• Wang, Zehuan; Tang, Feng; Fan, Hailong; Wang, Le; Jin, Zhaoxia 2017-06-13 Polydopamine (PDA) generally demonstrates as an efficient free-radical scavenger. However, its free-radical chemistry under illumination is unclear, which becomes important in view of growing studies of polydopamine applications in photoprotector and photothermal therapy. In this study, for the first time, we reported an experimental investigation of the generation of hydroxyl free radicals from ultraviolet (UV)- illuminated polydopamine in an aqueous environment. By using terephthalic acid as fluorescent probe, we measured hydroxyl radicals generated from UV- illuminated polydopamine with different shapes and sizes. The morphology of PDA shows significant influence on its productions of hydroxyl free radicals.

Through characterizations of UV-vis absorption spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectrometry, mass spectrometry, and thermogravimetric analysis, we demonstrated the change of PDA nanomaterials brought by UV- light illumination in composition and thermal stability. We proposed a tentative mechanism for interpreting the relationship between morphology and photostability of PDA nanomaterials. These results reveal underlying complexity of polydopamine chemistry under light illumination that will deepen our understanding and benefit its further application. • Uddin, Mohammad Shorif; Lee, Hwee Kuan; Preibisch, Stephan; Tomancak, Pavel 2011-08-01 Light microscopy images suffer from poor contrast due to light absorption and scattering by the media.

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The resulting decay in contrast varies exponentially across the image along the incident light path. Classical space invariant deconvolution approaches, while very effective in deblurring, are not designed for the restoration of uneven illumination in microscopy images. In this article, we present a modified radiative transfer theory approach to solve the contrast degradation problem of light sheet microscopy (LSM) images. We confirmed the effectiveness of our approach through simulation as well as real LSM images.

• Liu, Kai; Zhang, Qin-Wei; Gu, Yong-Jian; Li, Qing-Liang 2017-04-01 Quantum illumination is one of the most basic ways to realize the quantum radar for detection of low-reflectivity targets embedded in a thermal-noise bath. It preserves a strong advantage over the classical counterparts even though its fragile quantum entanglement is completely destroyed by a large amount of noise and losses.

In this paper, we describe and analyze a discrete- variable quantum illumination system with ancillary degrees of freedom of entangled photon pairs. Comparing the error probability bound, i.e., the quantum Chernoff bound, we identify that this system indeed offers higher accuracy than the single-photon illumination and quantum illumination with single degree of freedom of entangled photon pairs. Furthermore, the utilization of ancillary degrees of freedom exponentially enhances signal-to-noise ratio over quantum illumination without ancillary degrees of freedom. It means that this system reduces the necessary amount of signal photons to accurately determine whether the object is present or absent in the target region, which is absolutely crucial to the stealthiness of the radar system. • Izawa, Masumi R; French, Michael D; Hedge, Alan 2011-10-01 This study provides an historical and statistical analysis of archival data from the Hawthorne illumination experiments.

Previous accounts of the illumination experiments are fraught with inconsistencies because they have been based on secondary sources. The general consensus has been that variations in light levels had no effect on worker productivity at Hawthorne. All reports and data were thought to have been destroyed, but an archive at Cornell University was found to contain copies of the original documentation and much of the data from all three illumination experiments. Conclusions were originally drawn from visual comparisons of productivity graphs, and the data have never been properly statistically analyzed. Archival reports, notes, photographs, and letters on the experiments were consulted.

Productivity data were extracted from the tables and graphs in the reports and statistically analyzed for each experiment. Previously unpublished details of the illumination experiments emerged. An effect of lighting on productivity was found in the first treatment sequence for the first experiment, but this finding was not confirmed in the second sequence or in the second and third experiments.

Experimental results provided inconsistent evidence of an association between light levels and productivity. All three experiments were found to be seriously flawed. This study challenges popular accounts of the 'Hawthorne effect,' and the shortcomings of these experiments also have implications for the design of field studies. • Olkkonen, K.

Maria; Brainard, David H. 2010-01-01 Color, lightness, and glossiness are perceptual attributes associated with object reflectance. For these perceptual representations to be useful, they must correlate with physical reflectance properties of objects, and not be overly affected by changes in illumination or the viewing context. Color and lightness constancy have received much attention in past investigations, but little is known about the perception of glossiness under changing lighting conditions.

We employed a matching paradigm to investigate the perception of lightness and glossiness under geometric changes in illumination. Stimuli were computer simulations of scenes with spheres displayed on a high-dynamic-range display. Observers matched the specular and diffuse reflectance of a test sphere to match the appearance of a reference sphere simulated under a different light field. Observers were veridical in their diffuse component matches across geometric changes in light fields. In contrast, surface specularity was either overestimated or underestimated relative to the reference sphere depending on the light field comparison. The effect of changing light field geometry on perceived glossiness and lightness was independent of surface diffuse and specular reflectance and approximately independent of the roughness of the specular component. Luminance histogram statistics (standard deviation, skewness, kurtosis) were not good predictors of the specular component matches.

PMID:20884603 • El-Henawy, Sally I; Mohamed, Mohamed W N; Mashaly, Islam A; Mohamed, Osama N; Galal, Ola; Taha, Iman; Nassar, Khaled; Safwat, Amr M E 2014-05-05 With the high population growth rate, especially in developing countries, and the scarcity of land resources, buildings are becoming so close to each other, depriving the lower floors and the alleys from sunlight and consequently causing health problems. Therefore, there is an urgent need for cost-effective efficient light redirecting panels that guide sun rays into those dim places. In this paper, we address this problem. A novel sine wave based panel is presented to redirect/diverge light downward and enhance the illumination level in those dark places.

Simulation results show that the proposed panel improves the illuminance values by more than 200% and 400% in autumn and winter respectively, operates over wide solar altitude ranges, and redirects light efficiently. Experimental and simulation results are in good agreement.

• Zorn, C.J.; Kross, B.J.; Majewski, S.; Wojcik, R.F. 1998-08-25 The present invention comprises an illumination system for specialized decorative lighting including a light source, a flexible plastic tube sheath for distributing the light to a remote location, a transparent liquid core filling the tube that has an index of refraction greater than that of the plastic tube and an arrangement where light coupled from the light source is caused to leak from the liquid light guide at desired locations for the purposes of specialized lighting, such as underwater illumination in swimming pools. • Burlakov, V.

Goriely, A.; Foulds, I. 2013-12-16 We show that a flat surface of a polymer in rubber state illuminated with intense electromagnetic radiation is unstable with respect to periodic modulation. Initial periodic perturbation is amplified due to periodic thermal expansion of the material heated by radiation. Periodic heating is due to focusing-defocusing effects caused by the initial surface modulation. The surface modulation has a period longer than the excitation wavelength and does not require coherent light source.

Electronic Test Instruments Robert Witte Pdf Download here. Therefore, it is not related to the well-known laser induced periodic structures on polymer surfaces but may contribute to their formation and to other phenomena of light-matter interaction. • Takai, Akihiro; Takada, Yasutsugu; Motomura, Hideki; Teramukai, Satoshi 2014-02-01 The aim of this study was to evaluate the impact of attached shadow cues for laparoscopic task performance.

We developed a soft- light overhead illumination system (SOIS) that produced attached shadows on objects. We compared results using the SOIS with those using a conventional illumination system with regard to laparoscopic experience and laparoscope-to-target distances (LTDs).

Forty-two medical students and 23 surgeons participated in the study. A peg transfer task (LTD, 120 mm) for students and surgeons, and a suture removal task (LTD, 30 mm) for students were performed. Illumination systems were randomly assigned to each task. Endpoints were: total number of peg transfers; percentage of peg-dropping errors; and total execution time for suture removal. After the task, participants filled out a questionnaire on their preference for a particular illumination system.

Total number of peg transfers was greater with the SOIS for both students and surgeons. Percentage of peg-dropping errors for surgeons was lower with the SOIS. Total execution time for suture removal was shorter with the SOIS. Forty-five participants (69% in total) evaluated the SOIS for easier task performance.

The present results confirm that the SOIS improves laparoscopic task performance, regardless of previous laparoscopic experience or LTD. • Sun, Wen-Shing; Tien, Chuen-Lin; Tsuei, Chih-Hsuan; Pan, Jui-Wen 2014-10-10 We simulate and compare the illuminance, uniformity, and efficiency of metal-halide lamps, white LED light sources, and hybrid light box designs combining sunlight and white LED lighting used for indoor basketball court illumination. According to the optical simulation results and our examination of real situations, we find that hybrid light box designs combining sunlight and white LEDs do perform better than either metal-halide lamps or white LED lights.

An evaluation of the sunlight concentrator system used in our inverted solar cell shows that the energy consumption of stadium lighting can be reduced significantly. • Wang, Kun; Heidingsfelder, Philipp; Gao, Jun; Yu, Liandong; Ott, Peter 2015-04-01 In this contribution we present a new algorithm for structured illumination microscopy with incoherent light. Existing algorithms for determining the contrast values of the focal depth response require a high accurate phase shift of the fringe pattern illumination. The presented algorithm, which is robust against inaccurate phase shift of the fringe pattern, reduces significantly the requirements for the phase shift and consequently the costs of the microscope. The new algorithm was tested by a preliminary experiment, whereby the grating was shifted by an elastic guided micro-motion mechanism employing a low-cost stepper motor replacing the conventional expensive piezo drive.

The determined focal depth response is very smooth and corresponds very well to the theoretical focal depth response. • Llorente, Briardo; Martinez-Garcia, Jaime F; Stange, Claudia; Rodriguez-Concepcion, Manuel 2017-06-01 Light stimulates the biosynthesis of carotenoids and regulates the development of plastid structures to accommodate these photoprotective pigments. Work with Arabidopsis revealed molecular factors coordinating carotenoid biosynthesis and storage with photosynthetic development during deetiolation, when underground seedlings emerge to the light. Some of these factors also adjust carotenoid biosynthesis in response to plant proximity (i.e., shade), a mechanism that was readapted in tomato to monitor fruit ripening progression. While light positively impacts carotenoid production and accumulation in most cases, total carotenoid levels decrease in roots of colored carrot cultivars when illuminated. The recent discovery that such cultivars might be photomorphogenic mutants provides an explanation for this striking phenotype.

Copyright © 2017 Elsevier Ltd. All rights reserved. V.; Gavrilenko, V. 1993-08-01 The space and angle distributions of the radiation intensity in an absorbing anisotropically scattering medium are examined for slant illumination of the boundary by a limited beam. An analytic solution of the transport equation in a small-angle approximation is compared with Monte Carlo modeling of light propagation in sea water. The existence of a depth region in which the variances of the space and angle intensity distributions rise anomalously rapidly due to the presence of absorption and the asymmetry of the problem is pointed out. • Lin, Meiai; Su, Xuantao 2016-10-01 Two-dimensional (2D) light scattering cytometry has been demonstrated as an effective label-free technology for cell analysis.

Here we develop the light-sheet illumination in 2D light scattering static cytometry. In our cytometer, a cylindrical lens is used to form the light-sheet for better excitation of the static cells under an inverted microscope. The thickness of the light-sheet measured in fluorescent solution is about 13 μm. Two-dimensional light scattering patterns of standard microspheres and yeast cells are obtained by using a complementary metal oxide semiconductor (CMOS) detector via a low numerical aperture (NA 0.4) optical objective. The experimental patterns characterized with fringe structures agree well with Mie theory simulated ones. Our results suggest that the light-sheet illumination is an effective excitation method for 2D light scattering label-free cytometry. • Bullough, John D; Donnell, Eric T; Rea, Mark S 2013-04-01 A two-pronged effort to quantify the impact of lighting on traffic safety is presented.

In the statistical approach, the effects of lighting on crash frequency for different intersection types in Minnesota were assessed using count regression models. The models included many geometric and traffic control variables to estimate the association between lighting and nighttime and daytime crashes and the resulting night-to-day crash ratios. Overall, the presence of roadway intersection lighting was found to be associated with an approximately 12% lower night-to-day crash ratio than unlighted intersections.

In the parallel analytical approach, visual performance analyses based on roadway intersection lighting practices in Minnesota were made for the same intersection types investigated in the statistical approach. The results of both approaches were convergent, suggesting that visual performance improvements from roadway lighting could serve as input for predicting improvements in crash frequency.

A provisional transfer function allows transportation engineers to evaluate alternative lighting systems in the design phase so selections based on expected benefits and costs can be made. • Tsai, Chung-Yu 2013-05-01 A light-emitting diode (LED) projection system is proposed, composed of an LED chip and a variable-focus-parabolic (VFP) reflector, in which the focal length varies as a function of the vertical displacement of the incidence point relative to the horizontal centerline of the LED chip. The light-ray paths within the projection system are analyzed using an exact analytical model and a skew-ray tracing approach. The profile of the proposed VFP reflector and the position of the LED chip are then optimized in such a way as to enhance the uniformity of the illuminance distribution on the target region of the image plane.

The validity of the optimized design is demonstrated by means of ZEMAX simulations. It is shown that the optimized VFP projector system yields a significant improvement in illuminance uniformity compared to conventional spherical and parabolic projectors and therefore minimizes the glare effect. • Feng, Zexin; Luo, Yi; Han, Yanjun 2010-10-11 A systematic method is proposed for designing an optical system for road lighting using an LED and a freeform lens that is optimized to produce a certain luminance distribution on the road surface. The proposed design method takes account of the luminance characteristics of the road surface, the energy efficiency of the system, the glare problem of the luminaire and the effects of four adjacent luminaries illuminating a single road surface. Firstly, the road surface illuminance with a polynomial of cosine functions along the road is optimized to maximize Q (the ratio of the average luminance to the average illuminance) as well as satisfying the lighting requirements provided by CIE.

Then, a smooth freeform lens with this optimized illuminance is designed based on the variable separation method and the feedback modification method. Results show that, from two typical observer positions on the 2-lane C2 class road, luminaires with these freeform lenses can provide Q values of 7.90 × 10(-2) and 8.69 × 10(-2), the overall road surface luminance uniformity of 0.55 and 0.56, the longitudinal road surface luminance uniformity of 0.72 and 0.79, and the glare factors of 10.06% and 6.73%. • Desai, P.; Shakya, P.; Kreouzis, T.; Gillin, W. 2007-12-01 We have investigated the effect of illumination on the organic magnetoresistance (OMR) in organic light-emitting diode (OLED) structures. The results show that it is possible to obtain OMR at voltages below “turn-on,” where no OMR was visible for devices operated in the dark. The photoinduced OMR has a field dependence that is identical to that obtained for OLEDs containing very thin layers, where triplet dissociation at the cathode was a major component of the OMR.

At voltages around the open circuit voltage, where the current through the device is very small, very large OMRs of ˜300% can be observed. The results support our proposed model for organic magnetoresistance as being caused in part by the interaction of free carriers with triplet excitons within the device. The results suggest that the introduction of a low field magnet could provide a simple means of improving the efficiency of organic photovoltaic cells.

• Wu, Haining; Dong, Jianfei; Qi, Gaojin; Zhang, Guoqi 2015-07-01 Enhancing the colorfulness of illuminated objects is a promising application of LED lighting for commercial, exhibiting, and scientific purposes. This paper proposes a method to enhance the color of illuminated objects for a given polychromatic lamp. Meanwhile, the light color is restricted to white. We further relax the white light constraints by introducing soft margins. Based on the spectral and electrical characteristics of LEDs and object surface properties, we determine the optimal mixing of the LED light spectrum by solving a numerical optimization problem, which is a quadratic fractional programming problem by formulation.

Simulation studies show that the trade-off between the white light constraint and the level of the color enhancement can be adjusted by tuning an upper limit value of the soft margin. Furthermore, visual evaluation experiments are performed to evaluate human perception of the color enhancement. The experiments have verified the effectiveness of the proposed method. • Wang, Pengbo; Gao, Yuan; Chen, Xiao; Li, Ting 2016-03-01 Low-level light therapy (LLLT) has been clinically applied. Recently, more and more cases are reported with positive therapeutic effect by using transcranial light emitting diodes (LEDs) illumination. Here, we developed a LLLT helmet for treating brain injuries based on LED arrays. We designed the LED arrays in circle shape and assembled them in multilayered 3D printed helmet with water-cooling module.

The LED arrays can be adjust to touch the head of subjects. A control circuit was developed to drive and control the illumination of the LLLT helmet. The software portion provides the control of on and off of each LED arrays, the setup of illumination parameters, and 3D distribution of LLLT light dose in human subject according to the illumination setups. This LLLT light dose distribution was computed by a Monte Carlo model for voxelized media and the Visible Chinese Human head dataset and displayed in 3D view at the background of head anatomical structure. The performance of the whole system was fully tested.

One stroke patient was recruited in the preliminary LLLT experiment and the following neuropsychological testing showed obvious improvement in memory and executive functioning. This clinical case suggested the potential of this Illumination-parameter adjustable and illuminationdistribution visible LED helmet as a reliable, noninvasive, and effective tool in treating brain injuries. • Everdell, N. L.; Styles, I. B.; Calcagni, A.; Gibson, J.; Hebden, J.; Claridge, E.

2010-09-01 We present an imaging system based on light emitting diode (LED) illumination that produces multispectral optical images of the human ocular fundus. It uses a conventional fundus camera equipped with a high power LED light source and a highly sensitive electron-multiplying charge coupled device camera. It is able to take pictures at a series of wavelengths in rapid succession at short exposure times, thereby eliminating the image shift introduced by natural eye movements (saccades). In contrast with snapshot systems the images retain full spatial resolution. The system is not suitable for applications where the full spectral resolution is required as it uses discrete wavebands for illumination.

This is not a problem in retinal imaging where the use of selected wavelengths is common. The modular nature of the light source allows new wavelengths to be introduced easily and at low cost.

The use of wavelength-specific LEDs as a source is preferable to white light illumination and subsequent filtering of the remitted light as it minimizes the total light exposure of the subject. The system is controlled via a graphical user interface that enables flexible control of intensity, duration, and sequencing of sources in synchrony with the camera. Our initial experiments indicate that the system can acquire multispectral image sequences of the human retina at exposure times of 0.05 s in the range of 500-620 nm with mean signal to noise ratio of 17 dB (min 11, std 4.5), making it suitable for quantitative analysis with application to the diagnosis and screening of eye diseases such as diabetic retinopathy and age-related macular degeneration. • Fiedorowicz, Maciej; Chaczatrian, Gohar 2003-12-17 The alpha-amylolysis of potato, corn, waxy corn, and amaranthus starches with porcine pancreatic alpha-amylase upon illumination with visible polarized and nonpolarized light was studied. Samples were illuminated for 1 h either directly after blending the enzyme with starch or the enzyme solutions were illuminated for 1 h prior to the admixture of starch. Independently of the mode of illuminat.