report on the generation of bright white luminescence through solid-state illumination of remote phosphors based on novel cycloplatinated N-heterocyclic carbene (NHC) compounds. Following a stepwise protocol we got the new NHC compound [{Pt(μ-Cl)(C(∧)C*)}2] (4) (HC(∧)C*-κC* = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazol-2-ylidene), which was used together with the related ones 4a (HC(∧)C*-κC*= 1-(4-cyanophenyl)-3-methyl-1H-imidazol-2-ylidene) and 4b (HC(∧)C*-κC*= 3-methyl-1-(naphthalen-2-yl)-1H-imidazol-2-ylidene) as starting materials for the synthesis of the new ionic derivatives [Pt(R-C(∧)C*) (CNR')2]PF6 (R = -COOEt, R' = t-Bu (5), Xyl (6); R = -CN, R' = t-Bu (7), Xyl (8); R(∧)C = Naph, R' = t-Bu (9), Xyl (10)). The X-ray structures of 6 and 8-10 have been determined. The photophysical properties of these cationic compounds have been studied and supported by the time-dependent-density functional theory (TD-DFT) calculations. The compounds 5, 8, and 9 have been revealed as the most efficient emitters in the solid state with quantum yields of 41%, 21%, and 40%, respectively. White-light remote-phosphors have been prepared just by stacking different combinations of these compounds and [Pt(bzq) (CN) (CN(t)Bu)] (R1) as blue (5, 8), yellow (9), and red (R1) components onto the same substrate. The CCT (correlated color temperature) and the CRI (color rendering index) of the emitted white-light have been tuned by accurately controlling the individual contributions. PMID:27268265

  8. Optoelectronic Properties of Color-Tunable Mixed Ligand-Based Light-Emitting Zinc Complexes

    NASA Astrophysics Data System (ADS)

    Singh, Devender; Bhagwan, Shri; Saini, Raman Kumar; Tanwar, Vijeta; Nishal, Vandna

    2016-10-01

    A series of mixed ligand-based zinc complexes (Zn1-Zn5); [(8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn1), [(5-chloro-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn2), [(5,7-dichloro-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn3), [(2-methyl-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn4) and [(5,7-dimethyl-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn5) were synthesized and characterized. The photophysical properties of zinc complexes were examined by ultraviolet-visible absorption and photoluminescence emission spectroscopy. All prepared metal complexes produced intense luminescence on excitation with a UV light source. In this study, the color-tunable characteristics of metal complexes were investigated by introducing the electron-donating and electron-withdrawing groups on the 8-hydroxyquinoline ligand. The emission spectra of metal complexes showed emission wavelength at 500 nm for [ZnHBI(q)], 509 nm for [ZnHBI(Clq)], 504 nm for [Zn(HBI)(Cl2q)], 496 nm for [ZnHBI (Meq)] and 573 nm for [ZnHBI(Me2Q)] materials. A temperature-dependent PL spectrum was used to study the emission profile of zinc complex and observed that variation in the temperature altered the position and the intensity of emission peak. The synthesized metal complex also exhibited good thermal stability (>300°C). Photophysical characteristics of color-tunable light-emitting zinc complexes suggested that these materials could be efficiently used for emissive display device applications.

  9. Light extraction method for mixing rods based in grooves with elliptical shape

    NASA Astrophysics Data System (ADS)

    Sánchez-Guerrero, Guillermo E.; Viera-González, Perla M.; Ceballos-Herrera, Daniel E.; Selvas-Aguilar, Romeo

    2015-08-01

    Homogenize light is the principal purpose of mixing rods. Light extraction from mixing rods is proposed by changing the shape of the face, the rod or a combination of both for many applications. Light extraction also can be done by its lateral face by cutting the Mixing rod. In this work a simulation of square and hexagonal poly(methyl methacrylate) (PMMA) mixing rods were made in Radiant Zemax ® 12 release 2 designed with an elliptical transversal cut to extract light from a lateral face. The cut is specular for rays that fulfill the total internal reflection condition, the reflected rays are deviated and the Total Internal Reflection (TIR) condition broken, then, extracted. An advantage of this cut is that it can be controlled in depth to extract the amount of light required and the remaining light used for other purposes. Also it can reduce the size of the mixing rods and optical components. For the simulation, an LED light were used as source, the light were homogenized by the mixing rod and due to it, the light extracted is also homogenous. The polar power map, radiant intensity and color of the light extracted are presented and compared in both mixing rods.

  10. Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean.

    PubMed

    Fortunato, Antonio Emidio; Jaubert, Marianne; Enomoto, Gen; Bouly, Jean-Pierre; Raniello, Raffaella; Thaler, Michael; Malviya, Shruti; Bernardes, Juliana Silva; Rappaport, Fabrice; Gentili, Bernard; Huysman, Marie J J; Carbone, Alessandra; Bowler, Chris; d'Alcalà, Maurizio Ribera; Ikeuchi, Masahiko; Falciatore, Angela

    2016-03-01

    The absorption of visible light in aquatic environments has led to the common assumption that aquatic organisms sense and adapt to penetrative blue/green light wavelengths but show little or no response to the more attenuated red/far-red wavelengths. Here, we show that two marine diatom species, Phaeodactylum tricornutum and Thalassiosira pseudonana, possess a bona fide red/far-red light sensing phytochrome (DPH) that uses biliverdin as a chromophore and displays accentuated red-shifted absorbance peaks compared with other characterized plant and algal phytochromes. Exposure to both red and far-red light causes changes in gene expression in P. tricornutum, and the responses to far-red light disappear in DPH knockout cells, demonstrating that P. tricornutum DPH mediates far-red light signaling. The identification of DPH genes in diverse diatom species widely distributed along the water column further emphasizes the ecological significance of far-red light sensing, raising questions about the sources of far-red light. Our analyses indicate that, although far-red wavelengths from sunlight are only detectable at the ocean surface, chlorophyll fluorescence and Raman scattering can generate red/far-red photons in deeper layers. This study opens up novel perspectives on phytochrome-mediated far-red light signaling in the ocean and on the light sensing and adaptive capabilities of marine phototrophs. PMID:26941092

  11. Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean.

    PubMed

    Fortunato, Antonio Emidio; Jaubert, Marianne; Enomoto, Gen; Bouly, Jean-Pierre; Raniello, Raffaella; Thaler, Michael; Malviya, Shruti; Bernardes, Juliana Silva; Rappaport, Fabrice; Gentili, Bernard; Huysman, Marie J J; Carbone, Alessandra; Bowler, Chris; d'Alcalà, Maurizio Ribera; Ikeuchi, Masahiko; Falciatore, Angela

    2016-03-01

    The absorption of visible light in aquatic environments has led to the common assumption that aquatic organisms sense and adapt to penetrative blue/green light wavelengths but show little or no response to the more attenuated red/far-red wavelengths. Here, we show that two marine diatom species, Phaeodactylum tricornutum and Thalassiosira pseudonana, possess a bona fide red/far-red light sensing phytochrome (DPH) that uses biliverdin as a chromophore and displays accentuated red-shifted absorbance peaks compared with other characterized plant and algal phytochromes. Exposure to both red and far-red light causes changes in gene expression in P. tricornutum, and the responses to far-red light disappear in DPH knockout cells, demonstrating that P. tricornutum DPH mediates far-red light signaling. The identification of DPH genes in diverse diatom species widely distributed along the water column further emphasizes the ecological significance of far-red light sensing, raising questions about the sources of far-red light. Our analyses indicate that, although far-red wavelengths from sunlight are only detectable at the ocean surface, chlorophyll fluorescence and Raman scattering can generate red/far-red photons in deeper layers. This study opens up novel perspectives on phytochrome-mediated far-red light signaling in the ocean and on the light sensing and adaptive capabilities of marine phototrophs.

  12. GaN-based light-emitting diodes on various substrates: a critical review

    NASA Astrophysics Data System (ADS)

    Li, Guoqiang; Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Wang, Haiyan; Lin, Zhiting; Zhou, Shizhong

    2016-05-01

    GaN and related III-nitrides have attracted considerable attention as promising materials for application in optoelectronic devices, in particular, light-emitting diodes (LEDs). At present, sapphire is still the most popular commercial substrate for epitaxial growth of GaN-based LEDs. However, due to its relatively large lattice mismatch with GaN and low thermal conductivity, sapphire is not the most ideal substrate for GaN-based LEDs. Therefore, in order to obtain high-performance and high-power LEDs with relatively low cost, unconventional substrates, which are of low lattice mismatch with GaN, high thermal conductivity and low cost, have been tried as substitutes for sapphire. As a matter of fact, it is not easy to obtain high-quality III-nitride films on those substrates for various reasons. However, by developing a variety of techniques, distincts progress has been made during the past decade, with high-performance LEDs being successfully achieved on these unconventional substrates. This review focuses on state-of-the-art high-performance GaN-based LED materials and devices on unconventional substrates. The issues involved in the growth of GaN-based LED structures on each type of unconventional substrate are outlined, and the fundamental physics behind these issues is detailed. The corresponding solutions for III-nitride growth, defect control, and chip processing for each type of unconventional substrate are discussed in depth, together with a brief introduction to some newly developed techniques in order to realize LED structures on unconventional substrates. This is very useful for understanding the progress in this field of physics. In this review, we also speculate on the prospects for LEDs on unconventional substrates.

  13. GaN-based light-emitting diodes on various substrates: a critical review.

    PubMed

    Li, Guoqiang; Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Wang, Haiyan; Lin, Zhiting; Zhou, Shizhong

    2016-05-01

    GaN and related III-nitrides have attracted considerable attention as promising materials for application in optoelectronic devices, in particular, light-emitting diodes (LEDs). At present, sapphire is still the most popular commercial substrate for epitaxial growth of GaN-based LEDs. However, due to its relatively large lattice mismatch with GaN and low thermal conductivity, sapphire is not the most ideal substrate for GaN-based LEDs. Therefore, in order to obtain high-performance and high-power LEDs with relatively low cost, unconventional substrates, which are of low lattice mismatch with GaN, high thermal conductivity and low cost, have been tried as substitutes for sapphire. As a matter of fact, it is not easy to obtain high-quality III-nitride films on those substrates for various reasons. However, by developing a variety of techniques, distincts progress has been made during the past decade, with high-performance LEDs being successfully achieved on these unconventional substrates. This review focuses on state-of-the-art high-performance GaN-based LED materials and devices on unconventional substrates. The issues involved in the growth of GaN-based LED structures on each type of unconventional substrate are outlined, and the fundamental physics behind these issues is detailed. The corresponding solutions for III-nitride growth, defect control, and chip processing for each type of unconventional substrate are discussed in depth, together with a brief introduction to some newly developed techniques in order to realize LED structures on unconventional substrates. This is very useful for understanding the progress in this field of physics. In this review, we also speculate on the prospects for LEDs on unconventional substrates.

  14. Efficient near-infrared organic light-emitting devices based on low-gap fluorescent oligomers

    NASA Astrophysics Data System (ADS)

    Yang, Yixing; Farley, Richard T.; Steckler, Timothy T.; Eom, Sang-Hyun; Reynolds, John R.; Schanze, Kirk S.; Xue, Jiangeng

    2009-08-01

    We report efficient near-infrared (NIR) organic light-emitting devices (OLEDs) based on fluorescent donor-acceptor-donor conjugated oligomers. The energies of the highest occupied and lowest unoccupied molecular orbitals of these oligomers are controlled by the donor and acceptor components, respectively; hence the energy gap and therefore the emission wavelength can be tuned by changing the strengths of the donor and acceptor components. External quantum efficiencies (EQEs) up to 1.6% and power efficiencies up to 7.0 mW/W are achieved in NIR OLEDs based on 4,9-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-6,7-dimethyl-[1,2,5]thiadiazolo[3,4-g]-quinoxaline (BEDOT-TQMe2), in which the electroluminescence peaks at a wavelength of 692 nm but extends to well above 800 nm. With a stronger acceptor in the oligomer, 4,8-bis(2,3-dihydrothieno-[3,4-b][1,4]dioxin-5-yl)benzo[1,2-c;4,5-c']bis [1,2,5]thiadiazole (BEDOT-BBT) based devices show longer wavelength emission peaked at 815 nm, although the maximum EQE is reduced to 0.51% due to the lower fluorescent quantum yield of the NIR emitter. The efficiencies of these NIR OLEDs are further increased by two to three times by using the sensitized fluorescent device structure, leading to a maximum EQE of 3.1% for BEDOT-TQMe2 and 1.6% for BEDOT-BBT based devices.

  15. Nano-particle based scattering layers for optical efficiency enhancement of organic light-emitting diodes and organic solar cells

    NASA Astrophysics Data System (ADS)

    Chang, Hong-Wei; Lee, Jonghee; Hofmann, Simone; Hyun Kim, Yong; Müller-Meskamp, Lars; Lüssem, Björn; Wu, Chung-Chih; Leo, Karl; Gather, Malte C.

    2013-05-01

    The performance of both organic light-emitting diodes (OLEDs) and organic solar cells (OSC) depends on efficient coupling between optical far field modes and the emitting/absorbing region of the device. Current approaches towards OLEDs with efficient light-extraction often are limited to single-color emission or require expensive, non-standard substrates or top-down structuring, which reduces compatibility with large-area light sources. Here, we report on integrating solution-processed nano-particle based light-scattering films close to the active region of organic semiconductor devices. In OLEDs, these films efficiently extract light that would otherwise remain trapped in the device. Without additional external outcoupling structures, translucent white OLEDs containing these scattering films achieve luminous efficacies of 46 lm W-1 and external quantum efficiencies of 33% (both at 1000 cd m-2). These are by far the highest numbers ever reported for translucent white OLEDs and the best values in the open literature for any white device on a conventional substrate. By applying additional light-extraction structures, 62 lm W-1 and 46% EQE are reached. Besides universally enhancing light-extraction in various OLED configurations, including flexible, translucent, single-color, and white OLEDs, the nano-particle scattering film boosts the short-circuit current density in translucent organic solar cells by up to 70%.

  16. Porphyrin-based polymeric nanostructures for light harvesting applications: Ab initio calculations

    NASA Astrophysics Data System (ADS)

    Orellana, Walter

    The capture and conversion of solar energy into electricity is one of the most important challenges to the sustainable development of mankind. Among the large variety of materials available for this purpose, porphyrins concentrate great attention due to their well-known absorption properties in the visible range. However, extended materials like polymers with similar absorption properties are highly desirable. In this work, we investigate the stability, electronic and optical properties of polymeric nanostructures based on free-base porphyrins and phthalocyanines (H2P, H2Pc), within the framework of the time-dependent density functional perturbation theory. The aim of this work is the stability, electronic, and optical characterization of polymeric sheets and nanotubes obtained from H2P and H2Pc monomers. Our results show that H2P and H2Pc sheets exhibit absorption bands between 350 and 400 nm, slightly different that the isolated molecules. However, the H2P and H2Pc nanotubes exhibit a wide absorption in the visible and near-UV range, with larger peaks at 600 and 700 nm, respectively, suggesting good characteristic for light harvesting. The stability and absorption properties of similar structures obtained from ZnP and ZnPc molecules is also discussed. Departamento de Ciencias Físicas, República 220, 037-0134 Santiago, Chile.

  17. Lower body kinematics evaluation based on a multidirectional four-dimensional structured light measurement.

    PubMed

    Lenar, Janusz; Witkowski, Marcin; Carbone, Vincenzo; Kolk, Sjoerd; Adamczyk, Marcin; Sitnik, Robert; van der Krogt, Marjolein; Verdonschot, Nico

    2013-05-01

    We report on a structured light-scanning system, the OGX|4DSCANNER, capable of capturing the surface of a human body with 2 mm spatial resolution at a 60 Hz frame-rate. The performance of modeling the human lower body dynamics is evaluated by comparing the system with the current gold standard, i.e., the VICON system. The VICON system relies on the application of reflective markers on a person's body and tracking their positions in three-dimensional space using multiple cameras [optical motion capture (OMC)]. For the purpose of validation of the 4DSCANNER, a set of "virtual" markers was extracted from the measured surface. A set of musculoskeletal models was built for three subjects based on the trajectories of real and virtual markers. Next, the corresponding models were compared in terms of joint angles, joint moments, and activity of a number of major lower body muscles. Analyses showed a good overall agreement of the modeling outcome. We conclude that the 4DSCANNER within its limitations has the potential to be used in clinical gait analysis instead of optical marker-based systems. The advantage of the 4DSCANNER over OMC solutions is that it does not burden patients with time-consuming marker application. This study demonstrates the versatility of this measurement technique.

  18. Identification of Behavior Based Safety by Using Traffic Light Analysis to Reduce Accidents

    NASA Astrophysics Data System (ADS)

    Mansur, A.; Nasution, M. I.

    2016-01-01

    This work present the safety assessment of a case study and describes an important area within the field production in oil and gas industry, namely behavior based safety (BBS). The company set a rigorous BBS and its intervention program that implemented and deployed continually. In this case, observers requested to have discussion and spread a number of determined questions related with work behavior to the workers during observation. Appraisal of Traffic Light Analysis (TLA) as one tools of risk assessment used to determine the estimated score of BBS questionnaire. Standardization of TLA appraisal in this study are based on Regulation of Minister of Labor and Occupational Safety and Health No:PER.05/MEN/1996. The result shown that there are some points under 84%, which categorized in yellow category and should corrected immediately by company to prevent existing bad behavior of workers. The application of BBS expected to increase the safety performance at work time-by-time and effective in reducing accidents.

  19. Synthesis and Characterization of Plant based Polythiophene Copolymers for Light Harvesting Applications

    NASA Astrophysics Data System (ADS)

    Kodithuwakku, Udari; Malavi Arachchi, Prashantha; Ratnaweera, Dilru

    Polythiophenes became more attractive in diverse applications due to some of their inherent properties including thermal and environmental stability as well as optical and electronic conductive properties. Commonly thiophene monomers are obtained from byproducts of crude oils. The current study discuss for the first time the synthesis and characterization of light harvesting polythiophenes copolymers from thiophene derivatives extracted from Tagetes species. There were mainly two thiophenes derivatives, 5-(3-buten-1-ynyl)-2, 2-bithienyl and 2, 2', 5, 2''-terthienyl (terthiophene), in the roots of the plant. Chemical oxidative radical polymerization was followed during the synthesis of copolymers with various block compositions of plant based terthiophenes and 3-hexyl terthiophenes. Structural characterization of the synthetic products was done using FTIR, NMR, Uv-vis, XRD and DSC techniques. Polythiophene homopolymers obtained from plant based terthiophenes have limited processability of solar cells due to poor solubility in common organic solvents. A significant solubility improvement was observed with copolymers having minor contributions of 3-hexylthiophenes. Research Grants, University of Sri Jayewardenepura, Sri Lanka.

  20. High thermal stability fluorene-based hole-injecting material for organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Li, Lu; Jiao, Bo; Li, Sanfeng; Ma, Lin; Yu, Yue; Wu, Zhaoxin

    2016-03-01

    Novel N1,N3,N5-tris(9,9-diphenyl-9H-fluroen-2-yl)-N1,N3,N5-triphenylbenzene-1,3,5-triamine (TFADB) was synthesized and characterized as a hole-injecting material (HIM) for organic light-emitting devices (OLEDs). By incorporating fluorene group TFADB shows a high glass-transition temperature Tg > 168 °C, indicative of excellent thermal stability. TFADB-based devices exhibited the highest performance in terms of the maximum current efficiency (6.0 cd/A), maximum power efficiency (4.0 lm/W), which is improved than that of the standard device based on 4-4‧-4″Tris(N-(naphthalene-2-yl)-N-phenyl-amino)triphenylamine (2T-NATA) (5.2 cd/A, 3.6 lm/W). This material could be a promising hole-injecting material, especially for the high temperature applications of OLEDs and other organic electronic devices.