Effects of monochromatic light stimuli during embryogenesis on some performance traits, behavior, and fear responses in Japanese quails.

PubMed

Sabuncuoglu, Kübra Melis; Korkmaz, Firdevs; Gürcan, Eser Kemal; Narinç, Dogan; Saml X, Hasan Ersin

2018-04-14

Lighting is crucial in poultry rearing and the subjects with light intensity, source, and color having been addressed in numerous studies. Numerous studies with monochromatic light from light-emitting diode (LED) bulbs have been reported. In the current study, fertile Japanese quail eggs were exposed to a dark environment (Control) or monochromatic green (560 nm) and blue (480 nm) lighting throughout incubation. There were no significant differences in hatch weight, hatchability, total embryonic mortality, hatch time, growth performance, and slaughter-carcass traits in the study (P > 0.05). Furthermore, the lowest mean in terms of early embryonic mortalities (12.37%) was determined in the group treated with green LED lighting (P < 0.05), whereas it was discovered that the lowest mean in terms of late embryonic mortalities (13.59%) was in the group treated with blue LED lighting (P < 0.05). During the test time, the green LED group showed higher averages in terms of the number of peeps and first defecation time as response to environmental stimuli (P < 0.05). The highest mean for jumping (7.6 times) was detected in the group treated with blue LED lighting (P < 0.05). In conclusion, it was revealed that the blue and green LED lighting applied to the Japanese quail eggs in incubation had no effects on incubation traits, growth, and slaughter-carcass traits but had positive effects on some behavioral traits.

White light photothermal lens spectrophotometer for the determination of absorption in scattering samples.

PubMed

Marcano, Aristides; Alvarado, Salvador; Meng, Junwei; Caballero, Daniel; Moares, Ernesto Marín; Edziah, Raymond

2014-01-01

We developed a pump-probe photothermal lens spectrophotometer that uses a broadband arc-lamp and a set of interference filters to provide tunable, nearly monochromatic radiation between 370 and 730 nm as the pump light source. This light is focused onto an absorbing sample, generating a photothermal lens of millimeter dimensions. A highly collimated monochromatic probe light from a low-power He-Ne laser interrogates the generated lens, yielding a photothermal signal proportional to the absorption of light. We measure the absorption spectra of scattering dye solutions using the device. We show that the spectra are not affected by the presence of scattering, confirming that the method only measures the absorption of light that results in generation of heat. By comparing the photothermal spectra with the usual absorption spectra determined using commercial transmission spectrophotometers, we estimate the quantum yield of scattering of the sample. We discuss applications of the device for spectroscopic characterization of samples such as blood and gold nanoparticles that exhibit a complex behavior upon interaction with light.

An experimental evaluation of monochromatic x-ray beam position monitors at diamond light source

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

Bloomer, Chris, E-mail: chris.bloomer@diamond.ac.uk; Rehm, Guenther; Dolbnya, Igor P.

Maintaining the stability of the X-ray beam relative to the sample point is of paramount importance for beamlines and users wanting to perform cutting-edge experiments. The ability to detect, and subsequently compensate for, variations in X-ray beam position with effective diagnostics has multiple benefits: a reduction in commissioning and start-up time, less ‘down-time’, and an improvement in the quality of acquired data. At Diamond Light Source a methodical evaluation of a selection of monochromatic X-ray Beam Position Monitors (XBPMs), using a range of position detection techniques, and from a range of suppliers, was carried out. The results of these experimentsmore » are presented, showing the measured RMS noise on the position measurement of each device for a given flux, energy, beam size, and bandwidth. A discussion of the benefits and drawbacks of each of the various devices and techniques is also included.« less

Low Illumination Light (LIL) Solar Cells: Indoor and Monochromatic Light Harvesting

DTIC Science & Technology

2015-11-01

photovoltaic ( PV ) solar cells under low intensity and narrow light spectrum conditions has not been clearly examined. PV operating values under 1 sun...3. PV Fundamental Losses under Low-Light Conditions 5 4. Experiment Setup 9 4.1 Materials 9 4.1.1 Light Sources and Spectra 9 4.1.2 PV Solar ...http://www.mjinc.com/newsArticle2012_Mar15.html ..........................4 Fig. 4 Three energy and power densities ranges for PV solar cells

Effect of a combination of green and blue monochromatic light on broiler immune response.

PubMed

Zhang, Ziqiang; Cao, Jing; Wang, Zixu; Dong, Yulan; Chen, Yaoxing

2014-09-05

Our previous study suggested that green light or blue light would enhance the broiler immune response; this study was conducted to evaluate whether a combination of green and blue monochromatic light would result in improved immune response. A total of 192 Arbor Acre male broilers were exposed to white light, red light, green light, and blue light from 0 to 26 days. From 27 to 49 days, half of the broilers in green light and blue light were switched to blue light (G-B) and green light (B-G), respectively. The levels of anti-Newcastle disease virus (NDV) and anti-bovine serum albumin (BSA) IgG in G-B group were elevated by 11.9-40.3% and 17.4-48.7%, respectively, compared to single monochromatic lights (P<0.05). Moreover, the proliferation of peripheral blood T and B lymphocytes and the IL-2 concentration in the G-B groups increased by 10.4-36.2%, 10.0-50.0% and 24.7-60.3% (P<0.05), respectively, compared with the single monochromatic light groups. However, the serum TNF-α concentration in the G-B group was reduced by 3.64-40.5% compared to other groups, and no significant difference was found between the G-B and B-G groups in any type of detection index at the end of the experiment. These results suggested that the combination of G-B and B-G monochromatic light could effectively enhance the antibody titer, the proliferation index of lymphocytes and alleviate the stress response in broilers. Therefore, the combination of green and blue monochromatic light can improve the immune function of broilers. Copyright © 2014 Elsevier B.V. All rights reserved.

Expected scientific performance of the three spectrometers on the extreme ultraviolet explorer

NASA Technical Reports Server (NTRS)

Vallerga, J. V.; Jelinsky, P.; Vedder, P. W.; Malina, R. F.

1990-01-01

The expected in-orbit performance of the three spectrometers included on the Extreme Ultraviolet Explorer astronomical satellite is presented. Recent calibrations of the gratings, mirrors and detectors using monochromatic and continuum EUV light sources allow the calculation of the spectral resolution and throughput of the instrument. An effective area range of 0.2 to 2.8 sq cm is achieved over the wavelength range 70-600 A with a peak spectral resolution (FWHM) of 360 assuming a spacecraft pointing knowledge of 10 arc seconds (FWHM). For a 40,000 sec observation, the average 3 sigma sensitivity to a monochromatic line source is 0.003 photons/sq cm s. Simulated observations of known classes of EUV sources, such as hot white dwarfs, and cataclysmic variables are also presented.

Effects of monochromatic light sources on sex hormone levels in serum and on semen quality of ganders.

PubMed

Chang, Shen-Chang; Zhuang, Zi-Xuan; Lin, Min-Jung; Cheng, Chuen-Yu; Lin, Tsung-Yi; Jea, Yu-Shine; Huang, San-Yuan

2016-04-01

Light is an essential external factor influencing various physiological processes, including reproductive performance, in birds. Although several attempts have been made to understand the effect of light on poultry production, the effect of light of a particular wavelength (color) on the reproductive function in geese remains unclear. This study evaluated the effect of various monochromatic light sources on the levels of sex hormone and on semen quality of ganders. Of 30 male White Roman geese in their third reproductive season (average age=3 years), 27 were divided into three groups receiving monochromatic white or red or blue lights. The birds were kept in an environmentally controlled house with a lighting photoperiod of 7L:17D for six weeks as the adaptation period. The photoperiod was subsequently changed to 9L:15D and maintained for 24 weeks. Three ganders at the beginning of the study and three from each group at the end of the adjusting period and the 20th and 30th week of the study period were sacrificed, and their testes and blood samples were collected for determining the sex hormone levels. Semen samples were collected for determining semen quality parameters, including the semen collection index, sperm concentration, semen volume, sperm motility, sperm viability, sperm morphology, and semen quality factor. The results showed that the testosterone and estradiol levels remained unchanged in all three groups at all time points. The ratio of testosterone to estradiol of ganders exposed to white light was significantly higher than that of ganders exposed to red light at the 30th week (P<0.05). Semen collection index and sperm viability of ganders exposed to blue light were significantly the lowest (P<0.05). Moreover, sperm motility, sperm viability, and percentage of morphologically normal spermatozoa of ganders in white light were the highest (P<0.05). In conclusion, the results of this study suggested that artificial illumination with white light may maintain a better semen quality than that with red or blue lights in ganders. Copyright © 2016 Elsevier B.V. All rights reserved.

A scheiner-principle vernier optometer

NASA Astrophysics Data System (ADS)

Cushman, William B.

1989-06-01

A method and optometer apparatus is disclosed for measuring the dark focus of accommodation. In a preferred embodiment, the optometer apparatus includes: a pinhole aperture plate having first and second horizontally positioned apertures disposed on opposite sides of a first optical axis; first and second orthogonally-oriented polarizing filters respectively covering the first and second horizontally positioned apertures; a positive lens having an optical axis on the first optical axis and being positioned at a distance of approximately one focal length from the pinhole aperture plate; a lens system having an optical axis on the first optical axis; a slit aperture plate having a vertical slit and being disposed on the first optical axis and between the positive lens and the lens system; third and fourth vertically positioned polarizing filters selectively disposed adjacent to the slit aperture plate to divide the slit vertically, a monochromatic light source for propagating light along the first optical axis through the lens system; and movable means attached to the slit aperture plate, the lens system and the monochromatic light source for moving the slit aperture plate.

Single slit interference made easy with a strand of hair and a laser

NASA Astrophysics Data System (ADS)

Messer, Rebecca

2018-01-01

Students can easily measure the width of a strand of their own hair with a monochromatic light source such as a laser. This inexpensive activity engages students in an application of single slit diffraction using Babinet's principle.

Apparatus for Teaching Physics.

ERIC Educational Resources Information Center

Gottlieb, Herbert H., Ed.

1980-01-01

Presents two experimental set-ups. The first demonstrates the law of Malus using a pair of Polaroid polarizers and a monochromatic light source with an interference filter. The second describes a modification of Hilton's apparatus to demonstrate the effects of the magnetic hysteresis on an overhead projector. (CS)

The effect of RGB monochromatic and polychromatic LED lighting on growth performance, behavior, and development of broilers

NASA Astrophysics Data System (ADS)

Morrill, Waldirene B. B.; Barnabé, Janice M. C.; da Silva, Tatiana P. N.; Pandorfi, Héliton; Gouveia-Neto, Artur S.; Souza, Wellington S.

2014-03-01

Growth performance, behavior, and development of broilers reared under red, green, and blue monochromatic and/or multicolor LED-based illuminants is investigated. The lighting treatments were performed on a 24h lighting basis during six weeks. Monochromatic red(630 nm), green(520 nm), and blue(460 nm), and simultaneous blue-green, and whitelight housing illumination was employed. Bodyweight, food consumption, and behavior were monitored and compared amongst light treatments. The behavioral data showed that broilers reared under green lighting presented the lowest respiratory rate (87 mov. min-1) while those under red lighting presented the highest (96 mov. min-1). Results also showed that broilers under blue and/or green monochromatic illumination exhibited up to 6%, and 8.9 % increase in final bodyweight when compared to those under red or white-light, respectively. The highest feed intake, and lowest body weight gain was observed in broilers reared under blue and red illumination, respectively.

Analysis of monochromatic and quasi-monochromatic X-ray sources in imaging and therapy

NASA Astrophysics Data System (ADS)

Westphal, Maximillian; Lim, Sara; Nahar, Sultana; Orban, Christopher; Pradhan, Anil

2017-04-01

We studied biomedical imaging and therapeutic applications of recently developed quasi-monochromatic and monochromatic X-ray sources. Using the Monte Carlo code GEANT4, we found that the quasi-monochromatic 65 keV Gaussian X-ray spectrum created by inverse Compton scattering with relatavistic electron beams were capable of producing better image contrast with less radiation compared to conventional 120 kV broadband CT scans. We also explored possible experimental detection of theoretically predicted K α resonance fluorescence in high-Z elements using the European Synchrotron Research Facility with a tungsten (Z = 74) target. In addition, we studied a newly developed quasi-monochromatic source generated by converting broadband X-rays to monochromatic K α and β X-rays with a zirconium target (Z = 40). We will further study how these K α and K β dominated spectra can be implemented in conjunction with nanoparticles for targeted therapy. Acknowledgement: Ohio Supercomputer Center, Columbus, OH.

A Cross Structured Light Sensor and Stripe Segmentation Method for Visual Tracking of a Wall Climbing Robot

PubMed Central

Zhang, Liguo; Sun, Jianguo; Yin, Guisheng; Zhao, Jing; Han, Qilong

2015-01-01

In non-destructive testing (NDT) of metal welds, weld line tracking is usually performed outdoors, where the structured light sources are always disturbed by various noises, such as sunlight, shadows, and reflections from the weld line surface. In this paper, we design a cross structured light (CSL) to detect the weld line and propose a robust laser stripe segmentation algorithm to overcome the noises in structured light images. An adaptive monochromatic space is applied to preprocess the image with ambient noises. In the monochromatic image, the laser stripe obtained is recovered as a multichannel signal by minimum entropy deconvolution. Lastly, the stripe centre points are extracted from the image. In experiments, the CSL sensor and the proposed algorithm are applied to guide a wall climbing robot inspecting the weld line of a wind power tower. The experimental results show that the CSL sensor can capture the 3D information of the welds with high accuracy, and the proposed algorithm contributes to the weld line inspection and the robot navigation. PMID:26110403

I12: the Joint Engineering, Environment and Processing (JEEP) beamline at Diamond Light Source.

PubMed

Drakopoulos, Michael; Connolley, Thomas; Reinhard, Christina; Atwood, Robert; Magdysyuk, Oxana; Vo, Nghia; Hart, Michael; Connor, Leigh; Humphreys, Bob; Howell, George; Davies, Steve; Hill, Tim; Wilkin, Guy; Pedersen, Ulrik; Foster, Andrew; De Maio, Nicoletta; Basham, Mark; Yuan, Fajin; Wanelik, Kaz

2015-05-01

I12 is the Joint Engineering, Environmental and Processing (JEEP) beamline, constructed during Phase II of the Diamond Light Source. I12 is located on a short (5 m) straight section of the Diamond storage ring and uses a 4.2 T superconducting wiggler to provide polychromatic and monochromatic X-rays in the energy range 50-150 keV. The beam energy enables good penetration through large or dense samples, combined with a large beam size (1 mrad horizontally × 0.3 mrad vertically). The beam characteristics permit the study of materials and processes inside environmental chambers without unacceptable attenuation of the beam and without the need to use sample sizes which are atypically small for the process under study. X-ray techniques available to users are radiography, tomography, energy-dispersive diffraction, monochromatic and white-beam two-dimensional diffraction/scattering and small-angle X-ray scattering. Since commencing operations in November 2009, I12 has established a broad user community in materials science and processing, chemical processing, biomedical engineering, civil engineering, environmental science, palaeontology and physics.

I12: the Joint Engineering, Environment and Processing (JEEP) beamline at Diamond Light Source

PubMed Central

Drakopoulos, Michael; Connolley, Thomas; Reinhard, Christina; Atwood, Robert; Magdysyuk, Oxana; Vo, Nghia; Hart, Michael; Connor, Leigh; Humphreys, Bob; Howell, George; Davies, Steve; Hill, Tim; Wilkin, Guy; Pedersen, Ulrik; Foster, Andrew; De Maio, Nicoletta; Basham, Mark; Yuan, Fajin; Wanelik, Kaz

2015-01-01

I12 is the Joint Engineering, Environmental and Processing (JEEP) beamline, constructed during Phase II of the Diamond Light Source. I12 is located on a short (5 m) straight section of the Diamond storage ring and uses a 4.2 T superconducting wiggler to provide polychromatic and monochromatic X-rays in the energy range 50–150 keV. The beam energy enables good penetration through large or dense samples, combined with a large beam size (1 mrad horizontally × 0.3 mrad vertically). The beam characteristics permit the study of materials and processes inside environmental chambers without unacceptable attenuation of the beam and without the need to use sample sizes which are atypically small for the process under study. X-ray techniques available to users are radiography, tomography, energy-dispersive diffraction, monochromatic and white-beam two-dimensional diffraction/scattering and small-angle X-ray scattering. Since commencing operations in November 2009, I12 has established a broad user community in materials science and processing, chemical processing, biomedical engineering, civil engineering, environmental science, palaeontology and physics. PMID:25931103

Deep sequencing identification of miRNAs in pigeon ovaries illuminated with monochromatic light.

PubMed

Wang, Ying; Yang, Hai-Ming; Cao, Wei; Li, Yang-Bai; Wang, Zhi-Yue

2018-06-08

The use of light of different wavelengths has grown popular in the poultry industry. An optimum wavelength is believed to improve pigeon egg production, but little is known about the role of microRNAs (miRNAs) in the effects of monochromatic light on ovarian pigeon function. Herein, we harvested ovaries from pigeons reared under monochromatic light of different wavelength and performed deep sequencing on various tissues using an Illumina Solexa high-throughput instrument. We obtained 66,148,548, 67,873,805, and 71,661,771 clean reads from ovaries of pigeons reared under red light (RL), blue light (BL), and white light (WL), respectively. We identified 1917 known miRNAs in nine libraries, of which 524 were novel. Three and five differentially expressed miRNAs were identified in BL vs. WL and RL vs. WL groups, respectively. Quantitative reverse transcription PCR was used to validate differentially expressed miRNAs (miR-200, miR-122, and miR-205b). In addition, 5824 target genes were annotated as differentially expressed miRNAs, most of which are involved in reproductive pathways including oestrogen signalling, cell cycle, and oocyte maturation. Notably, ovarian miR-205b expression was significantly negatively correlated with its target 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1). miRNA-mRNA network analysis suggests that miR-205b targeting of HSD11B1 plays a key role in the effects of monochromatic light on pigeon egg production. These findings indicate that monochromatic light shortens the oviposition interval of pigeons, which may be useful for egg production and pigeon breeding.

Daytime Effect of Monochromatic Blue Light on EEG Activity Depends on Duration and Timing of Exposure in Young Men

PubMed Central

Iskra-Golec, Irena; Golonka, Krystyna; Wyczesany, Miroslaw; Smith, Lawrence; Siemiginowska, Patrycja; Wątroba, Joanna

2017-01-01

Growing evidence suggests an alerting effect of monochromatic blue light on brain activity. Little is known about the moderation of those effects by timing and duration of exposure. The present electroencephalography (EEG ) study examined such moderations on delta, theta, alpha1, alpha2, and beta EEG bands. A counterbalanced repeated-measures design was applied. The 16-hr daytime period was divided into three sessions: 07:00-12:20, 12:20-17:40, and 17:40-23:00 (timing of exposure). Two light conditions comparable in luminance but differing in wavelength were applied, namely polychromatic white light and monochromatic blue light (460 nm). There were two durations of exposure—the shorter one lasting 30 min and the longer one lasting 4 hrs. Thirty male students participated in the study. Four factors analyses of variance (ANOV As, for light conditions, timing of exposure, duration of exposure, and brain area) were performed on each EEG band. Results indicated an alerting effect of short exposure to monochromatic blue light at midday and in the evening, which was demonstrated by a decrease in lower frequency bands (alpha1, delta, and theta, respectively). Long exposure to blue light may have a reverse effect, especially in the morning and at midday, when increases in lower frequency bands (theta in the morning and theta and alpha1 at midday) were observed. It can be concluded that the daytime effect of monochromatic blue light on EEG activity depends on timing and duration of exposure. PMID:29062437

Side-emitting illuminators using LED sources

NASA Astrophysics Data System (ADS)

Zhao, Feng; Van Derlofske, John F.

2003-11-01

This study investigates illuminators composed of light emitting diode (LED) array sources and side-emitting light guides to provide efficient general illumination. Specifically, new geometries are explored to increase the efficiency of current systems while maintaining desired light distribution. LED technology is already successfully applied in many illumination applications, such as traffic signals and liquid crystal display (LCD) backlighting. It provides energy-efficient, small-package, long-life, and color-adjustable illumination. However, the use of LEDs in general illumination is still in its early stages. Current side-emitting systems typically use a light guide with light sources at one end, an end-cap surface at the other end, and light releasing sidewalls. This geometry introduces efficiency loss that can be as high as 40%. The illuminators analyzed in this study use LED array sources along the longitude of a light guide to increase the system efficiency. These new geometries also provide the freedom of elongating the system without sacrificing system efficiency. In addition, alternative geometries can be used to create white light with monochromatic LED sources. As concluded by this study, the side-emitting illuminators using LED sources gives the possibility of an efficient, distribution-controllable linear lighting system.

Use of a supercontinuum white light in evaluating the spectral sensitivity of the pupil light reflex

NASA Astrophysics Data System (ADS)

Chin, Catherine; Leick, Lasse; Podoleanu, Adrian; Lall, Gurprit S.

2018-03-01

We assessed the spectral sensitivity of the pupillary light reflex in mice using a high power super continuum white light (SCWL) source in a dual wavelength configuration. This novel approach was compared to data collected from a more traditional setup using a Xenon arc lamp fitted with monochromatic interference filters. Irradiance response curves were constructed using both systems, with the added benefit of a two-wavelength, equivocal power, output using the SCWL. The variables applied to the light source were intensity, wavelength and stimulus duration through which the physiological output measured was the minimum pupil size attained under such conditions. We show that by implementing the SCWL as our novel stimulus we were able to dramatically increase the physiological usefulness of our pupillometry system.

Pseudo color ghost coding imaging with pseudo thermal light

NASA Astrophysics Data System (ADS)

Duan, De-yang; Xia, Yun-jie

2018-04-01

We present a new pseudo color imaging scheme named pseudo color ghost coding imaging based on ghost imaging but with multiwavelength source modulated by a spatial light modulator. Compared with conventional pseudo color imaging where there is no nondegenerate wavelength spatial correlations resulting in extra monochromatic images, the degenerate wavelength and nondegenerate wavelength spatial correlations between the idle beam and signal beam can be obtained simultaneously. This scheme can obtain more colorful image with higher quality than that in conventional pseudo color coding techniques. More importantly, a significant advantage of the scheme compared to the conventional pseudo color coding imaging techniques is the image with different colors can be obtained without changing the light source and spatial filter.

Day light quality affects the night-break response in the short-day plant chrysanthemum, suggesting differential phytochrome-mediated regulation of flowering.

PubMed

Higuchi, Yohei; Sumitomo, Katsuhiko; Oda, Atsushi; Shimizu, Hiroshi; Hisamatsu, Tamotsu

2012-12-15

Chrysanthemum (Chrysanthemum morifolium) is a short-day plant, which flowers when the night length is longer than a critical minimum. Flowering is effectively inhibited when the required long-night phase is interrupted by a short period of exposure to red light (night break; NB). The reversal of this inhibition by subsequent exposure to far-red (FR) light indicates the involvement of phytochromes in the flowering response. Here, we elucidated the role of light quality in photoperiodic regulation of chrysanthemum flowering, by applying a range of different conditions. Flowering was consistently observed under short days with white light (W-SD), SD with monochromatic red light (R-SD), or SD with monochromatic blue light (B-SD). For W-SD, NB with monochromatic red light (NB-R) was most effective in inhibiting flowering, while NB with monochromatic blue light (NB-B) and NB with far-red light (NB-FR) caused little inhibition. In contrast, for B-SD, flowering was strongly inhibited by NB-B and NB-FR. However, when B-SD was supplemented with monochromatic red light (B+R-SD), no inhibition by NB-B and NB-FR was observed. Furthermore, the inhibitory effect of NB-B following B-SD was partially reversed by subsequent exposure to a FR light pulse. The conditions B-SD/NB-B (no flowering) and B+R-SD/NB-B (flowering) similarly affected the expression of circadian clock-related genes. However, only the former combination suppressed expression of the chrysanthemum orthologue of FLOWERING LOCUS T (CmFTL3). Our results suggest the involvement of at least 2 distinct phytochrome responses in the flowering response of chrysanthemum. Furthermore, it appears that the light quality supplied during the daily photoperiod affects the light quality required for effective NB. Copyright © 2012 Elsevier GmbH. All rights reserved.

Method And Apparatus For Examining A Tissue Using The Spectral Wing Emission Therefrom Induced By Visible To Infrared Photoexcitation.

DOEpatents

Alfano, Robert R.; Demos, Stavros G.; Zhang, Gang

2003-12-16

Method and an apparatus for examining a tissue using the spectral wing emission therefrom induced by visible to infrared photoexcitation. In one aspect, the method is used to characterize the condition of a tissue sample and comprises the steps of (a) photoexciting the tissue sample with substantially monochromatic light having a wavelength of at least 600 nm; and (b) using the resultant far red and near infrared spectral wing emission (SW) emitted from the tissue sample to characterize the condition of the tissue sample. In one embodiment, the substantially monochromatic photoexciting light is a continuous beam of light, and the resultant steady-state far red and near infrared SW emission from the tissue sample is used to characterize the condition of the tissue sample. In another embodiment, the substantially monochromatic photoexciting light is a light pulse, and the resultant time-resolved far red and near infrared SW emission emitted from the tissue sample is used to characterize the condition of the tissue sample. In still another embodiment, the substantially monochromatic photoexciting light is a polarized light pulse, and the parallel and perpendicular components of the resultant polarized time-resolved SW emission emitted from the tissue sample are used to characterize the condition of the tissue sample.

Opacity meter for monitoring exhaust emissions from non-stationary sources

DOEpatents

Dec, John Edward

2000-01-01

Method and apparatus for determining the opacity of exhaust plumes from moving emissions sources. In operation, a light source is activated at a time prior to the arrival of a diesel locomotive at a measurement point, by means of a track trigger switch or the Automatic Equipment Identification system, such that the opacity measurement is synchronized with the passage of an exhaust plume past the measurement point. A beam of light from the light source passes through the exhaust plume of the locomotive and is detected by a suitable detector, preferably a high-rate photodiode. The light beam is well-collimated and is preferably monochromatic, permitting the use of a narrowband pass filter to discriminate against background light. In order to span a double railroad track and provide a beam which is substantially stronger than background, the light source, preferably a diode laser, must provide a locally intense beam. A high intensity light source is also desirable in order to increase accuracy at the high sampling rates required. Also included is a computer control system useful for data acquisition, manipulation, storage and transmission of opacity data and the identification of the associated diesel engine to a central data collection center.

Effects of the chromatic defocus caused by interchange of two monochromatic lights on refraction and ocular dimension in guinea pigs.

PubMed

Qian, Yi-Feng; Dai, Jin-Hui; Liu, Rui; Chen, Min-Jie; Zhou, Xing-Tao; Chu, Ren-Yuan

2013-01-01

To investigate refractive and axial responses to the shift of focal plane resulting from the interchange of two monochromatic lights separately corresponding to the peak wavelengths of the cones absorption spectrum in retina, fifty 2-week-old pigmented guinea pigs were randomly assigned to five groups based on the mode of illumination: short-wavelength light (SL), middle-wavelength light (ML) and broad-band white light (BL) for 20 weeks, SL for 10 weeks followed by ML for 10 weeks (STM), as well as ML for 10 weeks followed by SL for 10 weeks (MTS). Biometric and refractive measurements were then performed every 2 weeks. After 10 weeks, SL and STM groups became more hyperopic and had less vitreous elongation than BL group. However, ML and MTS groups became more myopic and had more vitreous elongation. After interchange of the monochromatic light, the refractive error decreased rapidly by about 1.93D and the vitreous length increased by 0.14 mm in STM group from 10 to 12 weeks. After that, there were no significant intergroup differences between STM and BL groups. The interchange from ML to SL quickly increased the refractive error by about 1.53D and decreased the vitreous length by about 0.13 mm in MTS group after two weeks. At this time, there were also no significant intergroup differences between MTS and BL groups. The guinea pig eye can accurately detect the shift in focal plane caused by interchange of two monochromatic lights and rapidly generate refractive and axial responses. However, an excessive compensation was induced. Some properties of photoreceptors or retina may be changed by the monochromatic light to influence the following refractive development.

Wavelength calibration of an imaging spectrometer based on Savart interferometer

NASA Astrophysics Data System (ADS)

Li, Qiwei; Zhang, Chunmin; Yan, Tingyu; Quan, Naicheng; Wei, Yutong; Tong, Cuncun

2017-09-01

The basic principle of Fourier-transform imaging spectrometer (FTIS) based on Savart interferometer is outlined. The un-identical distribution of the optical path difference which leads to the wavelength drift of each row of the interferogram is analyzed. Two typical methods for wavelength calibration of the presented system are described. The first method unifies different spectral intervals and maximum spectral frequencies of each row by a reference monochromatic light with known wavelength, and the dispersion compensation of Savart interferometer is also involved. The second approach is based on the least square fitting which builds the functional relation between recovered wavelength, row number and calibrated wavelength by concise equations. The effectiveness of the two methods is experimentally demonstrated with monochromatic lights and mixed light source across the detecting band of the system, and the results indicate that the first method has higher precision and the mean root-mean-square error of the recovered wavelengths is significantly reduced from 19.896 nm to 1.353 nm, while the second method is more convenient to implement and also has good precision of 2.709 nm.

Pustular Palmoplantar Psoriasis Successfully Treated with Nb-UVB Monochromatic Excimer Light: A Case-Report.

PubMed

Gianfaldoni, Serena; Tchernev, Georgi; Wollina, Uwe; Lotti, Torello

2017-07-25

Barber's palmoplantar pustulosis (PPP) is a form of localised pustular psoriasis, affecting the palmar and plantar surfaces. It is a chronic disease, with a deep impact on the patients' quality of life. The Authors discuss a case of Baber Psoriasis successfully treated with monochromatic excimer light.

Colour Mixing Based on Daylight

ERIC Educational Resources Information Center

Meyn, Jan-Peter

2008-01-01

Colour science is based on the sensation of monochromatic light. In contrast to that, surface colours are caused by reflection of wide sections of the daylight spectrum. Non-spectral colours like magenta and purple appear homologous to colours with spectral hue, if the approach of mixing monochromatic light is abandoned. It is shown that a large…

Pustular Palmoplantar Psoriasis Successfully Treated with Nb-UVB Monochromatic Excimer Light: A Case-Report

PubMed Central

Gianfaldoni, Serena; Tchernev, Georgi; Wollina, Uwe; Lotti, Torello

2017-01-01

Barber’s palmoplantar pustulosis (PPP) is a form of localised pustular psoriasis, affecting the palmar and plantar surfaces. It is a chronic disease, with a deep impact on the patients’ quality of life. The Authors discuss a case of Baber Psoriasis successfully treated with monochromatic excimer light. PMID:28785333

Surface Imaging Skin Friction Instrument and Method

NASA Technical Reports Server (NTRS)

Brown, James L. (Inventor); Naughton, Jonathan W. (Inventor)

1999-01-01

A surface imaging skin friction instrument allowing 2D resolution of spatial image by a 2D Hilbert transform and 2D inverse thin-oil film solver, providing an innovation over prior art single point approaches. Incoherent, monochromatic light source can be used. The invention provides accurate, easy to use, economical measurement of larger regions of surface shear stress in a single test.

Lasers and light sources for rosacea.

PubMed

Goldberg, David J

2005-03-01

Pharmacologic agents remain the mainstay for initial and maintenance treatment of rosacea. However, monochromatic (i.e., laser) and polychromatic light-based therapies are increasingly being used for the treatment of certain signs of rosacea. Despite the increased use of lasers and other light-based therapies, few well-controlled studies have been conducted on their use for the treatment of rosacea. The studies that do exist suggest that these modalities have value in treating erythematotelangiectatic rosacea, including persistent erythema and phymatous rosacea. Light-based therapies should be strongly considered in cases of serious erythema, flushing, and telangiectasia because these signs are not optimally addressed by pharmacologic interventions.

Exotic X-ray Sources from Intermediate Energy Electron Beams

NASA Astrophysics Data System (ADS)

Chouffani, K.; Wells, D.; Harmon, F.; Jones, J. L.; Lancaster, G.

2003-08-01

High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, "novel" x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic "structure" of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR).

An interferometer having fused optical fibers, and apparatus and method using the interferometer

NASA Technical Reports Server (NTRS)

Hellbaum, Richard F. (Inventor); Claus, Richard O. (Inventor); Murphy, Kent A. (Inventor); Gunther, Michael F. (Inventor)

1992-01-01

An interferometer includes a first optical fiber coupled to a second optical fiber by fusing. At a fused portion, the first and second optical fibers are cut to expose respective cores. The cut or fused end of the first and second optical fibers is arranged to oppose a diaphragm or surface against which a physical phenomenon such as pressure or stress, is applied. In a first embodiment, a source light which is generally single-mode monochromatic, coherent light, is input to the first optical fiber and by evanescence, effectively crosses to the second optical fiber at the fused portion. Source light from the second optical fiber is reflected by the diaphragm or surface, and received at the second optical fiber to generate an output light which has an intensity which depends upon interference of reference light based on the source light, and the reflected light reflected from the diaphragm or surface. The intensity of the output light represents a positional relationship or displacement between the interferometer and the diaphragm or surface.

Fused monochromatic imaging acquired by single source dual energy CT in hepatocellular carcinoma during arterial phase: an initial experience.

PubMed

Gao, Shun-Yu; Zhang, Xiao-Peng; Cui, Yong; Sun, Ying-Shi; Tang, Lei; Li, Xiao-Ting; Zhang, Xiao-Yan; Shan, Jun

2014-08-01

To explore whether single and fused monochromatic images can improve liver tumor detection and delineation by single source dual energy CT (ssDECT) in patients with hepatocellular carcinoma (HCC) during arterial phase. Fifty-seven patients with HCC who underwent ssDECT scanning at Beijing Cancer Hospital were enrolled retrospectively. Twenty-one sets of monochromatic images from 40 to 140 keV were reconstructed at 5 keV intervals in arterial phase. The optimal contrast-noise ratio (CNR) monochromatic images of the liver tumor and the lowest-noise monochromatic images were selected for image fusion. We evaluated the image quality of the optimal-CNR monochromatic images, the lowest-noise monochromatic images and the fused monochromatic images, respectively. The evaluation indicators included the spatial resolution of the anatomical structure, the noise level, the contrast and CNR of the tumor. In arterial phase, the anatomical structure of the liver can be displayed most clearly in the 65-keV monochromatic images, with the lowest image noise. The optimal-CNR monochromatic images of HCC tumor were 50-keV monochromatic images in which the internal structural features of the liver tumors were displayed most clearly and meticulously. For tumor detection, the fused monochromatic images and the 50-keV monochromatic images had similar performances, and were more sensitive than 65-keV monochromatic images. We achieved good arterial phase images by fusing the optimal-CNR monochromatic images of the HCC tumor and the lowest-noise monochromatic images. The fused images displayed liver tumors and anatomical structures more clearly, which is potentially helpful for identifying more and smaller HCC tumors.

Dim light adaptation attenuates acute melatonin suppression in humans.

PubMed

Jasser, Samar A; Hanifin, John P; Rollag, Mark D; Brainard, George C

2006-10-01

Abstract Studies in rodents with retinal degeneration indicated that neither the rod nor the cone photoreceptors obligatorily participate in circadian responses to light, including melatonin suppression and photoperiodic response. Yet there is a residual phase-shifting response in melanopsin knockout mice, which suggests an alternate or redundant means for light input to the SCN of the hypothalamus. The findings of Aggelopoulos and Meissl suggest a complex, dynamic interrelationship between the classic visual photoreceptors and SCN cell sensitivity to light stimuli, relative to various adaptive lighting conditions. These studies raised the possibility that the phototransductive physiology of the retinohypothalamic tract in humans might be modulated by the visual rod and cone photoreceptors. The aim of the following two-part study was to test the hypothesis that dim light adaptation will dampen the subsequent suppression of melatonin by monochromatic light in healthy human subjects. Each experiment included 5 female and 3 male human subjects between the ages of 18 and 30 years, with normal color vision. Dim white light and darkness adaptation exposures occurred between midnight and 0200 h, and a full-field 460-nm light exposure subsequently occurred between 0200 and 0330-h for each adaptation condition, at 2 different intensities. Plasma samples were drawn following the 2-h adaptation, as well as after the 460-nm monochromatic light exposure, and melatonin was measured by radioimmunoassay. Comparison of melatonin suppression responses to monochromatic light in both studies revealed a loss of significant suppression after dim white light adaptation compared with dark adaptation (p < 0.04 and p < 0.01). These findings indicate that the activity of the novel circadian photoreceptive system in humans is subject to subthreshold modulation of its sensitivity to subsequent monochromatic light exposure, varying with the conditions of light adaptation prior to exposure.

A non-laser light source for photodynamic therapy: in vitro effects on normal and malignant cells.

PubMed

Kashtan, Hanoch; Haddad, Riad; Greenberg, Ron; Skornick, Yehuda; Kaplan, Ofer

2002-01-01

Photodynamic therapy (PDT) involves the use of photosensitizing drugs combined with light to treat tumors. Laser systems, the current source of light for PDT, have several inherent drawbacks: the spectrum is essentially monochromatic which may be problematic for second generation photosensitizers, the systems are bulky and nearly impossible to move between hospital locations and require complicated electrical and cooling installations, the cost of a typical system is enormous, and its maintenance and operation require highly trained personnel. We now introduce a new non-laser light system, Versa-Light, which appears to work as effectively and has none of the above drawbacks. A series of in vitro studies were performed using various murine and human normal and cancer cells which underwent PDT using aluminum phthalocyanine (AlPcS4) as a photosensitizer and Versa-Light as the light source. PDT of cancer cells at light energy levels of 50, 100 and 200 j/cm2 significantly decreased cell viability. PDT also decreased cell viability of normal murine splenocytes and normal human lymphocytes, but to a lesser extent. The observed significant hyperthermia was light dose-dependent. We believe that Versa-Light can replace laser systems as an enhanced light source for PDT. Further in vitro and pre-clinical studies are in progress.

Precision phase estimation based on weak-value amplification

NASA Astrophysics Data System (ADS)

Qiu, Xiaodong; Xie, Linguo; Liu, Xiong; Luo, Lan; Li, Zhaoxue; Zhang, Zhiyou; Du, Jinglei

2017-02-01

In this letter, we propose a precision method for phase estimation based on the weak-value amplification (WVA) technique using a monochromatic light source. The anomalous WVA significantly suppresses the technical noise with respect to the intensity difference signal induced by the phase delay when the post-selection procedure comes into play. The phase measured precision of this method is proportional to the weak-value of a polarization operator in the experimental range. Our results compete well with the wide spectrum light phase weak measurements and outperform the standard homodyne phase detection technique.

Analysis of JPSS J1 VIIRS Polarization Sensitivity Using the NIST T-SIRCUS

NASA Technical Reports Server (NTRS)

McIntire, Jeffrey W.; Young, James B.; Moyer, David; Waluschka, Eugene; Oudrari, Hassan; Xiong, Xiaoxiong

2015-01-01

The polarization sensitivity of the Joint Polar Satellite System (JPSS) J1 Visible Infrared Imaging Radiometer Suite (VIIRS) measured pre-launch using a broadband source was observed to be larger than expected for many reflective bands. Ray trace modeling predicted that the observed polarization sensitivity was the result of larger diattenuation at the edges of the focal plane filter spectral bandpass. Additional ground measurements were performed using a monochromatic source (the NIST T-SIRCUS) to input linearly polarized light at a number of wavelengths across the bandpass of two VIIRS spectral bands and two scan angles. This work describes the data processing, analysis, and results derived from the T-SIRCUS measurements, comparing them with broadband measurements. Results have shown that the observed degree of linear polarization, when weighted by the sensor's spectral response function, is generally larger on the edges and smaller in the center of the spectral bandpass, as predicted. However, phase angle changes in the center of the bandpass differ between model and measurement. Integration of the monochromatic polarization sensitivity over wavelength produced results consistent with the broadband source measurements, for all cases considered.

Joint transform correlators with spatially incoherent illumination

NASA Astrophysics Data System (ADS)

Bykovsky, Yuri A.; Karpiouk, Andrey B.; Markilov, Anatoly A.; Rodin, Vladislav G.; Starikov, Sergey N.

1997-03-01

Two variants of joint transform correlators with monochromatic spatially incoherent illumination are considered. The Fourier-holograms of the reference and recognized images are recorded simultaneously or apart in a time on the same spatial light modulator directly by monochromatic spatially incoherent light. To create the signal of mutual correlation of the images it is necessary to execute nonlinear transformation when the hologram is illuminated by coherent light. In the first scheme of the correlator this aim was achieved by using double pas of a restoring coherent wave through the hologram. In the second variant of the correlator the non-linearity of the characteristic of the spatial light modulator for hologram recording was used. Experimental schemes and results on processing teste images by both variants of joint transform correlators with monochromatic spatially incoherent illumination. The use of spatially incoherent light on the input of joint transform correlators permits to reduce the requirements to optical quality of elements, to reduce accuracy requirements on elements positioning and to expand a number of devices suitable to input images in correlators.

Longitudinal spatial coherence gated high-resolution tomography and quantitative phase microscopy of biological cells and tissues with uniform illumination

NASA Astrophysics Data System (ADS)

Mehta, Dalip Singh; Ahmad, Azeem; Dubey, Vishesh; Singh, Veena; Butola, Ankit; Mohanty, Tonmoy; Nandi, Sreyankar

2018-02-01

We report longitudinal spatial coherence (LSC) gated high-resolution tomography and quantitative phase microscopy of biological cells and tissues with uniform illumination using laser as a light source. To accomplish this a pseudo thermal light source was synthesized by passing laser beams through an optical system, which is basically a speckle reduction system with combined effect of spatial, temporal, angular and polarisation diversity. The longitudinal spatial coherence length of such light was significantly reduced by synthesizing a pseudo thermal source with the combined effect of spatial, angular and temporal diversity. This results in a low spatially coherent (i.e., broad angular frequency spectrum) light source with narrow temporal frequency spectrum. Light from such a pseudo thermal light source was passed through an interference microscope with varying magnification, such as, 10X and 50X. The interference microscope was used for full-field OCT imaging of multilayer objects and topography of industrial objects. Experimental results of optical sectioning of multilayer biological objects with high axial-resolution less than 10μm was achieved which is comparable to broadband white light source. The synthesized light source with reduced speckles having uniform illumination on the sample, which can be very useful for fluorescence microscopy as well as quantitative phase microscopy with less phase noise. The present system does not require any dispersion compensation optical system for biological samples as a highly monochromatic light source is used.

A review of monochromatic light devices for the treatment of alopecia areata.

PubMed

Darwin, Evan; Arora, Harleen; Hirt, Penelope A; Wikramanayake, Tongyu Cao; Jimenez, Joaquin J

2018-02-01

There are many laser technologies that are being tested that claim to support hair regrowth for patients with alopecia areata (AA). In this paper, we will determine whether the body of evidence supports the use of devices using monochromatic light sources to treat AA. Articles were gathered from PubMed, Embase, and the Cochrane database using these keywords: lasers, excimer laser, low-level laser therapy (LLLT), low-level light therapy, alopecia, alopecia areata, and hair loss with a category modifier of English. Ten clinical trials and seven case reports/abstracts were assessed. Eight clinical trials and two case reports demonstrated hair regrowth with the 308-nm excimer laser/light in men, women, and children. One case report demonstrated hair regrowth with the ALBA 355® laser. One clinical trial and two case reports demonstrated hair regrowth with LLLT. While two case reports demonstrated hair regrowth with fractional laser therapy, one clinical trial showed no improvement. The 308-nm excimer laser is a safe and effective treatment for men, women, and children with refractory AA of the scalp and beard. Larger, double-blinded clinical trials should be conducted to compare excimer laser therapy to standard treatments. More data is needed to determine the efficacy of LLLT and fractional laser therapy in the treatment of AA.

Anomalous refraction of a low divergence monochromatic light beam in a transparent slab.

PubMed

Lequime, Michel; Amra, Claude

2018-04-01

An exact formulation for the propagation of a monochromatic wave packet impinging on a transparent, homogeneous, isotropic, and parallel slab at oblique incidence is given. Approximate formulas are derived for low divergence light beams. These formulas show the presence of anomalous refraction phenomena at any slab thickness, including negative refraction and flat lensing effects, induced by reflection at the rear face.

High-energy and ultra-wideband tunable terahertz source with DAST crystal via difference frequency generation

NASA Astrophysics Data System (ADS)

He, Yixin; Wang, Yuye; Xu, Degang; Nie, Meitong; Yan, Chao; Tang, Longhuang; Shi, Jia; Feng, Jiachen; Yan, Dexian; Liu, Hongxiang; Teng, Bing; Feng, Hua; Yao, Jianquan

2018-01-01

We have demonstrated a high-energy and broadly tunable monochromatic terahertz (THz) source based on difference frequency generation (DFG) in DAST crystal. A high-energy dual-wavelength optical parametric oscillator with two KTP crystals was constructed as a light source for DFG, where the effect of blue light was first observed accompanying with tunable dual-wavelength pump light due to different nonlinear processes. The THz frequency was tuned randomly in the range of 0.3-19.6 THz. The highest energy of 870 nJ/pulse was obtained at 18.9 THz under the intense pump intensity of 247 MW/cm2. The THz energy dips above 3 THz have been analyzed and mainly attributed to the resonance absorption induced by lattice vibration in DAST crystal. The dependence of THz output on the input energy was studied experimentally, and THz output saturation was observed. Furthermore, tests of transmission spectroscopy of four typical samples were demonstrated with this ultra-wideband THz source.

Monochromatic body waves excited by great subduction zone earthquakes

NASA Astrophysics Data System (ADS)

Ihmlé, Pierre F.; Madariaga, Raúl

Large quasi-monochromatic body waves were excited by the 1995 Chile Mw=8.1 and by the 1994 Kurile Mw=8.3 events. They are observed on vertical/radial component seismograms following the direct P and Pdiff arrivals, at all azimuths. We devise a slant stack algorithm to characterize the source of the oscillations. This technique aims at locating near-source isotropic scatterers using broadband data from global networks. For both events, we find that the oscillations emanate from the trench. We show that these monochromatic waves are due to localized oscillations of the water column. Their period corresponds to the gravest ID mode of a water layer for vertically traveling compressional waves. We suggest that these monochromatic body waves may yield additional constraints on the source process of great subduction zone earthquakes.

In-ovo green light photostimulation during different embryonic stages affect somatotropic axis.

PubMed

Dishon, L; Avital-Cohen, N; Zaguri, S; Bartman, J; Heiblum, R; Druyan, S; Porter, T E; Gumulka, M; Rozenboim, I

2018-06-01

Previous studies demonstrated that in-ovo photostimulation with monochromatic green light increased the somatotropic axis expression in broilers embryos. The objective of the current study was to detect the critical period for in-ovo GL photostimulation, in order to find the optimal targeted photostimulation period during the incubation process. Three hundred thirty-six fertile broiler eggs were divided into 4 groups. The first group was incubated under dark conditions as a negative control. The second incubated under intermittent monochromatic green light using light-emitting diode (LED) lamps with an intensity of 0.1 W\\m2 at shell level from d 0 of the incubation as a positive control. The third group incubated under intermittent monochromatic green light from d 10 of the incubation. The last group incubated under intermittent monochromatic green light from d 15 of the incubation. In-ovo green light photostimulation from embryonic d 0 (ED0) increased plasma growth hormone (GH), as well as hypothalamic growth hormone releasing hormone (GHRH) and liver growth hormone receptor (GHR) and insulin-like growth factor-1 (IGF-1) mRNA levels. In-ovo green light photostimulation from ED10 increased the GH plasma levels compared to the negative control group, without affecting somatotropic axis mRNA genes expressions of GHRH, GHR, and IGF-1. In-ovo green light photostimulation from ED15 caused an increase in both the plasma GH levels and the somatotropic axis mRNA genes expressions of GHRH, GHR, and IGF-1, compared to the negative control group. These results suggest that the critical period of somatotropic axis acceleration by GL photostimulation start at 15 d of incubation.

Quantum theory of structured monochromatic light

NASA Astrophysics Data System (ADS)

Punnoose, Alexander; Tu, J. J.

2017-08-01

Applications that envisage utilizing the orbital angular momentum (OAM) at the single photon level assume that the OAM degrees of freedom of the photons are orthogonal. To test this critical assumption, we quantize the beam-like solutions of the vector Helmholtz equation from first principles. We show that although the photon operators of a diffracting monochromatic beam do not in general satisfy the canonical commutation relations, implying that the photon states in Fock space are not orthogonal, the states are bona fide eigenstates of the number and Hamiltonian operators. As a result, the representation for the photon operators presented in this work form a natural basis to study structured monochromatic light at the single photon level.

Photostimulation of osteogenic differentiation on silk scaffolds by plasma arc light source.

PubMed

Çakmak, Anıl Sera; Çakmak, Soner; Vatansever, H Seda; Gümüşderelioğlu, Menemşe

2018-05-01

Low-level laser therapy (LLLT) has been used for more than 30 years to heal wounds. In recent years, LLLT or photostimulation has been indicated as an effective tool for regenerative and dental medicine by using monochromatic light. The aim of this study is to indicate the usability of plasma arc light source for bone regeneration. This is why we used polychromatic light source providing effective wavelengths in the range of 590-1500 nm for cellular response and investigated photostimulation effects on osteogenic differentiation of human mesenchymal stem cells (hMSCs) seeded on 3D silk scaffolds. Cellular responses were examined by using cell culture methods in terms of proliferation, differentiation, and morphological analyses. The results showed that photostimulation with a polychromatic light source (applied for 5 min from the 3rd day after seeding up to the 28th day in 2-day intervals with 92-mW/cm 2 power from 10-cm distance to the cells) enhanced osteogenic differentiation of hMSCs according to higher alkaline phosphatase (ALP) activity, collagen and calcium content, osteogenic gene expressions, and matrix mineralization. In conclusion, we suggest that the plasma arc light source that was used here has a great potential for bone regeneration.

Cone signals for spectacle-lens compensation: differential responses to short and long wavelengths.

PubMed

Rucker, Frances J; Wallman, Josh

2008-09-01

Chick eyes compensate for defocus imposed by spectacle lenses by making compensatory changes in eye length and choroidal thickness, a laboratory model of emmetropization. To investigate the roles of longitudinal chromatic aberration and of chromatic mechanisms in emmetropization, we examined the participation of different cone classes, and we compared the efficacy of lens compensation under monochromatic illumination with that under white light of the same illuminance to the chick eye. Chicks wore positive or negative 6D or 8D lenses on one eye for 3 days, under either blue (460 nm) or red (620 nm) light at 0.67 lux or under white light at 0.67 or 0.2 lux (all measures are corrected for chick photopic sensitivity). The illumination conditions were chosen to differentially stimulate either the short-wavelength and ultraviolet cones or the long-wavelength and double cones. Measurements are expressed as the relative change: the inter-ocular difference in the amount of change over the 3 days of lens wear. We find that under this low illumination the two components of lens compensation were differentially affected by the monochromatic illumination: in blue light lens compensation was mainly due to changes in eye length, whereas in red light lens compensation was mainly due to changes in choroidal thickness. In general, white light produced better lens compensation than monochromatic illumination. NEGATIVE LENSES: Under white light negative lenses caused an increase in eye length (60 microm) together with a decrease in choroidal thickness (-51 microm) relative to the fellow eye. Under blue light, although there was an increase in eye length (32 microm), there was no change in choroidal thickness (5 microm). In contrast, under red light there was a decrease in choroidal thickness (-62 microm) but no increase in eye length (8 microm). Relative ocular elongation was the same in white and monochromatic light. POSITIVE LENSES: Under white light positive lenses caused a decrease in eye length (-142 microm) together with an increase in choroidal thickness (68 microm) relative to the fellow eye. Under blue light, there was a decrease in eye length (-64 microm), but no change in choroidal thickness (2 microm). In contrast, under red light there was an increase (90 microm) in choroidal thickness but less of a decrease (-36 microm) in eye length. Lens compensation by inhibition of ocular elongation was less effective under monochromatic illumination than under white light (white v red: p=0.003; white v blue p=.014). The differential effects of red and blue light on the choroidal and ocular length compensatory responses suggest that they are driven by different proportions of the cone-types, implying that, although chromatic contrast is not essential for lens compensation and presumably for emmetropization as well, the retinal substrates exist for utilizing chromatic contrast in these compensatory responses. The generally better lens compensation in white than monochromatic illumination suggests that longitudinal chromatic aberration may be used in lens compensation.

Curved crystal x-ray optics for monochromatic imaging with a clinical source.

PubMed

Bingölbali, Ayhan; MacDonald, C A

2009-04-01

Monochromatic x-ray imaging has been shown to increase contrast and reduce dose relative to conventional broadband imaging. However, clinical sources with very narrow energy bandwidth tend to have limited intensity and field of view. In this study, focused fan beam monochromatic radiation was obtained using doubly curved monochromator crystals. While these optics have been in use for microanalysis at synchrotron facilities for some time, this work is the first investigation of the potential application of curved crystal optics to clinical sources for medical imaging. The optics could be used with a variety of clinical sources for monochromatic slot scan imaging. The intensity was assessed and the resolution of the focused beam was measured using a knife-edge technique. A simulation model was developed and comparisons to the measured resolution were performed to verify the accuracy of the simulation to predict resolution for different conventional sources. A simple geometrical calculation was also developed. The measured, simulated, and calculated resolutions agreed well. Adequate resolution and intensity for mammography were predicted for appropriate source/optic combinations.

Noise pair velocity and range echo location system

DOEpatents

Erskine, D.J.

1999-02-16

An echo-location method for microwaves, sound and light capable of using incoherent and arbitrary waveforms of wide bandwidth to measure velocity and range (and target size) simultaneously to high resolution is disclosed. Two interferometers having very long and nearly equal delays are used in series with the target interposed. The delays can be longer than the target range of interest. The first interferometer imprints a partial coherence on an initially incoherent source which allows autocorrelation to be performed on the reflected signal to determine velocity. A coherent cross-correlation subsequent to the second interferometer with the source determines a velocity discriminated range. Dithering the second interferometer identifies portions of the cross-correlation belonging to a target apart from clutter moving at a different velocity. The velocity discrimination is insensitive to all slowly varying distortions in the signal path. Speckle in the image of target and antenna lobing due to parasitic reflections is minimal for an incoherent source. An arbitrary source which varies its spectrum dramatically and randomly from pulse to pulse creates a radar elusive to jamming. Monochromatic sources which jigger in frequency from pulse to pulse or combinations of monochromatic sources can simulate some benefits of incoherent broadband sources. Clutter which has a symmetrical velocity spectrum will self-cancel for short wavelengths, such as the apparent motion of ground surrounding target from a sidelooking airborne antenna. 46 figs.

Noise pair velocity and range echo location system

DOEpatents

Erskine, David J.

1999-01-01

An echo-location method for microwaves, sound and light capable of using incoherent and arbitrary waveforms of wide bandwidth to measure velocity and range (and target size) simultaneously to high resolution. Two interferometers having very long and nearly equal delays are used in series with the target interposed. The delays can be longer than the target range of interest. The first interferometer imprints a partial coherence on an initially incoherent source which allows autocorrelation to be performed on the reflected signal to determine velocity. A coherent cross-correlation subsequent to the second interferometer with the source determines a velocity discriminated range. Dithering the second interferometer identifies portions of the cross-correlation belonging to a target apart from clutter moving at a different velocity. The velocity discrimination is insensitive to all slowly varying distortions in the signal path. Speckle in the image of target and antenna lobing due to parasitic reflections is minimal for an incoherent source. An arbitrary source which varies its spectrum dramatically and randomly from pulse to pulse creates a radar elusive to jamming. Monochromatic sources which jigger in frequency from pulse to pulse or combinations of monochromatic sources can simulate some benefits of incoherent broadband sources. Clutter which has a symmetrical velocity spectrum will self-cancel for short wavelengths, such as the apparent motion of ground surrounding target from a sidelooking airborne antenna.

Effect of Altered Retinal Cones/Opsins on Refractive Development under Monochromatic Lights in Guinea Pigs

PubMed Central

Zou, Leilei; Zhu, Xiaoyu; Liu, Rui; Ma, Fei; Yu, Manrong

2018-01-01

Purpose To analyze the changes of refraction and metabolism of the retinal cones under monochromatic lights in guinea pigs. Methods Sixty guinea pigs were randomly divided into a short-wavelength light (SL) group, a middle-wavelength light (ML) group, and a white light (WL) group. Refraction and axial length were measured before and after 10-week illumination. The densities of S-cones and M-cones were determined by retinal cone immunocytochemistry, and the expressions of S-opsins and M-opsins were determined by real-time PCR and Western blot. Results After 10-week illumination, the guinea pigs developed relative hyperopia in the SL group and relative myopia in the ML group. Compared with the WL group, the density of S-cones and S-opsins increased while M-cones and M-opsins decreased in the SL group (all, p < 0.05); conversely, the density of S-cones and S-opsins decreased while M-cones and M-opsins increased in the ML group (all, p < 0.05). Increased S-cones/opsins and decreased M-cones/opsins were induced by short-wavelength lights. Decreased S-cones/opsins and increased M-cones/opsins were induced by middle-wavelength lights. Conclusions Altered retinal cones/opsins induced by monochromatic lights might be involved in the refractive development in guinea pigs. PMID:29675275

Solar spectrum matching with white OLED and monochromatic LEDs.

PubMed

Yu, Hui-Yuan; Cao, Guan-Ying; Zhang, Jing-Hui; Yang, Yi; Sun, Wen-Liang; Wang, Li-Ping; Zou, Nian-Yu

2018-04-01

In this paper, the solar spectrum matching in the visible range of 380-780 nm with white organic light-emitting diode (OLED) and monochromatic light-emitting diodes (LEDs) is investigated. The correlation index ( R 2 ) is used to evaluate the difference between the matching spectrum and the solar spectrum. The optimal combination is obtained by the least squares method. We also perform subtraction experiments to find the optimal combination. We utilize a common white OLED device design and just change the species of monochromatic LEDs used. We report and evaluate different degrees of matching effects. The results show that the correlation index of the best combination can reach 94.09% with white OLED and 36 monochromatic LEDs. We define three levels of performance as an evaluation system in accordance with the matching effect. The level is excellent with an R 2 above 90.14%. The good level is from 86.65% to 58.28%. From 42.08% to 33.06% is the reasonable level. Compared with other methods, using white OLED combined with monochromatic LEDs achieves the best solar spectrum matching effect. The results can be applied to different requirements of engineering practice.

Monochromatic X-ray sources based on a mechanism of real and virtual photon diffraction in crystals

NASA Astrophysics Data System (ADS)

Wagner, A. R.; Kuznetsov, S. I.; Potylitsyn, A. P.; Razin, S. V.; Uglov, S. R.; Zabaev, V. N.

2008-09-01

A source of monochromatic X-ray radiation is wanted in industry, science, medicine and so on. Many ways of making such a source are known. The present work describes two mechanisms for the creation of a monochromatic X-ray beam, which are parametric X-ray radiation (PXR) and bremsstrahlung diffraction (DBS). Both the experiments were carried out using an electron beam at a microtron. During the first experiment, the DBS process was investigated as a scattering of the Bremsstrahlung (BS) beam on the crystallographic surfaces of tungsten and pyrolytic graphite crystals. The second experiment consisted in the registration of the PXR and DBS yield during the passage of the electrons through the same crystals as in the first experiment. The spectral and orientation radiation characteristics and simulation results obtained for the DBS and PXR processes are presented. It is shown that the usage of mosaic crystalline targets is rather useful in order to obtain a monochromatic X-ray source based on bremsstrahlung diffraction from moderately relativistic electrons.

Analysis of gas exchange, stomatal behaviour and micronutrients uncovers dynamic response and adaptation of tomato plants to monochromatic light treatments.

PubMed

O'Carrigan, Andrew; Babla, Mohammad; Wang, Feifei; Liu, Xiaohui; Mak, Michelle; Thomas, Richard; Bellotti, Bill; Chen, Zhong-Hua

2014-09-01

Light spectrum affects the yield and quality of greenhouse tomato, especially over a prolonged period of monochromatic light treatments. Physiological and chemical analysis was employed to investigate the influence of light spectral (blue, green and red) changes on growth, photosynthesis, stomatal behaviour, leaf pigment, and micronutrient levels. We found that plants are less affected under blue light treatment, which was evident by the maintenance of higher A, gs, Tr, and stomatal parameters and significantly lower VPD and Tleaf as compared to those plants grown in green and red light treatments. Green and red light treatments led to significantly larger increase in the accumulation of Fe, B, Zn, and Cu than blue light. Moreover, guard cell length, width, and volume all showed highly significant positive correlations to gs, Tr and negative links to VPD. There was negative impact of monochromatic lights-induced accumulation of Mn, Cu, and Zn on photosynthesis, leaf pigments and plant growth. Furthermore, most of the light-induced significant changes of the physiological traits were partially recovered at the end of experiment. A high degree of morphological and physiological plasticity to blue, green and red light treatments suggested that tomato plants may have developed mechanisms to adapt to the light treatments. Thus, understanding the optimization of light spectrum for photosynthesis and growth is one of the key components for greenhouse tomato production. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Spectral characteristics of light sources for S-cone stimulation.

PubMed

Schlegelmilch, F; Nolte, R; Schellhorn, K; Husar, P; Henning, G; Tornow, R P

2002-11-01

Electrophysiological investigations of the short-wavelength sensitive pathway of the human eye require the use of a suitable light source as a S-cone stimulator. Different light sources with their spectral distribution properties were investigated and compared with the ideal S-cone stimulator. First, the theoretical background of the calculation of relative cone energy absorption from the spectral distribution function of the light source is summarized. From the results of the calculation, the photometric properties of the ideal S-cone stimulator will be derived. The calculation procedure was applied to virtual light sources (computer generated spectral distribution functions with different medium wavelengths and spectrum widths) and to real light sources (blue and green light emitting diodes, blue phosphor of CRT-monitor, multimedia projector, LCD monitor and notebook display). The calculated relative cone absorbencies are compared to the conditions of an ideal S-cone stimulator. Monochromatic light sources with wavelengths of less than 456 nm are close to the conditions of an ideal S-cone stimulator. Spectrum widths up to 21 nm do not affect the S-cone activation significantly (S-cone activation change < 0.2%). Blue light emitting diodes with peak wavelength at 448 nm and spectrum bandwidth of 25 nm are very useful for S-cone stimulation (S-cone activation approximately 95%). A suitable display for S-cone stimulation is the Trinitron computer monitor (S-cone activation approximately 87%). The multimedia projector has a S-cone activation up to 91%, but their spectral distribution properties depends on the selected intensity. LCD monitor and notebook displays have a lower S-cone activation (< or = 74%). Carefully selecting the blue light source for S-cone stimulation can reduce the unwanted L-and M-cone activation down to 4% for M-cones and 1.5% for L-cones.

Comparative effects of exposure to different light sources (He-Ne laser, InGaAl diode laser, a specific type of noncoherent LED) on skin blood flow for the head.

PubMed

Pöntinen, P J; Aaltokallio, T; Kolari, P J

1996-01-01

This study assessed the effects of optic stimuli emitted by three different light sources on head skin blood flow. The irradiation effects of the He-Ne laser (632.8 nm, 10 mW, total energy appr. 9.4 J), the InGaAl diode laser (670 nm, 60 mW, appr. 108 J) and monochromatic light (635 nm, 112.5 mW, appr. 202.5 J) were measured using laser Doppler technology. The corresponding fluences (energy densities) varied from 0.01 J/cm2 (He-Ne) to a range of 0.12-0.72 J/cm2 (InGaAl) and 0.22-1.36 J/cm2 (LED). The investigation was completed under single-blind, placebo-controlled conditions where the subjects (10 male healthy volunteers) were exposed on two occasions to the placebo (LED)-device against the laser (He-Ne or InGaAl). A short lasting vasodilation, a 54 per cent increase (p < 0.05) in skin blood flow was seen after the InGaAl irradiation (fluences between 0.12-0.36 J/cm2) whereas the non-coherent monochromatic irradiation (0.68-1.36 J/cm2) used in this particular study decreased blood flow by 36 per cent (p < 0.05). The He-Ne irradiation (0.01 J/cm2) had no effect. Skin temperature changes were insignificant. Skin blood flow changes seemed to be related more on radiant exposures then coherency.

Emphysema diagnosis using X-ray dark-field imaging at a laser-driven compact synchrotron light source

PubMed Central

Schleede, Simone; Meinel, Felix G.; Bech, Martin; Herzen, Julia; Achterhold, Klaus; Potdevin, Guillaume; Malecki, Andreas; Adam-Neumair, Silvia; Thieme, Sven F.; Bamberg, Fabian; Nikolaou, Konstantin; Bohla, Alexander; Yildirim, Ali Ö.; Loewen, Roderick; Gifford, Martin; Ruth, Ronald; Eickelberg, Oliver; Reiser, Maximilian; Pfeiffer, Franz

2012-01-01

In early stages of various pulmonary diseases, such as emphysema and fibrosis, the change in X-ray attenuation is not detectable with absorption-based radiography. To monitor the morphological changes that the alveoli network undergoes in the progression of these diseases, we propose using the dark-field signal, which is related to small-angle scattering in the sample. Combined with the absorption-based image, the dark-field signal enables better discrimination between healthy and emphysematous lung tissue in a mouse model. All measurements have been performed at 36 keV using a monochromatic laser-driven miniature synchrotron X-ray source (Compact Light Source). In this paper we present grating-based dark-field images of emphysematous vs. healthy lung tissue, where the strong dependence of the dark-field signal on mean alveolar size leads to improved diagnosis of emphysema in lung radiographs. PMID:23074250

Modulation of cardiac tissue electrophysiological properties with light-sensitive proteins.

PubMed

Nussinovitch, Udi; Shinnawi, Rami; Gepstein, Lior

2014-04-01

Optogenetics approaches, utilizing light-sensitive proteins, have emerged as unique experimental paradigms to modulate neuronal excitability. We aimed to evaluate whether a similar strategy could be used to control cardiac-tissue excitability. A combined cell and gene therapy strategy was developed in which fibroblasts were transfected to express the light-activated depolarizing channel Channelrhodopsin-2 (ChR2). Patch-clamp studies confirmed the development of a robust inward current in the engineered fibroblasts following monochromatic blue-light exposure. The engineered cells were co-cultured with neonatal rat cardiomyocytes (or human embryonic stem cell-derived cardiomyocytes) and studied using a multielectrode array mapping technique. These studies revealed the ability of the ChR2-fibroblasts to electrically couple and pace the cardiomyocyte cultures at varying frequencies in response to blue-light flashes. Activation mapping pinpointed the source of this electrical activity to the engineered cells. Similarly, diffuse seeding of the ChR2-fibroblasts allowed multisite optogenetics pacing of the co-cultures, significantly shortening their electrical activation time and synchronizing contraction. Next, optogenetics pacing in an in vitro model of conduction block allowed the resynchronization of the tissue's electrical activity. Finally, the ChR2-fibroblasts were transfected to also express the light-sensitive hyperpolarizing proton pump Archaerhodopsin-T (Arch-T). Seeding of the ChR2/ArchT-fibroblasts allowed to either optogentically pace the cultures (in response to blue-light flashes) or completely suppress the cultures' electrical activity (following continuous illumination with 624 nm monochromatic light, activating ArchT). The results of this proof-of-concept study highlight the unique potential of optogenetics for future biological pacemaking and resynchronization therapy applications and for the development of novel anti-arrhythmic strategies.

Accuracy of Dual-Energy Virtual Monochromatic CT Numbers: Comparison between the Single-Source Projection-Based and Dual-Source Image-Based Methods.

PubMed

Ueguchi, Takashi; Ogihara, Ryota; Yamada, Sachiko

2018-03-21

To investigate the accuracy of dual-energy virtual monochromatic computed tomography (CT) numbers obtained by two typical hardware and software implementations: the single-source projection-based method and the dual-source image-based method. A phantom with different tissue equivalent inserts was scanned with both single-source and dual-source scanners. A fast kVp-switching feature was used on the single-source scanner, whereas a tin filter was used on the dual-source scanner. Virtual monochromatic CT images of the phantom at energy levels of 60, 100, and 140 keV were obtained by both projection-based (on the single-source scanner) and image-based (on the dual-source scanner) methods. The accuracy of virtual monochromatic CT numbers for all inserts was assessed by comparing measured values to their corresponding true values. Linear regression analysis was performed to evaluate the dependency of measured CT numbers on tissue attenuation, method, and their interaction. Root mean square values of systematic error over all inserts at 60, 100, and 140 keV were approximately 53, 21, and 29 Hounsfield unit (HU) with the single-source projection-based method, and 46, 7, and 6 HU with the dual-source image-based method, respectively. Linear regression analysis revealed that the interaction between the attenuation and the method had a statistically significant effect on the measured CT numbers at 100 and 140 keV. There were attenuation-, method-, and energy level-dependent systematic errors in the measured virtual monochromatic CT numbers. CT number reproducibility was comparable between the two scanners, and CT numbers had better accuracy with the dual-source image-based method at 100 and 140 keV. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Action spectrum for cryptochrome-dependent hypocotyl growth inhibition in Arabidopsis.

PubMed

Ahmad, Margaret; Grancher, Nicholas; Heil, Mary; Black, Robert C; Giovani, Baldissera; Galland, Paul; Lardemer, Danielle

2002-06-01

Cryptochrome blue-light photoreceptors are found in both plants and animals and have been implicated in numerous developmental and circadian signaling pathways. Nevertheless, no action spectrum for a physiological response shown to be entirely under the control of cryptochrome has been reported. In this work, an action spectrum was determined in vivo for a cryptochrome-mediated high-irradiance response, the blue-light-dependent inhibition of hypocotyl elongation in Arabidopsis. Comparison of growth of wild-type, cry1cry2 cryptochrome-deficient double mutants, and cryptochrome-overexpressing seedlings demonstrated that responsivity to monochromatic light sources within the range of 390 to 530 nm results from the activity of cryptochrome with no other photoreceptor having a significant primary role at the fluence range tested. In both green- and norflurazon-treated (chlorophyll-deficient) seedlings, cryptochrome activity is fairly uniform throughout its range of maximal response (390-480 nm), with no sharply defined peak at 450 nm; however, activity at longer wavelengths was disproportionately enhanced in CRY1-overexpressing seedlings as compared with wild type. The action spectrum does not correlate well with the absorption spectra either of purified recombinant cryptochrome photoreceptor or to that of a second class of blue-light photoreceptor, phototropin (PHOT1 and PHOT2). Photoreceptor concentration as determined by western-blot analysis showed a greater stability of CRY2 protein under the monochromatic light conditions used in this study as compared with broad band blue light, suggesting a complex mechanism of photoreceptor activation. The possible role of additional photoreceptors (in particular phytochrome A) in cryptochrome responses is discussed.

Interferometric angle monitor

NASA Technical Reports Server (NTRS)

Minott, P. O. (Inventor)

1983-01-01

Two mutually coherent light beams formed from a single monochromatic light source were directed to a reflecting surface of a rotatable object. They were reflected into an imaging optical lens having a focal plane optically at infinity. A series of interference fringes were formed in the focal plane which were translated linearly in response to angular rotation of the object. Photodetectors were located adjacent the focal plane to detect the fringe translation and output a signal in response to the translation. The signal was fed to a signal processor which was adapted to count the number of fringes detected and develop a measure of the angular rotation and direction of the object.

Light trapping for photovoltaic cells using polarization-insensitive angle-selective filters under monochromatic illumination.

PubMed

Takeda, Yasuhiko; Iizuka, Hideo; Yamada, Noboru; Ito, Tadashi

2017-07-10

We have proposed a light-trapping concept for photovoltaic (PV) cells under monochromatic illumination with restricted incident angles. We employed a configuration consisting of a shortpass filter (SPF) on the front surface and a diffuse reflector on the rear surface of the cell. The SPF was designed so that it functioned as a polarization-insensitive angle-selective filter. We fabricated 30-80-μm-thick crystalline silicon samples for incident angles changing within 30°, and analyzed the measured results using a ray-trace simulation with the Monte Carlo method. The ratio of the absorbed intensity to the 1064 nm illumination intensity was 0.69-0.85, which was higher than those equipped with antireflection coatings instead of the SPFs by 0.19-0.13. Thus, we have proven the light-trapping concept of the SPF/diffuse reflector configuration for monochromatic illumination. The PV cells could be applied to wireless power supply, in particular from solar-pumped lasers.

Effects of monochromatic light on proliferation response of splencyte in broilers.

PubMed

Xie, D; Wang, Z; Cao, J; Dong, Y; Chen, Y

2008-10-01

To investigate the effects of various monochromatic lights on splenocyte proliferation responses, a total of 260 Arbor Acre male broilers on P1 (post-hatching day 1) were exposed to blue light (BL), green light (GL), red light (RL) and white light treatments by light emitting diode system for 7 weeks, respectively. All light sources were equalized on the intensity of 15 lx and light period of 23 h daily. Morphological change of spleen and response of splenocyte proliferation were assessed by using histochemistry staining and colorimetric test in cultures of purified splenic cells. The results were as follows: (1) At P21, GL increased significantly the spleen weight by 163.6% and spleen index by 118.8% compared with RL (P < 0.05). Until P49, BL enhanced significantly the spleen weights by 42.2% compared with RL (P < 0.05), but no significant difference was found in the spleen index among four light-treated groups (P > 0.05). (2) Compared with RL, GL increased significantly the diameter of splenic nodule and area of periarterial lymphatic sheath at P21 by 87.2 and 58.1%, respectively (P < 0.05); BL increased significantly the diameter of splenic nodule and area of periarterial lymphatic sheath at P49 by 64.4 and 50.5%, respectively (P < 0.05). (3) At P21, GL enhanced spleen lymphocytes proliferation in response to concanavalin A compared with RL by 50.0% (P < 0.05). Until P49, the mitogenic response in BL was significantly higher (29.4%) than that of RL (P < 0.05). (4) The interleukin-2 (IL-2) bioactivity was significantly increased to 34.3% in GL than in RL at P21 (P < 0.05). Until P49, the IL-2 bioactivity in BL was significantly higher (62.2%) than that of RL (P < 0.05). (5) There was no significant difference in the nitric oxide (NO) concentration of splenocyte among RL, GL and BL groups at P21 (P > 0.05), but the concentration in RL group at P49 was significantly increased, 59.0 and 63.7% compared to that of GL and BL groups, respectively (P < 0.05). These results suggested that the monochromatic light affected splenocyte proliferation mainly because of alterations in IL-2 bioactivity and NO production in splenocyte of broiler. In early stage of broiler growth, the action of GL was obvious, while the response of BL was stronger in later stage.

Propagation-based phase-contrast x-ray tomography of cochlea using a compact synchrotron source.

PubMed

Töpperwien, Mareike; Gradl, Regine; Keppeler, Daniel; Vassholz, Malte; Meyer, Alexander; Hessler, Roland; Achterhold, Klaus; Gleich, Bernhard; Dierolf, Martin; Pfeiffer, Franz; Moser, Tobias; Salditt, Tim

2018-03-21

We demonstrate that phase retrieval and tomographic imaging at the organ level of small animals can be advantageously carried out using the monochromatic radiation emitted by a compact x-ray light source, without further optical elements apart from source and detector. This approach allows to carry out microtomography experiments which - due to the large performance gap with respect to conventional laboratory instruments - so far were usually limited to synchrotron sources. We demonstrate the potential by mapping the functional soft tissue within the guinea pig and marmoset cochlea, including in the latter case an electrical cochlear implant. We show how 3d microanatomical studies without dissection or microscopic imaging can enhance future research on cochlear implants.

Formalism of photons in a nonlinear microring resonator

NASA Astrophysics Data System (ADS)

Tran, Quang Loc; Yupapin, Preecha

2018-03-01

In this paper, using short Gaussian pulses input from a monochromatic light source, we simulate the photon distribution and analyse the output gate's signals of PANDA nonlinear ring resonator. The present analysis is restricted to directional couplers characterized by two parameters, the power coupling coefficient κ and power coupling loss γ. Add/drop filters are also employed and investigated for the suitable to implement in the practical communication system. The experiment was conducted by using the combination of Lumerical FDTD Solutions and Lumerical MODE Solutions software.

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

Budagovsky, A V; Solovykh, N V; Budagovskaya, O N

By the example of vegetable organisms differing in structure and functional properties it is shown that their response to the action of quasi-monochromatic light from laser sources does not obey the Bunsen – Roscoe dose law. The dependence of biological effect on the irradiation time has the multimodal (multiextremal) form with alternating maxima and minima of the stimulating effect. Such a property manifests itself in the spectral ranges, corresponding to photoinduced conversion of chromoproteins of photocontrol systems and is probably related to the cyclic variations of metabolic activity in vegetable cells. (biophotonics)

Biological Effects of Laser Radiation. Volume I. Review of the Literature on Biological Effects of Laser Radiation-to 1965.

DTIC Science & Technology

1978-10-17

because of the rapid progress made in laser technology to date. The use of the Laser Microprobe in spectrochemical analysis of the elements is based on...spectroscopy to vaporize microscopic amounts of samples for elemental analysis . On the other hand, the intense, highly monochromatic laser beam is being...employed as a light source for Raman spectroscopy to study molecular structure. These two uses of lasers in spectroscopic analysis have been sucessful

Parallel neural pathways in higher visual centers of the Drosophila brain that mediate wavelength-specific behavior

PubMed Central

Otsuna, Hideo; Shinomiya, Kazunori; Ito, Kei

2014-01-01

Compared with connections between the retinae and primary visual centers, relatively less is known in both mammals and insects about the functional segregation of neural pathways connecting primary and higher centers of the visual processing cascade. Here, using the Drosophila visual system as a model, we demonstrate two levels of parallel computation in the pathways that connect primary visual centers of the optic lobe to computational circuits embedded within deeper centers in the central brain. We show that a seemingly simple achromatic behavior, namely phototaxis, is under the control of several independent pathways, each of which is responsible for navigation towards unique wavelengths. Silencing just one pathway is enough to disturb phototaxis towards one characteristic monochromatic source, whereas phototactic behavior towards white light is not affected. The response spectrum of each demonstrable pathway is different from that of individual photoreceptors, suggesting subtractive computations. A choice assay between two colors showed that these pathways are responsible for navigation towards, but not for the detection itself of, the monochromatic light. The present study provides novel insights about how visual information is separated and processed in parallel to achieve robust control of an innate behavior. PMID:24574974

A dedicated superbend x-ray microdiffraction beamline for materials, geo-, and environmental sciences at the advanced light source.

PubMed

Kunz, Martin; Tamura, Nobumichi; Chen, Kai; MacDowell, Alastair A; Celestre, Richard S; Church, Matthew M; Fakra, Sirine; Domning, Edward E; Glossinger, James M; Kirschman, Jonathan L; Morrison, Gregory Y; Plate, Dave W; Smith, Brian V; Warwick, Tony; Yashchuk, Valeriy V; Padmore, Howard A; Ustundag, Ersan

2009-03-01

A new facility for microdiffraction strain measurements and microfluorescence mapping has been built on beamline 12.3.2 at the advanced light source of the Lawrence Berkeley National Laboratory. This beamline benefits from the hard x-radiation generated by a 6 T superconducting bending magnet (superbend). This provides a hard x-ray spectrum from 5 to 22 keV and a flux within a 1 microm spot of approximately 5x10(9) photons/s (0.1% bandwidth at 8 keV). The radiation is relayed from the superbend source to a focus in the experimental hutch by a toroidal mirror. The focus spot is tailored by two pairs of adjustable slits, which serve as secondary source point. Inside the lead hutch, a pair of Kirkpatrick-Baez (KB) mirrors placed in a vacuum tank refocuses the secondary slit source onto the sample position. A new KB-bending mechanism with active temperature stabilization allows for more reproducible and stable mirror bending and thus mirror focusing. Focus spots around 1 microm are routinely achieved and allow a variety of experiments, which have in common the need of spatial resolution. The effective spatial resolution (approximately 0.2 microm) is limited by a convolution of beam size, scan-stage resolution, and stage stability. A four-bounce monochromator consisting of two channel-cut Si(111) crystals placed between the secondary source and KB-mirrors allows for easy changes between white-beam and monochromatic experiments while maintaining a fixed beam position. High resolution stage scans are performed while recording a fluorescence emission signal or an x-ray diffraction signal coming from either a monochromatic or a white focused beam. The former allows for elemental mapping, whereas the latter is used to produce two-dimensional maps of crystal-phases, -orientation, -texture, and -strain/stress. Typically achieved strain resolution is in the order of 5x10(-5) strain units. Accurate sample positioning in the x-ray focus spot is achieved with a commercial laser-triangulation unit. A Si-drift detector serves as a high-energy-resolution (approximately 150 eV full width at half maximum) fluorescence detector. Fluorescence scans can be collected in continuous scan mode with up to 300 pixels/s scan speed. A charge coupled device area detector is utilized as diffraction detector. Diffraction can be performed in reflecting or transmitting geometry. Diffraction data are processed using XMAS, an in-house written software package for Laue and monochromatic microdiffraction analysis.

Supercontinuum Fourier transform spectrometry with balanced detection on a single photodiode

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

Goncharov, Vasily; Hall, Gregory

Here, we have developed phase-sensitive signal detection and processing algorithms for Fourier transform spectrometers fitted with supercontinuum sources for applications requiring ultimate sensitivity. Similar to well-established approach of source noise cancellation through balanced detection of monochromatic light, our method is capable of reducing the relative intensity noise of polychromatic light by 40 dB. Unlike conventional balanced detection, which relies on differential absorption measured with a well matched pair of photo-detectors, our algorithm utilizes phase-sensitive differential detection on a single photodiode and is capable of the real-time correction for instabilities in supercontinuum spectral structure over a broad range of wavelengths. Inmore » the resulting method is universal in terms of applicable wavelengths and compatible with commercial spectrometers. We present a proof-of-principle experimental« less

Supercontinuum Fourier transform spectrometry with balanced detection on a single photodiode

DOE PAGES

Goncharov, Vasily; Hall, Gregory

2016-08-25

Here, we have developed phase-sensitive signal detection and processing algorithms for Fourier transform spectrometers fitted with supercontinuum sources for applications requiring ultimate sensitivity. Similar to well-established approach of source noise cancellation through balanced detection of monochromatic light, our method is capable of reducing the relative intensity noise of polychromatic light by 40 dB. Unlike conventional balanced detection, which relies on differential absorption measured with a well matched pair of photo-detectors, our algorithm utilizes phase-sensitive differential detection on a single photodiode and is capable of the real-time correction for instabilities in supercontinuum spectral structure over a broad range of wavelengths. Inmore » the resulting method is universal in terms of applicable wavelengths and compatible with commercial spectrometers. We present a proof-of-principle experimental« less

Method and apparatus for measuring film spectral properties

DOEpatents

Forrest, Stephen R.; Burrows, Paul E.; Garbuzov, Dmitri Z.; Bulovic, Vladimir

1999-12-21

Film spectral properties are measured by projecting chopped monochromatic light onto a luminescent film sample deposited on a substrate, and coupling through use of immersion oil the reflection of light therefrom to a light detector.

Tracing the phase of focused broadband laser pulses

NASA Astrophysics Data System (ADS)

Hoff, Dominik; Krüger, Michael; Maisenbacher, Lothar; Sayler, A. M.; Paulus, Gerhard G.; Hommelhoff, Peter

2017-10-01

Precise knowledge of the behaviour of the phase of light in a focused beam is fundamental to understanding and controlling laser-driven processes. More than a hundred years ago, an axial phase anomaly for focused monochromatic light beams was discovered and is now commonly known as the Gouy phase. Recent theoretical work has brought into question the validity of applying this monochromatic phase formulation to the broadband pulses becoming ubiquitous today. Based on electron backscattering at sharp nanometre-scale metal tips, a method is available to measure light fields with sub-wavelength spatial resolution and sub-optical-cycle time resolution. Here we report such a direct, three-dimensional measurement of the spatial dependence of the optical phase of a focused, 4-fs, near-infrared pulsed laser beam. The observed optical phase deviates substantially from the monochromatic Gouy phase--exhibiting a much more complex spatial dependence, both along the propagation axis and in the radial direction. In our measurements, these significant deviations are the rule and not the exception for focused, broadband laser pulses. Therefore, we expect wide ramifications for all broadband laser-matter interactions, such as in high-harmonic and attosecond pulse generation, femtochemistry, ophthalmological optical coherence tomography and light-wave electronics.

Effects of monochromatic light on quality properties and antioxidation of meat in broilers.

PubMed

Ke, Y Y; Liu, W J; Wang, Z X; Chen, Y X

2011-11-01

Our previous study demonstrated that blue monochromatic light was better to promote the growth and development of broilers than red light. However, consumer research suggests that the eating quality of the meat is more important. The present study was, therefore, designed to further evaluate the effects of various monochromatic lights on the muscle growth and quality properties and antioxidation of meat. A total of 288 newly hatched Arbor Acre male broilers were exposed to blue light (BL), green light (GL), red light (RL), and white light (WL) by a light-emitting diode system for 49 d, respectively. Results showed that the broilers reared under BL significantly increased BW and carcass yield as compared with RL, WL, and GL (P < 0.05), but no statistical difference was found between GL and BL in weight of thigh muscle and carcass yield (P > 0.05). Compared with RL, the muscles of breast and thigh in GL and BL had higher pH, water-holding capacity, and protein content, whereas cooking loss, lightness value, shear value, and fat content were lower (P < 0.05). Moreover, BL significantly elevated superoxide dismutase, glutathione peroxidase, and total antioxidant capability activities and reduced malondialdehyde content both in breast and thigh muscles as compared with RL and WL (P < 0.05), but there was no significant difference in the superoxide dismutase and glutathione peroxidase activities between GL and BL (P > 0.05). These results suggest that BL better improves meat quality of Arbor Acre broilers by elevating antioxidative capacity than does RL.

Optimal monochromatic color combinations for fusion imaging of FDG-PET and diffusion-weighted MR images.

PubMed

Kamei, Ryotaro; Watanabe, Yuji; Sagiyama, Koji; Isoda, Takuro; Togao, Osamu; Honda, Hiroshi

2018-05-23

To investigate the optimal monochromatic color combination for fusion imaging of FDG-PET and diffusion-weighted MR images (DW) regarding lesion conspicuity of each image. Six linear monochromatic color-maps of red, blue, green, cyan, magenta, and yellow were assigned to each of the FDG-PET and DW images. Total perceptual color differences of the lesions were calculated based on the lightness and chromaticity measured with the photometer. Visual lesion conspicuity was also compared among the PET-only, DW-only and PET-DW-double positive portions with mean conspicuity scores. Statistical analysis was performed with a one-way analysis of variance and Spearman's rank correlation coefficient. Among all the 12 possible monochromatic color-map combinations, the 3 combinations of red/cyan, magenta/green, and red/green produced the highest conspicuity scores. Total color differences between PET-positive and double-positive portions correlated with conspicuity scores (ρ = 0.2933, p < 0.005). Lightness differences showed a significant negative correlation with conspicuity scores between the PET-only and DWI-only positive portions. Chromaticity differences showed a marginally significant correlation with conspicuity scores between DWI-positive and double-positive portions. Monochromatic color combinations can facilitate the visual evaluation of FDG-uptake and diffusivity as well as registration accuracy on the FDG-PET/DW fusion images, when red- and green-colored elements are assigned to FDG-PET and DW images, respectively.

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

Yoshimura, D.; Setoyama, H.; Okajima, T.

A new soft X-ray beamline (BL10) at the SAGA Light Source (SAGA-LS) was constructed at the end of 2008. Commissioning of this new beamline started at the beginning of 2009. Synchrotron radiation from a variably polarizing undulator (APPLE-II) can be used in this beamline. The obtained light is monochromatized by a varied-line-spacing plane grating monochromator with the variable included angle mechanism. Its designed resolving power and photon flux are 3,000-10,000 and 10{sup 12}-10{sup 9} photons/s at 300 mA, respectively. The performance test results were generally satisfactory. An overview of the optical design of the beamline and the current status ofmore » commissioning are reported.« less

Uphill energy transfer from long-wavelength absorbing chlorophylls to PS II in Ostreobium sp. is functional in carbon assimilation.

PubMed

Wilhelm, Christian; Jakob, Torsten

2006-03-01

From the algal genus Ostrobium two species are known which express a chlorophyll antenna absorbing between 710 and 725 nm to a different extent. In a comparative study with these two species it is shown that quanta absorbed by this long wavelength antenna can be transferred to PS II leading to significant PS II-related electron transfer. It is documented that under monochromatic far red light illumination growth continues with rather high efficiency. The data show that the uphill-energy transfer to PS II reduces the quantum yield under white light significantly. It is discussed that this strategy of energy conversion might play a role in special environments where far red light is the predominant energy source.

Implications of low-power He-Ne laser and monochromatic red light biostimulation in the metabolism of proteins and glucosides

NASA Astrophysics Data System (ADS)

Onac, I.; Pop, L.; Ungur, Rodica; Giurgiu, Ioana

2001-06-01

We checked the changes occurring in the metabolism of proteins (seric cholinesterase, total proteins) and in the metabolism of glycosides (seric glucose) in Cavia cobaia. A simple blind study was carried out and the results were checked on the first, tenth and twentieth days of treatment. The data thus obtained were graphically represented and statistically processed according to the Duncan test. The technique and treatment doses were similar and they were compared with the data obtained from controls and environment controls. In the groups biostimulated with He-Ne laser, seric cholinesterase levels increased proportionally with the dose reaching a peak on day 10, which was not the case with the controls. Monochromatic red light caused a similar but quantitatively lower effect. The same results were obtained in the case of seric proteins as well, however, the effect did not depend on the dose and it was less significant statistically than in the case of seric cholinesterase both in laser treated and in monochromatic red light treated groups.

Polarization of light and hopf fibration

NASA Astrophysics Data System (ADS)

Jurčo, B.

1987-09-01

A set of polarization states of quasi-monochromatic light is described geometrically in terms of the Hopf fibration. Several associated alternative polarization parametrizations are given explicitly, including the Stokes parameters.

PePSS - A portable sky scanner for measuring extremely low night-sky brightness

NASA Astrophysics Data System (ADS)

Kocifaj, Miroslav; Kómar, Ladislav; Kundracik, František

2018-05-01

A new portable sky scanner designed for low-light-level detection at night is developed and employed in night sky brightness measurements in a rural region. The fast readout, adjustable sensitivity and linear response guaranteed in 5-6 orders of magnitude makes the device well suited for narrow-band photometry in both dark areas and bright urban and suburban environments. Quasi-monochromatic night-sky brightness data are advantageous in the accurate characterization of spectral power distribution of scattered and emitted light and, also allows for the possibility to retrieve light output patterns from whole-city light sources. The sky scanner can operate in both night and day regimes, taking advantage of the complementarity of both radiance data types. Due to its inherent very high sensitivity the photomultiplier tube could be used in night sky radiometry, while the spectrometer-equipped system component capable of detecting elevated intensities is used in daylight monitoring. Daylight is a source of information on atmospheric optical properties that in turn are necessary in processing night sky radiances. We believe that the sky scanner has the potential to revolutionize night-sky monitoring systems.

X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

DOE PAGES

Kroll, Thomas; Kern, Jan; Kubin, Markus; ...

2016-09-19

X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. But, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. We compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based onmore » self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. Lastly, we show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.« less

Geometrical theory to predict eccentric photorefraction intensity profiles in the human eye

NASA Astrophysics Data System (ADS)

Roorda, Austin; Campbell, Melanie C. W.; Bobier, W. R.

1995-08-01

In eccentric photorefraction, light returning from the retina of the eye is photographed by a camera focused on the eye's pupil. We use a geometrical model of eccentric photorefraction to generate intensity profiles across the pupil image. The intensity profiles for three different monochromatic aberration functions induced in a single eye are predicted and show good agreement with the measured eccentric photorefraction intensity profiles. A directional reflection from the retina is incorporated into the calculation. Intensity profiles for symmetric and asymmetric aberrations are generated and measured. The latter profile shows a dependency on the source position and the meridian. The magnitude of the effect of thresholding on measured pattern extents is predicted. Monochromatic aberrations in human eyes will cause deviations in the eccentric photorefraction measurements from traditional crescents caused by defocus and may cause misdiagnoses of ametropia or anisometropia. Our results suggest that measuring refraction along the vertical meridian is preferred for screening studies with the eccentric photorefractor.

X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

PubMed Central

Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D.; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L.; Moeller, Stefan; Turner, Joshua J.; Alonso-Mori, Roberto; Nordlund, Dennis L.; Rehanek, Jens; Weniger, Christian; Firsov, Alexander; Brzhezinskaya, Maria; Chatterjee, Ruchira; Lassalle-Kaiser, Benedikt; Sierra, Raymond G.; Laksmono, Hartawan; Hill, Ethan; Borovik, Andrew; Erko, Alexei; Föhlisch, Alexander; Mitzner, Rolf; Yachandra, Vittal K.; Yano, Junko; Wernet, Philippe; Bergmann, Uwe

2016-01-01

X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements. PMID:27828320

X-ray lithography using holographic images

DOEpatents

Howells, M.S.; Jacobsen, C.

1997-03-18

Methods for forming X-ray images having 0.25 {micro}m minimum line widths on X-ray sensitive material are presented. A holographic image of a desired circuit pattern is projected onto a wafer or other image-receiving substrate to allow recording of the desired image in photoresist material. In one embodiment, the method uses on-axis transmission and provides a high flux X-ray source having modest monochromaticity and coherence requirements. A layer of light-sensitive photoresist material on a wafer with a selected surface is provided to receive the image(s). The hologram has variable optical thickness and variable associated optical phase angle and amplitude attenuation for transmission of the X-rays. A second embodiment uses off-axis holography. The wafer receives the holographic image by grazing incidence reflection from a hologram printed on a flat metal or other highly reflecting surface or substrate. In this second embodiment, an X-ray beam with a high degree of monochromaticity and spatial coherence is required. 15 figs.

X-ray lithography using holographic images

DOEpatents

Howells, Malcolm S.; Jacobsen, Chris

1997-01-01

Methods for forming X-ray images having 0.25 .mu.m minimum line widths on X-ray sensitive material are presented. A holgraphic image of a desired circuit pattern is projected onto a wafer or other image-receiving substrate to allow recording of the desired image in photoresist material. In one embodiment, the method uses on-axis transmission and provides a high flux X-ray source having modest monochromaticity and coherence requirements. A layer of light-sensitive photoresist material on a wafer with a selected surface is provided to receive the image(s). The hologram has variable optical thickness and variable associated optical phase angle and amplitude attenuation for transmission of the X-rays. A second embodiment uses off-axis holography. The wafer receives the holographic image by grazing incidence reflection from a hologram printed on a flat metal or other highly reflecting surface or substrate. In this second embodiment, an X-ray beam with a high degree of monochromaticity and spatial coherence is required.

Picture of the global field of quasi-monochromatic gravity waves observed by stratospheric balloons and MST radars

NASA Technical Reports Server (NTRS)

Yamanaka, M. D.

1989-01-01

In MAP observations, it was found that: (1) gravity waves in selected or filtered portions of data are fit for monochromatic structures, whereas (2) those in fully continuous and resolved observations take universal continuous spectra. It is possible to explain (2) by dispersion of quasi-monochromatic (or slowly varying) wave packets observed locally as (1), since the medium atmosphere is unsteady and nonuniform. Complete verification of the wave-mean flow interactions by tracking individual wave packets seems hopeless, because the wave induced flow cannot be distinguished from the basic flow independent of the waves. Instead, the primitive picture is looked at before MAP, that is, the atmosphere is just like an entertainment stage illuminated by cocktail lights of quasi-monochromatic gravity waves. The wave parameters are regarded as functions of time and spatial coordinates. The observational evidences (1) and (2) suggest that the wave parameter field is rather homogeneous, which can be explained by interference of quasi-monochromatic wave packets.

Solar cell and module performance assessment based on indoor calibration methods

NASA Astrophysics Data System (ADS)

Bogus, K.

A combined space/terrestrial solar cell test calibration method that requires five steps and can be performed indoors is described. The test conditions are designed to qualify the cell or module output data in standard illumination and temperature conditions. Measurements are made of the short-circuit current, the open circuit voltage, the maximum power, the efficiency, and the spectral response. Standard sunlight must be replicated both in earth surface and AM0 conditions; Xe lamps are normally used for the light source, with spectral measurements taken of the light. Cell and module spectral response are assayed by using monochromators and narrow band pass monochromatic filters. Attention is required to define the performance characteristics of modules under partial shadowing. Error sources that may effect the measurements are discussed, as are previous cell performance testing and calibration methods and their effectiveness in comparison with the behaviors of satellite solar power panels.

Energy-angle correlation correction algorithm for monochromatic computed tomography based on Thomson scattering X-ray source

NASA Astrophysics Data System (ADS)

Chi, Zhijun; Du, Yingchao; Huang, Wenhui; Tang, Chuanxiang

2017-12-01

The necessity for compact and relatively low cost x-ray sources with monochromaticity, continuous tunability of x-ray energy, high spatial coherence, straightforward polarization control, and high brightness has led to the rapid development of Thomson scattering x-ray sources. To meet the requirement of in-situ monochromatic computed tomography (CT) for large-scale and/or high-attenuation materials based on this type of x-ray source, there is an increasing demand for effective algorithms to correct the energy-angle correlation. In this paper, we take advantage of the parametrization of the x-ray attenuation coefficient to resolve this problem. The linear attenuation coefficient of a material can be decomposed into a linear combination of the energy-dependent photoelectric and Compton cross-sections in the keV energy regime without K-edge discontinuities, and the line integrals of the decomposition coefficients of the above two parts can be determined by performing two spectrally different measurements. After that, the line integral of the linear attenuation coefficient of an imaging object at a certain interested energy can be derived through the above parametrization formula, and monochromatic CT can be reconstructed at this energy using traditional reconstruction methods, e.g., filtered back projection or algebraic reconstruction technique. Not only can monochromatic CT be realized, but also the distributions of the effective atomic number and electron density of the imaging object can be retrieved at the expense of dual-energy CT scan. Simulation results validate our proposal and will be shown in this paper. Our results will further expand the scope of application for Thomson scattering x-ray sources.

High convergence efficiency design of flat Fresnel lens with large aperture

NASA Astrophysics Data System (ADS)

Ke, Jieyao; Zhao, Changming; Guan, Zhe

2018-01-01

This paper designed a circle-shaped Fresnel lens with large aperture as part of the solar pumped laser design project. The Fresnel lens designed in this paper simulate in size 1000mm×1000mm, focus length 1200mm and polymethyl methacrylate (PMMA) material in order to conduct high convergence efficiency. In the light of design requirement of concentric ring with same width of 0.3mm, this paper proposed an optimized Fresnel lens design based on previous sphere design and conduct light tracing simulation in Matlab. This paper also analyzed the effect of light spot size, light intensity distribution, optical efficiency under four conditions, monochromatic parallel light, parallel spectrum light, divergent monochromatic light and sunlight. Design by 550nm wavelength and under the condition of Fresnel reflection, the results indicated that the designed lens could convergent sunlight in diffraction limit of 11.8mm with a 78.7% optical efficiency, better than the sphere cutting design results of 30.4%.

A mirror for lab-based quasi-monochromatic parallel x-rays

NASA Astrophysics Data System (ADS)

Nguyen, Thanhhai; Lu, Xun; Lee, Chang Jun; Jung, Jin-Ho; Jin, Gye-Hwan; Kim, Sung Youb; Jeon, Insu

2014-09-01

A multilayered parabolic mirror with six W/Al bilayers was designed and fabricated to generate monochromatic parallel x-rays using a lab-based x-ray source. Using this mirror, curved bright bands were obtained in x-ray images as reflected x-rays. The parallelism of the reflected x-rays was investigated using the shape of the bands. The intensity and monochromatic characteristics of the reflected x-rays were evaluated through measurements of the x-ray spectra in the band. High intensity, nearly monochromatic, and parallel x-rays, which can be used for high resolution x-ray microscopes and local radiation therapy systems, were obtained.

Control of cell interaction using quasi-monochromatic light with varying spatiotemporal coherence

NASA Astrophysics Data System (ADS)

Budagovsky, A. V.; Maslova, M. V.; Budagovskaya, O. N.; Budagovsky, I. A.

2017-02-01

By the example of plants, fungi and bacteria, we consider the possibility of controlling the interaction of cells, being in competitive, antagonistic, or parasitic relations. For this aim we used short-time irradiation (a few seconds or minutes) with the red (633 nm) quasi-monochromatic light having different spatiotemporal coherence. It is shown that the functional activity is mostly increased in the cells whose size does not exceed the coherence length and the correlation radius of the light field. Thus, in the case of cells essentially differing in size, it is possible to increase the activity of smaller cells, avoiding the stimulation of larger ones. For example, the radiation having relatively low coherence (Lcoh, rcor <= 10 μm) facilitates mainly the damage of large-size plant cells by pathogen fungi, while the exposure to light with less statistical regularity (Lcoh = 4 μm, rcor = 5 μm) inhibits the growth of the Fusarium microcera fungus, infected by the bacterium of the Pseudomonas species. The quasi-monochromatic radiation with sufficiently high spatiotemporal coherence stimulated all interacting species (bacteria, fungi, plants). In the considered biocenosis, the equilibrium was shifted towards the favour of organisms having the highest rate of cell division or the ones better using their adaptation potential.

A stand-alone compact EUV microscope based on gas-puff target source.

PubMed

Torrisi, Alfio; Wachulak, Przemyslaw; Węgrzyński, Łukasz; Fok, Tomasz; Bartnik, Andrzej; Parkman, Tomáš; Vondrová, Šárka; Turňová, Jana; Jankiewicz, Bartłomiej J; Bartosewicz, Bartosz; Fiedorowicz, Henryk

2017-02-01

We report on a very compact desk-top transmission extreme ultraviolet (EUV) microscope based on a laser-plasma source with a double stream gas-puff target, capable of acquiring magnified images of objects with a spatial (half-pitch) resolution of sub-50 nm. A multilayer ellipsoidal condenser is used to focus and spectrally narrow the radiation from the plasma, producing a quasi-monochromatic EUV radiation (λ = 13.8 nm) illuminating the object, whereas a Fresnel zone plate objective forms the image. Design details, development, characterization and optimization of the EUV source and the microscope are described and discussed. Test object and other samples were imaged to demonstrate superior resolution compared to visible light microscopy. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Source mechanics for monochromatic icequakes produced during iceberg calving at Columbia Glacier, AK

USGS Publications Warehouse

O'Neel, Shad; Pfeffer, W.T.

2007-01-01

Seismograms recorded during iceberg calving contain information pertaining to source processes during calving events. However, locally variable material properties may cause signal distortions, known as site and path effects, which must be eliminated prior to commenting on source mechanics. We applied the technique of horizontal/vertical spectral ratios to passive seismic data collected at Columbia Glacier, AK, and found no dominant site or path effects. Rather, monochromatic waveforms generated by calving appear to result from source processes. We hypothesize that a fluid-filled crack source model offers a potential mechanism for observed seismograms produced by calving, and fracture-processes preceding calving.

Supplemental shielding of BMIT SOE-1 at the Canadian Light Source

NASA Astrophysics Data System (ADS)

Bassey, Bassey; Abueidda, Abdallah; Cubbon, Grant; Street, Darin; Sabbir Ahmed, Asm; Wysokinski, Tomasz W.; Belev, George; Chapman, Dean

2014-07-01

High field superconducting wiggler beamlines present shielding challenges due to the high critical energy of the synchrotron spectrum. An unexpected, but predictable, weakness in the secondary optical enclosure (SOE-1) was discovered on the BioMedical Imaging and Therapy (BMIT) insertion device (ID) beamline 05ID-2 at the Canadian Light Source (CLS). SOE-1 is a monochromatic beam hutch; the beam in it is supplied by three monochromators housed in an upstream primary optical enclosure (POE-3). The initial shielding of SOE-1 was based on a shielding calculation against target scattered and direct monochromatic (fundamental and harmonics) beams from the monochromators in POE-3. During a radiation survey of the hutch, radiation above the expected level was measured at the downstream end of SOE-1. This increment in radiation level is attributed to scattered white beam into SOE-1 by a K-Edge subtraction (KES) monochromator's crystal (a single crystal monochromator) in POE-3. Though this is peculiar to the BMIT beamline 05ID-2, it may not be uncommon for other beamlines that use single crystal monochromators. Calculations of the level of expected leakage radiation due to the scattered white beam arriving on the downstream wall of the SOE-1 are presented, as well as the supplemental shielding that will reduce the leakage to less than 1 μSv/h as required at the CLS. Also presented are the installed supplemental shielding, and a comparison of the calculations and measurements of the dose rates on the back wall of SOE-1 End Wall, before and after installation of the supplemental shielding.

Polarization changes at Lyot depolarizer output for different types of input beams.

PubMed

de Sande, J Carlos G; Piquero, Gemma; Teijeiro, Cristina

2012-03-01

Lyot depolarizers are optical devices made of birefringent materials used for producing unpolarized beams from totally polarized incident light. The depolarization is produced for polychromatic input beams due to the different phase introduced by the Lyot depolarizer for each wavelength. The effect of this device on other types of incident fields is investigated. In particular two cases are analyzed: (i) monochromatic and nonuniformly polarized incident beams and (ii) incident light synthesized by superposition of two monochromatic orthogonally polarized beams with different wavelengths. In the last case, it is theoretically and experimentally shown that the Lyot depolarizer increases the degree of polarization instead of depolarizes.

X-ray phase-contrast tomosynthesis of a human ex vivo breast slice with an inverse Compton x-ray source

NASA Astrophysics Data System (ADS)

Eggl, E.; Schleede, S.; Bech, M.; Achterhold, K.; Grandl, S.; Sztrókay, A.; Hellerhoff, K.; Mayr, D.; Loewen, R.; Ruth, R. D.; Reiser, M. F.; Pfeiffer, F.

2016-12-01

While the performance of conventional x-ray tube sources often suffers from the broad polychromatic spectrum, synchrotrons that could provide highly brilliant x-rays are restricted to large research facilities and impose high investment and maintenance costs. Lately, a new type of compact synchrotron sources has been investigated. These compact light sources (CLS) based on inverse Compton scattering provide quasi-monochromatic hard x-rays. The flux and brilliance yielded by a CLS currently lie between x-ray tube sources and third-generation synchrotrons. The relatively large partially coherent x-ray beam is well suited for the investigation of preclinical applications of grating-based phase-contrast and dark-field imaging. Here we present the first grating-based multimodal tomosynthesis images of a human breast slice acquired at a CLS to investigate the possibilities of improved breast cancer diagnostics.

Fundamentals of Polarized Light

NASA Technical Reports Server (NTRS)

Mishchenko, Michael

2003-01-01

The analytical and numerical basis for describing scattering properties of media composed of small discrete particles is formed by the classical electromagnetic theory. Although there are several excellent textbooks outlining the fundamentals of this theory, it is convenient for our purposes to begin with a summary of those concepts and equations that are central to the subject of this book and will be used extensively in the following chapters. We start by formulating Maxwell's equations and constitutive relations for time- harmonic macroscopic electromagnetic fields and derive the simplest plane-wave solution that underlies the basic optical idea of a monochromatic parallel beam of light. This solution naturally leads to the introduction of such fundamental quantities as the refractive index and the Stokes parameters. Finally, we define the concept of a quasi-monochromatic beam of light and discuss its implications.

Enhancing lutein productivity of an indigenous microalga Scenedesmus obliquus FSP-3 using light-related strategies.

PubMed

Ho, Shih-Hsin; Chan, Ming-Chang; Liu, Chen-Chun; Chen, Chun-Yen; Lee, Wen-Lung; Lee, Duu-Jong; Chang, Jo-Shu

2014-01-01

Lutein, one of the main photosynthetic pigments, is a promising natural product with both nutritional and pharmaceutical applications. In this study, light-related strategies were applied to enhance the cell growth and lutein production of a lutein-rich microalga Scenedesmus obliquus FSP-3. The results demonstrate that using white LED resulted in better lutein production efficiency when compared to the other three monochromatic LEDs (red, blue, and green). The lutein productivity of S. obliquus FSP-3 was further improved by adjusting the type of light source and light intensity. The optimal lutein productivity of 4.08 mg/L/d was obtained when using a TL5 fluorescent lamp at a light intensity of 300 μmol/m(2)/s, and this performance is better than that reported in most related studies. Moreover, the time-course profile of lutein accumulation in the microalga shows that the maximal lutein content and productivity were obtained at the onset of nitrogen depletion. Copyright © 2013 Elsevier Ltd. All rights reserved.

Rotary encoding device using polygonal mirror with diffraction gratings on each facet

NASA Technical Reports Server (NTRS)

Leviton, Douglas B. (Inventor)

1993-01-01

A device for position encoding of a rotating shaft in which a polygonal mirror having a number of facets is mounted to the shaft and a monochromatic light beam is directed towards the facets. The facets of the polygonal mirror each have a low line density diffraction grating to diffract the monochromatic light beam into a number of diffracted light beams such that a number of light spots are created on a linear array detector. An analog-to-digital converter is connected to the linear array detector for reading the position of the spots on the linear array detector means. A microprocessor with memory is connected to the analog-to-digital converter to hold and manipulate the data provided by the analog-to-digital converter on the position of the spots and to compute the position of the shaft based upon the data from the analog-to-digital converter.

Final Environmental Assessment for the Installation of a Range Safety Lighting System at Avon Park Air Force Range, Florida

DTIC Science & Technology

2010-08-01

considered with other activities that require additional artificial night lighting. For instance, the development of the new town of Destiny planned...Mobarkey, M. Barak, A. Hoyzman, and O. Halevy, 2004. Monochromatic Light Stimuli During Embryogenesis Enhances Embryo Development and Posthatch

A comprehensive comparable study of the physiological properties of four microalgal species under different light wavelength conditions.

PubMed

Zhong, Yu; Jin, Peng; Cheng, Jay J

2018-05-19

Microalgae treated with blue light have potential for production of human nutrition supplement and biofuel due to their higher biomass productivity and favorable fatty acid composition. Chlorella vulgaris, Chlorella pyrenoidosa, Scenedesmus quadricauda and Scenedesmus obliquus are representative green microalgae which are widely reported for algal production. In this study, we provide a systematic investigation of the biomass productivity, photosynthetic pigments, chlorophyll fluorescence and fatty acid content of the four green microalgae. The strains were grown in two primary monochromatic light wavelengths [red and blue LEDs (light emitting diode)], and in white LED conditions, respectively. Among them, blue LED light was determined as the best light for growth rate, followed by red LED and white LED. The chlorophyll generation was more sensitive to the monochromatic blue light. The polyunsaturated fatty acids (PUFAs) such as α-linolenic acid (18:3), which were perfect for human nutrition supplementation, showed high concentrations in these algae strains under blue LED. Collectively, the results indicate that the blue LED is suitable for various food, feed, and algal biofuel productions due to both biomass and fatty acid productivity.

Laser Technology Is Primed for the Classroom.

ERIC Educational Resources Information Center

Lytle, Jim

1986-01-01

Explains the three characteristics of laser light (monochromatic light, divergence, and coherence), the components of a laser, applications of the laser (alignment, distance measurement, welding/cutting, marking, medical applications), and a complete laser training system appropriate for classroom use. (CT)

X-Ray Topography of Tetragonal Lysozyme Grown by the Temperature-Controlled Technique

NASA Technical Reports Server (NTRS)

Stojanoff, V.; Siddons, D. P.; Monaco, Lisa A.; Vekilov, Peter; Rosenberger, Franz

1997-01-01

Growth-induced defects in lysozyme crystals were observed by white-beam and monochromatic X-ray topography at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL). The topographic methods were non-destructive to the extent that traditional diffraction data collection could be performed to high resolution after topography. It was found that changes in growth parameters, defect concentration as detected by X-ray topography, and the diffraction quality obtainable from the crystals were all strongly correlated. In addition, crystals with fewer defects showed lower mosaicity and higher diffraction resolution as expected.

High Angular Sensitivity, Absolute Rotary Encoding Device with Polygonal Mirror and Stand-Alone Diffraction Gratings

NASA Technical Reports Server (NTRS)

Leviton, Douglas B. (Inventor)

1996-01-01

A device for position encoding of a rotating shaft in which a polygonal mirror having a number of facets is mounted to the shaft and a monochromatic light beam is directed towards the facets. The facets of the polygonal mirror direct the light beam to a stand-alone low line density diffraction grating to diffract the monochromatic light beam into a number of diffracted light beams such that a number of light spots are created on a linear array detector. An analog-to-digital converter is connected to the linear array detector for reading the position of the spots on the linear array detector means. A microprocessor with memory is connected to the analog-to-digital converter to hold and manipulate the data provided by the analog-to-digital converter on the position of the spots and to compute the position of the shaft based upon the data from the analog-lo-digital converter.

Inhibition of enteric pathogens and surrogates using integrated, high intensity 405nm led light on the surface of almonds

USDA-ARS?s Scientific Manuscript database

The disinfecting properties of 405 nm light were investigated against Escherichia coli O157:H7, Salmonella, and their non-pathogenic surrogate bacteria on the surface of almonds. High intensity monochromatic blue light (MBL) was generated from an array of narrow-band 405 nm light-emitting diodes (LE...

Effect of the combination of white and red LED lighting during incubation on layer, broiler, and Pekin duck hatchability.

PubMed

Archer, G S; Jeffrey, D; Tucker, Z

2017-08-01

Previous research has shown that providing light during incubation can have positive effects on hatchability and chick quality; however, white light alone has been observed to improve these factors only in pigmented broiler eggs and non-pigmented white layer eggs. Monochromatic red light has been shown to improve hatchability in layer eggs. Therefore the objective of this study was to utilize one light fixture that emitted both white and monochromatic red light to determine if this one light source could improve hatchability in both types of chicken eggs and pigmented Pekin duck egg. To determine this, 3 experiments were conducted, the first using White Leghorn eggs (N = 6912), the second using commercial broiler eggs (N = 4608), and the third using commercial Pekin duck eggs (N = 3564) in which eggs were incubated with 12 h of light and 12 h of darkness (LED) or complete darkness (DARK); the light level was 250 lux. Hatchability, embryo mortality, and hatchling quality were measured. In Experiment 1, LED had fewer early dead embryos (P = 0.03), less overall embryo mortality (P = 0.05), fewer chicks with unhealed navels (P < 0.001), fewer chicks with defects (P < 0.001), and a higher percentage of fertile eggs that hatched (P = 0.05) than DARK. In Experiment 2, LED had fewer chicks with unhealed navels (P = 0.003), fewer chicks with defects (P = 0.001), and a higher percentage of fertile eggs that hatched (P = 0.04) than DARK. In Experiment 3, LED had fewer early dead embryos (P = 0.05), lower overall embryo mortality (P = 0.04), and a higher percentage of fertile eggs that hatched (P = 0.05), and had ducklings with lower bodyweights at hatch (P = 0.04) than DARK. These results indicate that providing both white and red light during incubation can improve chick quality across poultry varieties. This type of fixture could be used to improve commercial hatchery efficiency and chick quality. © 2017 Poultry Science Association Inc.

The non-radiating component of the field generated by a finite monochromatic scalar source distribution

NASA Astrophysics Data System (ADS)

Hoenders, Bernhard J.; Ferwerda, Hedzer A.

1998-09-01

We separate the field generated by a spherically symmetric bounded scalar monochromatic source into a radiative and non-radiative part. The non-radiative part is obtained by projecting the total field on the space spanned by the non-radiating inhomogeneous modes, i.e. the modes which satisfy the inhomogeneous wave equation. Using residue techniques, introduced by Cauchy, we obtain an explicit analytical expression for the non-radiating component. We also identify the part of the source distribution which corresponds to this non-radiating part. The analysis is based on the scalar wave equation.

Simultaneous three wavelength imaging with a scanning laser ophthalmoscope.

PubMed

Reinholz, F; Ashman, R A; Eikelboom, R H

1999-11-01

Various imaging properties of scanning laser ophthalmoscopes (SLO) such as contrast or depth discrimination, are superior to those of the traditional photographic fundus camera. However, most SLO are monochromatic whereas photographic systems produce colour images, which inherently contain information over a broad wavelength range. An SLO system has been modified to allow simultaneous three channel imaging. Laser light sources in the visible and infrared spectrum were concurrently launched into the system. Using different wavelength triads, digital fundus images were acquired at high frame rates. Favourable wavelengths combinations were established and high contrast, true (red, green, blue) or false (red, green, infrared) colour images of the retina were recorded. The monochromatic frames which form the colour image exhibit improved distinctness of different retinal structures such as the nerve fibre layer, the blood vessels, and the choroid. A multi-channel SLO combines the advantageous imaging properties of a tunable, monochrome SLO with the benefits and convenience of colour ophthalmoscopy. The options to modify parameters such as wavelength, intensity, gain, beam profile, aperture sizes, independently for every channel assign a high degree of versatility to the system. Copyright 1999 Wiley-Liss, Inc.

Carbon Nanotubes as an Ultrafast Emitter with a Narrow Energy Spread at Optical Frequency.

PubMed

Li, Chi; Zhou, Xu; Zhai, Feng; Li, Zhenjun; Yao, Fengrui; Qiao, Ruixi; Chen, Ke; Cole, Matthew Thomas; Yu, Dapeng; Sun, Zhipei; Liu, Kaihui; Dai, Qing

2017-08-01

Ultrafast electron pulses, combined with laser-pump and electron-probe technologies, allow ultrafast dynamics to be characterized in materials. However, the pursuit of simultaneous ultimate spatial and temporal resolution of microscopy and spectroscopy is largely subdued by the low monochromaticity of the electron pulses and their poor phase synchronization to the optical excitation pulses. Field-driven photoemission from metal tips provides high light-phase synchronization, but suffers large electron energy spreads (3-100 eV) as driven by a long wavelength laser (>800 nm). Here, ultrafast electron emission from carbon nanotubes (≈1 nm radius) excited by a 410 nm femtosecond laser is realized in the field-driven regime. In addition, the emitted electrons have great monochromaticity with energy spread as low as 0.25 eV. This great performance benefits from the extraordinarily high field enhancement and great stability of carbon nanotubes, superior to metal tips. The new nanotube-based ultrafast electron source opens exciting prospects for extending current characterization to sub-femtosecond temporal resolution as well as sub-nanometer spatial resolution. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inhibition of enteric pathogens using integrated high intensity 405 nm LED on the surface of almonds

USDA-ARS?s Scientific Manuscript database

The disinfecting properties of 405 nm light were investigated against Escherichia coli O157:H7, Salmonella, and their non-pathogenic surrogates inoculated onto the surface of almonds. High intensity monochromatic light was generated from an array of narrow-band 405 nm light emitting diodes (LED). Al...

Developing a new supplemental lighting device with ultra-bright white LED for vegetables

NASA Astrophysics Data System (ADS)

Hu, Yongguang; Li, Pingping; Jiang, Jianghai

2007-02-01

It has been proved that monochromatic or compound light-emitting diode (LED) or laser diode (LD) can promote the photosynthesis of horticultural crops, but the promotion of polychromatic light like white LED is unclear. A new type of ultra-bright white LED (LUW56843, InGaN, \

Harnessing structural darkness in the visible and infrared wavelengths for a new source of light.

PubMed

Huang, Jianfeng; Liu, Changxu; Zhu, Yihan; Masala, Silvia; Alarousu, Erkki; Han, Yu; Fratalocchi, Andrea

2016-01-01

Engineering broadband light absorbers is crucial to many applications, including energy-harvesting devices and optical interconnects. The performances of an ideal absorber are that of a black body, a dark material that absorbs radiation at all angles and polarizations. Despite advances in micrometre-thick films, the absorbers available to date are still far from an ideal black body. Here, we describe a disordered nanostructured material that shows an almost ideal black-body absorption of 98-99% between 400 and 1,400 nm that is insensitive to the angle and polarization of the incident light. The material comprises nanoparticles composed of a nanorod with a nanosphere of 30 nm diameter attached. When diluted into liquids, a small concentration of nanoparticles absorbs on average 26% more than carbon nanotubes, the darkest material available to date. By pumping a dye optical amplifier with nanosecond pulses of ∼100 mW power, we harness the structural darkness of the material and create a new type of light source, which generates monochromatic emission (∼5 nm wide) without the need for any resonance. This is achieved through the dynamics of light condensation in which all absorbed electromagnetic energy spontaneously generates single-colour energy pulses.

Can the RUVIS reflected UV imaging system visualize fingerprint corrosion on brass cartridge casings postfiring?

PubMed

Leintz, Rachel; Bond, John W

2013-05-01

Comparisons are made between the visualization of fingerprint corrosion ridge detail on fired brass cartridge casings, where fingerprint sweat was deposited prefiring, using both ultraviolet (UV) and visible (natural daylight) light sources. A reflected ultraviolet imaging system (RUVIS), normally used for visualizing latent fingerprint sweat deposits, is compared with optical interference and digital color mapping of visible light, the latter using apparatus constructed to easily enable selection of the optimum viewing angle. Results show that reflected UV, with a monochromatic UV source of 254 nm, was unable to visualize fingerprint ridge detail on any of 12 casings analyzed, whereas optical interference and digital color mapping using natural daylight yielded ridge detail on three casings. Reasons for the lack of success with RUVIS are discussed in terms of the variation in thickness of the thin film of metal oxide corrosion and absorption wavelengths for the corrosion products of brass. © 2013 American Academy of Forensic Sciences.

Light refocusing with up-scalable resonant waveguide gratings in confocal prolate spheroid arrangements

NASA Astrophysics Data System (ADS)

Quaranta, Giorgio; Basset, Guillaume; Benes, Zdenek; Martin, Olivier J. F.; Gallinet, Benjamin

2018-01-01

Resonant waveguide gratings (RWGs) are thin-film structures, where coupled modes interfere with the diffracted incoming wave and produce strong angular and spectral filtering. The combination of two finite-length and impedance matched RWGs allows the creation of a passive beam steering element, which is compatible with up-scalable fabrication processes. Here, we propose a design method to create large patterns of such elements able to filter, steer, and focus the light from one point source to another. The method is based on ellipsoidal mirrors to choose a system of confocal prolate spheroids where the two focal points are the source point and observation point, respectively. It allows finding the proper orientation and position of each RWG element of the pattern, such that the phase is constructively preserved at the observation point. The design techniques presented here could be implemented in a variety of systems, where large-scale patterns are needed, such as optical security, multifocal or monochromatic lenses, biosensors, and see-through optical combiners for near-eye displays.

Refractive-index determination of solids from first- and second-order critical diffraction angles of periodic surface patterns

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

Meichner, Christoph, E-mail: christoph.meichner@uni-bayreuth.de; Kador, Lothar, E-mail: lothar.kador@uni-bayreuth.de; Schedl, Andreas E.

2015-08-15

We present two approaches for measuring the refractive index of transparent solids in the visible spectral range based on diffraction gratings. Both require a small spot with a periodic pattern on the surface of the solid, collimated monochromatic light, and a rotation stage. We demonstrate the methods on a polydimethylsiloxane film (Sylgard{sup ®} 184) and compare our data to those obtained with a standard Abbe refractometer at several wavelengths between 489 and 688 nm. The results of our approaches show good agreement with the refractometer data. Possible error sources are analyzed and discussed in detail; they include mainly the linewidthmore » of the laser and/or the angular resolution of the rotation stage. With narrow-band light sources, an angular accuracy of ±0.025{sup ∘} results in an error of the refractive index of typically ±5 ⋅ 10{sup −4}. Information on the sample thickness is not required.« less

Extracting and focusing of surface plasmon polaritons inside finite asymmetric metal/insulator/metal structure at apex of optical fiber by subwavelength holes

NASA Astrophysics Data System (ADS)

Oshikane, Yasushi; Murai, Kensuke; Nakano, Motohiro

2013-09-01

We have been studied a finite asymmetric metal-insulator-metal (MIM) structure on glass plate for near-future visible light communication (VLC) system with white LED illuminations in the living space (DOI: 10.1117/12.929201). The metal layers are vacuum-evaporated thin silver (Ag) films (around 50 nm and 200 nm, respectively), and the insulator layer (around 150 nm) is composed of magnesium fluoride (MgF2). A characteristic narrow band filtering of the MIM structure at visible region might cause a confinement of intense surface plasmon polaritons (SPPs) at specific monochromatic frequency inside a subwavelength insulator layer of the MIM structure. Central wavelength and depth of such absorption dip in flat spectral reflectance curve is controlled by changing thicknesses of both insulator and thinner metal layers. On the other hand, we have proposed a twin-hole pass-through wave guide for SPPs in thick Ag film (DOI: 10.1117/12.863587). At that time, the twin-hole converted a incoming plane light wave into a pair of channel plasmon polaritons (CPPs), and united them at rear surface of the Ag film. This research is having an eye to extract, guide, and focus the SPPs through a thicker metal layer of the MIM with FIBed subwavelength pass-through holes. The expected outcome is a creation of noble, monochromatic, and tunable fiber probe for scanning near-field optical microscopes (SNOMs) with intense white light sources. Basic experimental and FEM simulation results will be presented.

Evaluation of 405 nm monochromatic light for inactivation of tulane virus on blueberry surfaces

USDA-ARS?s Scientific Manuscript database

The aim of this study was to evaluate the potential of 405 nm light as an intervention for virus contaminated blueberries. Tulane virus-contaminated-blueberries were treated with 4.2 mW/sq cm of 405 nm light for 5 to 30 min. To mitigate thermal heating due to the intense light, a dry ice-chilled ni...

Role of monochromatic light on daily variation of clock gene expression in the pineal gland of chick.

PubMed

Jiang, Nan; Wang, Zixu; Cao, Jing; Dong, Yulan; Chen, Yaoxing

2016-11-01

The avian pineal gland is a master clock that can receive external photic cues and translate them into output rhythms. To clarify whether a shift in light wavelength can influence the circadian expression in chick pineal gland, a total of 240 Arbor Acre male broilers were exposed to white light (WL), red light (RL), green light (GL) or blue light (BL). After 2weeks light illumination, circadian expressions of seven core clock genes in pineal gland and the level of melatonin in plasma were examined. The results showed after illumination with monochromatic light, 24h profiles of all clock gene mRNAs retained circadian oscillation, except that RL tended to disrupt the rhythm of cCry2. Compared to WL, BL advanced the acrophases of the negative elements (cCry1, cCry2, cPer2 and cPer3) by 0.1-1.5h and delayed those of positive elements (cClock, cBmal1 and cBmal2) by 0.2-0.8h. And, RL advanced all clock genes except cClock and cPer2 by 0.3-2.1h, while GL delayed all clock genes by 0.5-1.5h except cBmal2. Meanwhile, GL increased the amplitude and mesor of positive and reduced both parameters of negative clock genes, but RL showed the opposite pattern. Although the acrophase of plasma melatonin was advanced by both GL and RL, the melatonin level was significantly increased in GL and decreased in RL. This tendency was consistent with the variations in the positive clock gene mRNA levels under monochromatic light and contrasted with those of negative clock genes. Therefore, we speculate that GL may enhance positive clock genes expression, leading to melatonin synthesis, whereas RL may enhance negative genes expression, suppressing melatonin synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

Multiple-input multiple-output visible light communication system based on disorder dispersion components

NASA Astrophysics Data System (ADS)

Yang, Tao; Zhang, Qi; Hao, Yue; Zhou, Xin-hui; Yi, Ming-dong; Wei, Wei; Huang, Wei; Li, Xing-ao

2017-10-01

A multiple-input multiple-output visible light communication (VLC) system based on disorder dispersion components is presented. Instead of monochromatic sources and large size photodetectors used in the traditional VLC systems, broadband sources with different spectra act as the transmitters and a compact imaging chip sensor accompanied by a disorder dispersion component and a calculating component serve as the receivers in the proposed system. This system has the merits of small size, more channels, simple structure, easy integration, and low cost. Simultaneously, the broadband sources are suitable to act as illumination sources for their white color. A regularized procedure is designed to solve a matrix equation for decoding the signals at the receivers. A proof-of-concept experiment using on-off keying modulation has been done to prove the feasibility of the design. The experimental results show that the signals decoded by the receivers fit well with those generated from the transmitters, but the bit error ratio is increased with the number of the signal channels. The experimental results can be further improved using a high-speed charge-coupled device, decreasing noises, and increasing the distance between the transmitters and the receivers.

Study of Amorphous Ferrimagnet Fe0.66Er0.19B0.15 by Means of Monochromatic Circularly Polarised Source

NASA Astrophysics Data System (ADS)

Kalska, B.; Szymański, K.; Dobrzyński, L.; Satuła, D.; Wäppling, R.; Broddefalk, A.; Nordblad, P.

2002-06-01

Properties of amorphous alloy Fe0.66Er0.19B0.15 are reported. A reorientation of the Fe and Er magnetic moments during sample cooling through the compensation point in a large magnetic field is found by means of monochromatic circularly polarised radiation.

Velocity selection in a Doppler-broadened ensemble of atoms interacting with a monochromatic laser beam

NASA Astrophysics Data System (ADS)

Hughes, Ifan G.

2018-03-01

There is extensive use of monochromatic lasers to select atoms with a narrow range of velocities in many atomic physics experiments. For the commonplace situation of the inhomogeneous Doppler-broadened (Gaussian) linewidth exceeding the homogeneous (Lorentzian) natural linewidth by typically two orders of magnitude, a substantial narrowing of the velocity class of atoms interacting with the light can be achieved. However, this is not always the case, and here we show that for a certain parameter regime there is essentially no selection - all of the atoms interact with the light in accordance with the velocity probability density. An explanation of this effect is provided, emphasizing the importance of the long tail of the constituent Lorentzian distribution in a Voigt profile.

Fiber Grating Coupled Light Source Capable of Tunable, Single Frequency Operation

NASA Technical Reports Server (NTRS)

Krainak, Michael A. (Inventor); Duerksen, Gary L. (Inventor)

2001-01-01

Fiber Bragg grating coupled light sources can achieve tunable single-frequency (single axial and lateral spatial mode) operation by correcting for a quadratic phase variation in the lateral dimension using an aperture stop. The output of a quasi-monochromatic light source such as a Fabry Perot laser diode is astigmatic. As a consequence of the astigmatism, coupling geometries that accommodate the transverse numerical aperture of the laser are defocused in the lateral dimension, even for apsherical optics. The mismatch produces the quadratic phase variation in the feedback along the lateral axis at the facet of the laser that excites lateral modes of higher order than the TM(sub 00). Because the instability entails excitation of higher order lateral submodes, single frequency operation also is accomplished by using fiber Bragg gratings whose bandwidth is narrower than the submode spacing. This technique is particularly pertinent to the use of lensed fiber gratings in lieu of discrete coupling optics. Stable device operation requires overall phase match between the fed-back signal and the laser output. The fiber Bragg grating acts as a phase-preserving mirror when the Bragg condition is met precisely. The phase-match condition is maintained throughout the fiber tuning range by matching the Fabry-Perot axial mode wavelength to the passband center wavelength of the Bragg grating.

Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

PubMed Central

Hur, M. S.; Ersfeld, B.; Noble, A.; Suk, H.; Jaroszynski, D. A.

2017-01-01

Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide. PMID:28071681

Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

NASA Astrophysics Data System (ADS)

Hur, M. S.; Ersfeld, B.; Noble, A.; Suk, H.; Jaroszynski, D. A.

2017-01-01

Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide.

X-ray Optics Testing Beamline 1-BM at the Advanced Photon Source

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

Macrander, Albert; Erdmann, Mark; Kujala, Naresh

2016-07-27

Beamline 1-BM at the APS has been reconfigured in part for testing of synchrotron optics with both monochromatic and white beams. Operational since 2013, it was reconfigured to accommodate users of the APS as well as users from other DOE facilities. Energies between 6 and 28 keV are available. The beamline was reconfigured to remove two large mirrors and to provide a 100 mm wide monochromatics beam at 54 m from the source. In addition a custom white beam shutter was implemented for topography exposures as short as 65 millisec over the full available horizontal width. Primary agendas include bothmore » white beam and monochromatic beam topography, Talbot grating interferometry, and tests of focusing optics. K-B mirrors, MLLs, and FZPs have been characterized. Measurements of the spatial coherence lengths on the beamline were obtained with Talbot interferometry. Topography data has been reported.« less

X-ray optics testing beamline 1-BM at the advanced photon source

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

Macrander, Albert, E-mail: atm@anl.gov; Erdmann, Mark; Kujala, Naresh

2016-07-27

Beamline 1-BM at the APS has been reconfigured in part for testing of synchrotron optics with both monochromatic and white beams. Operational since 2013, it was reconfigured to accommodate users of the APS as well as users from other DOE facilities. Energies between 6 and 28 keV are available. The beamline was reconfigured to remove two large mirrors and to provide a 100 mm wide monochromatic beam at 54 m from the source. In addition a custom white beam shutter was implemented for topography exposures as short as 65 millisec over the full available horizontal width. Primary agendas include bothmore » white beam and monochromatic beam topography, Talbot grating interferometry, and tests of focusing optics. K-B mirrors, MLLs, and FZPs have been characterized. Measurements of the spatial coherence lengths on the beamline were obtained with Talbot interferometry. Topography data has been reported.« less

A compact radiation source for digital subtractive angiography

NASA Astrophysics Data System (ADS)

Wiedemann, H.; Baltay, M.; Carr, R.; Hernandez, M.; Lavender, W.

1994-08-01

Beam requirements for 33 keV radiation used in digital subtraction angiography have been established through extended experimentation first at Stanford and later at the National Synchrotron Light Source in Brookhaven. So far research and development of this medical procedure to image coronary blood vessels have been undertaken on large high energy electron storage rings. With progress in this diagnostic procedure, it is interesting to look for an optimum concept for providing a 33 keV radiation source which would fit into the environment of a hospital. A variety of competing effects and technologies to produce 33 keV radiation are available, but none of these processes provides the combination of sufficient photon flux and monochromaticity except for synchrotron radiation from an electron storage ring. The conceptual design of a compact storage ring optimized to fit into a hospital environment and producing sufficient 33 keV radiation for digital subtraction radiography will be discussed.

Feasibility of Shipboard Laser-Attenuation Measurements With a Portable Transmissometer.

DTIC Science & Technology

1979-02-26

Aerosol Extinction The transmittance of monochromatic, single-scattered light through aerosol is given by - S the Bouguer .-Beer law, (1) o where is the...of Applicability of the Bouguer Law in Scattering Media for Collimated Light Beams,” (English trans.), Izu. Atm. and Oceanic Phys. 3, 724-732 (1967

VizieR Online Data Catalog: Coefficients for passband extinctions (Sale+, 2015)

NASA Astrophysics Data System (ADS)

Sale, S. E.; Magorrian, J.

2017-11-01

We have considered how one should measure the distance and extinction to individual stars for use in constructing extinction maps of the whole Galaxy. We advocate the use of monochromatic extinctions, since, unlike bandpass measures such as AV and E(B-V), monochromatic extinctions are linear functions of the dust column density and are independent of the source SED. In particular we suggest the use of A4000, the monochromatic extinction at 4000Å because of its insensitivity to the dust grain size distribution. Files for converting from A_4000 to passband extinctions at 35 RV extinction law value and for 11 photometric systems. (2 data files).

[Theory of lasers and lamps].

PubMed

Mordon, S; Michaud, T

2009-10-01

Lasers emit a coherent and monochromatic light beam, whereas pulsed lights produce a polychromatic light whose bandwidth is selected by adapted filters. The skin's chromophores are made up of water, hemoglobin, and melanin, to which must be added the exogenous pigments of tattoos. Each chromophore has its specific absorption spectrum. Lasers' main mechanisms of action are the photothermal effect and the photomechanical effect.

[Theory of lasers and lamps].

PubMed

Michaud, T; Mordon, S

2008-02-01

Lasers emit a coherent and monochromatic light beam, whereas pulsed lights produce a polychromatic light whose bandwidth is selected by adapted filters. The skin's chromophores are made up of water, hemoglobin, and melanin, to which must be added the exogenous pigments of tattoos. Each chromophore has its specific absorption spectrum. Lasers' main mechanisms of action are the photothermal effect and the photomechanical effect.

Secretion pathway of liver IGF-1 via JAK2/STAT3 in chick embryo under the monochromatic light.

PubMed

Wang, Tuanjie; Dong, Yulan; Wang, Zixu; Cao, Jing; Chen, Yaoxing

2016-02-01

This study reveals mechanism of monochromatic light on the IGF-1 secretion of chick embryo liver. The chick embryos were incubated and exposed to continuous red, green, blue light or a dark environment. Compared to other light-treated groups, green light increased IGF-1 and melatonin concentrations both in plasma and liver, and Mel1a, Mel1b and Mel1c receptors expressions in liver but decreased p-JAK2, p-STAT3 and ROS in liver. IGF-1 had a positive correlation with melatonin, but a negative relevance with p-JAK2 and p-STAT3. In vitro, the IGF-1 level in the hepatocyte supernatant was enhanced by melatonin with lower p-JAK2/p-STAT3 and ROS levels, which was suppressed by Mel1c antagonist but not Mel1a/Mel1b or Mel1b antagonists. AG490 (JAK/STAT inhibitor) promoted role of melatonin-Mel1c modulated IGF-1 secretion. These results suggest the antioxidant effect of melatonin mediated the green light-enhanced IGF-1 secretion of chick embryo liver through Mel1c receptor to inhibit the JAK2/STAT3 pathway.

Magnetic orientation in birds: non-compass responses under monochromatic light of increased intensity.

PubMed

Wiltschko, Wolfgang; Munro, Ursula; Ford, Hugh; Wiltschko, Roswitha

2003-10-22

Migratory Australian silvereyes (Zosterops lateralis) were tested under monochromatic light at wavelengths of 424 nm blue and 565 nm green. At a low light level of 7 x 10(15) quanta m(-2) s(-1) in the local geomagnetic field, the birds preferred their seasonally appropriate southern migratory direction under both wavelengths. Their reversal of headings when the vertical component of the magnetic field was inverted indicated normal use of the avian inclination compass. A higher light intensity of 43 x 10(15) quanta m(-2) s(-1), however, caused a fundamental change in behaviour: under bright blue, the silvereyes showed an axial tendency along the east-west axis; under bright green, they showed a unimodal preference of a west-northwesterly direction that followed a shift in magnetic north, but was not reversed by inverting the vertical component of the magnetic field. Hence it is not based on the inclination compass. The change in behaviour at higher light intensities suggests a complex interaction between at least two receptors. The polar nature of the response under bright green cannot be explained by the current models of light-dependent magnetoreception and will lead to new considerations on these receptive processes.

Black hole superradiance signatures of ultralight vectors

NASA Astrophysics Data System (ADS)

Baryakhtar, Masha; Lasenby, Robert; Teo, Mae

2017-08-01

The process of superradiance can extract angular momentum and energy from astrophysical black holes (BHs) to populate gravitationally bound states with an exponentially large number of light bosons. We analytically calculate superradiant growth rates for vectors around rotating BHs in the regime where the vector Compton wavelength is much larger than the BH size. Spin-1 bound states have superradiance times as short as a second around stellar BHs, growing up to a thousand times faster than their spin-0 counterparts. The fast rates allow us to use measurements of rapidly spinning BHs in x-ray binaries to exclude a wide range of masses for weakly coupled spin-1 particles, 5 ×10-14-2 ×10-11 eV ; lighter masses in the range 6 ×10-20-2 ×10-17 eV start to be constrained by supermassive BH spin measurements at a lower level of confidence. We also explore routes to detection of new vector particles possible with the advent of gravitational wave (GW) astronomy. The LIGO-Virgo Collaboration could discover hints of a new light vector particle in statistical analyses of masses and spins of merging BHs. Vector annihilations source continuous monochromatic gravitational radiation which could be observed by current GW observatories. At design sensitivity, Advanced LIGO may measure up to thousands of annihilation signals from within the Milky Way, while hundreds of BHs born in binary mergers across the observable Universe may superradiate vector bound states and become new beacons of monochromatic gravitational waves.

Virtual monochromatic imaging in dual-source and dual-energy CT for visualization of acute ischemic stroke

NASA Astrophysics Data System (ADS)

Hara, Hidetake; Muraishi, Hiroshi; Matsuzawa, Hiroki; Inoue, Toshiyuki; Nakajima, Yasuo; Satoh, Hitoshi; Abe, Shinji

2015-07-01

We have recently developed a phantom that simulates acute ischemic stroke. We attempted to visualize an acute-stage cerebral infarction by using dual-energy Computed tomography (DECT) to obtain virtual monochromatic images of this phantom. Virtual monochromatic images were created by using DECT voltages from 40 to 100 keV in steps of 10 keV and from 60 to 80 keV in steps of 1 keV, under three conditions of the tube voltage with thin (Sn) filters. Calculation of the CNR values allowed us to evaluate the visualization of acute-stage cerebral infarction. The CNR value of a virtual monochromatic image was the highest at 68 keV under 80 kV / Sn 140 kV, at 72 keV under 100 kV / Sn 140 kV, and at 67 keV under 140 kV / 80 kV. The CNR values of virtual monochromatic images at voltages between 65 and 75 keV were significantly higher than those obtained for all other created images. Therefore, the optimal conditions for visualizing acute ischemic stroke were achievable.

Experimental observation of disorder induced self-focusing in optical fibers

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

Leonetti, Marco, E-mail: marco.leonetti@roma1.infn.it; Karbasi, Salman; Mafi, Arash

2014-10-27

We observed disorder induced focusing nonlinearity activated by a monochromatic light beam in optical fibers composed by two kinds of plastics. The two materials, arranged in disordered fashion, support modes with a degree of localization which increases with the intensity of the optical beam. The temporal response of the optical fiber demonstrates the thermal origin of this nonlinearity. Measurements of the localization length as a function of the input power with broadband and monochromatic inputs show the effectiveness of focusing action with respect to the case of homogeneous fibers.

Laboratory instrumentation and techniques for characterizing multi-junction solar cells for space applications

NASA Technical Reports Server (NTRS)

Woodyard, James R.

1995-01-01

Multi-junction solar cells are attractive for space applications because they can be designed to convert a larger fraction of AMO into electrical power at a lower cost than single-junction cells. The performance of multi-junction cells is much more sensitive to the spectral irradiance of the illuminating source than single-junction cells. The design of high efficiency multi-junction cells for space applications requires matching the optoelectronic properties of the junctions to AMO spectral irradiance. Unlike single-junction cells, it is not possible to carry out quantum efficiency measurements using only a monochromatic probe beam and determining the cell short-circuit current assuming linearity of the quantum efficiency. Additionally, current-voltage characteristics can not be calculated from measurements under non-AMO light sources using spectral-correction methods. There are reports in the literature on characterizing the performance of multi junction cells by measuring and convoluting the quantum efficiency of each junction with the spectral irradiance; the technique is of limited value for the characterization of cell performance under AMO power-generating conditions. We report the results of research to develop instrumentation and techniques for characterizing multi junction solar cells for space . An integrated system is described which consists of a standard lamp, spectral radiometer, dual-source solar simulator, and personal computer based current-voltage and quantum efficiency equipment. The spectral radiometer is calibrated regularly using the tungsten-halogen standard lamp which has a calibration based on NIST scales. The solar simulator produces the light bias beam for current-voltage and cell quantum efficiency measurements. The calibrated spectral radiometer is used to 'fit' the spectral irradiance of the dual-source solar simulator to WRL AMO data. The quantum efficiency apparatus includes a monochromatic probe beam for measuring the absolute cell quantum efficiency at various voltage biases, including the voltage bias corresponding to the maximum-power point under AMO light bias. The details of the procedures to 'fit' the spectral irradiance to AMO will be discussed. An assessment of the role of the accuracy of the 'fit' of the spectral irradiance and probe beam intensity on measured cell characteristics will be presented. quantum efficiencies were measured with both spectral light bias and AMO light bias; the measurements show striking differences. Spectral irradiances were convoluted with cell quantum efficiencies to calculate cell currents as function of voltage. The calculated currents compare with measured currents at the 1% level. Measurements on a variety of multi-junction cells will be presented. The dependence of defects in junctions on cell quantum efficiencies measured under light and voltage bias conditions will be presented. Comments will be made on issues related to standards for calibration, and limitations of the instrumentation and techniques. Expeditious development of multi-junction solar cell technology for space presents challenges for cell characterization in the laboratory.

Comparison of diffraction-enhanced computed tomography and monochromatic synchrotron radiation computed tomography of human trabecular bone.

PubMed

Connor, D M; Hallen, H D; Lalush, D S; Sumner, D R; Zhong, Z

2009-10-21

Diffraction-enhanced imaging (DEI) is an x-ray-based medical imaging modality that, when used in tomography mode (DECT), can generate a three-dimensional map of both the apparent absorption coefficient and the out-of-plane gradient of the index of refraction of the sample. DECT is known to have contrast gains over monochromatic synchrotron radiation CT (SRCT) for soft tissue structures. The goal of this experiment was to compare contrast-to-noise ratio (CNR) and resolution in images of human trabecular bone acquired using SRCT with images acquired using DECT. All images were acquired at the National Synchrotron Light Source (Upton, NY, USA) at beamline X15 A at an x-ray energy of 40 keV and the silicon [3 3 3] reflection. SRCT, apparent absorption DECT and refraction DECT slice images of the trabecular bone were created. The apparent absorption DECT images have significantly higher spatial resolution and CNR than the corresponding SRCT images. Thus, DECT will prove to be a useful tool for imaging applications in which high contrast and high spatial resolution are required for both soft tissue features and bone.

A beamline for high-pressure studies at the Advanced Light Source with a superconducting bending magnet as the source.

PubMed

Kunz, Martin; MacDowell, Alastair A; Caldwell, Wendel A; Cambie, Daniella; Celestre, Richard S; Domning, Edward E; Duarte, Robert M; Gleason, Arianna E; Glossinger, James M; Kelez, Nicholas; Plate, David W; Yu, Tony; Zaug, Joeseph M; Padmore, Howard A; Jeanloz, Raymond; Alivisatos, A Paul; Clark, Simon M

2005-09-01

A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 T superconducting bending magnet (superbend). Useful X-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness-preserving optics of the beamline. These optics are comprised of a plane parabola collimating mirror, followed by a Kohzu monochromator vessel with Si(111) crystals (E/DeltaE approximately equal 7000) and W/B4C multilayers (E/DeltaE approximately equal 100), and then a toroidal focusing mirror with variable focusing distance. The experimental enclosure contains an automated beam-positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detector (CCD or image-plate detector). Future developments aim at the installation of a second endstation dedicated to in situ laser heating and a dedicated high-pressure single-crystal station, applying both monochromatic and polychromatic techniques.

A Photometric Technique for Determining Fluid Concentration using Consumer-Grade Hardware

NASA Technical Reports Server (NTRS)

Leslie, F.; Ramachandran, N.

1999-01-01

In support of a separate study to produce an exponential concentration gradient in a magnetic fluid, a noninvasive technique for determining, species concentration from off-the-shelf hardware has been developed. The approach uses a backlighted fluid test cell photographed with a commercial digital camcorder. Because the light extinction coefficient is wavelength dependent, tests were conducted to determine the best filter color to use, although some guidance was also provided using an absorption spectrophotometer. With the appropriate filter in place, the provide attenuation of the light passing, through the test cell was captured by the camcorder. The digital image was analyzed for intensity using, software from Scion Image Corp. downloaded from the Internet. The analysis provides a two-dimensional array of concentration with an average error of 0.0095 ml/ml. This technique is superior to invasive techniques, which require extraction of a sample that disturbs the concentration distribution in the test cell. Refinements of this technique using a true monochromatic laser light Source are also discussed.

Performance of the PRAXyS X-Ray Polarimeter

NASA Technical Reports Server (NTRS)

Iwakiri, W. B.; Black, J. K.; Cole, R.; Enoto, T.; Hayato, A.; Hill, J. E.; Jahoda, Keith M.; Kaaret, P.; Kitaguchi, T.; Kubota, M.

2016-01-01

The performance of the Time Projection Chamber (TPC) polarimeter for the Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small Explorer was evaluated using polarized and unpolarized X-ray sources. The PRAXyS mission will enable exploration of the universe through X-ray polarimetry in the 2-10 keV energy band. We carried out performance tests of the polarimeter at the Brookhaven National Laboratory, National Synchrotron Light Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The polarimeter was tested with linearly polarized, monochromatic X-rays at 11 different energies between 2.5 and 8.0 keV. At maximum sensitivity, the measured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%, respectively and the measured angle of polarization is consistent with the expected value at all energies. Measurements with a broadband, unpolarized X-ray source placed a limit of less than 1% on false polarization in the PRAXyS polarimeter.

Performance of the PRAXyS X-ray polarimeter

NASA Astrophysics Data System (ADS)

Iwakiri, W. B.; Black, J. K.; Cole, R.; Enoto, T.; Hayato, A.; Hill, J. E.; Jahoda, K.; Kaaret, P.; Kitaguchi, T.; Kubota, M.; Marlowe, H.; McCurdy, R.; Takeuchi, Y.; Tamagawa, T.

2016-12-01

The performance of the Time Projection Chamber (TPC) polarimeter for the Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small Explorer was evaluated using polarized and unpolarized X-ray sources. The PRAXyS mission will enable exploration of the universe through X-ray polarimetry in the 2-10 keV energy band. We carried out performance tests of the polarimeter at the Brookhaven National Laboratory, National Synchrotron Light Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The polarimeter was tested with linearly polarized, monochromatic X-rays at 11 different energies between 2.5 and 8.0 keV. At maximum sensitivity, the measured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%, respectively and the measured angle of polarization is consistent with the expected value at all energies. Measurements with a broadband, unpolarized X-ray source placed a limit of less than 1% on false polarization in the PRAXyS polarimeter.

Advances in Measurement of Skin Friction in Airflow

NASA Technical Reports Server (NTRS)

Brown, James L.; Naughton, Jonathan W.

2006-01-01

The surface interferometric skin-friction (SISF) measurement system is an instrument for determining the distribution of surface shear stress (skin friction) on a wind-tunnel model. The SISF system utilizes the established oil-film interference method, along with advanced image-data-processing techniques and mathematical models that express the relationship between interferograms and skin friction, to determine the distribution of skin friction over an observed region of the surface of a model during a single wind-tunnel test. In the oil-film interference method, a wind-tunnel model is coated with a thin film of oil of known viscosity and is illuminated with quasi-monochromatic, collimated light, typically from a mercury lamp. The light reflected from the outer surface of the oil film interferes with the light reflected from the oil-covered surface of the model. In the present version of the oil-film interference method, a camera captures an image of the illuminated model and the image in the camera is modulated by the interference pattern. The interference pattern depends on the oil-thickness distribution on the observed surface, and this distribution can be extracted through analysis of the image acquired by the camera. The oil-film technique is augmented by a tracer technique for observing the streamline pattern. To make the streamlines visible, small dots of fluorescentchalk/oil mixture are placed on the model just before a test. During the test, the chalk particles are embedded in the oil flow and produce chalk streaks that mark the streamlines. The instantaneous rate of thinning of the oil film at a given position on the surface of the model can be expressed as a function of the instantaneous thickness, the skin-friction distribution on the surface, and the streamline pattern on the surface; the functional relationship is expressed by a mathematical model that is nonlinear in the oil-film thickness and is known simply as the thin-oil-film equation. From the image data acquired as described, the time-dependent oil-thickness distribution and streamline pattern are extracted and by inversion of the thin-oil-film equation it is then possible to determine the skin-friction distribution. In addition to a quasi-monochromatic light source, the SISF system includes a beam splitter and two video cameras equipped with filters for observing the same area on a model in different wavelength ranges, plus a frame grabber and a computer for digitizing the video images and processing the image data. One video camera acquires the interference pattern in a narrow wavelength range of the quasi-monochromatic source. The other video camera acquires the streamline image of fluorescence from the chalk in a nearby but wider wavelength range. The interference- pattern and fluorescence images are digitized, and the resulting data are processed by an algorithm that inverts the thin-oil-film equation to find the skin-friction distribution.

A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters

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

Wang, Wenbo; Department of Dermatology and Skin Science, University of British Columbia, 835 West 10th Avenue, Vancouver, British Columbia V5Z 4E8; Department of Biomedical Engineering, University of British Columbia, KAIS 5500, 2332 Main Mall, Vancouver, British Columbia V6T 1Z4

Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra.more » Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to −0.70 nm within the spectral range of 500–850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s.« less

Modulatory Effect of Monochromatic Blue Light on Heat Stress Response in Commercial Broilers.

PubMed

Abdo, Safaa E; El-Kassas, Seham; El-Nahas, Abeer F; Mahmoud, Shawky

2017-01-01

In a novel approach, monochromatic blue light was used to investigate its modulatory effect on heat stress biomarkers in two commercial broiler strains (Ross 308 and Cobb 500). At 21 days old, birds were divided into four groups including one group housed in white light, a second group exposed to blue light, a 3rd group exposed to white light + heat stress, and a 4th group exposed to blue light + heat stress. Heat treatment at 33°C lasted for five h for four successive days. Exposure to blue light during heat stress reduced MDA concentration and enhanced SOD and CAT enzyme activities as well as modulated their gene expression. Blue light also reduced the degenerative changes that occurred in the liver tissue as a result of heat stress. It regulated, though variably, liver HSP70 , HSP90 , HSF1 , and HSF3 gene expression among Ross and Cobb chickens. Moreover, the Cobb strain showed better performance than Ross manifested by a significant reduction of rectal temperature in the case of H + B. Furthermore, a significant linear relationship was found between the lowered rectal temperature and the expression of all HSP genes. Generally, the performance of both strains by most assessed parameters under heat stress is improved when using blue light.

Modulatory Effect of Monochromatic Blue Light on Heat Stress Response in Commercial Broilers

PubMed Central

Abdo, Safaa E.; Mahmoud, Shawky

2017-01-01

In a novel approach, monochromatic blue light was used to investigate its modulatory effect on heat stress biomarkers in two commercial broiler strains (Ross 308 and Cobb 500). At 21 days old, birds were divided into four groups including one group housed in white light, a second group exposed to blue light, a 3rd group exposed to white light + heat stress, and a 4th group exposed to blue light + heat stress. Heat treatment at 33°C lasted for five h for four successive days. Exposure to blue light during heat stress reduced MDA concentration and enhanced SOD and CAT enzyme activities as well as modulated their gene expression. Blue light also reduced the degenerative changes that occurred in the liver tissue as a result of heat stress. It regulated, though variably, liver HSP70, HSP90, HSF1, and HSF3 gene expression among Ross and Cobb chickens. Moreover, the Cobb strain showed better performance than Ross manifested by a significant reduction of rectal temperature in the case of H + B. Furthermore, a significant linear relationship was found between the lowered rectal temperature and the expression of all HSP genes. Generally, the performance of both strains by most assessed parameters under heat stress is improved when using blue light. PMID:28698764

A Fabry-Perot interferometric imaging spectrometer in LWIR

NASA Astrophysics Data System (ADS)

Zhang, Fang; Gao, Jiaobo; Wang, Nan; Wu, Jianghui; Meng, Hemin; Zhang, Lei; Gao, Shan

2017-02-01

With applications ranging from the desktop to remote sensing, the long wave infrared (LWIR) interferometric spectral imaging system is always with huge volume and large weight. In order to miniaturize and light the instrument, a new method of LWIR spectral imaging system based on a variable gap Fabry-Perot (FP) interferometer is researched. With the system working principle analyzed, theoretically, it is researched that how to make certain the primary parameter, such as, wedge angle of interferometric cavity, f-number of the imaging lens and the relationship between the wedge angle and the modulation of the interferogram. A prototype is developed and a good experimental result of a uniform radiation source, a monochromatic source, is obtained. The research shows that besides high throughput and high spectral resolution, the advantage of miniaturization is also simultaneously achieved in this method.

A Novel Real-Time Data Acquisition Using an Excel Spreadsheet in Pendulum Experiment Tool with Light-Based Timer

ERIC Educational Resources Information Center

Adhitama, Egy; Fauzi, Ahmad

2018-01-01

In this study, a pendulum experimental tool with a light-based timer has been developed to measure the period of a simple pendulum. The obtained data was automatically recorded in an Excel spreadsheet. The intensity of monochromatic light, sensed by a 3DU5C phototransistor, dynamically changes as the pendulum swings. The changed intensity varies…

Lasers for Frontier Spectroscopy

NASA Astrophysics Data System (ADS)

Baldacchini, Giuseppe

The first laser has been invented in 1960 by using the red light from a ruby crystal, and since then the laser field exploded almost exponentially, and thousands of different materials, in the state of solids, liquids, vapors, gases, plasmas, and elementary particles have lased up to now from less than I Å to more than 1 mm. Many of them have been used with outstanding results both in basic science, and in industrial and commercial applications, by changing for ever the same lifestyle of humankind. As far as spectroscopy is concerned, the laser light has started an unprecedented revolution because of its unique properties as monochromaticity, coherence, power, brightness and short-pulse regime, unrivaled by any other natural and artificial light source. Spectroscopy applications increased qualitatively and quantitatively with the laser sources themselves, and they are still proceeding in parallel with the moving of the laser field towards new territories. Apart the opening up of new regions of the electromagnetic spectrum, like the terahertz gap, and the outstanding increase of the output power which is giving rise to completely new spectroscopic effects, the improvement of laser sources and auxiliary equipment is producing a growth of traditional laser spectroscopy with superior resolution and sensitivity. Moreover, spectroscopic techniques and laser light contributed to the development of new chemical and physical processes which have been used to fabricate photonic materials with new spectroscopic properties enriching the laser field itself, in a virtuous cycle spectroscopy→aser→material and back to spectroscopy with no end in sight.

New limb-darkening coefficients for modeling binary star light curves

NASA Technical Reports Server (NTRS)

Van Hamme, W.

1993-01-01

We present monochromatic, passband-specific, and bolometric limb-darkening coefficients for a linear as well as nonlinear logarithmic and square root limb-darkening laws. These coefficients, including the bolometric ones, are needed when modeling binary star light curves with the latest version of the Wilson-Devinney light curve progam. We base our calculations on the most recent ATLAS stellar atmosphere models for solar chemical composition stars with a wide range of effective temperatures and surface gravitites. We examine how well various limb-darkening approximations represent the variation of the emerging specific intensity across a stellar surface as computed according to the model. For binary star light curve modeling purposes, we propose the use of a logarithmic or a square root law. We design our tables in such a manner that the relative quality of either law with respect to another can be easily compared. Since the computation of bolometric limb-darkening coefficients first requires monochromatic coefficients, we also offer tables of these coefficients (at 1221 wavelength values between 9.09 nm and 160 micrometer) and tables of passband-specific coefficients for commonly used photometric filters.

Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

NASA Astrophysics Data System (ADS)

Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

2015-05-01

Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrating solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested and more than 19 months of measurements were collected at the Plataforma Solar de Almería and compared. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for Concentrating Solar Power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the actual, time-dependent by the collector reflected solar spectrum. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the Absorption and Broadband Correction (ABC) procedure, additional measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from one year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.6%. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8%. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.81%. Therefore, applying this new correction method, both instruments can now be utilized to determine the solar broadband extinction in tower plants sufficiently accurate.

Microcontroller based spectrophotometer using compact disc as diffraction grid

NASA Astrophysics Data System (ADS)

Bano, Saleha; Altaf, Talat; Akbar, Sunila

2010-12-01

This paper describes the design and implementation of a portable, inexpensive and cost effective spectrophotometer. The device combines the use of compact disc (CD) media as diffraction grid and 60 watt bulb as a light source. Moreover it employs a moving slit along with stepper motor for obtaining a monochromatic light, photocell with spectral sensitivity in visible region to determine the intensity of light and an amplifier with a very high gain as well as an advanced virtual RISC (AVR) microcontroller ATmega32 as a control unit. The device was successfully applied to determine the absorbance and transmittance of KMnO4 and the unknown concentration of KMnO4 with the help of calibration curve. For comparison purpose a commercial spectrophotometer was used. There are not significant differences between the absorbance and transmittance values estimated by the two instruments. Furthermore, good results are obtained at all visible wavelengths of light. Therefore, the designed instrument offers an economically feasible alternative for spectrophotometric sample analysis in small routine, research and teaching laboratories, because the components used in the designing of the device are cheap and of easy acquisition.

All-diamond optical assemblies for a beam-multiplexing X-ray monochromator at the Linac Coherent Light Source

PubMed Central

Stoupin, S.; Terentyev, S. A.; Blank, V. D.; Shvyd’ko, Yu. V.; Goetze, K.; Assoufid, L.; Polyakov, S. N.; Kuznetsov, M. S.; Kornilov, N. V.; Katsoudas, J.; Alonso-Mori, R.; Chollet, M.; Feng, Y.; Glownia, J. M.; Lemke, H.; Robert, A.; Sikorski, M.; Song, S.; Zhu, D.

2014-01-01

A double-crystal diamond (111) monochromator recently implemented at the Linac Coherent Light Source (LCLS) enables splitting of the primary X-ray beam into a pink (transmitted) and a monochromatic (reflected) branch. The first monochromator crystal, with a thickness of ∼100 µm, provides sufficient X-ray transmittance to enable simultaneous operation of two beamlines. This article reports the design, fabrication and X-ray characterization of the first and second (300 µm-thick) crystals utilized in the monochromator and the optical assemblies holding these crystals. Each crystal plate has a region of about 5 × 2 mm with low defect concentration, sufficient for use in X-ray optics at the LCLS. The optical assemblies holding the crystals were designed to provide mounting on a rigid substrate and to minimize mounting-induced crystal strain. The induced strain was evaluated using double-crystal X-ray topography and was found to be small over the 5 × 2 mm working regions of the crystals. PMID:25242912

Green light drives leaf photosynthesis more efficiently than red light in strong white light: revisiting the enigmatic question of why leaves are green.

PubMed

Terashima, Ichiro; Fujita, Takashi; Inoue, Takeshi; Chow, Wah Soon; Oguchi, Riichi

2009-04-01

The literature and our present examinations indicate that the intra-leaf light absorption profile is in most cases steeper than the photosynthetic capacity profile. In strong white light, therefore, the quantum yield of photosynthesis would be lower in the upper chloroplasts, located near the illuminated surface, than that in the lower chloroplasts. Because green light can penetrate further into the leaf than red or blue light, in strong white light, any additional green light absorbed by the lower chloroplasts would increase leaf photosynthesis to a greater extent than would additional red or blue light. Based on the assessment of effects of the additional monochromatic light on leaf photosynthesis, we developed the differential quantum yield method that quantifies efficiency of any monochromatic light in white light. Application of this method to sunflower leaves clearly showed that, in moderate to strong white light, green light drove photosynthesis more effectively than red light. The green leaf should have a considerable volume of chloroplasts to accommodate the inefficient carboxylation enzyme, Rubisco, and deliver appropriate light to all the chloroplasts. By using chlorophylls that absorb green light weakly, modifying mesophyll structure and adjusting the Rubisco/chlorophyll ratio, the leaf appears to satisfy two somewhat conflicting requirements: to increase the absorptance of photosynthetically active radiation, and to drive photosynthesis efficiently in all the chloroplasts. We also discuss some serious problems that are caused by neglecting these intra-leaf profiles when estimating whole leaf electron transport rates and assessing photoinhibition by fluorescence techniques.

Improved color coordinates of green monochromatic pc-LED capped with a band-pass filter.

PubMed

Oh, Ji Hye; Yang, Su Ji; Sung, Yeon-Goog; Do, Young Rag

2013-02-25

This study introduces a "greener" green monochromatic phosphor-converted light-emitting diode (pc-LED) using a band-pass filter (BPF) combined with a long-pass dichroic filter (LPDF) and a short-pass dichroic filter (SPDF) to improve the color quality of our previously developed LPDF-capped green pc-LED. This can also address the drawbacks of III-V semiconductor-type green LEDs, which show a low luminous efficacy and a poor current dependence of the efficacy and color coordinates compared to blue semiconductor-type LEDs. The optical properties of green monochromatic pc-LEDs using a BPF are compared with those of LPDF-capped green pc-LEDs, which have a broad band spectrum, and III-V semiconductor-type green LEDs by changing the transmittance wavelength range of the BPF and the peak wavelength of the green phosphors. BPF-capped green monochromatic pc-LEDs provide a high luminous efficacy (134 lm/W at 60 mA), and "greener" 1931 Commission Internationale d'Eclairage (CIE; CIEx, CIEy) color coordinates (0.24, 0.66) owing to the narrowed emission spectrum. We also propose a two-dimensional (2D) polystyrene (PS) microbead (2-μm diameter) monolayer as a scattering layer to overcome the poor angular dependence of the color coordinates of the transmitted light through a nano-multilayered dichroic filter such as an LPDF or BPF. The 2D PS scattering layer improves the angular dependence of the green color emitted from a BPF-capped green pc-LED with only 3% loss of luminous efficacy.

Absorption of monochromatic and narrow band radiation in the visible and near IR by both mitochondrial and non-mitochondrial photoacceptors results in photobiomodulation.

PubMed

Passarella, Salvatore; Karu, Tiina

2014-11-01

In addition to the major functions performed by in the cell, mitochondria play a major role in cell-light interaction. Accordingly it is generally accepted that mitochondria are crucial in cell photobiomodulation; however a variety of biomolecules themselves proved to be targets of light irradiation. We describe whether and how mitochondria can interact with monochromatic and narrow band radiation in the red and near IR optical regions with dissection of both structural and functional effects likely leading to photobiostimulation. Moreover we also report that a variety of biomolecules localized in mitochondria and/or in other cell compartments including cytochrome c oxidase, some proteins, nucleic acids and adenine nucleotides are light sensitive with major modifications in their biochemistry. All together the reported investigations show that the elucidation of the mechanism of the light interaction with biological targets still remains to be completed, this needing further research, however the light sensitivity of a variety of molecules strongly suggests that photobiomodulation could be used in both in photomedicine and in biotechnology. Copyright © 2014 Elsevier B.V. All rights reserved.

Neutral point testing of color vision in the domestic cat.

PubMed

Clark, Daria L; Clark, Robert A

2016-12-01

Despite extensive study, the basic nature of feline spectral sensitivity is still unresolved. Most electrophysiological studies have demonstrated two photopic receptors within the cat's retina, one most sensitive to longer wavelengths near 560 nm and the other most sensitive to shorter wavelengths near 460 nm, providing the neuroretinal basis for dichromatic vision. A few studies, however, have detected a third photopic receptor most sensitive to medium wavelengths between 500 and 520 nm, overlapping in spectrally sensitivity with the feline scotopic receptor, that potentially could allow trichromatic vision. Indeed, one behavioral study has demonstrated trichromatic vision in cats, but a flaw within its experimental design raises the possibility that achromatic intensity cues might have allowed the accurate identification of medium wavelength targets. This study tested for a spectral neutral point in the domestic cat using a two-choice discrimination task. The positive targets were created using monochromatic light from various single wavelength light emitting diodes (LEDs) combined with a white light of variable intensity, while the negative targets were created using white light of variable intensity. Trials were performed with varying intensities of positive and negative targets, from brighter positive targets to brighter negative targets, to eliminate achromatic intensity cues. Two cats with prior experience with two-choice discrimination tasks, one male and one female, successfully discriminated monochromatic light from 456 nm to 497 nm and from 510 nm to 524 nm, but both failed to discriminate monochromatic light at 505 nm over multiple trials. These results provide strong evidence that cats are dichromatic with a neutral point near 505 nm. This neutral point is nearly identical to the neutral point of the human deuteuranope, making feline vision a more accurate a model for red-green colorblind individuals than normal trichromats. Copyright © 2016 Elsevier Ltd. All rights reserved.

Relative intensity noise transfer of large-bandwidth pump lasers in Raman fiber amplifiers

NASA Astrophysics Data System (ADS)

Keita, Kafing; Delaye, Philippe; Frey, Robert; Roosen, Gérald

2006-12-01

A theoretical analysis of the Raman amplification in optical fibers and the pump-to-signal relative intensity noise (RIN) transfer has been performed in the spectral domain. An efficient Raman amplification of a monochromatic signal beam by a large-bandwidth pump beam has been demonstrated for a pump bandwidth much smaller than the Raman linewidth. Under the same approximation the pump-to-signal RIN transfer has been calculated in both cases of copropagating and counterpropagating beams in the two limiting cases of modulated monochromatic and smooth-profile large-bandwidth pump beams. At low frequencies the excess of noise evidenced in the case of a modulated monochromatic pump beam did not exist in the case of large-bandwidth pseudoincoherent sources. As this noise reduction can be as large as 13 dB for a 40 dB net gain of the amplifier, such incoherent pumping sources must be considered for the purpose of low-noise Raman amplifiers.

Light spectrum modifies the utilization pattern of energy sources in Pseudomonas sp. DR 5-09

PubMed Central

Rosberg, Anna Karin; Windstam, Sofia T.; Karlsson, Maria E.; Bergstrand, Karl-Johan; Khalil, Sammar; Wohanka, Walter

2017-01-01

Despite the overruling impact of light in the phyllosphere, little is known regarding the influence of light spectra on non-phototrophic bacteria colonizing the leaf surface. We developed an in vitro method to study phenotypic profile responses of bacterial pure cultures to different bands of the visible light spectrum using monochromatic (blue: 460 nm; red: 660 nm) and polychromatic (white: 350–990 nm) LEDs, by modification and optimization of a protocol for the Phenotype MicroArray™ technique (Biolog Inc., CA, USA). The new protocol revealed high reproducibility of substrate utilization under all conditions tested. Challenging the non-phototrophic bacterium Pseudomonas sp. DR 5–09 with white, blue, and red light demonstrated that all light treatments affected the respiratory profile differently, with blue LED having the most decisive impact on substrate utilization by impairing respiration of 140 substrates. The respiratory activity was decreased on 23 and 42 substrates under red and white LEDs, respectively, while utilization of one, 16, and 20 substrates increased in the presence of red, blue, and white LEDs, respectively. Interestingly, on four substrates contrasting utilization patterns were found when the bacterium was exposed to different light spectra. Although non-phototrophic bacteria do not rely directly on light as an energy source, Pseudomonas sp. DR 5–09 changed its respiratory activity on various substrates differently when exposed to different lights. Thus, ability to sense and distinguish between different wavelengths even within the visible light spectrum must exist, and leads to differential regulation of substrate usage. With these results, we hypothesize that different light spectra might be a hitherto neglected key stimulus for changes in microbial lifestyle and habits of substrate usage by non-phototrophic phyllospheric microbiota, and thus might essentially stratify leaf microbiota composition and diversity. PMID:29267321

Light spectrum modifies the utilization pattern of energy sources in Pseudomonas sp. DR 5-09.

PubMed

Gharaie, Samareh; Vaas, Lea A I; Rosberg, Anna Karin; Windstam, Sofia T; Karlsson, Maria E; Bergstrand, Karl-Johan; Khalil, Sammar; Wohanka, Walter; Alsanius, Beatrix W

2017-01-01

Despite the overruling impact of light in the phyllosphere, little is known regarding the influence of light spectra on non-phototrophic bacteria colonizing the leaf surface. We developed an in vitro method to study phenotypic profile responses of bacterial pure cultures to different bands of the visible light spectrum using monochromatic (blue: 460 nm; red: 660 nm) and polychromatic (white: 350-990 nm) LEDs, by modification and optimization of a protocol for the Phenotype MicroArray™ technique (Biolog Inc., CA, USA). The new protocol revealed high reproducibility of substrate utilization under all conditions tested. Challenging the non-phototrophic bacterium Pseudomonas sp. DR 5-09 with white, blue, and red light demonstrated that all light treatments affected the respiratory profile differently, with blue LED having the most decisive impact on substrate utilization by impairing respiration of 140 substrates. The respiratory activity was decreased on 23 and 42 substrates under red and white LEDs, respectively, while utilization of one, 16, and 20 substrates increased in the presence of red, blue, and white LEDs, respectively. Interestingly, on four substrates contrasting utilization patterns were found when the bacterium was exposed to different light spectra. Although non-phototrophic bacteria do not rely directly on light as an energy source, Pseudomonas sp. DR 5-09 changed its respiratory activity on various substrates differently when exposed to different lights. Thus, ability to sense and distinguish between different wavelengths even within the visible light spectrum must exist, and leads to differential regulation of substrate usage. With these results, we hypothesize that different light spectra might be a hitherto neglected key stimulus for changes in microbial lifestyle and habits of substrate usage by non-phototrophic phyllospheric microbiota, and thus might essentially stratify leaf microbiota composition and diversity.

The use of holographic and diffractive optics for optimized machine vision illumination for critical dimension inspection

NASA Astrophysics Data System (ADS)

Lizotte, Todd E.; Ohar, Orest

2004-02-01

Illuminators used in machine vision applications typically produce non-uniform illumination onto the targeted surface being observed, causing a variety of problems with machine vision alignment or measurement. In most circumstances the light source is broad spectrum, leading to further problems with image quality when viewed through a CCD camera. Configured with a simple light bulb and a mirrored reflector and/or frosted glass plates, these general illuminators are appropriate for only macro applications. Over the last 5 years newer illuminators have hit the market including circular or rectangular arrays of high intensity light emitting diodes. These diode arrays are used to create monochromatic flood illumination of a surface that is to be inspected. The problem with these illumination techniques is that most of the light does not illuminate the desired areas, but broadly spreads across the surface, or when integrated with diffuser elements, tend to create similar shadowing effects to the broad spectrum light sources. In many cases a user will try to increase the performance of these illuminators by adding several of these assemblies together, increasing the intensity or by moving the illumination source closer or farther from the surface being inspected. In this case these non-uniform techniques can lead to machine vision errors, where the computer machine vision may read false information, such as interpreting non-uniform lighting or shadowing effects as defects. This paper will cover a technique involving the use of holographic / diffractive hybrid optical elements that are integrated into standard and customized light sources used in the machine vision industry. The bulk of the paper will describe the function and fabrication of the holographic/diffractive optics and how they can be tailored to improve illuminator design. Further information will be provided a specific design and examples of it in operation will be disclosed.

The influence of non-ionic radiation on the chicken hatching.

PubMed

Veterány, Ladislav; Toman, Robert; Jedlicka, Jaroslav

2002-11-01

The study considers the influence of non-ionic radiation (white and monochromatic light) on the hatching of the Hampshire breed chickens. The chicken embryos were most sensitive to the white light (El), reaching the hatching time of 503.63 +/- 3.17 h, the hatchability of 95.12 +/- 3.72% and an average weight of incubated chickens 46.83 +/- 2.82 g. Of the monochromatic lights, the chicken embryos were most sensitive to yellow and green lights (E5, E4) with the hatching time of 505.22 +/- 4.03 and 507.14 +/- 3.95 h, respectively, the hatchability of 94.89 +/- 3.02 and 94.47 +/- 2.93%, respectively and the average weight of incubated chickens 45.72 +/- 1.93 and 45.05 +/- 2.66 g, respectively. The least reaction of chicken was observed with violet light (E2) with the hatching time of 510.04+/- 1.97 h, hatchability of 90.81 +/- 4.05% and the average weight of incubated chickens 42.02 +/- 3.72 g. The effect of violet light brings the same results as we observed in the case of hatching in darkness (control group C), when the hatching time was 510.41 +/- 2.82 h, hatchability 90.42 +/- 3.35% and average weight of incubated chickens 41.98 +/- 3.05 g.

Three-dimensional monochromatic x-ray computed tomography using synchrotron radiation

NASA Astrophysics Data System (ADS)

Saito, Tsuneo; Kudo, Hiroyuki; Takeda, Tohoru; Itai, Yuji; Tokumori, Kenji; Toyofuku, Fukai; Hyodo, Kazuyuki; Ando, Masami; Nishimura, Katsuyuki; Uyama, Chikao

1998-08-01

We describe a technique of 3D computed tomography (3D CT) using monochromatic x rays generated by synchrotron radiation, which performs a direct reconstruction of a 3D volume image of an object from its cone-beam projections. For the development, we propose a practical scanning orbit of the x-ray source to obtain complete 3D information on an object, and its corresponding 3D image reconstruction algorithm. The validity and usefulness of the proposed scanning orbit and reconstruction algorithm were confirmed by computer simulation studies. Based on these investigations, we have developed a prototype 3D monochromatic x-ray CT using synchrotron radiation, which provides exact 3D reconstruction and material-selective imaging by using the K-edge energy subtraction technique.

Submicron x-ray diffraction and its applications to problems in materials and environmental science

NASA Astrophysics Data System (ADS)

Tamura, N.; Celestre, R. S.; MacDowell, A. A.; Padmore, H. A.; Spolenak, R.; Valek, B. C.; Meier Chang, N.; Manceau, A.; Patel, J. R.

2002-03-01

The availability of high brilliance third generation synchrotron sources together with progress in achromatic focusing optics allows us to add submicron spatial resolution to the conventional century-old x-ray diffraction technique. The new capabilities include the possibility to map in situ, grain orientations, crystalline phase distribution, and full strain/stress tensors at a very local level, by combining white and monochromatic x-ray microbeam diffraction. This is particularly relevant for high technology industry where the understanding of material properties at a microstructural level becomes increasingly important. After describing the latest advances in the submicron x-ray diffraction techniques at the Advanced Light Source, we will give some examples of its application in material science for the measurement of strain/stress in metallic thin films and interconnects. Its use in the field of environmental science will also be discussed.

Effects of monochromatic light on mucosal mechanical and immunological barriers in the small intestine of broilers.

PubMed

Xie, D; Li, J; Wang, Z X; Cao, J; Li, T T; Chen, J L; Chen, Y X

2011-12-01

Our previous studies demonstrated that green and blue monochromatic lights were effective to stimulate immune response of the spleen in broilers. This study was designed to investigate the effects of monochromatic light on both gut mucosal mechanical and immunological barriers. A total of 120 Arbor Acre male broilers on post-hatching day (P) 0 were exposed to red light, green light (GL), blue light (BL), and white light (WL) for 49 d, respectively. As compared with broilers exposed to WL, the broilers exposed to GL showed that the villus height of small intestine was increased by 19.5% (P = 0.0205) and 38.8% (P = 0.0149), the crypt depth of small intestine was decreased by 15.1% (P = 0.0049) and 10.1% (P = 0.0005), and the ratios of villus height to crypt depth were increased by 39.3% (P < 0.0001) and 52.5% (P < 0.0001) at P7 and P21, respectively. Until P49, an increased villus height (33.6%, P = 0.0076), a decreased crypt depth (15.4%, P = 0.0201), and an increased villus height-to-crypt depth ratio (58.5%, P < 0.0001) were observed in the BL group as compared with the WL group. On the other hand, the numbers of intestinal intraepithelial lymphocytes (27.9%, P < 0.0001 and 37.0%, P < 0.0001), goblet cells (GC, 22.1%, P < 0.0001 and 18.1%, P < 0.0001), and IgA(+) cells (14.8%, P = 0.0543 and 47.9%, P = 0.0377) in the small intestine were significantly increased in the GL group as compared with the WL group at P7 and P21, respectively. The numbers of intestinal intraepithelial lymphocytes (36.2%, P < 0.0001), GC (26.5%, P < 0.0001), and IgA(+) cells (68.0%, P = 0.0177) in the BL group were also higher than those in the WL group at P49. These results suggest that both mucosal mechanical and immunological barriers of the small intestine may be improved by rearing broilers under GL at an early age and under BL at an older age.

Research and design of an optical system of biochemical analyzer based on the narrow-band pass filter

NASA Astrophysics Data System (ADS)

Xiao, Ze-xin; Chen, Kuan

2008-03-01

Biochemical analyzer is one of the important instruments in the clinical diagnosis, and its optical system is the important component. The operation of this optical system can be regard as three parts. The first is transforms the duplicate colored light as the monochromatic light. The second is transforms the light signal of the monochromatic, which have the information of the measured sample, as the electric signal by use the photoelectric detector. And the last is to send the signal to data processing system by use the control system. Generally, there are three types monochromators: prism, optical grating and narrow-band pass filter. Thereinto, the narrow-band pass filter were widely used in the semi-auto biochemical analyzer. Through analysed the principle of biochemical analyzer base on the narrow-band pass filter, we known that the optical has three features. The first is the optical path of the optical system is a non- imaging system. The second, this system is wide spectrum region that contain visible light and ultraviolet spectrum. The third, this is a little aperture and little field monochromatic light system. Therefore, design idea of this optical system is: (1) luminous energy in the system less transmission loss; (2) detector coupled to the luminous energy efficient; mainly correct spherical aberration. Practice showed the point of Image quality evaluation: (1) dispersion circle diameter equal the receiving device pixel effective width of 125%, and the energy distribution should point target of 80% of energy into the receiving device pixel width of the effective diameter in this dispersion circle; (2) With MTF evaluation, the requirements in 20lp/ mm spatial frequency, the MTF values should not be lower than 0.6. The optical system should be fit in with ultraviolet and visible light width spectrum, and the detector image plane can but suited the majority visible light spectrum when by defocus optimization, and the image plane of violet and ultraviolet excursion quite large. Traditional biochemical analyzer optical design not fully consider this point, the authors introduce a effective image plane compensation measure innovatively, it greatly increased the reception efficiency of the violet and ultraviolet.

Non-mechanical optical path switching and its application to dual beam spectroscopy including gas filter correlation radiometry

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor); Wang, Liang-Guo (Inventor)

1992-01-01

A non-mechanical optical switch is developed for alternately switching a monochromatic or quasi-monochromatic light beam along two optical paths. A polarizer polarizes light into a single, e.g., vertical component which is then rapidly modulated into vertical and horizontal components by a polarization modulator. A polarization beam splitter then reflects one of these components along one path and transmits the other along the second path. In the specific application of gas filter correlation radiometry, one path is directed through a vacuum cell and one path is directed through a gas correlation cell containing a desired gas. Reflecting mirrors cause these two paths to intersect at a second polarization beam splitter which reflects one component and transmits the other to recombine them into a polarization modulated beam which can be detected by an appropriate single sensor.

Photoelectric-enhanced radiation therapy with quasi-monochromatic computed tomography

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

Jost, Gregor; Mensing, Tristan; Golfier, Sven

2009-06-15

Photoelectric-enhanced radiation therapy is a bimodal therapy, consisting of the administration of highly radiation-absorbing substances into the tumor area and localized regional irradiation with orthovoltage x-rays. Irradiation can be performed by a modified computed tomography (CT) unit equipped with an additional x-ray optical module which converts the polychromatic, fan-shaped CT beam into a monochromatized and focused beam for energy-tuned photoelectric-enhanced radiotherapy. A dedicated x-ray optical module designed for spatial collimation, focusing, and monochromatization was mounted at the exit of the x-ray tube of a clinical CT unit. Spectrally resolved measurements of the resulting beam were performed using an energy-dispersive detectionmore » system calibrated by synchrotron radiation. The spatial photon fluence was determined by film dosimetry. Depth-dose measurements were performed and compared to the polychromatic CT and a therapeutic 6 MV beam. The spatial dose distribution in phantoms using a rotating radiation source (quasi-monochromatic CT and 6 MV, respectively) was investigated by gel dosimetry. The photoelectric dose enhancement for an iodine fraction of 1% in tissue was calculated and verified experimentally. The x-ray optical module selectively filters the energy of the tungsten K{alpha} emission line with an FWHM of 5 keV. The relative photon fluence distribution demonstrates the focusing characteristic of the x-ray optical module. A beam width of about 3 mm was determined at the isocenter of the CT gantry. The depth-dose measurements resulted in a half-depth value of approximately 36 mm for the CT beams (quasi-monochromatic, polychromatic) compared to 154 mm for the 6 MV beam. The rotation of the radiation source leads to a steep dose gradient at the center of rotation; the gel dosimetry yields an entrance-to-peak dose ratio of 1:10.8 for the quasi-monochromatic CT and 1:37.3 for a 6 MV beam of the same size. The photoelectric dose enhancement factor increases from 2.2 to 2.4 by using quasi-monochromatic instead of polychromatic radiation. An additional increase in the radiation dose by a factor of 1.4 due to the focusing characteristic of the x-ray optical module was calculated. Photoelectric-enhanced radiation therapy based on a clinical CT unit combined with an x-ray optical module is a novel therapy option in radiation oncology. The optimized quasi-monochromatic radiation is strongly focused and ensures high photoelectric dose enhancement for iodine.« less

Cell response to quasi-monochromatic light with different coherence

NASA Astrophysics Data System (ADS)

Budagovsky, A. V.; Solovykh, N. V.; Budagovskaya, O. N.; Budagovsky, I. A.

2015-04-01

The problem of the light coherence effect on the magnitude of the photoinduced cell response is discussed. The origins of ambiguous interpretation of the known experimental results are considered. Using the biological models, essentially differing in anatomy, morphology and biological functions (acrospires of radish, blackberry microsprouts cultivated in vitro, plum pollen), the effect of statistical properties of quasi-monochromatic light (λmax = 633 nm) on the magnitude of the photoinduced cell response is shown. It is found that for relatively low spatial coherence, the cell functional activity changes insignificantly. The maximal enhancement of growing processes (stimulating effect) is observed when the coherence length Lcoh and the correlation radius rcor are greater than the cell size, i.e., the entire cell fits into the field coherence volume. In this case, the representative indicators (germination of seeds and pollen, the spears length) exceeds those of non-irradiated objects by 1.7 - 3.9 times. For more correct assessment of the effect of light statistical properties on photocontrol processes, it is proposed to replace the qualitative description (coherent - incoherent) with the quantitative one, using the determination of spatial and temporal correlation functions and comparing them with the characteristic dimensions of the biological structures, e.g., the cell size.

Alternative Splicing Substantially Diversifies the Transcriptome during Early Photomorphogenesis and Correlates with the Energy Availability in Arabidopsis.

PubMed

Hartmann, Lisa; Drewe-Boß, Philipp; Wießner, Theresa; Wagner, Gabriele; Geue, Sascha; Lee, Hsin-Chieh; Obermüller, Dominik M; Kahles, André; Behr, Jonas; Sinz, Fabian H; Rätsch, Gunnar; Wachter, Andreas

2016-11-01

Plants use light as source of energy and information to detect diurnal rhythms and seasonal changes. Sensing changing light conditions is critical to adjust plant metabolism and to initiate developmental transitions. Here, we analyzed transcriptome-wide alterations in gene expression and alternative splicing (AS) of etiolated seedlings undergoing photomorphogenesis upon exposure to blue, red, or white light. Our analysis revealed massive transcriptome reprogramming as reflected by differential expression of ∼20% of all genes and changes in several hundred AS events. For more than 60% of all regulated AS events, light promoted the production of a presumably protein-coding variant at the expense of an mRNA with nonsense-mediated decay-triggering features. Accordingly, AS of the putative splicing factor REDUCED RED-LIGHT RESPONSES IN CRY1CRY2 BACKGROUND1, previously identified as a red light signaling component, was shifted to the functional variant under light. Downstream analyses of candidate AS events pointed at a role of photoreceptor signaling only in monochromatic but not in white light. Furthermore, we demonstrated similar AS changes upon light exposure and exogenous sugar supply, with a critical involvement of kinase signaling. We propose that AS is an integration point of signaling pathways that sense and transmit information regarding the energy availability in plants. © 2016 American Society of Plant Biologists. All rights reserved.

Development of Experimental Techniques Using LVP (Large Volume Press) at GSECARS Beamlines, Advanced Photon Source (in Japanese with English abstract)

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

Nishiyama, N.; Wang, Y.

GSECARS (GeoSoilEnviroCARS, the University of Chicago) operates a bending magnet and an undulator beamlines at Sector 13, Advanced Photon Source. Experimental technique for High Pressure X-ray Tomographic Microscope (HPXTM) using monochromatized X-rays has been developed. The module for HPXTM also has shear deformation capability, which enables us to perform HPXTM experiments for microstructure developed by shear deformation under high pressure. A combination of Deformation DIA (D-DIA) and monochromatic X-rays has been developed for quantitative deformation experiments under pressure above 10 GPa. Deformation experiments of e-iron was performed at pressures up to 19 GPa and temperatures up to 700 K.

Directional orientation of birds by the magnetic field under different light conditions

PubMed Central

Wiltschko, Roswitha; Stapput, Katrin; Thalau, Peter; Wiltschko, Wolfgang

2010-01-01

This paper reviews the directional orientation of birds with the help of the geomagnetic field under various light conditions. Two fundamentally different types of response can be distinguished. (i) Compass orientation controlled by the inclination compass that allows birds to locate courses of different origin. This is restricted to a narrow functional window around the total intensity of the local geomagnetic field and requires light from the short-wavelength part of the spectrum. The compass is based on radical-pair processes in the right eye; magnetite-based receptors in the beak are not involved. Compass orientation is observed under ‘white’ and low-level monochromatic light from ultraviolet (UV) to about 565 nm green light. (ii) ‘Fixed direction’ responses occur under artificial light conditions such as more intense monochromatic light, when 590 nm yellow light is added to short-wavelength light, and in total darkness. The manifestation of these responses depends on the ambient light regime and is ‘fixed’ in the sense of not showing the normal change between spring and autumn; their biological significance is unclear. In contrast to compass orientation, fixed-direction responses are polar magnetic responses and occur within a wide range of magnetic intensities. They are disrupted by local anaesthesia of the upper beak, which indicates that the respective magnetic information is mediated by iron-based receptors located there. The influence of light conditions on the two types of response suggests complex interactions between magnetoreceptors in the right eye, those in the upper beak and the visual system. PMID:19864263

Lasers' spectral and temporal profile can affect visual glare disability.

PubMed

Beer, Jeremy M A; Freeman, David A

2012-12-01

Experiments measured the effects of laser glare on visual orientation and motion perception. Laser stimuli were varied according to spectral composition and temporal presentation as subjects identified targets' tilt (Experiment 1) and movement (Experiment 2). The objective was to determine whether the glare parameters would alter visual disruption. Three spectral profiles (monochromatic Green vs. polychromatic White vs. alternating Red-Green) were used to produce a ring of laser glare surrounding a target. Two experiments were performed to measure the minimum contrast required to report target orientation or motion direction. The temporal glare profile was also varied: the ring was illuminated either continuously or discontinuously. Time-averaged luminance of the glare stimuli was matched across all conditions. In both experiments, threshold (deltaL) values were approximately 0.15 log units higher in monochromatic Green than in polychromatic White conditions. In Experiment 2 (motion identification), thresholds were approximately 0.17 log units higher in rapidly flashing (6, 10, or 14 Hz) than in continuous exposure conditions. Monochromatic extended-source laser glare disrupted orientation and motion identification more than polychromatic glare. In the motion task, pulse trains faster than 6 Hz (but below flicker fusion) elevated thresholds more than continuous glare with the same time-averaged luminance. Under these conditions, alternating the wavelength of monochromatic glare over time did not aggravate disability relative to green-only glare. Repetitively flashing monochromatic laser glare induced occasional episodes of impaired motion identification, perhaps resulting from cognitive interference. Interference speckle might play a role in aggravating monochromatic glare effects.

Magnetic Orientation in Birds and Other Animals

NASA Astrophysics Data System (ADS)

Wiltschko, Wolfgang

The use of the geomagnetic field for compass orientation is widespread among animals, with two types of magnetic compass mechanisms described: an shape inclination compass in birds, turtles and salamanders and a shape polarity compass in arthropods, fishes and mammals. Additionally, some vertebrates appear to derive positional information from the total intensity and/or inclination of the geomagnetic field. For magnetoreception by animals, two models are currently discussed, the shape Radical Pair model assuming light-dependent processes by specialized photopigments, and the shape Magnetite hypothesis proposing magnetoreception by crystals of magnetite, Fe304. Behavioral experiments with migratory birds, testing them under monochromatic lights and subjecting them to a brief, strong pulse that could reverse the magnetization of magnetite particles, produced evidence for both mechanisms. However, monochromatic lights affect old, experienced and young birds alike, whereas the pulse affects only experienced birds, leaving young, inexperienced birds unaffected. These observations suggest that a radical pair mechanism provides birds with directional information for their innate magnetic compass and a magnetite-based mechanism possibly mediates information about total intensity for indicating position.

94 Mo(γ,n) and 90Zr(γ,n) cross-section measurements towards understanding the origin of p-nuclei

NASA Astrophysics Data System (ADS)

Meekins, E.; Banu, A.; Karwowski, H.; Silano, J.; Zimmerman, W.; Muller, J.; Rich, G.; Bhike, M.; Tornow, W.; McClesky, M.; Travaglio, C.

2014-09-01

The nucleosynthesis beyond iron of the rarest stable isotopes in the cosmos, the so-called p-nuclei, is one of the forefront topics in nuclear astrophysics. Recently, a stellar source was found that, for the first time, was able to produce both light and heavy p-nuclei almost at the same level as 56Fe, including the most debated 92,94Mo and 96,98Ru; it was also found that there is an important contribution from the p-process nucleosynthesis to the neutron magic nucleus 90Zr. We focus here on constraining the origin of p-nuclei through nuclear physics by studying two key astrophysical photoneutron reaction cross sections for 94Mo(γ,n) and 90Zr(γ,n). Their energy dependencies were measured using quasi-monochromatic photon beams from Duke University's High Intensity Gamma-ray Source facility at the respective neutron threshold energies up to 18 MeV. Preliminary results of these experimental cross sections will be presented along with their comparison to predictions by a statistical model based on the Hauser-Feshbach formalism implemented in codes like TALYS and SMARAGD. The nucleosynthesis beyond iron of the rarest stable isotopes in the cosmos, the so-called p-nuclei, is one of the forefront topics in nuclear astrophysics. Recently, a stellar source was found that, for the first time, was able to produce both light and heavy p-nuclei almost at the same level as 56Fe, including the most debated 92,94Mo and 96,98Ru; it was also found that there is an important contribution from the p-process nucleosynthesis to the neutron magic nucleus 90Zr. We focus here on constraining the origin of p-nuclei through nuclear physics by studying two key astrophysical photoneutron reaction cross sections for 94Mo(γ,n) and 90Zr(γ,n). Their energy dependencies were measured using quasi-monochromatic photon beams from Duke University's High Intensity Gamma-ray Source facility at the respective neutron threshold energies up to 18 MeV. Preliminary results of these experimental cross sections will be presented along with their comparison to predictions by a statistical model based on the Hauser-Feshbach formalism implemented in codes like TALYS and SMARAGD. This research was supported by the Research Corporation for Science Advancement.

High-resolution monochromatic x-ray imaging system based on spherically bent crystals.

PubMed

Aglitskiy, Y; Lehecka, T; Obenschain, S; Bodner, S; Pawley, C; Gerber, K; Sethian, J; Brown, C M; Seely, J; Feldman, U; Holland, G

1998-08-01

We have developed an improved x-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser. A spherically curved quartz crystal (d = .?, R = mm) has been used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the x-ray optical system is 1.7 mum in selected places and 2-3 mum over a larger area. Time-resolved backlit monochromatic images of polystyrene planar targets driven by the Nike facility have been obtained with a spatial resolution of 2.5 mum in selected places and 5 mum over the focal spot of the Nike laser.

[The application of the modern phototherapeutic technologies for the medical rehabilitation of the children].

PubMed

Khan, M A; Chubarova, А I; Pogonchenkova, I V; Rassulova, M A; Sergeenko, E Y; Vakhova, E L; Lyan, N A; Mikitchenko, N A

2017-12-28

This literature review is focused on the application of polychromatic and monochromatic polarized light for the treatment of various diseases of the childhood including those in the newborns and the premature babies. The analysis of the data of scientific research gives evidence of the beneficial effect of polychromatic polarized light on the clinical course of various skin diseases in the newborn children. Moreover, the improved immunological and reparative processes were revealed after the surgical interventions for congenital heart defects in the newborns. The light-induced changes in the skin contribute to the realization of therapeutic effects of polarized polychromatic light in such children's diseases as atopic dermatitis, bronchitis, bronchial asthma, neurogenic urinary bladder dysfunction, and the traumatic injuries of the limbs. The biologically positive physiological effects of monochromatic polarized light are known to contribute to the improvement of the clinical and functional status in the children presenting with bronchial asthma and in the patients frequently suffering from acute respiratory diseases. The versatility of the biological effects of polarized light taken together with the possibility of its application from the first days of the child's life, the short duration of the procedure, the absence of unpleasant sensations and contact between the damaged surface and the device as well as the simplicity of using the equipment determine the promising prospects for the use of the proposed method in the clinical pediatric practice.

Metabolic Reprogramming in Leaf Lettuce Grown Under Different Light Quality and Intensity Conditions Using Narrow-Band LEDs.

PubMed

Kitazaki, Kazuyoshi; Fukushima, Atsushi; Nakabayashi, Ryo; Okazaki, Yozo; Kobayashi, Makoto; Mori, Tetsuya; Nishizawa, Tomoko; Reyes-Chin-Wo, Sebastian; Michelmore, Richard W; Saito, Kazuki; Shoji, Kazuhiro; Kusano, Miyako

2018-05-21

Light-emitting diodes (LEDs) are an artificial light source used in closed-type plant factories and provide a promising solution for a year-round supply of green leafy vegetables, such as lettuce (Lactuca sativa L.). Obtaining high-quality seedlings using controlled irradiation from LEDs is critical, as the seedling health affects the growth and yield of leaf lettuce after transplantation. Because key molecular pathways underlying plant responses to a specific light quality and intensity remain poorly characterised, we used a multi-omics-based approach to evaluate the metabolic and transcriptional reprogramming of leaf lettuce seedlings grown under narrow-band LED lighting. Four types of monochromatic LEDs (one blue, two green and one red) and white fluorescent light (control) were used at low and high intensities (100 and 300 μmol·m -2 ·s -1 , respectively). Multi-platform mass spectrometry-based metabolomics and RNA-Seq were used to determine changes in the metabolome and transcriptome of lettuce plants in response to different light qualities and intensities. Metabolic pathway analysis revealed distinct regulatory mechanisms involved in flavonoid and phenylpropanoid biosynthetic pathways under blue and green wavelengths. Taken together, these data suggest that the energy transmitted by green light is effective in creating a balance between biomass production and the production of secondary metabolites involved in plant defence.

Hot coronal plasma phenomena disclosed, classified and studied in the SPIRIT experiment on CORONAS-F mission

NASA Astrophysics Data System (ADS)

Urnov, Alexander; Kuzin, Sergey; Bogachev, Sergey; Goryaev, Farid; Dennis, Brian; Reva, Anton; Shestov, Sergey; Soloviev, Alexander; Zhitnik, Igor

The advent of XUV full-Sun monochromatic imaging spectroscopy in the SPIRIT experiment on CORONAS-F (2001-2005) helped to reveal highly dynamic 4 -20 MK coronal plasma structures characterized by various sizes from 6" through 0.3 solar radius and lifetimes from several minutes to several days. Due to the high dynamic range (more than four orders of magnitude) of the X-Ray detector, the monochromatic images in the Mg XII ion line at 8.42 ˚ allowed the A whole Sun light curves of the GOES 1-8˚ channel to be decomposed over the temporal flux A profiles of individual X-Ray sources. Thus, the GOES background emission was shown to be the result of a superposition of a series of low intensity "elemental bursts" each lasting for 10-20 min and recurring at different locations on the solar disk. A new phenomenon of small size, short-lived X-ray "hot spots" (hot X-ray bright points, HXBP) has been disclosed in addition to the previously reported giant post-eruptive sources ("spiders"). The classification has been proposed of hot plasma phenomena by their spatial and temporal properties being the "markers" of energy storage and release sites for all observable X-ray sources. It was also shown that these sources are characterized by complex topology rather than by the strength of the magnetic field since they associated only with active region loop systems comprising of more than two spots. Diagnostic techniques developed on the basis of monochromatic and broad band data simultaneously measured on CORONAS-F, GOES, and RHESSI were used to obtain space-time dynamics of the temperature and density content for hot coronal plasma structures in the range logT=6.0 -7.2. A theoretical description of the spider phenomena based on long-duration recurrently flaring giant magneto-plasma formations, is given using the Chandrasekhar-Prendergast model of a spherical magnetic vortex, generalized to account for density perturbations. This model presents a sequence of magnetic toroidal configurations stabilized within a spherical cover by an external potential magnetic field. It reveals remarkable properties that help to explain, by simple physical considerations, how the conditions sufficient for fast and efficient energy release, specific for a weak flare, may take place sporadically without disrupting the whole system. The generalized solution gives a realistic picture of observable phenomena allowing new possibilities for the generation of dissipative flare-like processes in the spherical magnetic vortex, and, thus, providing a natural description of their specific features.

The effects of wavelength on photodegradation depth profiles in Japanese cedar (Cryptomeria japonica D. Don) earlywood

Treesearch

Yutaka Kataoka; Makoto Kiguchi; R. Sam Williams; Philip D. Evans

2006-01-01

FT-IR microscopy was used to depth profile the photodegradation of Japanese cedar earlywood exposed to monochromatic light in the UV and visible ranges (band pass: 20nm). Parallel experiments assessed the transmission of the light through thin sections of Japanese cedar. The depth of photodegradation increased with wavelength up to and including the violet region of...

Measuring noise equivalent irradiance of a digital short-wave infrared imaging system using a broadband source to simulate the night spectrum

NASA Astrophysics Data System (ADS)

Green, John R.; Robinson, Timothy

2015-05-01

There is a growing interest in developing helmet-mounted digital imaging systems (HMDIS) for integration into military aircraft cockpits. This interest stems from the multiple advantages of digital vs. analog imaging such as image fusion from multiple sensors, data processing to enhance the image contrast, superposition of non-imaging data over the image, and sending images to remote location for analysis. There are several properties an HMDIS must have in order to aid the pilot during night operations. In addition to the resolution, image refresh rate, dynamic range, and sensor uniformity over the entire Focal Plane Array (FPA); the imaging system must have the sensitivity to detect the limited night light available filtered through cockpit transparencies. Digital sensor sensitivity is generally measured monochromatically using a laser with a wavelength near the peak detector quantum efficiency, and is generally reported as either the Noise Equivalent Power (NEP) or Noise Equivalent Irradiance (NEI). This paper proposes a test system that measures NEI of Short-Wave Infrared (SWIR) digital imaging systems using a broadband source that simulates the night spectrum. This method has a few advantages over a monochromatic method. Namely, the test conditions provide spectrum closer to what is experienced by the end-user, and the resulting NEI may be compared directly to modeled night glow irradiance calculation. This comparison may be used to assess the Technology Readiness Level of the imaging system for the application. The test system is being developed under a Cooperative Research and Development Agreement (CRADA) with the Air Force Research Laboratory.

Effects of longitudinal chromatic aberration on accommodation and emmetropization.

PubMed

Seidemann, Anne; Schaeffel, Frank

2002-09-01

Less accommodation was found when human subjects read in blue (peak at about 440 nm) than when they read in red light (above 600 nm; [Kroger & Binder, British Journal of Ophthalmology 84 (2000) 890]). On the other hand, emmetropization in chickens did not appear to compensate for the chromatic defocus (385 nm versus 665 nm; [Rohrer, Schaeffel & Zrenner, Journal of Physiology 449 (1992) 363]). The apparently contradictory result was studied in more detail in humans and chickens. Accommodation was measured with an eccentric infrared photorefractor, the PowerRefractor, in human subjects reading under quasi-monochromatic illumination conditions. Chickens were refracted in quasi-monochromatic ambient illumination but with no particular fixation target. In a second experiment, they were also raised in monochromatic light for two days and subsequently refracted both in complete darkness, in monochromatic light, and in white light, both without and with cycloplegia. Consistent with the initial report by Kroger and Binder [British Journal of Ophthalmology 84 (2000) 890], accommodation in human subjects was found to shift in accordance with the chromatic aberration function. An immediate shift in accommodation tonus was also found in the chickens when they were refracted under red and in blue ambient illumination (average difference between refractions in both conditions: 1.26+/-0.54 D, p<0.001 paired t-test). This value is close to the chromatic focus difference between the two wavelengths (1.5 D [Mandelman & Sivak, Vision Research 23 (1983) 1555]). When chickens were raised in blue or red light for two days, and their refractions were subsequently measured in complete darkness, they showed also a difference in refractions (1.41+/-1.00 D; ANOVA: p<0.0012, post hoc t-test: at least p<0.05 among different groups). This difference was no longer significant when they were refracted in white light but became again significant when they were cyclopleged (0.57+/-0.58 D, p=0.039, unpaired t-test). The latter observation makes it unlikely that the difference resulted just from a shift in the resting tonus of accommodation. (1) Imposed chromatic defocus produces a shift in accommodation tonus in both humans and chickens which is, in the case of the chicken, followed by a shift in cycloplegic refractive state into the same direction, (2) the difference to the previous study by Rohrer, Schaeffel and Zrenner [Journal of Physiology 449 (1992) 363] can be explained from the fact that shorter wavelengths were used than in the present study, at which emmetropization was no longer functional and, (3) the small amplitude and the variability of the shifts in refraction do not allow clear statements about the role of the "lag of accommodation" in refractive development but they show that several cone types contribute to emmetropization.

Towards novel compact laser sources for non-invasive diagnostics and treatment

NASA Astrophysics Data System (ADS)

Rafailov, Edik U.; Litvinova, Karina S.; Sokolovski, Sergei G.

2015-08-01

An important field of application of lasers is biomedical optics. Here, they offer great utility for diagnosis, therapy and surgery. For the development of novel methods of laser-based biomedical diagnostics careful study of light propagation in biological tissues is necessary to enhance our understanding of the optical measurements undertaken, increase research and development capacity and the diagnostic reliability of optical technologies. Ultimately, fulfilling these requirements will increase uptake in clinical applications of laser based diagnostics and therapeutics. To address these challenges informative biomarkers relevant to the biological and physiological function or disease state of the organism must be selected. These indicators are the results of the analysis of tissues and cells, such as blood. For non-invasive diagnostics peripheral blood, cells and tissue can potentially provide comprehensive information on the condition of the human organism. A detailed study of the light scattering and absorption characteristics can quickly detect physiological and morphological changes in the cells due to thermal, chemical, antibiotic treatments, etc [1-5]. The selection of a laser source to study the structure of biological particles also benefits from the fact that gross pathological changes are not induced and diagnostics make effective use of the monochromatic directional coherence properties of laser radiation.

An optical fiber guided ultrasonic excitation and sensing system for online monitoring of nuclear power plants

NASA Astrophysics Data System (ADS)

Yang, J.; Lee, H.; Sohn, H.

2012-05-01

This study presents an embedded laser ultrasonic system for pipeline monitoring under high temperature environment. Recently, laser ultrasonics is becoming popular because of their advantageous characteristics such as (a) noncontact inspection, (b) immunity against electromagnetic interference (EMI), and (c) applicability under high temperature. However, the performance of conventional laser ultrasonic techniques for pipeline monitoring has been limited because many pipelines are covered by insulating materials and target surfaces are inaccessible. To overcome the problem, this study designs an embeddable optical fibers and fixing devices that deliver laser beams from laser sources to a target pipe using embedded optical fibers. For guided wave generation, an optical fiber is furnished with a beam collimator for irradiating a laser beam onto a target structure. The corresponding response is measured based on the principle of laser interferometry. Light from a monochromatic source is colliminated and delivered to a target surface by another optical with a focusing module, and reflected light is transmitted back to the interferometer through the same fiber. The feasibility of the proposed system for embedded ultrasonic measurement has been experimentally verified using a pipe specimen under high temperature.

Physiological and genetic characterization of plant growth and gravitropism in LED light sources

NASA Technical Reports Server (NTRS)

Deitzer, Gerald F.

1994-01-01

Among the many problems of growing plants in completely controlled environments, such as those anticipated for the space station and the CELSS program, is the need to provide light that is both adequate for photosynthesis and of proper quality for normal growth and development. NASA scientists and engineers have recently become interested in the possibility of utilizing densely packed, solid state, light emitting diodes (LED's) as a source for this light. Unlike more conventional incandescent or electrical discharge lamps, these sources are highly monochromatic and lack energy in spectral regions thought to be important for normal plant development. In addition, a recent observation by NASA scientist has suggested that infra-red LED's, that are routinely used as photographic safelights for plants grown in darkness, may interact with the ability of plants to detect gravity. In order to establish how plants respond to light from these LED light sources we carried out a series of experiments with known pigment mutants of the model mustard plant, Arabidopsis thaliana, growing in either a gravity field or on a clinostat to simulate a micro-gravity environment. Results indicate that only red light from the 665 nm LED's disrupts the ability of normal wildtype seedlings to detect a gravity stimulus. There was no consistent effect found for the far-red (735 nm) LED's or either of the infrared (880 nm or 935 nm) LED sources but both showed some effect in one or more of the genotypes tested. Of these five members of the phytochrome multigene family in Arabidopsis, only the phytochrome B pigment mutant (hy3) lacked the ability to detect gravity under all conditions. There was no effect of either micro-gravity (clinostat) or the infra-red LED's on the light induced inhibition of hypocotyl elongation. Measurements of the pigment phytochrome in oats also showed no photoconversion by 15 min irradiations with the infra-red LED's. We conclude that phytochrome B is required for the perception of gravity and that only red light is able to disrupt this perception. The infra-red LED's also do not appear to interact with gravity perception in Arabidopsis, but caution should be exercised if infra-red LED's are to be used as photographic safelights for these types of experiments.

Reflection technique for thermal mapping of semiconductors

DOEpatents

Walter, Martin J.

1989-06-20

Semiconductors may be optically tested for their temperatures by illuminating them with tunable monochromatic electromagnetic radiation and observing the light reflected off of them. A transition point will occur when the wavelength of the light corresponds with the actual band gap energy of the semiconductor. At the transition point, the image of the semiconductor will appreciably darken as the light is transmitted through it, rather than being reflected off of it. The wavelength of the light at the transition point corresponds to the actual band gap energy and the actual temperature of the semiconductor.

Photobiology eye safety for horticultural LED lighting: Transmittance performance of eyewear protection using high-irradiant monochromatic LEDs.

PubMed

Wu, Bo-Sen; Lefsrud, Mark G

2018-02-01

Light emitting diodes have slowly gained market share as horticultural lighting systems in greenhouses due to their rapid improvement in color performances and light outputs. These advancements have increased the availability of the full spectrum of visible wavelengths and the corresponding irradiance outputs available to plants. However, light emitting diodes owners have limited information on the proper options for personal eyewear protection as the irradiance levels have increased. The objective of this study was to measure the light transmittance performance of 12 eyewear protection including welding goggles, safety goggles, polarized glasses, and sunglasses across the human visible spectrum (380-740 nm) up to an irradiance level of 1500 W·m -2 from high-irradiant light emitting diodes assemblies. Based on the spectral measurements, certain transmitted spectra exhibited spectrum shifts or an alteration in the bimodal distribution which were different than the light emitting diodes spectra, due to the uneven transmittance efficiencies of the glasses. As for the measured transmittance percentages in two experiments, each type of eyewear protection showed distinct transmittance performances, and the performance of the tested eyewear protection was not impacted by irradiance but was dependent on the wavelength. The mean light transmittance was 1.77% for the welding glasses, 13.12% for the polarized glasses, 15.27% for the safety goggles, and 27.65% for the sunglasses. According to these measured results and the spectral weighting exposure limits from the International Electrotechnical Commission 62471 and EU directive 2006/25, consumers and workers using horticultural lighting can select welding goggles or polarized glasses, to limit the possible ocular impact of the high irradiance of monochromatic light in electrical lighting environment. Sunglasses and safety goggles would not be advised as protection, especially if infrared radiation was used.

Light-dependent processes on the cathode enhance the electrical outputs of sediment microbial fuel cells.

PubMed

Bardarov, Ivo; Mitov, Mario; Ivanova, Desislava; Hubenova, Yolina

2018-02-27

In this study, we explored in details the influence of the light irradiation on the SMFCs electrical outputs. The experiments at both natural and artificial illumination firmly show that during the photoperiods the current grows up. The intensity of the current increase depends on the duration of the photoperiod as well as on the wavelength of the monochromatic light source applied. The highest influence of the light irradiation has been obtained at wavelengths, corresponding to the absorption peaks of essential pigments in the light-harvesting system of oxygenic photosynthesizing microorganisms. The decreased values as well as the discontinued fluctuations of the current as a result of suppressed illumination or substitution of the biocathode with a new one suggest that photosynthesizing microorganisms, co-existing in the cathodic biofilm consortium, contribute to the overall SMFC performance. The microscopic observations confirm the existence of chlorophyll-containing microorganisms on the cathode surface. Though the performed metagenomics DNA analysis has not certified a dominance of photosynthesizing microorganisms, all other results support the hypothesis that the current enhance during the photoperiods is due to the in situ bio-oxygen production on the cathode surface, thus lowering the mass transport limitations for the oxygen reduction reaction. Copyright © 2018 Elsevier B.V. All rights reserved.

[KINETICS OF PHOTO-INDUCED FREE RADICALS IN THE HUMAN HAIR CHESTNUT COLOR AFTER SHORT PERIODS OF RED, GREEN, BLUE AND WHITE LIGHT EXPOSURE].

PubMed

Tskhvediani, N; Chikvaidze, E; Tsibadze, A; Kvachadze, I; Gogoladze, T; Katsitadze, A

2016-04-01

The aim of the study was to investigate the kinetics of photo-induced free radicals in the human hair chestnut color with short-term exposure to visible light in different frequency ranges. Studies carried out on human volunteers aged 17-21 years (n=37). Hairs of volunteers of the study were not treated with dyes and other active cosmetic preparations. Hairs bundled in a bun had a length - 1.5 cm, weight - 40 mg. At the beginning background EPR-spectrum of a sample was measured and then hairs were irradiated with visible light (blue, green, red and white) of different wavelength subsequently; exposure duration - 60 minutes; after the exposure the kinetics of photo-induced free radicals was measured within 60 minutes. The radiation source was selected LED array of the four crystals that provides a nearly monochromatic radiation spectrum having no parasitic infrared and ultraviolet radiations. The studies give a reason to assume that the impact on hairs by visible electromagnetic rays a leading factor is their frequency characteristics: on the one hand - the proximity of the blue light to ultraviolet radiation, and on the other - the red light to the infrared range.

Laboratory simulations of PH3 photolysis in the atmospheres of Jupiter and Saturn

NASA Technical Reports Server (NTRS)

Ferris, J. P.; Khwaja, H.

1985-01-01

The effects of pressure, temperature, light wavelength and intensity, and components of the atmosphere of the Jovian planets on the photolysis of PH3 were experimentally studied. The products of the photolysis, P2H4 and red phosphorus, exhibited little variation when the irradiation experiments were performed under conditions prevalent in Jupiter's atmosphere. No quenching of PH2 radicals by the levels of hydrocarbons present in the Jovian atmosphere was noted. The high partial pressure of hydrogen present on Jupiter should have no effect on the course of the photolysis. The low temperatures on Jupiter and Saturn may result in some condensation of P2H4, but P2H4 had sufficient vapor pressure in the experimental studies at 157 K to be slowly converted to red phosphorus. The products of PH3 photolysis were the same whether a 147, 184.9, or 206.2 nm monochromatic light source or a xenon lamp with a broad spectral output was used.

White-light Interferometry using a Channeled Spectrum: II. Calibration Methods, Numerical and Experimental Results

NASA Technical Reports Server (NTRS)

Zhai, Chengxing; Milman, Mark H.; Regehr, Martin W.; Best, Paul K.

2007-01-01

In the companion paper, [Appl. Opt. 46, 5853 (2007)] a highly accurate white light interference model was developed from just a few key parameters characterized in terms of various moments of the source and instrument transmission function. We develop and implement the end-to-end process of calibrating these moment parameters together with the differential dispersion of the instrument and applying them to the algorithms developed in the companion paper. The calibration procedure developed herein is based on first obtaining the standard monochromatic parameters at the pixel level: wavenumber, phase, intensity, and visibility parameters via a nonlinear least-squares procedure that exploits the structure of the model. The pixel level parameters are then combined to obtain the required 'global' moment and dispersion parameters. The process is applied to both simulated scenarios of astrometric observations and to data from the microarcsecond metrology testbed (MAM), an interferometer testbed that has played a prominent role in the development of this technology.

Cell response to quasi-monochromatic light with different coherence

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

Budagovsky, A V; Solovykh, N V; Budagovskaya, O N

The problem of the light coherence effect on the magnitude of the photoinduced cell response is discussed. The origins of ambiguous interpretation of the known experimental results are considered. Using the biological models, essentially differing in anatomy, morphology and biological functions (acrospires of radish, blackberry microsprouts cultivated in vitro, plum pollen), the effect of statistical properties of quasi-monochromatic light (λ{sub max} = 633 nm) on the magnitude of the photoinduced cell response is shown. It is found that for relatively low spatial coherence, the cell functional activity changes insignificantly. The maximal enhancement of growing processes (stimulating effect) is observed whenmore » the coherence length L{sub coh} and the correlation radius r{sub cor} are greater than the cell size, i.e., the entire cell fits into the field coherence volume. In this case, the representative indicators (germination of seeds and pollen, the spears length) exceeds those of non-irradiated objects by 1.7 – 3.9 times. For more correct assessment of the effect of light statistical properties on photocontrol processes, it is proposed to replace the qualitative description (coherent – incoherent) with the quantitative one, using the determination of spatial and temporal correlation functions and comparing them with the characteristic dimensions of the biological structures, e.g., the cell size. (biophotonics)« less

Effects of White Leds on Growth and Phytonutrients of Outredgeous Romaine Lettuce When Supplemented with Various Monochromatic Wavelengths

NASA Technical Reports Server (NTRS)

Mickens, Matthew; Skoog, Emilie J.; Barnwell, Payton; Massa, Gioia; Wheeler, Raymond

2017-01-01

Growing plants in space will be an essential part of sustaining astronauts during long-range missions. To drive photosynthesis, light-emitting diodes (LEDs) are becoming superior because of their efficiency, longevity, small size, safety, and wavelength versatility. Isolating the effects of certain wavelengths on plant growth when combined with white light is attracting attention. To optimize crop production/quality in space, this study has aimed to configure novel light recipes for the Advanced Plant Habitat currently aboard the International Space Station (ISS). By using white light as a background to maintain normal growth, the addition of monochromatic wavelengths provides a clearer understanding of how each part of the visible spectrum affects plant growth. By growing Outredgeous lettuce under six treatments of White (W) LEDs, W + blue (B), W+ green (G), W + red (R), W + far red (FR), and RGB + FR LEDs with ratios similar to natural sunlight, this investigation has assessed differences in biomass, morphology, chlorophyll, and the synthesis of key phytonutrients. The potential for Outredgeous to produce anthocyanin, lutein, potassium, magnesium, and iron is paramount to maintaining astronaut health. The crop responses to each treatment have been evaluated and the optimal LED combination for both plant yield and nutrient content will be presented.

Excimer Laser Curing Of Polymer Coatings

NASA Astrophysics Data System (ADS)

Klick, David; Akerman, M. Alfred; Paul, George L.; Supurovic, Darko; Tsuda, Haruki

1988-12-01

The use of the excimer laser as a source of energy for photo-assisted curing of industrial polymeric coatings was investigated. Presently, UV lamps are sometimes used to excite a photoinitiating molecule mixed with the starting monomers and oligomers of a coating. The resulting polymeric chain reaction multiplies the effect of the initial photons, making economical use of the light source. The high cost of laser photons may thus be justifiable if lasers provide advantages over lamps. A series of visibly transparent 7 μm coatings (a typical thickness for 'slick' magazine coatings) with various photoinitiators, monomers, and oligomers was illuminated with excimer laser light of various wavelengths, fluences, and pulse repetition rates. For the optimum parameters, it was found that the laser had large advantages in curing speed over existing UV lamp processes, due to its monochromaticity. Pigmented coatings (20 μm TiO2 mixtures typical of appliance or automotive finishes) are not easily cured with UV lamps due to the inability of light to penetrate the absorbing and scattering pigmented layer. However, economically-viable cure rates were achieved with certain photoinitiators using a tunable excimer-pumped dye laser. A prototype of such a laser suitable for factory use was built and used to cure these coatings. Results are scaled to a factory situation, and costs are calculated to show the advantages of the laser method over currently used processes.

Continuous plasma laser. [method and apparatus for producing intense, coherent, monochromatic light from low temperature plasma

NASA Technical Reports Server (NTRS)

Libby, W. F.; Jensen, C. A.; Wood, L. L. (Inventor)

1977-01-01

The apparatus includes a housing for confining a gas at subatmospheric pressure and including a set of reflectors defining an optical cavity. At least one anode and cathode are positioned within the gas. First control means control the voltage applied to the anode and second control means independently control the temperature of the cathode. The pressure of the gas is controlled by a third control means. An intense monochromatic output is achieved by confining the gas in the housing at a controlled pre-determined reduced pressure, independently controlling the temperature of the electron emitting cathode and applying predetermined controlled low voltage to the anode.

Modulation of phytochrome signaling networks for improved biomass accumulation using a bioenergy crop model

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

Mockler, Todd C.

Plant growth and development, including stem elongation, flowering time, and shade-avoidance habits, are affected by wavelength composition (i.e., light quality) of the light environment. the molecular mechanisms underlying light perception and signaling pathways in plants have been best characterized in Arabidopsis thaliana where dozens of genes have been implicated in converging, complementary, and antagonistic pathways communicating light quality cues perceived by the phytochrome (red/far-red) cryptochrome (blue) and phototropin (blue) photorecptors. Light perception and signaling have been studied in grasses, including rice and sorghum but in much less detail than in Arabidopsis. During the course of the Mocker lab's DOE-funded wrokmore » generating a gene expression atlas in Brachypodium distachyon we observed that Brachypodium plants grown in continuous monochromatic red light or continuous white light enriched in far-red light accumulated significantly more biomass and exhibited significantly greater seed yield than plants grown in monochromatic blue light or white light. This phenomenon was also observed in two other grasses, switchgrass and rice. We will systematically manipulate the expression of genes predicted to function in Brachypodium phytochrome signaling and assess the phenotypic consequences in transgenic Brachypodium plants in terms of morphology, stature, biomass accumulation, and cell wall composition. We will also interrogate direct interactions between candidate phytochrome signaling transcription factors and target promoters using a high-throughput yeast one-hybrid system. Brachypodium distachyon has emerged as a model grass species and is closely related to candidate feedstock crops for bioethanol production. Identification of genes capable of modifying growth characteristics of Brachypodium, when misexpressed, in particular increasing biomass accumulation, by modulating photoreceptor signaling will provide valuable candidates for manipulation in biomass and biofuel feedstock grass crops through targeted breeding or engineering efforts.« less

Inactivation of B. subtilis spores by low pressure plasma—influence of optical filters and photon/particle fluxes on the inactivation efficiency

NASA Astrophysics Data System (ADS)

Fiebrandt, Marcel; Hillebrand, Bastian; Lackmann, Jan-Wilm; Raguse, Marina; Moeller, Ralf; Awakowicz, Peter; Stapelmann, Katharina

2018-01-01

Inactivation experiments were performed with Bacillus subtilis spores in a low pressure double inductively coupled plasma (DICP) system. Argon, nitrogen and oxygen at 5 Pa were used as feed gas to change the emission spectrum in the range of 100 nm to 400 nm, as well as between radical and metastable densities. Optical filters were applied, to block particles and selected wavelengths from the spores. By determining absolute photon fluxes, the sporicidal efficiency of various wavelength ranges was evaluated. The results showed good agreement with other plasma experiments, as well as with monochromatic light inactivation experiments from a synchrotron. The findings indicated that the inactivation rate constants of broadband plasma emission and monochromatic light were identical, and that no synergistic effect exists. Furthermore, the influence of radicals, ions and metastables on the inactivation efficiency was of minor importance in the set-up used, and radiation was the main reason for spore inactivation.

Hanle effect in nonmonochromatic laser light

NASA Astrophysics Data System (ADS)

Ryan, R. E.; Bergeman, T. H.

1991-06-01

We report results of calculations on the Hanle effect in a J=0⇆J=1 atomic transition with three types of model fluctuating light fields: (a) the Brownian-motion phase-diffusion field, as produced in recent experiments by Arnett et al. [Phys. Rev. A 41, 2580 (1990)]; (b) Gaussian amplitude fluctuations; and (c) the chaotic field model, in which real and imaginary parts of the electric-field amplitude fluctuate. For the stochastic density-matrix equations, we use methods developed by Zoller and co-workers [e.g., Dixit, Zoller, and Lambropoulos, Phys. Rev. A 21, 1289 (1980)] employing the Fokker-Planck operator and leading to matrix continued-fraction expansions. The Hanle effect is of interest as a prototype for multisublevel atomic transitions. The width of the Hanle dip at zero magnetic field reflects the tendency of the light field to preserve the coherence between excited-state sublevels. For monochromatic light, the Hanle dip width increases as the square root of light intensity. When the laser bandwidth increases, power broadening of the coherence dip normally decreases. However, with the Brownian-motion phase-diffusion model, if the laser spectral profile is nearly Gaussian, broadening the laser up to several times the natural width of the atomic line does not diminish the Hanle dip width. With amplitude fluctuations, even in the limit of monochromatic light, power broadening of the Hanle dip with intensity is reduced by one-third to one-half depending on the particular model.

Biological particle identification apparatus

DOEpatents

Salzman, Gary C.; Gregg, Charles T.; Grace, W. Kevin; Hiebert, Richard D.

1989-01-01

An apparatus and method for making multiparameter light scattering measurements from suspensions of biological particles is described. Fourteen of the sixteen Mueller matrix elements describing the particles under investigation can be substantially individually determined as a function of scattering angle and probing radiations wavelength, eight elements simultaneously for each of two apparatus configurations using an apparatus which incluees, in its simplest form, two polarization modulators each operating at a chosen frequency, one polarizer, a source of monochromatic electromagnetic radiation, a detector sensitive to the wavelength of radiation employed, eight phase-sensitive detectors, and appropriate electronics. A database of known biological particle suspensions can be assembled, and unknown samples can be quickly identified once measurements are performed on it according to the teachings of the subject invention, and a comparison is made with the database.

Theoretical and experimental determination of L -shell decay rates, line widths, and fluorescence yields in Ge

NASA Astrophysics Data System (ADS)

Guerra, M.; Sampaio, J. M.; Madeira, T. I.; Parente, F.; Indelicato, P.; Marques, J. P.; Santos, J. P.; Hoszowska, J.; Dousse, J.-Cl.; Loperetti, L.; Zeeshan, F.; Müller, M.; Unterumsberger, R.; Beckhoff, B.

2015-08-01

Fluorescence yields (FYs) for the Ge L shell were determined by a theoretical and two experimental groups within the framework of the International Initiative on X-Ray Fundamental Parameters Collaboration. Calculations were performed using the Dirac-Fock method, including relativistic and QED corrections. The experimental value of the L3FY ωL 3 was determined at the Physikalisch-Technische Bundesanstalt undulator beamline of the synchrotron radiation facility BESSY II in Berlin, Germany, and the L α1 ,2 and L β1 line widths were measured at the Swiss Light Source, Paul Scherrer Institute, Switzerland, using monochromatized synchrotron radiation and a von Hamos x-ray crystal spectrometer. The measured fluorescence yields and line widths are compared to the corresponding calculated values.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: An optical boiler generating singlet oxygen O2 (a1Δg)

NASA Astrophysics Data System (ADS)

Lipatov, N. I.; Biryukov, A. S.; Gulyamova, E. S.

2008-12-01

An ecologically perfect generator of singlet oxygen O2 (a1Δg) is proposed which fundamentally differs from existing singlet-oxygen generators. Excited O2 (a1Δg) molecules are generated due to interaction of the O2 (X3Σ-g) molecules with a quasi-monochromatic field, which is supplied from an external source to a closed volume — an optical boiler containing oxygen. It is shown that, by pumping continuously the optical boiler by the light field of power ~3×105 W, it is possible to accumulate up to 40% of singlet oxygen (O2(b1Σ+g)) + (O2 (a1Δg)) in the boiler volume during ~10-2 s.

Micron Scale Mineralogy

NASA Astrophysics Data System (ADS)

Caldwell, W. A.; Tamura, N.; Celestre, R. S.; Padmore, H. A.; Patel, J. R.

2002-12-01

Although x-ray diffraction has been used for nearly a century as the mineralogist's definitive tool in determining crystalline structures, it has proved impossible to use this technique to spatially resolve the highly heterogeneous nature of many minerals at the mesoscopic level. Due to recent revolutions in the brightness of x-ray sources and in our ability to focus x-rays, we can now carry out conventional monochromatic rotation crystallography as well as Laue diffraction with sub-micron spatial resolution and produce maps of orientation, strain, mineral type, and even chemical speciation over tens of microns in a short amount of time. We have pioneered the development of these techniques at the 3rd generation synchrotron radiation source (Advanced Light Source) in Berkeley, and will describe their application to understanding the structure of a quartz-geode. Our results show the manner in which grain structure and texture change as a function of distance from the cavity wall and are compared with models of crystal growth in such systems. This example highlights the great utility of a synchrotron based x-ray micro-diffraction beamline and the possibilities it opens to the mineralogist.

Pupillary response to direct and consensual chromatic light stimuli.

PubMed

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

2016-02-01

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

Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light.

PubMed

Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

2016-01-01

Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m(-2)⋅s(-1) irradiance for a 16 h⋅d(-1) photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (A max) and photosynthetic rate (P n) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. P n and A max under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between P n and shoot dry weight accumulation.

Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light

PubMed Central

Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

2016-01-01

Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m−2⋅s−1 irradiance for a 16 h⋅d−1 photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (Amax) and photosynthetic rate (Pn) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. Pn and Amax under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between Pn and shoot dry weight accumulation. PMID:27014285

2D Measurements of the Balmer Series in Proto-MPEX using a Fast Visible Camera Setup

NASA Astrophysics Data System (ADS)

Lindquist, Elizabeth G.; Biewer, Theodore M.; Ray, Holly B.

2017-10-01

The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) is a linear plasma device with densities up to 1020 m-3 and temperatures up to 20 eV. Broadband spectral measurements show the visible emission spectra are solely due to the Balmer lines of deuterium. Monochromatic and RGB color Sanstreak SC1 Edgertronic fast visible cameras capture high speed video of plasmas in Proto-MPEX. The color camera is equipped with a long pass 450 nm filter and an internal Bayer filter to view the Dα line at 656 nm on the red channel and the Dβ line at 486 nm on the blue channel. The monochromatic camera has a 434 nm narrow bandpass filter to view the Dγ intensity. In the setup, a 50/50 beam splitter is used so both cameras image the same region of the plasma discharge. Camera images were aligned to each other by viewing a grid ensuring 1 pixel registration between the two cameras. A uniform intensity calibrated white light source was used to perform a pixel-to-pixel relative and an absolute intensity calibration for both cameras. Python scripts that combined the dual camera data, rendering the Dα, Dβ, and Dγ intensity ratios. Observations from Proto-MPEX discharges will be presented. This work was supported by the US. D.O.E. contract DE-AC05-00OR22725.

CT with monochromatic synchrotron x rays and its potential in clinical research

NASA Astrophysics Data System (ADS)

Dilmanian, F. Avraham; Wu, Xiaoye; Ren, Baorui; Button, Terry M.; Chapman, L. D.; Dobbs, John M.; Huang, Xiaoling; Nickoloff, Edward L.; Parsons, Edward C., Jr.; Petersen, Michael J.; Thomlinson, William C.; Zhong, Zhong

1997-10-01

A monochromatic CT for imaging the human head and neck is being developed at the National Synchrotron Light Source. We compared the performance of this system, multiple energy computed tomography (MECT), with that of a conventional CT (CCT) using phantoms. The advantage in image contrast of MECT, with its beam energy tuned just above the K-edge of contrast element, over CCT carried out at 120 kVp, was approximately equal to 3.2-fold for iodine and approximately equal to 2.2 fold for gadolinium. Image noise was compared by simulations because this comparison requires matching the spatial resolutions of the two systems. Simulations at a 3- rad dose and 3-mm slice height on an 18-cm-diameter acrylic phantom, with MECT operating at 60.5 keV, showed that image noise for MECT was 1.4 HU vs. 1.8 HU for CCT. Simulations in the dual-energy quantitative CT mode showed a two-fold advantage for MECT in image noise, as well as its superior quantification. MECT operated in the planar mode revealed fatty tissue in the body of a rat using xenon K-edge subtraction. Our initial pan for clinical application of the system is to image the composition of carotid artery plaques non-invasively, separating the plaques' main constituents: the fatty, fibrous, and calcified tissues.

Structure of polarization singularities of a light beam at triple frequency generated in isotropic medium by singularly polarized beam.

PubMed

Grigoriev, K S; Ryzhikov, P S; Cherepetskaya, E B; Makarov, V A

2017-10-16

The components of electric field of the third harmonic beam, generated in isotropic medium with cubic nonlinearity by a monochromatic light beam carrying polarization singularity of an arbitrary type, are found analytically. The relation between C-points characteristics in the fundamental and signal beams are determined, as well as the impact of the phase mismatch on the shape of the C-lines.

Solution processed, white emitting tandem organic light-emitting diodes with inverted device architecture.

PubMed

Höfle, Stefan; Schienle, Alexander; Bernhard, Christoph; Bruns, Michael; Lemmer, Uli; Colsmann, Alexander

2014-08-13

Fully solution processed monochromatic and white-light emitting tandem or multi-photon polymer OLEDs with an inverted device architecture have been realized by employing WO3 /PEDOT:PSS/ZnO/PEI charge carrier generation layers. The luminance of the sub-OLEDs adds up in the stacked device indicating multi-photon emission. The white OLEDs exhibit a CRI of 75. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrahigh Pressure Dynamic Compression

NASA Astrophysics Data System (ADS)

Duffy, T. S.

2017-12-01

Laser-based dynamic compression provides a new opportunity to study the lattice structure and other properties of geological materials to ultrahigh pressure conditions ranging from 100 - 1000 GPa (1 TPa) and beyond. Such studies have fundamental applications to understanding the Earth's core as well as the interior structure of super-Earths and giant planets. This talk will review recent dynamic compression experiments using high-powered lasers on materials including Fe-Si, MgO, and SiC. Experiments were conducted at the Omega laser (University of Rochester) and the Linac Coherent Light Source (LCLS, Stanford). At Omega, laser drives as large as 2 kJ are applied over 10 ns to samples that are 50 microns thick. At peak compression, the sample is probed with quasi-monochromatic X-rays from a laser-plasma source and diffraction is recorded on image plates. At LCLS, shock waves are driven into the sample using a 40-J laser with a 10-ns pulse. The sample is probed with X-rays form the LCLS free electron laser providing 1012 photons in a monochromatic pulse near 10 keV energy. Diffraction is recorded using pixel array detectors. By varying the delay between the laser and the x-ray beam, the sample can be probed at various times relative to the shock wave transiting the sample. By controlling the shape and duration of the incident laser pulse, either shock or ramp (shockless) loading can be produced. Ramp compression produces less heating than shock compression, allowing samples to be probed to ultrahigh pressures without melting. Results for iron alloys, oxides, and carbides provide new constraints on equations of state and phase transitions that are relevant to the interior structure of large, extrasolar terrestrial-type planets.

Broadband Phase Retrieval for Image-Based Wavefront Sensing

NASA Technical Reports Server (NTRS)

Dean, Bruce H.

2007-01-01

A focus-diverse phase-retrieval algorithm has been shown to perform adequately for the purpose of image-based wavefront sensing when (1) broadband light (typically spanning the visible spectrum) is used in forming the images by use of an optical system under test and (2) the assumption of monochromaticity is applied to the broadband image data. Heretofore, it had been assumed that in order to obtain adequate performance, it is necessary to use narrowband or monochromatic light. Some background information, including definitions of terms and a brief description of pertinent aspects of image-based phase retrieval, is prerequisite to a meaningful summary of the present development. Phase retrieval is a general term used in optics to denote estimation of optical imperfections or aberrations of an optical system under test. The term image-based wavefront sensing refers to a general class of algorithms that recover optical phase information, and phase-retrieval algorithms constitute a subset of this class. In phase retrieval, one utilizes the measured response of the optical system under test to produce a phase estimate. The optical response of the system is defined as the image of a point-source object, which could be a star or a laboratory point source. The phase-retrieval problem is characterized as image-based in the sense that a charge-coupled-device camera, preferably of scientific imaging quality, is used to collect image data where the optical system would normally form an image. In a variant of phase retrieval, denoted phase-diverse phase retrieval [which can include focus-diverse phase retrieval (in which various defocus planes are used)], an additional known aberration (or an equivalent diversity function) is superimposed as an aid in estimating unknown aberrations by use of an image-based wavefront-sensing algorithm. Image-based phase-retrieval differs from such other wavefront-sensing methods, such as interferometry, shearing interferometry, curvature wavefront sensing, and Shack-Hartmann sensing, all of which entail disadvantages in comparison with image-based methods. The main disadvantages of these non-image based methods are complexity of test equipment and the need for a wavefront reference.

Color speckle in laser displays

NASA Astrophysics Data System (ADS)

Kuroda, Kazuo

2015-07-01

At the beginning of this century, lighting technology has been shifted from discharge lamps, fluorescent lamps and electric bulbs to solid-state lighting. Current solid-state lighting is based on the light emitting diodes (LED) technology, but the laser lighting technology is developing rapidly, such as, laser cinema projectors, laser TVs, laser head-up displays, laser head mounted displays, and laser headlamps for motor vehicles. One of the main issues of laser displays is the reduction of speckle noise1). For the monochromatic laser light, speckle is random interference pattern on the image plane (retina for human observer). For laser displays, RGB (red-green-blue) lasers form speckle patterns independently, which results in random distribution of chromaticity, called color speckle2).

Optical system for determining physical characteristics of a solar cell

DOEpatents

Sopori, Bhushan L.

2001-01-01

The invention provides an improved optical system for determining the physical characteristics of a solar cell. The system comprises a lamp means for projecting light in a wide solid-angle onto the surface of the cell; a chamber for receiving the light through an entrance port, the chamber having an interior light absorbing spherical surface, an exit port for receiving a beam of light reflected substantially normal to the cell, a cell support, and an lower aperture for releasing light into a light absorbing baffle; a means for dispersing the reflection into monochromatic components; a means for detecting an intensity of the components; and a means for reporting the determination.

How Monochromatic Is Laser Light?

ERIC Educational Resources Information Center

Jacobs, Stephen F.

1979-01-01

Presents two derivations of the fundamental laser linewidth that have been used successfully in introductory physics courses. The cause of the finite linewidth is identified with phase fluctuations in the electric field due to spontaneous emissions. A factor of 2 discrepancy between the energy and field analysis is explained. (Author/GA)

Challenges of UV light processing of low UVT foods and beverages

NASA Astrophysics Data System (ADS)

Koutchma, Tatiana

2010-08-01

Ultraviolet (UV) technology holds promise as a low cost non-thermal alternative to heat pasteurization of liquid foods and beverages. However, its application for foods is still limited due to low UV transmittance (LUVT). LUVT foods have a diverse range of chemical (pH, Brix, Aw), physical (density and viscosity) and optical properties (absorbance and scattering) that are critical for systems and process designs. The commercially available UV sources tested for foods include low and medium pressure mercury lamps (LPM and MPM), excimer and pulsed lamps (PUV). The LPM and excimer lamps are monochromatic sources whereas emission of MPM and PUV is polychromatic. The optimized design of UV-systems and UV-sources with parameters that match to specific product spectra have a potential to make UV treatments of LUVT foods more effective and will serve its further commercialization. In order to select UV source for specific food application, processing effects on nutritional, quality, sensorial and safety markers have to be evaluated. This paper will review current status of UV technology for food processing along with regulatory requirements. Discussion of approaches and results of measurements of chemico-physical and optical properties of various foods (fresh juices, milk, liquid whey proteins and sweeteners) that are critical for UV process and systems design will follow. Available UV sources did not prove totally effective either resulting in low microbial reduction or UV over-dosing of the product thereby leading to sensory changes. Beam shaping of UV light presents new opportunities to improve dosage uniformity and delivery of UV photons in LUVT foods.

CITIUS: An infrared-extreme ultraviolet light source for fundamental and applied ultrafast science

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

Grazioli, C.; Gauthier, D.; Ivanov, R.

2014-02-15

We present the main features of CITIUS, a new light source for ultrafast science, generating tunable, intense, femtosecond pulses in the spectral range from infrared to extreme ultraviolet (XUV). The XUV pulses (about 10{sup 5}-10{sup 8} photons/pulse in the range 14-80 eV) are produced by laser-induced high-order harmonic generation in gas. This radiation is monochromatized by a time-preserving monochromator, also allowing one to work with high-resolution bandwidth selection. The tunable IR-UV pulses (10{sup 12}-10{sup 15} photons/pulse in the range 0.4-5.6 eV) are generated by an optical parametric amplifier, which is driven by a fraction of the same laser pulse thatmore » generates high order harmonics. The IR-UV and XUV pulses follow different optical paths and are eventually recombined on the sample for pump-probe experiments. We also present the results of two pump-probe experiments: with the first one, we fully characterized the temporal duration of harmonic pulses in the time-preserving configuration; with the second one, we demonstrated the possibility of using CITIUS for selective investigation of the ultra-fast dynamics of different elements in a magnetic compound.« less

Coupled Mode Formalism: Connecting Phasor, Matrix, and Geometrical Approaches

DTIC Science & Technology

2014-05-30

the Poincare sphere in classical optics, and was generalized to incoherent light as the Stokes and Mueller approach [4]. The Stokes description reduces...to the Poincare sphere description when one treats monochromatic light, and we restrict ourselves to this case. Background There are several...waves, cast as plane waves of the form g(z, t) = f(z − vt) = Aej(ω t −k z) , (1) namely a sinusoidal wave travelling in the positive z direction at phase

Development of ultrahigh-resolution inelastic x-ray scattering optics

NASA Astrophysics Data System (ADS)

Huang, Xian-Rong; Zhong, Zhong; Cai, Yong Q.; Coburn, S.

2008-08-01

One of the major goals of the National Synchrotron Light Source II project is to achieve ultrahigh energy resolution up to 0.1 meV for medium-energy inelastic X-ray scattering spectroscopy based on the angular dispersion optics employing extremely asymmetric backscattering geometry. In this papaer, we describe the complete monochromatization mechanisms underlying the new optics. We have also designed and tested a CDW-CDW prototype under ambient condition, with which we have successfully demonstrated the important angular dispersion effect, the Borrman enhanced transmission effect, and other optical principles involved in every step of the entire diffraction process, and found good agreement with the theoretical expectations. These studies indicate that the new optics are feasible in principle but face some technical challenges that need to be solved by our future systematic research and development activities before their practical applications.

Low-energy antikaon-nuclei interactions studies by AMADEUS: from QCD with strangeness to neutron stars

NASA Astrophysics Data System (ADS)

Piscicchia, K.; Curceanu, C.; Cargnelli, M.; Del Grande, R.; Fabbietti, L.; Marton, J.; Scordo, A.; Sirghi, D.; Tucakovic, I.; Vazquez Doce, O.; Wycech, S.; Zmeskal, J.; Mandaglio, G.; Martini, M.; Moskal, P.

2018-01-01

The AMADEUS collaboration aims to provide unique quality results from K- hadronic interactions in light nuclear targets, in order to solve fundamental open questions in the non-perturbative strangeness QCD sector, like the controversial nature of the Λ(1405) state, the yield of hyperon formation below threshold, the yield and shape of multi-nucleon K- absorption, processes which are intimately connected to the possible existence of exotic antikaon multi-nucleon clusters and to the role of strangeness in neutron stars. AMADEUS takes advantage of the DAΦNE collider, which provides a unique source of monochromatic low-momentum kaons and exploits the KLOE detector as an active target, in order to obtain excellent acceptance and resolution data for K- nuclear capture on H, 4He, 9Be and 12C, both at-rest and in-flight.

Melanopsin (Opn4) requirement for normal light-induced circadian phase shifting.

PubMed

Panda, Satchidananda; Sato, Trey K; Castrucci, Ana Maria; Rollag, Mark D; DeGrip, Willem J; Hogenesch, John B; Provencio, Ignacio; Kay, Steve A

2002-12-13

The master circadian oscillator in the hypothalamic suprachiasmatic nucleus is entrained to the day/night cycle by retinal photoreceptors. Melanopsin (Opn4), an opsin-based photopigment, is a primary candidate for photoreceptor-mediated entrainment. To investigate the functional role of melanopsin in light resetting of the oscillator, we generated melanopsin-null mice (Opn4-/-). These mice entrain to a light/dark cycle and do not exhibit any overt defect in circadian activity rhythms under constant darkness. However, they display severely attenuated phase resetting in response to brief pulses of monochromatic light, highlighting the critical role of melanopsin in circadian photoentrainment in mammals.

Direct imaging of slow, stored and stationary EIT polaritons

NASA Astrophysics Data System (ADS)

Campbell, Geoff T.; Cho, Young-Wook; Su, Jian; Everett, Jesse; Robins, Nicholas; Lam, Ping Koy; Buchler, Ben

2017-09-01

Stationary and slow light effects are of great interest for quantum information applications. Using laser-cooled Rb87 atoms, we performed side imaging of our atomic ensemble under slow and stationary light conditions, which allows direct comparison with numerical models. The polaritons were generated using electromagnetically induced transparency (EIT), with stationary light generated using counter-propagating control fields. By controlling the power ratio of the two control fields, we show fine control of the group velocity of the stationary light. We also compare the dynamics of stationary light using monochromatic and bichromatic control fields. Our results show negligible difference between the two situations, in contrast to previous work in EIT-based systems.

Melatonin modulates monochromatic light-induced melatonin receptor expression in the hypothalamus of chicks.

PubMed

Zhang, Liwei; Chen, Funing; Cao, Jing; Dong, Yulan; Wang, Zixu; Chen, Yaoxing

2017-09-01

To study the mechanism of the effect of monochromatic light on physiological function in chicken, a total of 192 newly hatched chicks were randomly divided into intact, sham-operated and pinealectomy groups then exposed to white light (WL), red light (RL), green light (GL) and blue light (BL) using a light-emitting diode (LED) system for two weeks. At P14, the hypothalami were immediately collected for immunohistochemical staining of melatonin receptor subtypes (Mel1a and Mel1b) and detection of Mel1a and Mel1b expressions using RT-PCR and western blot. Immunohistochemical staining of the hypothalamus showed that the Mel1a-ir cells were distributed in the preoptic area (POA), nucleus preopticus periventricularis (POP) and suprachiasmatic nuclei (SCN), and the Mel1b-ir cells were presented in the POA and SCN. Analysis of RT-PCR and western blot showed that the mRNA and protein levels of Mel1a and Mel1b in the hypothalamus of chick exposed to GL were increased by 10.7-29.3%, 9.18-35.9% and 8.97-27.3% compared to those in the chicks exposed to WL (P=0.029-0.002), RL (P=0.027-0.001) and BL (P=0.038-0.007) in the intact group, respectively. After pinealectomy, however, these parameters decreased and there were no significant differences among the WL, RL, GL and BL groups. These findings suggested that melatonin plays a critical role in GL illumination-enhanced Mel1a and Mel1b expressions in the hypothalamus of chicks. Copyright © 2017 Elsevier GmbH. All rights reserved.

Effect of monochromatic light on circadian rhythmic expression of clock genes in the hypothalamus of chick.

PubMed

Jiang, Nan; Wang, Zixu; Cao, Jing; Dong, Yulan; Chen, Yaoxing

2017-08-01

To clarify the effect of monochromatic light on circadian clock gene expression in chick hypothalamus, a total 240 newly hatched chickens were reared under blue light (BL), green light (GL), red light (RL) and white light (WL), respectively. On the post-hatched day 14, 24-h profiles of seven core clock genes (cClock, cBmal1, cBmal2, cCry1, cCry2, cPer2 and cPer3) were measured at six time points (CT 0, CT 4, CT 8, CT 12, CT 16, CT 20, circadian time). We found all these clock genes expressed with a significant rhythmicity in different light wavelength groups. Meanwhile, cClock and cBmal1 showed a high level under GL, and followed a corresponding high expression of cCry1. However, RL decreased the expression levels of these genes. Be consistent with the mRNA level, CLOCK and BMAL1 proteins also showed a high level under GL. The CLOCK-like immunoreactive neurons were observed not only in the SCN, but also in the non-SCN brain region such as the nucleus anterior medialis hypothalami, the periventricularis nucleus, the paraventricular nucleus and the median eminence. All these results are consistent with the auto-regulatory circadian feedback loop, and indicate that GL may play an important role on the circadian time generation and development in the chick hypothalamus. Our results also suggest that the circadian clock in the chick hypothalamus such as non-SCN brain region were involved in the regulation of photo information. Copyright © 2017 Elsevier B.V. All rights reserved.

Dichromatic Colour Vision in Wallabies as Characterised by Three Behavioural Paradigms

PubMed Central

Ebeling, Wiebke; Hemmi, Jan M.

2014-01-01

Despite lacking genetic evidence of a third cone opsin in the retina of any Australian marsupial, most species tested so far appear to be trichromatic. In the light of this, we have re-examined colour vision of the tammar wallaby which had previously been identified as a dichromat. Three different psychophysical tests, based on an operant conditioning paradigm, were used to confirm that colour perception in the wallaby can be predicted and conclusively explained by the existence of only two cone types. Firstly, colour-mixing experiments revealed a Confusion Point between the three primary colours of a LCD monitor that can be predicted by the cone excitation ratio of the short- and middle-wavelength sensitive cones. Secondly, the wavelength discrimination ability in the wallaby, when tested with monochromatic stimuli, was found to be limited to a narrow range between 440 nm and 500 nm. Lastly, an experiment designed to test the wallaby’s ability to discriminate monochromatic lights from a white light provided clear evidence for a Neutral Point around 485 nm where discrimination consistently failed. Relative colour discrimination seemed clearly preferred but it was possible to train a wallaby to perform absolute colour discriminations. The results confirm the tammar wallaby as a dichromat, and so far the only behaviourally confirmed dichromat among the Australian marsupials. PMID:24489742

Dichromatic colour vision in wallabies as characterised by three behavioural paradigms.

PubMed

Ebeling, Wiebke; Hemmi, Jan M

2014-01-01

Despite lacking genetic evidence of a third cone opsin in the retina of any Australian marsupial, most species tested so far appear to be trichromatic. In the light of this, we have re-examined colour vision of the tammar wallaby which had previously been identified as a dichromat. Three different psychophysical tests, based on an operant conditioning paradigm, were used to confirm that colour perception in the wallaby can be predicted and conclusively explained by the existence of only two cone types. Firstly, colour-mixing experiments revealed a Confusion Point between the three primary colours of a LCD monitor that can be predicted by the cone excitation ratio of the short- and middle-wavelength sensitive cones. Secondly, the wavelength discrimination ability in the wallaby, when tested with monochromatic stimuli, was found to be limited to a narrow range between 440 nm and 500 nm. Lastly, an experiment designed to test the wallaby's ability to discriminate monochromatic lights from a white light provided clear evidence for a Neutral Point around 485 nm where discrimination consistently failed. Relative colour discrimination seemed clearly preferred but it was possible to train a wallaby to perform absolute colour discriminations. The results confirm the tammar wallaby as a dichromat, and so far the only behaviourally confirmed dichromat among the Australian marsupials.

Adaptive ophthalmologic system

DOEpatents

Olivier, Scot S.; Thompson, Charles A.; Bauman, Brian J.; Jones, Steve M.; Gavel, Don T.; Awwal, Abdul A.; Eisenbies, Stephen K.; Haney, Steven J.

2007-03-27

A system for improving vision that can diagnose monochromatic aberrations within a subject's eyes, apply the wavefront correction, and then enable the patient to view the results of the correction. The system utilizes a laser for producing a beam of light; a corrector; a wavefront sensor; a testing unit; an optic device for directing the beam of light to the corrector, to the retina, from the retina to the wavefront sensor, and to the testing unit; and a computer operatively connected to the wavefront sensor and the corrector.

Three-dimensional monochromatic x-ray CT

NASA Astrophysics Data System (ADS)

Saito, Tsuneo; Kudo, Hiroyuki; Takeda, Tohoru; Itai, Yuji; Tokumori, Kenji; Toyofuku, Fukai; Hyodo, Kazuyuki; Ando, Masami; Nishimura, Ktsuyuki; Uyama, Chikao

1995-08-01

In this paper, we describe a 3D computed tomography (3D CT) using monochromatic x-rays generated by synchrotron radiation, which performs a direct reconstruction of 3D volume image of an object from its cone-beam projections. For the develpment of 3D CT, scanning orbit of x-ray source to obtain complete 3D information about an object and corresponding 3D image reconstruction algorithm are considered. Computer simulation studies demonstrate the validities of proposed scanning method and reconstruction algorithm. A prototype experimental system of 3D CT was constructed. Basic phantom examinations and specific material CT image by energy subtraction obtained in this experimental system are shown.

Pink-beam serial crystallography

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

Meents, A.; Wiedorn, M. O.; Srajer, V.

Serial X-ray crystallography allows macromolecular structure determination at both X-ray free electron lasers (XFELs) and, more recently, synchrotron sources. The time resolution for serial synchrotron crystallography experiments has been limited to millisecond timescales with monochromatic beams. The polychromatic, “pink”, beam provides a more than two orders of magnitude increased photon flux and hence allows accessing much shorter timescales in diffraction experiments at synchrotron sources. Here we report the structure determination of two different protein samples by merging pink-beam diffraction patterns from many crystals, each collected with a single 100 ps X-ray pulse exposure per crystal using a setup optimized formore » very low scattering background. In contrast to experiments with monochromatic radiation, data from only 50 crystals were required to obtain complete datasets. The high quality of the diffraction data highlights the potential of this method for studying irreversible reactions at sub-microsecond timescales using high-brightness X-ray facilities.« less

Pink-beam serial crystallography

DOE PAGES

Meents, A.; Wiedorn, M. O.; Srajer, V.; ...

2017-11-03

Serial X-ray crystallography allows macromolecular structure determination at both X-ray free electron lasers (XFELs) and, more recently, synchrotron sources. The time resolution for serial synchrotron crystallography experiments has been limited to millisecond timescales with monochromatic beams. The polychromatic, “pink”, beam provides a more than two orders of magnitude increased photon flux and hence allows accessing much shorter timescales in diffraction experiments at synchrotron sources. Here we report the structure determination of two different protein samples by merging pink-beam diffraction patterns from many crystals, each collected with a single 100 ps X-ray pulse exposure per crystal using a setup optimized formore » very low scattering background. In contrast to experiments with monochromatic radiation, data from only 50 crystals were required to obtain complete datasets. The high quality of the diffraction data highlights the potential of this method for studying irreversible reactions at sub-microsecond timescales using high-brightness X-ray facilities.« less

Mass attenuation coefficients in the range 3.8⩽E⩽11 keV, K fluorescence yield and Kβ/Kα relative X-ray emission rate for Ti, V, Fe, Co, Ni, Cu and Zn measured with a tunable monochromatic X-ray source

NASA Astrophysics Data System (ADS)

Ménesguen, Y.; Lépy, M.-C.

2010-08-01

This work presents new measurements of mass attenuation coefficients in the range 3.8⩽E⩽11 keV, K-absorption jump-ratios, Kα and Kβ fluorescence yields for Ti, V, Fe, Co, Ni, Cu and Zn. We use the experimental facility SOLEX, a tunable monochromatic X-ray source combined with an energy-dispersive high-purity germanium detector. The results are compared with theoretical values as well as with other experimental data and show a relatively good agreement. However, the derived K-jump-ratios appear larger than those widely used in the XCOM database. The Kα and Kβ fluorescence yields and the corresponding relative emission rates Kβ/Kα are also derived, which was made possible by the use of energy-dispersive detectors with good spectral resolution.

Lighting the Way for Quicker, Safer Healing

NASA Technical Reports Server (NTRS)

2005-01-01

Who's to say that a little light can t go a long way? Tiny light-emitting diode (LED) chips used to grow plants in space are lighting the way for cancer treatment, wound healing, and chronic pain alleviation on Earth. In 1993, Quantum Devices, Inc. (QDI), of Barneveld, Wisconsin, began developing the HEALS (High Emissivity Aluminiferous Light-emitting Substrate) technology to provide high-intensity, solid-state LED lighting systems for NASA Space Shuttle plant growth experiments. The company evolved out of cooperative efforts with the Wisconsin Center for Space Automation and Robotics (WCSAR) at the University of Wisconsin-Madison a NASA center for the Commercial Development of Space. Ronald W. Ignatius, QDI s president and chairman, represented one of WCSAR s industrial partners at the time. WCSAR was conducting research on light sources for promoting food growth within closed environments where humans would be present for a long duration, such as the Space Shuttle and the International Space Station. With the support of WCSAR, Ignatius experimented with LEDs, which provide high-energy efficiency and virtually no heat, despite releasing waves of light 10 times brighter than the Sun. Ignatius admits that some scientists involved in the project were skeptical at first, thinking that the idea of using LEDs to promote plant growth was far-fetched. The experiments, however, demonstrated that red LED wavelengths could boost the energy metabolism of cells to advance plant growth and photosynthesis. This finding prompted Ignatius to develop a line of LED products that emit the exact wavelength of light that plants use in photosynthesis. Our company gives credit to Dr. Ray Bula, the director of WCSAR, for having the foresight to go against the prevailing dogma of the time and design the first plant experiment using monochromatic light to grow lettuce plants, Ignatius proclaims. In 1989, Ignatius formed QDI to bring the salt grain-sized LEDs to market, and in October 1995, the light sources made their Space Shuttle flight debut on the second U.S. Microgravity Laboratory Spacelab mission (STS-73, Columbia)

REANALYSIS OF F-STATISTIC GRAVITATIONAL-WAVE SEARCHES WITH THE HIGHER CRITICISM STATISTIC

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

Bennett, M. F.; Melatos, A.; Delaigle, A.

2013-04-01

We propose a new method of gravitational-wave detection using a modified form of higher criticism, a statistical technique introduced by Donoho and Jin. Higher criticism is designed to detect a group of sparse, weak sources, none of which are strong enough to be reliably estimated or detected individually. We apply higher criticism as a second-pass method to synthetic F-statistic and C-statistic data for a monochromatic periodic source in a binary system and quantify the improvement relative to the first-pass methods. We find that higher criticism on C-statistic data is more sensitive by {approx}6% than the C-statistic alone under optimal conditionsmore » (i.e., binary orbit known exactly) and the relative advantage increases as the error in the orbital parameters increases. Higher criticism is robust even when the source is not monochromatic (e.g., phase-wandering in an accreting system). Applying higher criticism to a phase-wandering source over multiple time intervals gives a {approx}> 30% increase in detectability with few assumptions about the frequency evolution. By contrast, in all-sky searches for unknown periodic sources, which are dominated by the brightest source, second-pass higher criticism does not provide any benefits over a first-pass search.« less

[Experience in using helium laser therapy for acute anorectal thrombosis and thrombophlebitis].

PubMed

Mun, N V; Kalugin, V V

1978-10-01

Clinical observation over 61 cases of acute anorectal thrombosis and thrombophlebitis was carried out. The duration of the disease ranged from some months to 35 years. The clinical observations have proved the advantages of laserotherapy over phototherapy with monochromatic incoherent red light and its high therapeutic activity in acute anorectal thrombosis and thrombophlebitis.

Close Up of Monochromatic Aberrations Using Snell's Law: An Undergraduate Computational Experiment

ERIC Educational Resources Information Center

Levesque, L.

2009-01-01

Images formed from light rays refracting a spherical surface are often introduced in textbooks using the paraxial approximation. Incoming rays propagating from the object meeting the surface of a transparent medium at a given point for which the angle is larger than 15 degrees with respect to the normal are not described accurately from the…

Effect of melatonin on monochromatic light-induced T-lymphocyte proliferation in the thymus of chickens.

PubMed

Chen, Fuju; Reheman, Aikebaier; Cao, Jing; Wang, Zixu; Dong, Yulan; Zhang, Yuxian; Chen, Yaoxing

2016-08-01

A total of 360 post-hatching day 0 (P0) Arbor Acre male broilers, including intact, sham operation and pinealectomy groups, were exposed to white light (WL), red light (RL), green light (GL) and blue light (BL) from a light-emitting diode (LED) system until for P14. We studied the effects of melatonin and its receptors on monochromatic light-induced T-lymphocyte proliferation in the thymus of broilers. The density of proliferating cell nuclear antigen (PCNA) cells and the proliferation of T-lymphocytes in response to Concanavalin A (ConA) in GL significantly increased both in vivo and in vitro (from 9.57% to 32.03% and from 34.30% to 50.53%, respectively) compared with other lights (p<0.005) and was strongly correlated with melatonin levels in plasma (p<0.005). Pinealectomy reduced the levels of circulatory melatonin and the proliferation of T-lymphocytes and eliminated the differences between GL and other lights (p<0.005). However, exogenous melatonin (10(-9)M) significantly increased the proliferative activity of T-lymphocyte by 9.64% (p=0.002). In addition, GL significantly increased mRNA expression levels of Mel1a, Mel1b and Mel1c receptors from 21.09% to 32.57%, and protein expression levels from 24.43% to 42.92% compared with RL (p<0.05). However, these effects were blocked after pinealectomy. Furthermore, 4P-PDOT (a selective Mel1b antagonist) and prazosin (a selective Mel1c antagonist) attenuated GL-induced T-lymphocyte proliferation in response to ConA (p=0.000). Luzindole (a nonselective Mel1a/Mel1b antagonist), however, did not induce these effects (p=0.334). These results suggest that melatonin may mediate GL-induced T-lymphocyte proliferation via the Mel1b and Mel1c receptors but not via the Mel1a receptor. Copyright © 2016 Elsevier B.V. All rights reserved.

Short-range/Long-range Integrated Target (SLIT) for Video Guidance Sensor Rendezvous and Docking

NASA Technical Reports Server (NTRS)

Roe, Fred D. (Inventor); Bryan, Thomas C. (Inventor)

2009-01-01

A laser target reflector assembly for mounting upon spacecraft having a long-range reflector array formed from a plurality of unfiltered light reflectors embedded in an array pattern upon a hemispherical reflector disposed upon a mounting plate. The reflector assembly also includes a short-range reflector array positioned upon the mounting body proximate to the long-range reflector array. The short-range reflector array includes three filtered light reflectors positioned upon extensions from the mounting body. The three filtered light reflectors retro-reflect substantially all incident light rays that are transmissive by their monochromatic filters and received by the three filtered light reflectors. In one embodiment the short-range reflector array is embedded within the hemispherical reflector,

A novel real-time data acquisition using an Excel spreadsheet in pendulum experiment tool with light-based timer

NASA Astrophysics Data System (ADS)

Adhitama, Egy; Fauzi, Ahmad

2018-05-01

In this study, a pendulum experimental tool with a light-based timer has been developed to measure the period of a simple pendulum. The obtained data was automatically recorded in an Excel spreadsheet. The intensity of monochromatic light, sensed by a 3DU5C phototransistor, dynamically changes as the pendulum swings. The changed intensity varies the resistance value and was processed by the microcontroller, ATMega328, to obtain a signal period as a function of time and brightness when the pendulum crosses the light. Through the experiment, using calculated average periods, the gravitational acceleration value has been accurately and precisely determined.

Coherent light squeezing states within a modified microring system

NASA Astrophysics Data System (ADS)

Ali, J.; Pornsuwancharoen, N.; Youplao, P.; Aziz, M. S.; Amiri, I. S.; Chaiwong, K.; Chiangga, S.; Singh, G.; Yupapin, P.

2018-06-01

We have proposed the simple method of the squeezed light generation in the modified microring resonator, which is known as the microring conjugate mirror (MCM). When the monochromatic light is input into the MCM, the general form of the squeezed coherent states for a quantum harmonic oscillator can be generated by controlling the additional two side rings, which are the phase modulators. By using the graphical method called the Optiwave program, the coherent squeezed states of coherent light within an MCM can be obtained and interpreted as the amplitude, phase, quadrature and photon number-squeezed states. This method has shown potentials for microring related device design, which can be used before practical applications.

Vacuum-ultraviolet lasers and spectroscopy

NASA Astrophysics Data System (ADS)

Hollenstein, U.

2012-01-01

Single-photon ionisation of most atoms and molecules requires short-wavelength radiation, typically in the vacuum-ultraviolet (VUV, λ < 200 nm) or extreme ultraviolet (XUV, λ < 105 nm) region of the electromagnetic spectrum. The first VUV and XUV radiation sources used to study molecular photoabsorption and photoionisation spectra were light sources emitting a broad continuous spectrum, such as high pressure lamps or synchrotrons. Monochromatic VUV and XUV radiation was obtained using diffraction gratings in evacuated monochromators, which resulted in a resolving power ν/Δv of at best 106 (i. e. 0.1 cm-1 at 100 000 cm-1), but more typically in the range 104-105 . The invention of the laser and the development of nonlinear optical frequency-upconversion techniques enabled the development of table-top narrow-bandwidth, coherent VUV and XUV laser sources with which VUV photoabsorption, photoionisation and photoelectron spectra of molecules can be recorded at much higher resolution, the best sources having bandwidths better than 50 MHz. Such laser sources are ideally suited to study the structure and dynamics of electronically excited states of atoms and molecules and molecular photoionisation using photoabsorption, photoionisation and photoelectron spectroscopy. This chapter presents the general principles that are exploited to generate tunable narrow-band laser radiation below 200 nm and describes spectroscopic methods such as photoabsorption spectroscopy, photoionisation spectroscopy and threshold photoelectron spectroscopy that relay on the broad tunability and narrow-bandwidth of VUV radiation sources.

Role of root UV-B sensing in Arabidopsis early seedling development.

PubMed

Tong, Hongyun; Leasure, Colin D; Hou, Xuewen; Yuen, Gigi; Briggs, Winslow; He, Zheng-Hui

2008-12-30

All sun-exposed organisms are affected by UV-B [(UVB) 280-320 nm], an integral part of sunlight. UVB can cause stresses or act as a developmental signal depending on its fluence levels. In plants, the mechanism by which high-fluence-rate UVB causes damages and activates DNA-repair systems has been extensively studied. However, little is known about how nondamaging low-fluence-rate UVB is perceived to regulate plant morphogenesis and development. Here, we report the identification of an Arabidopsis mutant, root UVB sensitive 1 (rus1), whose primary root is hypersensitive to very low-fluence-rate (VLF) UVB. Under standard growth-chamber fluorescent white light, rus1 displays stunted root growth and fails to form postembryonic leaves. Experiments with different monochromatic light sources showed that rus1 phenotypes can be rescued if the seedlings are allowed to grow in light conditions with minimum UVB. We determined that roots, not other organs, perceive the UVB signal. Genetic and molecular analyses confirmed that the root light-sensitive phenotypes are independent of all other known plant photoreceptors. Three rus1 alleles have been identified and characterized. A map-based approach was used to identify the RUS1 locus. RUS1 encodes a protein that contains DUF647 (domain of unknown function 647), a domain highly conserved in eukaryotes. Our results demonstrate a root VLF UVB-sensing mechanism that is involved in Arabidopsis early seedling morphogenesis and development.

Surface plasmon resonance sensor using vari-focal liquid lens under angular interrogation

NASA Astrophysics Data System (ADS)

Lee, Muyoung; Bang, Yousung; Lee, Jooho; Jang, Wonjae; Won, Yong Hyub

2017-02-01

In this paper, a surface plasmon resonance sensor for the detection of refractive index variation is presented. A novel waveguide type surface plasmon resonance sensing configuration with focal length variable liquid lens is introduced. The method of surface plasmon resonance sensor is based on the waveguide type with incident angle variation. The incident angle is varied by using an electrowetting liquid lens which is possible to actively change focal length as applying voltage. The optical system, which is adapted to electrowetting lens can continuously change the incident angle of light from 73 to 78 degrees with compact size. The surface plasmon waves are excited between metal and dielectric interface. The sensing surfaces are prepared by a coating of gold metal above high refractive index glass substrate. The incident light which is 532nm monochromatic light source passes through a noble metal coated substrate to detect intensity with incident angle variation. An analysis to distinguish the contribution of light with various incident angle is focused on the angular characteristics of the surface plasmon sensor under wavelength interrogation. The resonance angle is determined corresponding to sensing material refractive index with high sensitivity. The result suggests that the performance of surface plasmon resonance sensor can be improved by real time varying incident angle. From this presented study, it provides a different approach for angular interrogation surface plasmon resonance sensor and can be miniaturized for a portable device.

Multifunction interferometry using the electron mobility visibility and mean free path relationship.

PubMed

Pornsuwancharoen, N; Youplao, P; Amiri, I S; Aziz, M S; Tran, Q L; Ali, J; Yupapin, P; Grattan, K T V

2018-05-08

A conventional Michelson interferometer is modified and used to form the various types of interferometers. The basic system consists of a conventional Michelson interferometer with silicon-graphene-gold embedded between layers on the ports. When light from the monochromatic source is input into the system via the input port (silicon waveguide), the change in optical path difference (OPD) of light traveling in the stacked layers introduces the change in the optical phase, which affects to the electron mean free path within the gold layer, induces the change in the overall electron mobility can be seen by the interferometer output visibility. Further plasmonic waves are introduced on the graphene thin film and the electron mobility occurred within the gold layer, in which the light-electron energy conversion in terms of the electron mobility can be observed, the gold layer length is 100 nm. The measurement resolution in terms of the OPD of ∼50 nm is achieved. In applications, the outputs of the drop port device of the modified Michelson interferometer can be arranged by the different detectors, where the polarized light outputs, the photon outputs, the electron spin outputs can be obtained by the interference fringe visibility, mobility visibility and the spin up-down splitting output energies. The modified Michelson interferometer theory and the detection schemes are given in details. © 2018 Wiley Periodicals, Inc.

Detection of fissionable materials in cargoes using monochromatic photon radiography

NASA Astrophysics Data System (ADS)

Danagoulian, Areg; Lanza, Richard; O'Day, Buckley; LNSP Team

2015-04-01

The detection of Special Nuclear Materials (e.g. Pu and U) and nuclear devices in the commercial cargo traffic is one of the challenges posed by the threat of nuclear terrorism. Radiography and active interrogation of heavily loaded cargoes require ~ 1 - 10MeV photons for penetration. In a proof-of-concept system under development at MIT, the interrogating monochromatic photon beam is produced via a 11B(d , nγ) 12C reaction. To achieve this, a boron target is used along with the 3 MeV d+ RFQ accelerator at MIT-Bates. The reactions results in the emission of very narrow 4.4 MeV and 15.1 MeV gammas lines. The photons, after traversing the cargo, are detected by an array of NaI(Tl) detectors. A spectral analysis of the transmitted gammas allows to independently determine the areal density and the atomic number (Z) of the cargo. The proposed approach could revolutionize cargo inspection, which, in its current fielded form has to rely on simple but high dose bremsstrahlung sources. Use of monochromatic sources would significantly reduce the necessary dose and allow for better determination of the cargo's atomic number. The general methodology will be described and the preliminary results from the proof-of-concept system will be presented and discussed. Supported by NSF/DNDO Collaborative Research ARI-LA Award ECCS-1348328.

Approaches to Study Light Effects on Brassinosteroid Sensitivity.

PubMed

Paulišić, Sandi; Molina-Contreras, Maria José; Roig-Villanova, Irma; Martínez-García, Jaime F

2017-01-01

Light perception and hormone signaling in plants are likely connected at multiple points. Light conditions, perceived by photoreceptors, control plant responses by altering hormone concentration, tissue sensitivity, or a combination of both. Whereas it is relatively straightforward to assess the light effects on hormone levels, hormone sensitivity is subjected to interpretation. In Arabidopsis thaliana seedlings, hypocotyl length is strongly affected by light conditions. As hypocotyl elongation also depends on brassinosteroids (BRs), assaying this response provides a valuable and easy way to measure the responsiveness of seedlings to BRs and the impact of light. We describe a simple protocol to evaluate the responsiveness of hypocotyls to commercial BRs and/or BR inhibitors under a range of light conditions. These assays can be used to establish whether light affects BR sensitivity or whether BRs affect light sensitivity. Overall, our protocol can be easily applied for deetiolation (under polychromatic or monochromatic light) and simulated shade treatments combined with BR treatments.

Absolute calibration of the Agfa Structurix series films at energies between 2.7 and 6.2 keV.

PubMed

Lanier, N E; Cowan, J S

2014-11-01

Although photo-emulsion technology is many decades old, x-ray film still remains a key asset for diagnosing hydrodynamic features in High-Energy Density (HED) experiments. For decades, the preferred option had been Kodak's direct exposure film. After its discontinuance in 2004, the push to find alternatives began. In many situations, the Agfa Structurix series offers the most favorable substitute, but being new to the HED community, its characterization was lacking. To remedy this, recent experiments, conducted at Brookhaven's National Synchrotron Light Source, provide absolute, monochromatic calibration data for the Agfa Structurix series films at K-shell backlighter energies between 2.7 and 6.2 keV. Absolute response curves are presented for Agfa D8, D7, D4, D4sc, D3, and D2. Moreover, the transmission of each film type is also measured.

Color sensitivity of the multi-exposure HDR imaging process

NASA Astrophysics Data System (ADS)

Lenseigne, Boris; Jacobs, Valéry Ann; Withouck, Martijn; Hanselaer, Peter; Jonker, Pieter P.

2013-04-01

Multi-exposure high dynamic range(HDR) imaging builds HDR radiance maps by stitching together different views of a same scene with varying exposures. Practically, this process involves converting raw sensor data into low dynamic range (LDR) images, estimate the camera response curves, and use them in order to recover the irradiance for every pixel. During the export, applying white balance settings and image stitching, which both have an influence on the color balance in the final image. In this paper, we use a calibrated quasi-monochromatic light source, an integrating sphere, and a spectrograph in order to evaluate and compare the average spectral response of the image sensor. We finally draw some conclusion about the color consistency of HDR imaging and the additional steps necessary to use multi-exposure HDR imaging as a tool to measure the physical quantities such as radiance and luminance.

Absolute calibration of the Agfa Structurix series films at energies between 2.7 and 6.2 keVa)

NASA Astrophysics Data System (ADS)

Lanier, N. E.; Cowan, J. S.

2014-11-01

Although photo-emulsion technology is many decades old, x-ray film still remains a key asset for diagnosing hydrodynamic features in High-Energy Density (HED) experiments. For decades, the preferred option had been Kodak's direct exposure film. After its discontinuance in 2004, the push to find alternatives began. In many situations, the Agfa Structurix series offers the most favorable substitute, but being new to the HED community, its characterization was lacking. To remedy this, recent experiments, conducted at Brookhaven's National Synchrotron Light Source, provide absolute, monochromatic calibration data for the Agfa Structurix series films at K-shell backlighter energies between 2.7 and 6.2 keV. Absolute response curves are presented for Agfa D8, D7, D4, D4sc, D3, and D2. Moreover, the transmission of each film type is also measured.

Shaping the spatial and spectral emissivity at the diffraction limit

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

Makhsiyan, Mathilde; MiNaO, Laboratoire de Photonique et de Nanostructures; Bouchon, Patrick, E-mail: patrick.bouchon@onera.fr

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

Noninvasive detection of diabetes mellitus

NASA Astrophysics Data System (ADS)

Eppstein, Jonathan A.; Bursell, Sven-Erik

1992-05-01

Recent advances in fluorescence spectroscopy of the lens reveal the potential of a non-invasive device and methodology to sensitively measure changes in the lens of the eye associated with diabetes mellitus. The system relies on the detection of the spectrum of fluorescence emitted from a selected volume (approximately 1/10 mm3) of the lens of living human subjects using low power excitation illumination from monochromatic light sources. The sensitivity of this technique is based on the measurement of the fluorescence intensity in a selected region of the fluorescence spectrum and normalization of this fluorescence with respect to attenuation (scattering and absorption) of the incident excitation light. The amplitude of the unshifted Rayleigh line, measured as part of the fluorescence spectrum, is used as a measure of the attenuation of the excitation light in the lens. Using this methodology we have demonstrated that the normalized lens fluorescence provides a more sensitive discrimination between diabetic and non-diabetic lenses than more conventional measurements of fluorescence intensity from the lens. The existing instrumentation will be described as well as the proposed design for a commercial version of the instrument expected to be ready for FDA trials by late 1992. The results from clinical measurements are used to describe a relationship between normalized lens fluorescence and hemoglobin A1c levels in diabetic patients.

Circularly Polarized Light with Sense and Wavelengths To Regulate Azobenzene Supramolecular Chirality in Optofluidic Medium.

PubMed

Wang, Laibing; Yin, Lu; Zhang, Wei; Zhu, Xiulin; Fujiki, Michiya

2017-09-20

Circularly polarized light (CPL) as a massless physical force causes absolute asymmetric photosynthesis, photodestruction, and photoresolution. CPL handedness has long been believed to be the determining factor in the resulting product's chirality. However, product chirality as a function of the CPL handedness, irradiation wavelength, and irradiation time has not yet been studied systematically. Herein, we investigate this topic using achiral polymethacrylate carrying achiral azobenzene as micrometer-size aggregates in an optofluidic medium with a tuned refractive index. Azobenzene chirality with a high degree of dissymmetry ratio (±1.3 × 10 -2 at 313 nm) was generated, inverted, and switched in multiple cycles by irradiation with monochromatic incoherent CPL (313, 365, 405, and 436 nm) for 20 s using a weak incoherent light source (≈ 30 μW·cm -2 ). Moreover, the optical activity was retained for over 1 week in the dark. Photoinduced chirality was swapped by the irradiating wavelength, regardless of whether the CPL sense was the same. This scenario is similar to the so-called Cotton effect, which was first described in 1895. The tandem choice of both CPL sense and its wavelength was crucial for azobenzene chirality. Our experimental proof and theoretical simulation should provide new insight into the chirality of CPL-controlled molecules, supramolecules, and polymers.

Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

NASA Astrophysics Data System (ADS)

Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

2015-08-01

Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in ray-tracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC) procedure, additional measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from 1-year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.57 %. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8 %. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.8 %. Additionally, a simulation approach which just uses sun photometer and common meteorological data to determine the on-site atmospheric extinction at surface is presented and corrected FS11 and LPV4 measurements are validated with the simulation results. For T1 km equal to 0.9 and a 10 min time resolution, an uncertainty analysis showed that an absolute uncertainty of about 0.038 is expected for the FS11 and about 0.057 for the LPV4. Combining both uncertainties results in an overall absolute uncertainty of 0.068 which justifies quite well the mean RMSE between both corrected data sets. For yearly averages several error influences average out and absolute uncertainties of 0.020 and 0.054 can be expected for the FS11 and the LPV4, respectively. Therefore, applying this new correction method, both instruments can now be utilized to sufficiently accurately determine the solar broadband extinction in tower plants.

X-ray lithography using holographic images

DOEpatents

Howells, Malcolm R.; Jacobsen, Chris

1995-01-01

A non-contact X-ray projection lithography method for producing a desired X-ray image on a selected surface of an X-ray-sensitive material, such as photoresist material on a wafer, the desired X-ray image having image minimum linewidths as small as 0.063 .mu.m, or even smaller. A hologram and its position are determined that will produce the desired image on the selected surface when the hologram is irradiated with X-rays from a suitably monochromatic X-ray source of a selected wavelength .lambda.. On-axis X-ray transmission through, or off-axis X-ray reflection from, a hologram may be used here, with very different requirements for monochromaticity, flux and brightness of the X-ray source. For reasonable penetration of photoresist materials by X-rays produced by the X-ray source, the wavelength X, is preferably chosen to be no more than 13.5 nm in one embodiment and more preferably is chosen in the range 1-5 nm in the other embodiment. A lower limit on linewidth is set by the linewidth of available microstructure writing devices, such as an electron beam.

Directional and monochromatic thermal emitter from epsilon-near-zero conditions in semiconductor hyperbolic metamaterials

DOE PAGES

Campione, Salvatore; Marquier, Francois; Hugonin, Jean -Paul; ...

2016-10-05

The development of novel thermal sources that control the emission spectrum and the angular emission pattern is of fundamental importance. In this paper, we investigate the thermal emission properties of semiconductor hyperbolic metamaterials (SHMs). Our structure does not require the use of any periodic corrugation to provide monochromatic and directional emission properties. We show that these properties arise because of epsilon-near-zero conditions in SHMs. The thermal emission is dominated by the epsilon-near-zero effect in the doped quantum wells composing the SHM. In conclusion, different properties are observed for s and p polarizations, following the characteristics of the strong anisotropy ofmore » hyperbolic metamaterials.« less

Directional and monochromatic thermal emitter from epsilon-near-zero conditions in semiconductor hyperbolic metamaterials

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

Campione, Salvatore; Marquier, Francois; Hugonin, Jean -Paul

The development of novel thermal sources that control the emission spectrum and the angular emission pattern is of fundamental importance. In this paper, we investigate the thermal emission properties of semiconductor hyperbolic metamaterials (SHMs). Our structure does not require the use of any periodic corrugation to provide monochromatic and directional emission properties. We show that these properties arise because of epsilon-near-zero conditions in SHMs. The thermal emission is dominated by the epsilon-near-zero effect in the doped quantum wells composing the SHM. In conclusion, different properties are observed for s and p polarizations, following the characteristics of the strong anisotropy ofmore » hyperbolic metamaterials.« less

Monochromatic radiography of high energy density physics experiments on the MAGPIE generator.

PubMed

Hall, G N; Burdiak, G C; Suttle, L; Stuart, N H; Swadling, G F; Lebedev, S V; Smith, R A; Patankar, S; Suzuki-Vidal, F; de Grouchy, P; Harvey-Thompson, A J; Bennett, M; Bland, S N; Pickworth, L; Skidmore, J

2014-11-01

A monochromatic X-ray backlighter based on Bragg reflection from a spherically bent quartz crystal has been developed for the MAGPIE pulsed power generator at Imperial College (1.4 MA, 240 ns) [I. H. Mitchell et al., Rev. Sci. Instrum. 67, 1533 (2005)]. This instrument has been used to diagnose high energy density physics experiments with 1.865 keV radiation (Silicon He-α) from a laser plasma source driven by a ∼7 J, 1 ns pulse from the Cerberus laser. The design of the diagnostic, its characterisation and performance, and initial results in which the instrument was used to radiograph a shock physics experiment on MAGPIE are discussed.

The acoustic monopole in motion

NASA Technical Reports Server (NTRS)

Norum, T. D.; Liu, C. H.

1976-01-01

The results of an experiment are presented in which a small monochromatic source which behaves like an acoustic monopole when stationary is moved at a constant speed over an asphalt surface past stationary microphones. An analysis of the monopole moving above a finite impedance reflecting plane is given. The theoretical and experimental results are compared for different ground to observer heights, source frequencies, and source velocities. A computation of the effects of source acceleration on the noise radiated by the monopole is also presented.

Note: Fiber optic transport probe for Hall measurements under light and magnetic field at low temperatures: Case study of a two dimensional electron gas

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

Bhadauria, P. P. S.; Gupta, Anurag; Kumar, Pramod

2015-05-15

A fiber optic based probe is designed and developed for electrical transport measurements in presence of quasi-monochromatic (360–800 nm) light, varying temperature (T = 1.8–300 K), and magnetic field (B = 0–7 T). The probe is tested for the resistivity and Hall measurements performed on a LaAlO{sub 3}–SrTiO{sub 3} heterointerface system with a conducting two dimensional electron gas.

Fusion of microlitre water-in-oil droplets for simple, fast and green chemical assays.

PubMed

Chiu, S-H; Urban, P L

2015-08-07

A simple format for microscale chemical assays is proposed. It does not require the use of test tubes, microchips or microtiter plates. Microlitre-range (ca. 0.7-5.0 μL) aqueous droplets are generated by a commercial micropipette in a non-polar matrix inside a Petri dish. When two droplets are pipetted nearby, they spontaneously coalesce within seconds, priming a chemical reaction. Detection of the reaction product is accomplished by colorimetry, spectrophotometry, or fluorimetry using simple light-emitting diode (LED) arrays as the sources of monochromatic light, while chemiluminescence detection of the analytes present in single droplets is conducted in the dark. A smartphone camera is used as the detector. The limits of detection obtained for the developed in-droplet assays are estimated to be: 1.4 nmol (potassium permanganate by colorimetry), 1.4 pmol (fluorescein by fluorimetry), and 580 fmol (sodium hypochlorite by chemiluminescence detection). The format has successfully been used to monitor the progress of chemical and biochemical reactions over time with sub-second resolution. A semi-quantitative analysis of ascorbic acid using Tillman's reagent is presented. A few tens of individual droplets can be scanned in parallel. Rapid switching of the LED light sources with different wavelengths enables a spectral analysis of multiple droplets. Very little solid waste is produced. The assay matrix is readily recycled, thus the volume of liquid waste produced each time is also very small (typically, 1-10 μL per analysis). Various water-immiscible translucent liquids can be used as the reaction matrix: including silicone oil, 1-octanol as well as soybean cooking oil.

Enhancing the safety and quality of fresh produce and low-moisture foods by waterless non-thermal technologies: Cold plasma and monochromatic light

USDA-ARS?s Scientific Manuscript database

NIFA Project 2015-69003-23410 addresses the urgent need for novel technologies that improve the safety of fresh and fresh-cut fruits and vegetables that preserve quality while reducing water usage. This portion of the project is to investigate emerging non-thermal technologies, such as antimicrobial...

Precision Engineering - SRO 154.

DTIC Science & Technology

1986-01-01

Operation The principle of interferometric displacement measurement devices is that if two identical, coherent, monochromatic light beams are directed...laser interferometric feedback to enhance the accuracy and precision of a lead screw stage. The precision translation stage was designed to produce...and the deepest was 22 micrometers (875 microinches). Figures 5, 6 and 7 are Nomarsky photomicrographs showing the begin- ning, middle and end of a

Photonic homeostatics

NASA Astrophysics Data System (ADS)

Liu, Timon C.; Li, Fan-Hui

2010-11-01

Photonic homeostatics is a discipline to study the establishment, maintenance, decay, upgrading and representation of function-specific homoestasis (FSH) by using photonics. FSH is a negative-feedback response of a biosystem to maintain the function-specific fluctuations inside the biosystem so that the function is perfectly performed. A stress may increase sirtuin 1 (SIRT1) activities above FSH-specific SIRT1 activity to induce a function far from its FSH. On the one hand, low level laser irradiation or monochromatic light (LLL) can not modulate a function in its FSH or a stress in its stress-specific homeostasis (StSH), but modulate a function far from its FSH or a stress far from its StSH. On the other hand, the biophotons from a biosystem with its function in its FSH should be less than the one from the biosystem with its function far from its FSH. The non-resonant interaction of low intensity laser irradiation or monochromatic light (LIL) and a kind of membrane protein can be amplified by all the membrane proteins if the function is far from its FSH. This amplification might hold for biophoton emission of the membrane protein so that the photonic spectroscopy can be used to represent the function far from its FSH, which is called photonomics.

Dark Skies: Local Success, Global Challenge

NASA Astrophysics Data System (ADS)

Lockwood, G. W.

2009-01-01

The Flagstaff, Arizona 1987 lighting code reduced the growth rate of man-made sky glow by a third. Components of the code include requirements for full cutoff lighting, lumens per acre limits in radial zones around observatories, and use of low-pressure sodium monochromatic lighting for roadways and parking lots. Broad public acceptance of Flagstaff's lighting code demonstrates that dark sky preservation has significant appeal and few visibility or public safety negatives. An inventory by C. Luginbuhl et al. of the light output and shielding of a sampling of various zoning categories (municipal, commercial, apartments, single-family residences, roadways, sports facilities, industrial, etc.), extrapolated over the entire city, yields a total output of 139 million lumens. Commercial and industrial sources account for 62% of the total. Outdoor sports lighting increases the total by 24% on summer evenings. Flagstaff's per capita lumen output is 2.5 times greater than the nominal 1,000 lumens per capita assumed by R. Garstang in his early sky glow modeling work. We resolved the discrepancy with respect to Flagstaff's measured sky glow using an improved model that includes substantial near ground attenuation by foliage and structures. A 2008 university study shows that astronomy contributes $250M annually to Arizona's economy. Another study showed that the application of lighting codes throughout Arizona could reduce energy consumption significantly. An ongoing effort led by observatory directors statewide will encourage lighting controls in currently unregulated metropolitan areas whose growing sky glow threatens observatory facilities more than 100 miles away. The national press (New York Times, the New Yorker, the Economist, USA Today, etc.) have publicized dark sky issues but frequent repetition of the essential message and vigorous action will be required to steer society toward darker skies and less egregious waste.

Quenching and Sensitizing Fullerene Photoreactions by Natural Organic Matter

EPA Science Inventory

Effects of natural organic matter (NOM) on the photoreaction kinetics of fullerenes (i.e., C60 and fullerenol) were investigated using simulated sunlight and monochromatic radiation (365 nm). NOM from several sources quenched (slowed) the photoreaction of C60 aggregates in water ...

Polymer dispensing and embossing technology for the lens type LED packaging

NASA Astrophysics Data System (ADS)

Chien, Chien-Lin Chang; Huang, Yu-Che; Hu, Syue-Fong; Chang, Chung-Min; Yip, Ming-Chuen; Fang, Weileun

2013-06-01

This study presents a ring-type micro-structure design on the substrate and its corresponding micro fabrication processes for a lens-type light-emitting diode (LED) package. The dome-type or crater-type silicone lenses are achieved by a dispensing and embossing process rather than a molding process. Silicone with a high viscosity and thixotropy index is used as the encapsulant material. The ring-type micro structure is adopted to confine the dispensed silicone encapsulant so as to form the packaged lens. With the architecture and process described, this LED package technology herein has three merits: (1) the flexibility of lens-type LED package designs is enhanced; (2) a dome-type package design is used to enhance the intensity; (3) a crater-type package design is used to enhance the view angle. Measurement results show the ratio between the lens height and lens radius can vary from 0.4 to 1 by changing the volume of dispensed silicone. The view angles of dome-type and crater-type packages can reach 155° ± 5° and 175° ± 5°, respectively. As compared with the commercial plastic leaded chip carrier-type package, the luminous flux of a monochromatic blue light LED is improved by 15% by the dome-type package (improved by 7% by the crater-type package) and the luminous flux of a white light LED is improved by 25% by the dome-type package (improved by 13% by the crater-type package). The luminous flux of monochromatic blue light LED and white light LED are respectively improved by 8% and 12% by the dome-type package as compare with the crater-type package.

Replication of adeno-associated virus in cells irradiated with UV light at 254 nm

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

Yakobson, B.; Hrynko, T.A.; Peak, M.J.

1989-03-01

Irradiation of simian virus 40 (ori mutant)-transformed Chinese hamster embryo cells (OD4 line) with UV light induced a cellular capacity which supported a full cycle of helper-independent adeno-associated virus replication. Monochromatic UV light at 254 nm was about 1,000-fold more effective than UV light at 313 nm, indicating that cellular nucleic acid is the primary chromophore in the UV-induced process leading to permissiveness for adeno-associated virus replication. The UV irradiation and the infection could be separated for up to 12 h without substantial loss of permissiveness. During this time interval, the induction process was partly sensitive to cycloheximide, suggesting amore » requirement for de novo protein synthesis.« less

Evaluation of image quality metrics for the prediction of subjective best focus.

PubMed

Kilintari, Marina; Pallikaris, Aristophanis; Tsiklis, Nikolaos; Ginis, Harilaos S

2010-03-01

Seven existing and three new image quality metrics were evaluated in terms of their effectiveness in predicting subjective cycloplegic refraction. Monochromatic wavefront aberrations (WA) were measured in 70 eyes using a Shack-Hartmann based device (Complete Ophthalmic Analysis System; Wavefront Sciences). Subjective cycloplegic spherocylindrical correction was obtained using a standard manifest refraction procedure. The dioptric amount required to optimize each metric was calculated and compared with the subjective refraction result. Metrics included monochromatic and polychromatic variants, as well as variants taking into consideration the Stiles and Crawford effect (SCE). WA measurements were performed using infrared light and converted to visible before all calculations. The mean difference between subjective cycloplegic and WA-derived spherical refraction ranged from 0.17 to 0.36 diopters (D), while paraxial curvature resulted in a difference of 0.68 D. Monochromatic metrics exhibited smaller mean differences between subjective cycloplegic and objective refraction. Consideration of the SCE reduced the standard deviation (SD) of the difference between subjective and objective refraction. All metrics exhibited similar performance in terms of accuracy and precision. We hypothesize that errors pertaining to the conversion between infrared and visible wavelengths rather than calculation method may be the limiting factor in determining objective best focus from near infrared WA measurements.

Light beam frequency comb generator

DOEpatents

Priatko, G.J.; Kaskey, J.A.

1992-11-24

A light beam frequency comb generator uses an acousto-optic modulator to generate a plurality of light beams with frequencies which are uniformly separated and possess common noise and drift characteristics. A well collimated monochromatic input light beam is passed through this modulator to produce a set of both frequency shifted and unshifted optical beams. An optical system directs one or more frequency shifted beams along a path which is parallel to the path of the input light beam such that the frequency shifted beams are made incident on the modulator proximate to but separated from the point of incidence of the input light beam. After the beam is thus returned to and passed through the modulator repeatedly, a plurality of mutually parallel beams are generated which are frequency-shifted different numbers of times and possess common noise and drift characteristics. 2 figs.

Light beam frequency comb generator

DOEpatents

Priatko, Gordon J.; Kaskey, Jeffrey A.

1992-01-01

A light beam frequency comb generator uses an acousto-optic modulator to generate a plurality of light beams with frequencies which are uniformly separated and possess common noise and drift characteristics. A well collimated monochromatic input light beam is passed through this modulator to produce a set of both frequency shifted and unshifted optical beams. An optical system directs one or more frequency shifted beams along a path which is parallel to the path of the input light beam such that the frequency shifted beams are made incident on the modulator proximate to but separated from the point of incidence of the input light beam. After the beam is thus returned to and passed through the modulator repeatedly, a plurality of mutually parallel beams are generated which are frequency-shifted different numbers of times and possess common noise and drift characteristics.

Contrast agent choice for intravenous coronary angiography

NASA Astrophysics Data System (ADS)

Zeman, H. D.; Siddons, D. P.

1990-05-01

The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with monochromatic synchrotron radiation X-rays and an iodine-containing contrast agent at the Stanford Synchrotron Radiation Laboratory have shown that such an intravenous angiography procedure would be possible with an adequately intense monochromatic X-ray source. Because of the size and cost of synchrotron radiation facilities it would be desirable to make the most efficient use of the intensity available, while reducing as much as possible the radiation dose experienced by the patient. By choosing contrast agents containing elements with a higher atomic number than iodine, it is possible to both improve the image quality and reduce the patient radiation dose, while using the same synchrotron radiation source. By using Si monochromator crystals with a small mosaic spread, it is possible to increase the X-ray flux available for imaging by over an order of magnitude, without any changes in the storage ring or wiggler magnet. The most critical imaging task for intravenous coronary angiography utilizing synchrotron radiation X-rays is visualizing a coronary artery through the left ventricle or aorta which also contain contrast agent. Calculations have been made of the signal to noise ratio expected for this imaging task for various contrast agents with atomic numbers between that of iodine and bismuth. The X-ray energy spectrum of the X-17 superconduction wiggler beam line at the National Synchrotron Light Source at Brookhaven National Laboratory has been used for these calculations. Both perfect Si crystals and Si crystals with a small mosaic spread are considered as monochromators. Contrast agents containing Gd or Yb seem to have about the optimal calculated signal to noise ratio. Gd-DTPA is already approved for use as a contrast agent for magnetic resonance imaging. Experiments have already been performed with Yb-DTPA in animals, and it appears to have a lower toxicity than that of Gd-DTPA. Reported animal experiments with Gd-DOTA contrast agent show no toxicity at all.

Effects of intraocular lenses with different diopters on chromatic aberrations in human eye models.

PubMed

Song, Hui; Yuan, Xiaoyong; Tang, Xin

2016-01-11

In this study, the effects of intraocular lenses (IOLs) with different diopters (D) on chromatic aberration were investigated in human eye models, and the influences of the central thickness of IOLs on chromatic aberration were compared. A Liou-Brennan-based IOL eye model was constructed using ZEMAX optical design software. Spherical IOLs with different diopters (AR40e, AMO Company, USA) were implanted; modulation transfer function (MTF) values at 3 mm of pupil diameter and from 0 to out-of-focus blur were collected and graphed. MTF values, measured at 555 nm of monochromatic light under each spatial frequency, were significantly higher than the values measured at 470 to 650 nm of polychromatic light. The influences of chromatic aberration on MTF values decreased with the increase in IOL diopter when the spatial frequency was ≤12 c/d, while increased effects were observed when the spatial frequency was ≥15 c/d. The MTF values of each IOL eye model were significantly lower than the MTF values of the Liou-Brennan eye models when measured at 555 nm of monochromatic light and at 470 to 650 nm of polychromatic light. The MTF values were also found to be increased with the increase in IOL diopter. With higher diopters of IOLs, the central thickness increased accordingly, which could have created increased chromatic aberration and decreased the retinal image quality. To improve the postoperative visual quality, IOLs with lower chromatic aberration should be selected for patients with short axial lengths.

Electromagnetic energy momentum in dispersive media

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

Philbin, T. G.

2011-01-15

The standard derivations of electromagnetic energy and momentum in media take Maxwell's equations as the starting point. It is well known that for dispersive media this approach does not directly yield exact expressions for the energy and momentum densities. Although Maxwell's equations fully describe electromagnetic fields, the general approach to conserved quantities in field theory is not based on the field equations, but rather on the action. Here an action principle for macroscopic electromagnetism in dispersive, lossless media is used to derive the exact conserved energy-momentum tensor. The time-averaged energy density reduces to Brillouin's simple formula when the fields aremore » monochromatic. The time-averaged momentum density for monochromatic fields corresponds to the familiar Minkowski expression DxB, but for general fields in dispersive media the momentum density does not have the Minkowski value. The results are unaffected by the debate over momentum balance in light-matter interactions.« less

The protein crystallography beamline at LNLS, the Brazilian National Synchrotron Light Source

NASA Astrophysics Data System (ADS)

Polikarpov, I.; Oliva, G.; Castellano, E. E.; Garratt, R. C.; Arruda, P.; Leite, A.; Craievich, A.

1998-02-01

The Brazilian National Synchrotron Light Laboratory - LNLS, will have a dedicated protein crystallography beamline. The beamline under construction includes cylindrical mirror and bent crystal monochromator focusing the high flux of synchrotron radiation in the horizontal plane at the position of the sample. The monochromatic radiation will be tuneable between 2.0 and 1.0 Å with the optimum wavelength at 1.3-1.6 Å, chosen with the aim of maximizing the photon flux from the bending magnets of the storage ring (1.37 GeV). Diffraction images will be recorded on a commercial image plate detector system with on-line readout. The beamline set-up will include cooler/chiller for the samples and biochemical lab for crystallization, heavy-metal soaks, crystal storage and mounting at 22°C and 4°C, will also be available. The facility, intended to serve the national and international community, is planned to be brought into operation in the second half of 1997. It is foreseen that the commissioning of the first protein crystallography beamline in Latin America will boost the number of protein structures determined locally and will increase the general interest of the molecular biology and biochemical research community of Brazil in this area.

Fixation light hue bias revisited: implications for using adaptive optics to study color vision.

PubMed

Hofer, H J; Blaschke, J; Patolia, J; Koenig, D E

2012-03-01

Current vision science adaptive optics systems use near infrared wavefront sensor 'beacons' that appear as red spots in the visual field. Colored fixation targets are known to influence the perceived color of macroscopic visual stimuli (Jameson, D., & Hurvich, L. M. (1967). Fixation-light bias: An unwanted by-product of fixation control. Vision Research, 7, 805-809.), suggesting that the wavefront sensor beacon may also influence perceived color for stimuli displayed with adaptive optics. Despite its importance for proper interpretation of adaptive optics experiments on the fine scale interaction of the retinal mosaic and spatial and color vision, this potential bias has not yet been quantified or addressed. Here we measure the impact of the wavefront sensor beacon on color appearance for dim, monochromatic point sources in five subjects. The presence of the beacon altered color reports both when used as a fixation target as well as when displaced in the visual field with a chromatically neutral fixation target. This influence must be taken into account when interpreting previous experiments and new methods of adaptive correction should be used in future experiments using adaptive optics to study color. Copyright © 2012 Elsevier Ltd. All rights reserved.

Scheme of Optical Image Encryption with Digital Information Input and Dynamic Encryption Key based on Two LC SLMs

NASA Astrophysics Data System (ADS)

Bondareva, A. P.; Cheremkhin, P. A.; Evtikhiev, N. N.; Krasnov, V. V.; Starikov, S. N.

Scheme of optical image encryption with digital information input and dynamic encryption key based on two liquid crystal spatial light modulators and operating with spatially-incoherent monochromatic illumination is experimentally implemented. Results of experiments on images optical encryption and numerical decryption are presented. Satisfactory decryption error of 0.20÷0.27 is achieved.

Coherent bremsstrahlung used for digital subtraction angiography

NASA Astrophysics Data System (ADS)

Überall, Herbert

2007-05-01

Digital subtraction angiography (DSA), also known as Dichromography, using synchrotron radiation beams has been developed at Stanford University (R. Hofstadter) and was subsequently taken over at the Brookhaven Synchrotron and later at Hamburg (HASYLAB) [see, e.g., W.R. Dix, Physik in unserer Zeit. 30 (1999) 160]. The imaging of coronary arteries is carried out with an iodine-based contrast agent which need not be injected into the heart. The radiation must be monochromatized and is applied above and below the K-edge of iodine (33.16 keV), with a subsequent digital subtraction of the two images. Monochromatization of the synchrotron radiation causes a loss of intensity of 10 -3. We propose instead the use of coherent bremsstrahlung [see, e.g., A.W. Saenz and H. Uberall, Phys. Rev. B25 (1982) 448] which is inherently monochromatic, furnishing a flux of 10 12 photon/sec. This requires a 10-20 MeV electron linac which can be obtained by many larger hospitals, eliminating the scheduling problems present at synchrotrons. The large, broad incoherent bremsstrahlung background underlying the monochromatic spike would lead to inadmissible overexposure of the patient. This problem can be solved with the use of Kumakhov's capillary optics [see e.g., S.B.Dabagov, Physics-Uspekhi 46 (2003) 1053]: the low-energy spiked radiation can be deflected towards the patient, while the higher energy incoherent background continues forward, avoiding the patient who is placed several meters from the source.

A Laboratory Demonstration of the Three-Dimensional Nature of In-Line Holography.

ERIC Educational Resources Information Center

Baez, Albert V.; Castro, George

1999-01-01

Describes an experiment in which two semi-transparent reticles and a photographic plate separated by several centimeters are illuminated by a monochromatic point source in a typical in-line configuration that results in a hologram that contains information from both reticles. (Author/WRM)

Modeling the photoacoustic signal during the porous silicon formation

NASA Astrophysics Data System (ADS)

Ramirez-Gutierrez, C. F.; Castaño-Yepes, J. D.; Rodriguez-García, M. E.

2017-01-01

Within this work, the kinetics of the growing stage of porous silicon (PS) during the etching process was studied using the photoacoustic technique. A p-type Si with low resistivity was used as a substrate. An extension of the Rosencwaig and Gersho model is proposed in order to analyze the temporary changes that take place in the amplitude of the photoacoustic signal during the PS growth. The solution of the heat equation takes into account the modulated laser beam, the changes in the reflectance of the PS-backing heterostructure, the electrochemical reaction, and the Joule effect as thermal sources. The model includes the time-dependence of the sample thickness during the electrochemical etching of PS. The changes in the reflectance are identified as the laser reflections in the internal layers of the system. The reflectance is modeled by an additional sinusoidal-monochromatic light source and its modulated frequency is related to the velocity of the PS growth. The chemical reaction and the DC components of the heat sources are taken as an average value from the experimental data. The theoretical results are in agreement with the experimental data and hence provided a method to determine variables of the PS growth, such as the etching velocity and the thickness of the porous layer during the growing process.

Coronagraphic Notch Filter for Raman Spectroscopy

NASA Technical Reports Server (NTRS)

Cohen, David; Stirbl, Robert

2004-01-01

A modified coronagraph has been proposed as a prototype of improved notch filters in Raman spectrometers. Coronagraphic notch filters could offer alternatives to both (1) the large and expensive double or triple monochromators in older Raman spectrometers and (2) holographic notch filters, which are less expensive but are subject to environmental degradation as well as to limitations of geometry and spectral range. Measurement of a Raman spectrum is an exercise in measuring and resolving faint spectral lines close to a bright peak: In Raman spectroscopy, a monochromatic beam of light (the pump beam) excites a sample of material that one seeks to analyze. The pump beam generates a small flux of scattered light at wavelengths slightly greater than that of the pump beam. The shift in wavelength of the scattered light from the pump wavelength is known in the art as the Stokes shift. Typically, the flux of scattered light is of the order of 10 7 that of the pump beam and the Stokes shift lies in the wave-number range of 100 to 3,000 cm 1. A notch filter can be used to suppress the pump-beam spectral peak while passing the nearby faint Raman spectral lines. The basic principles of design and operation of a coronagraph offer an opportunity for engineering the spectral transmittance of the optics in a Raman spectrometer. A classical coronagraph may be understood as two imaging systems placed end to end, such that the first system forms an intermediate real image of a nominally infinitely distant object and the second system forms a final real image of the intermediate real image. If the light incident on the first telescope is collimated, then the intermediate image is a point-spread function (PSF). If an appropriately tailored occulting spot (e.g., a Gaussian-apodized spot with maximum absorption on axis) is placed on the intermediate image plane, then the instrument inhibits transmission of light from an on-axis source. However, the PSFs of off-axis light sources are formed off axis - that is, away from the occulting spot - so that they become refocused onto the final image plane.

Concept of coherence of learning physical optics

NASA Astrophysics Data System (ADS)

Colombo, Elisa M.; Jaen, Mirta; de Cudmani, Leonor C.

1995-10-01

The aim of the actual paper is to enhance achievements of the text 'Optica Fisica Basica: estructurada alrededor del concepto de coherencia luminosa' (in English 'Basic Physical Optics centered in the concept of coherence'). We consider that this book is a very worth tool when one has to learn or to teach some fundamental concepts of physical optics. It is well known that the topics of physical optics present not easy understanding for students. Even more they also present some difficulties for the teachers when they have to introduce them to the class. First, we think that different phenomena like diffraction and polarization could be well understood if the starting point is a deep comprehension of the concept of interference of light and, associated with this, the fundamental and nothing intuitive concept of coherence of the light. In the reference text the authors propose the use of expression 'stable interference pattern of no uniform intensity' instead of 'pattern of interference' and 'average pattern of uniform untested' instead of 'lack of interference' to make reference that light always interfere but just under restrictive conditions it can be got temporal and spatial stability of the pattern. Another idea we want to stand out is that the ability to observe a 'stable interference pattern of no uniform intensity' is associated not only with the coherence of the source but also with the dimensions of the experimental system and with the temporal and spatial characteristics of the detector used - human eye, photographic film, etc. The proposal is well support by quantitative relations. With an alternate model: a train of waves with a finite length of coherence, it is possible to get range of validity of models, to decide when a source could be considered a 'point' or 'monochromatic' or 'remote', an 'infinite' wave or a train of waves, etc. Using this concept it is possible to achieve a better understanding of phenomena like the polarization of light. Here, it is easier to recognize limitations of the model of light. For example, in the interpretation of the effect of retarding plates on polarizated light. When the plate is wider than the coherence length of the wavetrain of light, the effect disappears.

Bistability By Self-Reflection In A Saturable Absorber

NASA Astrophysics Data System (ADS)

Roso-Franco, Luis

1987-01-01

Propagation of laser light through a saturable absorber is theoretically studied. Computed steady state solutions of the Maxwell equations describing the unidimensional propagation of a plane monochromatic wave without introducing the slowly-varying envelope approximation are presented showing how saturation effects can influence the absorption of the field. At a certain range of refractive index and extintion coefficients, computed solutions display a very susprising behaviour, and a self-reflected wave appears inside the absorber. This can be useful for a new kind of biestable device, similar to a standard bistable cavity but with the back mirror self-induced by the light.

Silicon solar cell process development, fabrication and analysis

NASA Technical Reports Server (NTRS)

Leung, D. C.; Iles, P. A.

1983-01-01

Measurements of minority carrier diffusion lengths were made on the small mesa diodes from HEM Si and SILSO Si. The results were consistent with previous Voc and Isc measurements. Only the medium grain SILSO had a distinct advantage for the non grain boundary diodes. Substantial variations were observed for the HEM ingot 4141C. Also a quantitatively scaled light spot scan was being developed for localized diffusion length measurements in polycrystalline silicon solar cells. A change to a more monochromatic input for the light spot scan results in greater sensitivity and in principle, quantitative measurement of local material qualities is now possible.

Mechanical properties and polymerization shrinkage of composite resins light-cured using two different lasers.

PubMed

Kim, Tae-Wan; Lee, Jang-Hoon; Jeong, Seung-Hwa; Ko, Ching-Chang; Kim, Hyung-Il; Kwon, Yong Hoon

2015-04-01

The purpose of the present study was to investigate the usefulness of 457 and 473 nm lasers for the curing of composite resins during the restoration of damaged tooth cavity. Monochromaticity and coherence are attractive features of laser compared with most other light sources. Better polymerization of composite resins can be expected. Eight composite resins were light cured using these two lasers and a light-emitting diode (LED) light-curing unit (LCU). To evaluate the degrees of polymerization achieved, polymerization shrinkage and flexural and compressive properties were measured and compared. Polymerization shrinkage values by 457 and 473 nm laser, and LED ranged from 10.9 to 26.8, from 13.2 to 26.1, and from 11.5 to 26.3 μm, respectively. The values by 457 nm laser was significantly different from those by 473 and LED LCU (p<0.05). However, there was no statistical difference between values by 473 and LED LCU. Before immersion in distilled water, flexural strength (FS) and compressive modulus (CM) of the specimens were inconsistently influenced by LCUs. On the other hand, flexural modulus (FM) and compressive strength (CS) were not significantly different for the three LCUs (p>0.05). For the tested LCUs, no specific LCU could consistently achieve highest strength and modulus from the specimens tested. Two lasers (457 and 473 nm) can polymerize composite resins to the level that LED LCU can achieve despite inconsistent trends of polymerization shrinkage and flexural and compressive properties of the tested specimens.

Programmable spectral engine design of hyperspectral image projectors based on digital micro-mirror device (DMD)

NASA Astrophysics Data System (ADS)

Wang, Xicheng; Gao, Jiaobo; Wu, Jianghui; Li, Jianjun; Cheng, Hongliang

2017-02-01

Recently, hyperspectral image projectors (HIP) have been developed in the field of remote sensing. For the advanced performance of system-level validation, target detection and hyperspectral image calibration, HIP has great possibility of development in military, medicine, commercial and so on. HIP is based on the digital micro-mirror device (DMD) and projection technology, which is capable to project arbitrary programmable spectra (controlled by PC) into the each pixel of the IUT1 (instrument under test), such that the projected image could simulate realistic scenes that hyperspectral image could be measured during its use and enable system-level performance testing and validation. In this paper, we built a visible hyperspectral image projector also called the visible target simulator with double DMDs, which the first DMD is used to product the selected monochromatic light from the wavelength of 410 to 720 um, and the light come to the other one. Then we use computer to load image of realistic scenes to the second DMD, so that the target condition and background could be project by the second DMD with the selected monochromatic light. The target condition can be simulated and the experiment could be controlled and repeated in the lab, making the detector instrument could be tested in the lab. For the moment, we make the focus on the spectral engine design include the optical system, research of DMD programmable spectrum and the spectral resolution of the selected spectrum. The detail is shown.

Response of the seagrass Halophila ovalis to altered light quality in a simulated dredge plume.

PubMed

Strydom, Simone; McMahon, Kathryn; Lavery, Paul S

2017-08-15

Seagrass meadows are globally threatened, largely through activities that reduce light quantity (photosynthetic photon flux density) such as dredging. However, these activities can simultaneously alter the spectral quality of light. Previous studies showed that Halophila ovalis seagrass productivity is reduced under monochromatic yellow/green light, wavelengths associated with dredge plumes, but it is unclear how they respond to spectra produced by real dredging projects. We simultaneously subjected adult H. ovalis plants to altered light quality and quantity simulating a real commercial dredging operation (15mgL -1 TSS, 50 and 200μmol photonsm -2 s -1 ). There was a significant effect of reduced light quantity on physiological and morphological variables and a significant effect of light quality on the pigment antheraxanthin. The lack of effect of light quality on growth indicates that while seagrass are sensitive to changes in light quality, natural- and anthropogenic-driven changes may not always be sufficient to produce strong effects on H. ovalis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relative efficiency calibration between two silicon drift detectors performed with a monochromatized X-ray generator over the 0.1-1.5 keV range

NASA Astrophysics Data System (ADS)

Hubert, S.; Boubault, F.

2018-03-01

In this article, we present the first X-ray calibration performed over the 0.1-1.5 keV spectral range by means of a soft X-ray Manson source and the monochromator SYMPAX. This monochromator, based on a classical Rowland geometry, presents the novelty to be able to board simultaneously two detectors and move them under vacuum in front of the exit slit of the monochromatizing stage. This provides the great advantage to perform radiometric measurements of the monochromatic X-ray photon flux with one reference detector while calibrating another X-ray detector. To achieve this, at least one secondary standard must be operated with SYMPAX. This paper presents thereby an efficiency transfer experiment between a secondary standard silicon drift detector (SDD), previously calibrated on BESSY II synchrotron Facility, and another one ("unknown" SDD), devoted to be used permanently with SYMPAX. The associated calibration process is described as well as corresponding results. Comparison with calibrated measurements performed at the Physikalisch-Technische Bundesanstalt (PTB) Radiometric Laboratory shows a very good agreement between the secondary standard and the unknown SDD.

RAiSE III: 3C radio AGN energetics and composition

NASA Astrophysics Data System (ADS)

Turner, Ross J.; Shabala, Stanislav S.; Krause, Martin G. H.

2018-03-01

Kinetic jet power estimates based exclusively on observed monochromatic radio luminosities are highly uncertain due to confounding variables and a lack of knowledge about some aspects of the physics of active galactic nuclei (AGNs). We propose a new methodology to calculate the jet powers of the largest, most powerful radio sources based on combinations of their size, lobe luminosity, and shape of their radio spectrum; this approach avoids the uncertainties encountered by previous relationships. The outputs of our model are calibrated using hydrodynamical simulations and tested against independent X-ray inverse-Compton measurements. The jet powers and lobe magnetic field strengths of radio sources are found to be recovered using solely the lobe luminosity and spectral curvature, enabling the intrinsic properties of unresolved high-redshift sources to be inferred. By contrast, the radio source ages cannot be estimated without knowledge of the lobe volumes. The monochromatic lobe luminosity alone is incapable of accurately estimating the jet power or source age without knowledge of the lobe magnetic field strength and size, respectively. We find that, on average, the lobes of the Third Cambridge Catalogue of Radio Sources (3C) have magnetic field strengths approximately a factor three lower than the equipartition value, inconsistent with equal energy in the particles and the fields at the 5σ level. The particle content of 3C radio lobes is discussed in the context of complementary observations; we do not find evidence favouring an energetically dominant proton population.

Effects of Ionization-Induced Smog on Air Chemistry.

DTIC Science & Technology

1987-01-30

After leaving the monochromater, the beam was incident on the window of a HgCdTe Detector ( Infrared Assoc., Inc.), hereafter referred to as the...regulated power supply (Model 68735). The intensity of infrared light produced was measured by a thermopile detector (ORIEL Model 7102), hereafter...process measurements from the bolometer and detector and to control the stepper motor were located outside of the exposure room so as to reduce noise

Genomic evidence for rod monochromacy in sloths and armadillos suggests early subterranean history for Xenarthra

PubMed Central

Emerling, Christopher A.; Springer, Mark S.

2015-01-01

Rod monochromacy is a rare condition in vertebrates characterized by the absence of cone photoreceptor cells. The resulting phenotype is colourblindness and low acuity vision in dim-light and blindness in bright-light conditions. Early reports of xenarthrans (armadillos, sloths and anteaters) suggest that they are rod monochromats, but this has not been tested with genomic data. We searched the genomes of Dasypus novemcinctus (nine-banded armadillo), Choloepus hoffmanni (Hoffmann's two-toed sloth) and Mylodon darwinii (extinct ground sloth) for retinal photoreceptor genes and examined them for inactivating mutations. We performed PCR and Sanger sequencing on cone phototransduction genes of 10 additional xenarthrans to test for shared inactivating mutations and estimated the timing of inactivation for photoreceptor pseudogenes. We concluded that a stem xenarthran became an long-wavelength sensitive-cone monochromat following a missense mutation at a critical residue in SWS1, and a stem cingulate (armadillos, glyptodonts and pampatheres) and stem pilosan (sloths and anteaters) independently acquired rod monochromacy early in their evolutionary history following the inactivation of LWS and PDE6C, respectively. We hypothesize that rod monochromacy in armadillos and pilosans evolved as an adaptation to a subterranean habitat in the early history of Xenarthra. The presence of rod monochromacy has major implications for understanding xenarthran behavioural ecology and evolution. PMID:25540280

Pixelated transmission-mode diamond X-ray detector.

PubMed

Zhou, Tianyi; Ding, Wenxiang; Gaowei, Mengjia; De Geronimo, Gianluigi; Bohon, Jen; Smedley, John; Muller, Erik

2015-11-01

Fabrication and testing of a prototype transmission-mode pixelated diamond X-ray detector (pitch size 60-100 µm), designed to simultaneously measure the flux, position and morphology of an X-ray beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on the front and horizontal stripes on the back of an electronic-grade chemical vapor deposition single-crystal diamond. The bias is rotated through the back horizontal stripes and the current is read out on the front vertical stripes at a rate of ∼ 1 kHz, which leads to an image sampling rate of ∼ 30 Hz. This novel signal readout scheme was tested at beamline X28C at the National Synchrotron Light Source (white beam, 5-15 keV) and at beamline G3 at the Cornell High Energy Synchrotron Source (monochromatic beam, 11.3 keV) with incident beam flux ranges from 1.8 × 10(-2) to 90 W mm(-2). Test results show that the novel detector provides precise beam position (positional noise within 1%) and morphology information (error within 2%), with an additional software-controlled single channel mode providing accurate flux measurement (fluctuation within 1%).

A compact "water-window" microscope with 60-nm spatial resolution based on a double stream gas-puff target and Fresnel zone plate optics

NASA Astrophysics Data System (ADS)

Wachulak, Przemyslaw; Torrisi, Alfio; Nawaz, Muhammad F.; Adjei, Daniel; Bartnik, Andrzej; Kostecki, Jerzy; Wegrzynski, Łukasz; Vondrová, Šárka; Turňová, Jana; Fok, Tomasz; Jančarek, Alexandr; Fiedorowicz, Henryk

2015-05-01

Radiation with shorter illumination wavelength allows for extension of the diffraction limit towards nanometer scale, which is a straightforward way to significantly improve a spatial resolution in photon based microscopes. Soft X-ray (SXR) radiation, from the so called "water window" spectral range, λ=2.3-4.4 nm, which is particularly suitable for biological imaging due to natural optical contrast, providing much better spatial resolution than one obtained with visible light microscopes. The high contrast is obtained because of selective absorption of radiation by carbon and water, being constituents of the biological samples. We present a desk-top system, capable of resolving 60 nm features in few seconds exposure time. We exploit the advantages of a compact, laser-plasma SXR source, based on a double stream nitrogen gas puff target, developed at the Institute of Optoelectronics, Military University of Technology. The source, emitting quasi-monochromatic, incoherent radiation, in the "water widow" spectral range at λ = 2.88 nm, is coupled with ellipsoidal, grazing incidence condenser and Fresnel zone plate objective. The construction of the microscope with some recent images of test and real samples will be presented and discussed.

Algorithms and physical parameters involved in the calculation of model stellar atmospheres

NASA Astrophysics Data System (ADS)

Merlo, D. C.

This contribution summarizes the Doctoral Thesis presented at Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba for the degree of PhD in Astronomy. We analyze some algorithms and physical parameters involved in the calculation of model stellar atmospheres, such as atomic partition functions, functional relations connecting gaseous and electronic pressure, molecular formation, temperature distribution, chemical compositions, Gaunt factors, atomic cross-sections and scattering sources, as well as computational codes for calculating models. Special attention is paid to the integration of hydrostatic equation. We compare our results with those obtained by other authors, finding reasonable agreement. We make efforts on the implementation of methods that modify the originally adopted temperature distribution in the atmosphere, in order to obtain constant energy flux throughout. We find limitations and we correct numerical instabilities. We integrate the transfer equation solving directly the integral equation involving the source function. As a by-product, we calculate updated atomic partition functions of the light elements. Also, we discuss and enumerate carefully selected formulae for the monochromatic absorption and dispersion of some atomic and molecular species. Finally, we obtain a flexible code to calculate model stellar atmospheres.

Monochromatic green light induces an aberrant accumulation of geranylgeranyled chlorophylls in plants.

PubMed

Materová, Zuzana; Sobotka, Roman; Zdvihalová, Barbora; Oravec, Michal; Nezval, Jakub; Karlický, Václav; Vrábl, Daniel; Štroch, Michal; Špunda, Vladimír

2017-07-01

Light quality is an important environmental factor affecting the biosynthesis of photosynthetic pigments whose production seems to be affected not only quantitatively but also qualitatively. In this work, we set out to identify unusual pigment detected in leaves of barley (Hordeum vulgare L.) and explain its presence in plants grown under monochromatic green light (GL; 500-590 nm). The chromatographic analysis (HPLC-DAD) revealed that a peak belonging to this unknown pigment is eluted between chlorophyll (Chl) a and b. This pigment exhibited the same absorption spectrum and fluorescence excitation and emission spectra as Chl a. It was negligible in control plants cultivated under white light of the same irradiance (photosynthetic photon flux density of 240 μmol m -2  s -1 ). Mass spectrometry analysis of this pigment (ions m/z = 889 [M-H] - ; m/z = 949 [M+acetic acid-H] - ) indicates that it is Chl a with a tetrahydrogengeranylgeraniol side chain (containing two double bonds in a phytyl side chain; Chl a THGG ), which is an intermediate in Chl a synthesis. In plants grown under GL, the proportion of Chl a THGG to total Chl content rose to approximately 8% and 16% after 7 and 14 days of cultivation, respectively. Surprisingly, plants cultivated under GL exhibited drastically increased concentration of the enzyme geranylgeranyl reductase, which is responsible for the reduction of phytyl chain double bonds in the Chl synthesis pathway. This indicates impaired activity of this enzyme in GL-grown plants. A similar effect of GL on Chl synthesis was observed for distinct higher plant species. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

The importance of monochromatic lights in the production of phenolic acids and flavonoids in shoot cultures of Aronia melanocarpa, Aronia arbutifolia and Aronia × prunifolia.

PubMed

Szopa, Agnieszka; Starzec, Anna; Ekiert, Halina

2018-02-01

Shoot cultures of Aronia melanocarpa, A. arbutifolia and A. × prunifolia were maintained on Murashige and Skoog medium with 1 mg/l each of BA and NAA under monochromatic lights (far-red, red, blue lights, UV-A-irradiation), in darkness, and under white light (control). HPLC-DAD analyses of 19 phenolic acids and 11 flavonoids in methanolic extracts from the shoots revealed in all of them the presence of three depsides (chlorogenic, neochlorogenic and rosmarinic acids), protocatechuic acid, four flavonoid glycosides (cynaroside, quercitrin, hyperoside and rutoside), and additionally, in A. arbutifolia, 3,4-dihydroxyphenylacetic acid. Depending on light quality, the total amounts of these metabolites increased 1.8-5.9 times, reaching maximum values under blue light: 527.40 and 144.61 mg 100 g -1 DW (A. melanocarpa), 543.27 and 85.82 mg 100 g -1 DW (A. arbutifolia) and 1615.18 and 220.65 mg 100 g -1 DW (A. × prunifolia), respectively. The maximum total amounts were 1.3-3.6 times higher than under white light. The quantities of individual metabolites changed from 1.2 to 11.0 times, with high amounts of neochlorogenic acid and quercitrin in A. melanocarpa (243.35 and 75.64 mg 100 g -1 DW), and of chlorogenic and rosmarinic acids and quercitrin in A. arbutifolia (236.52, 219.35 and 51.01 mg 100 g -1 DW). Extremely high amounts of depsides (418.83, 644.68, 548.86 mg 100 g -1 DW) and quercitrin (165.88 mg 100 g -1 DW) were produced in cultures of the hybrid - A. × prunifolia. The results are potentially useful for practical applications. This is the first report documented the importance of light quality on the production of phenolic acids and flavonoids in three aronia in vitro cultures. Copyright © 2018. Published by Elsevier B.V.

Organic light-emitting diodes from homoleptic square planar complexes

DOEpatents

Omary, Mohammad A

2013-11-12

Homoleptic square planar complexes [M(N.LAMBDA.N).sub.2], wherein two identical N.LAMBDA.N bidentate anionic ligands are coordinated to the M(II) metal center, including bidentate square planar complexes of triazolates, possess optical and electrical properties that make them useful for a wide variety of optical and electrical devices and applications. In particular, the complexes are useful for obtaining white or monochromatic organic light-emitting diodes ("OLEDs"). Improved white organic light emitting diode ("WOLED") designs have improved efficacy and/or color stability at high brightness in single- or two-emitter white or monochrome OLEDs that utilize homoleptic square planar complexes, including bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) ("Pt(ptp).sub.2").

Faraday-Active Fabry-Perot Resonator: Transmission, Reflection, and Emissivity

NASA Technical Reports Server (NTRS)

Liptuga, Anatoliy; Morozhenko, Vasyl; Pipa, Viktor; Venger, Evgen; Kostiuk, Theodor

2011-01-01

The propagation of light within a semiconductor Faraday-active Fabry-Perot resonator (FAFR) is investigated theoretically and experimentally. It is shown that an external magnetic field radically changes the angular and spectral characteristics of transmission, reflection and emissivity of the resonator not only for polarized, but also for unpolarized light. Suppression of interference patterns and phase inversion of the interference extrema were observed in both monochromatic and polychromatic light. The investigations were carried out for the plane-parallel plates of n-InAs in the spectral range of free charge carrier absorption. The results can be used to create new controllable optical and spectroscopic devices for investigation of Faraday-active material properties and for control of parameters of plane-parallel layers and structures.

Using a laser source to measure the refractive index of glass beads and Debye theory analysis.

PubMed

Li, Shui-Yan; Qin, Shuang; Li, Da-Hai; Wang, Qiong-Hua

2015-11-20

Using a monochromatic laser beam to illuminate a homogeneous glass bead, some rainbows will appear around it. This paper concentrates on the study of the scattering intensity distribution and the method of measuring the refractive index for glass beads based on the Debye theory. It is found that the first rainbow due to the scattering superposition of backward light of the low-refractive-index glass beads can be explained approximately with the diffraction, the external reflection plus the one internal reflection, while the second rainbow of high-refractive-index glass beads is due to the contribution from the diffraction, the external reflection, the direct transmission, and the two internal reflections. The scattering intensity distribution is affected by the refractive index, the radius of the glass bead, and the incident beam width. The effects of the refractive index and the glass bead size on the first and second minimum deviation angle position are analyzed in this paper. The results of the measurements agree very well with the specifications.

Dielectrophoresis-Assisted Raman Spectroscopy of Intravesicular Analytes on Metallic Pyramids.

PubMed

Barik, Avijit; Cherukulappurath, Sudhir; Wittenberg, Nathan J; Johnson, Timothy W; Oh, Sang-Hyun

2016-02-02

Chemical analysis of membrane-bound containers such as secretory vesicles, organelles, and exosomes can provide insights into subcellular biology. These containers are loaded with a range of important biomolecules, which further underscores the need for sensitive and selective analysis methods. Here we present a metallic pyramid array for intravesicular analysis by combining site-selective dielectrophoresis (DEP) and Raman spectroscopy. Sharp pyramidal tips act as a gradient force generator to trap nanoparticles or vesicles from the solution, and the tips are illuminated by a monochromatic light source for concurrent spectroscopic detection of trapped analytes. The parameters suitable for DEP trapping were optimized by fluorescence microscopy, and the Raman spectroscopy setup was characterized by a nanoparticle based model system. Finally, vesicles loaded with 4-mercaptopyridine were concentrated at the tips and their Raman spectra were detected in real time. These pyramidal tips can perform large-area array-based trapping and spectroscopic analysis, opening up possibilities to detect molecules inside cells or cell-derived vesicles.

X-ray vision of fuel sprays.

PubMed

Wang, Jin

2005-03-01

With brilliant synchrotron X-ray sources, microsecond time-resolved synchrotron X-ray radiography and tomography have been used to elucidate the detailed three-dimensional structure and dynamics of high-pressure high-speed fuel sprays in the near-nozzle region. The measurement allows quantitative determination of the fuel distribution in the optically impenetrable region owing to the multiple scattering of visible light by small atomized fuel droplets surrounding the jet. X-radiographs of the jet-induced shock waves prove that the fuel jets become supersonic under appropriate injection conditions and that the quantitative analysis of the thermodynamic properties of the shock waves can also be derived from the most direct measurement. In other situations where extremely axial-asymmetric sprays are encountered, mass deconvolution and cross-sectional fuel distribution models can be computed based on the monochromatic and time-resolved X-radiographic images collected from various rotational orientations of the sprays. Such quantitative analysis reveals the never-before-reported characteristics and most detailed near-nozzle mass distribution of highly transient fuel sprays.

The Si(1-x)Nx Rugate

NASA Astrophysics Data System (ADS)

Bassel, R. H.

1989-08-01

With the advent of lasers, intense sources of monochromatic light are now available. The problem of eye and sensor protection from these devices is now crucial to the field operations of troops and military weapons systems. In other words it is necessary to construct a filter which will reject particular laser lines from impinging upon a material. The results are presented in the infrared and near infrared region of the spectrum. The effectiveness of a Rugate filter constructed of a silicon nitrogen alloy is calculated. Single and double line rugates are discussed. The dependence on the rugate on the various parameters such as the number of cycles, the amplitudes of the sine waves and the phase angle are presented. The effects of absorption, constructional malfunctions, and the angle of incidence of the laser beam are studied. It is found that quite large optical densities can be achieved with rather thin films, thus the silicon nitrogen rugate is a viable candidate for a laser rejection filter.

Microfocus/Polycapillary-Optic Crystallographic X-Ray System

NASA Technical Reports Server (NTRS)

Joy, Marshall; Gubarev, Mikhail; Ciszak, Ewa

2005-01-01

A system that generates an intense, nearly collimated, nearly monochromatic, small-diameter x-ray beam has been developed for use in macromolecular crystallography. A conventional x-ray system for macromolecular crystallography includes a rotating-anode x-ray source, which is massive (.500 kg), large (approximately 2 by 2 by 1 m), and power-hungry (between 2 and 18 kW). In contrast, the present system generates a beam of the required brightness from a microfocus source, which is small and light enough to be mounted on a laboratory bench, and operates at a power level of only tens of watts. The figure schematically depicts the system as configured for observing x-ray diffraction from a macromolecular crystal. In addition to the microfocus x-ray source, the system includes a polycapillary optic . a monolithic block (typically a bundle of fused glass tubes) that contains thousands of straight or gently curved capillary channels, along which x-rays propagate with multiple reflections. This particular polycapillary optic is configured to act as a collimator; the x-ray beam that emerges from its output face consists of quasi-parallel subbeams with a small angular divergence and a diameter comparable to the size of a crystal to be studied. The gap between the microfocus x-ray source and the input face of the polycapillary optic is chosen consistently with the focal length of the polycapillary optic and the need to maximize the solid angle subtended by the optic in order to maximize the collimated x-ray flux. The spectrum from the source contains a significant component of Cu K (photon energy is 8.08 keV) radiation. The beam is monochromatized (for Cu K ) by a nickel filter 10 m thick. In a test, this system was operated at a power of 40 W (current of 897 A at an accelerating potential of 45 kV), with an anode x-ray spot size of 41+/-2 microns. Also tested, in order to provide a standard for comparison, was a commercial rotating-anode x-ray crystallographic system with a pyrolytic graphite monochromator and a 250-micron pinhole collimator, operating at a power of 3.15 kW (current of 70 mA at an accelerating potential of 45 kV). The flux of collimated Cu K radiation in this system was found to be approximately 16 times that in the rotatinganode system. Data on x-ray diffraction from crystals of tetragonal form of lysozyme (protein) in this system were found to be of high quality and to be reducible by use of standard crystallographic software.

Ultra-precision fabrication of 500 mm long and laterally graded Ru/C multilayer mirrors for X-ray light sources.

PubMed

Störmer, M; Gabrisch, H; Horstmann, C; Heidorn, U; Hertlein, F; Wiesmann, J; Siewert, F; Rack, A

2016-05-01

X-ray mirrors are needed for beam shaping and monochromatization at advanced research light sources, for instance, free-electron lasers and synchrotron sources. Such mirrors consist of a substrate and a coating. The shape accuracy of the substrate and the layer precision of the coating are the crucial parameters that determine the beam properties required for various applications. In principal, the selection of the layer materials determines the mirror reflectivity. A single layer mirror offers high reflectivity in the range of total external reflection, whereas the reflectivity is reduced considerably above the critical angle. A periodic multilayer can enhance the reflectivity at higher angles due to Bragg reflection. Here, the selection of a suitable combination of layer materials is essential to achieve a high flux at distinct photon energies, which is often required for applications such as microtomography, diffraction, or protein crystallography. This contribution presents the current development of a Ru/C multilayer mirror prepared by magnetron sputtering with a sputtering facility that was designed in-house at the Helmholtz-Zentrum Geesthacht. The deposition conditions were optimized in order to achieve ultra-high precision and high flux in future mirrors. Input for the improved deposition parameters came from investigations by transmission electron microscopy. The X-ray optical properties were investigated by means of X-ray reflectometry using Cu- and Mo-radiation. The change of the multilayer d-spacing over the mirror dimensions and the variation of the Bragg angles were determined. The results demonstrate the ability to precisely control the variation in thickness over the whole mirror length of 500 mm thus achieving picometer-precision in the meter-range.

Flow visualization and modeling for education and outreach in low-income countries

NASA Astrophysics Data System (ADS)

Motanated, K.

2016-12-01

Being able to visualize the dynamic interaction between the movement of water and sediment flux is undeniably a profound tool for students and novices to understand complicated earth surface processes. In a laser-sheet flow visualization technique, a light source that is thin and monochromatic is required to illuminate sediments or tracers in the flow. However, an ideal laser sheet generator is rather expensive, especially for schools and universities residing in low-income countries. This project is proposing less-expensive options for a laser-sheet source and flow visualization experiment configuration for qualitative observation and quantitative analysis of the interaction between fluid media and sediments. Here, Fresnel lens is used to convert from point laser into sheet laser. Multiple combinations of laser diodes of various wavelength (nanometer) and power (milliwatt) and Fresnel lenses of various dimensions are analyzed. The pair that is able to produce the thinnest and brightest light sheet is not only effective but also affordable. The motion of sediments in a flow can be observed by illuminating the laser-sheet in an interested flow region. The particle motion is recorded by a video camera that is capable of taking multiple frames per second and having a narrow depth of view. The recorded video file can be played in a slow-motion mode so students can visually observe and qualitatively analyze the particle motion. An open source software package for Particle Imaging Velocimetry (PIV) can calculate the local velocity of particles from still images extracted from the video and create a vector map depicting particle motion. This flow visualization experiment is inexpensive and the configuration is simple to setup. Most importantly, this flow visualization technique serves as a fundamental tool for earth surface process education and can further be applied to sedimentary process modeling.

Ultra-precision fabrication of 500 mm long and laterally graded Ru/C multilayer mirrors for X-ray light sources

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

Störmer, M., E-mail: michael.stoermer@hzg.de; Gabrisch, H.; Horstmann, C.

2016-05-15

X-ray mirrors are needed for beam shaping and monochromatization at advanced research light sources, for instance, free-electron lasers and synchrotron sources. Such mirrors consist of a substrate and a coating. The shape accuracy of the substrate and the layer precision of the coating are the crucial parameters that determine the beam properties required for various applications. In principal, the selection of the layer materials determines the mirror reflectivity. A single layer mirror offers high reflectivity in the range of total external reflection, whereas the reflectivity is reduced considerably above the critical angle. A periodic multilayer can enhance the reflectivity atmore » higher angles due to Bragg reflection. Here, the selection of a suitable combination of layer materials is essential to achieve a high flux at distinct photon energies, which is often required for applications such as microtomography, diffraction, or protein crystallography. This contribution presents the current development of a Ru/C multilayer mirror prepared by magnetron sputtering with a sputtering facility that was designed in-house at the Helmholtz-Zentrum Geesthacht. The deposition conditions were optimized in order to achieve ultra-high precision and high flux in future mirrors. Input for the improved deposition parameters came from investigations by transmission electron microscopy. The X-ray optical properties were investigated by means of X-ray reflectometry using Cu- and Mo-radiation. The change of the multilayer d-spacing over the mirror dimensions and the variation of the Bragg angles were determined. The results demonstrate the ability to precisely control the variation in thickness over the whole mirror length of 500 mm thus achieving picometer-precision in the meter-range.« less

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, S.M.; Sharma, S.K.

1988-11-01

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber having a metal coating on at least a portion of a light transmissive core. The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the absorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode may function as a working electrode of an electrochemical cell while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface. 6 figs.

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, S.M.; Sharma, S.K.

1987-11-30

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber having a metal coating on at least a portion of a light transmissive core. The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the adsorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode may function as a working electrode of an electrochemical cell while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface. 6 figs.

Ultrashort Laser Pulse Propagation in Water

DTIC Science & Technology

2009-01-01

It should be noted that the so called Lambert-Beer law was first discovered by Pierre Bouguer in his published work in 1729 titled Essai d’optique...sur la gradation de la lumiére and we will hereafter refer to it as the Bouguer -Lambert-Beer Law or BLB. The law is valid for monochromatic sources

SPECIAL ISSUE ON OPTICAL PROCESSING OF INFORMATION: Optical information processing with transformation of the spatial coherence of light

NASA Astrophysics Data System (ADS)

Bykovskii, Yurii A.; Markilov, A. A.; Rodin, V. G.; Starikov, S. N.

1995-10-01

A description is given of systems with spatially incoherent illumination, intended for spectral and correlation analysis, and for the recording of Fourier holograms. These systems make use of transformation of the degree of the spatial coherence of light. The results are given of the processing of images and signals, including those transmitted by a bundle of fibre-optic waveguides both as monochromatic light and as quasimonochromatic radiation from a cathode-ray tube. The feasibility of spatial frequency filtering and of correlation analysis of images with a bipolar impulse response is considered for systems with spatially incoherent illumination where these tasks are performed by double transformation of the spatial coherence of light. A description is given of experimental systems and the results of image processing are reported.

A general purpose wideband optical spatial frequency spectrum analyzer

NASA Technical Reports Server (NTRS)

Ballard, G. S.; Mellor, F. A.

1972-01-01

The light scattered at various angles by a transparent media is studied. An example of these applications is the optical Fourier spectrum measurement resulting from various spatial frequencies which were recorded on a photographic emulsion. A method for obtaining these measurements consists of illuminating the test object with parallel monochromatic light. A stationary lens, placed in the resulting wavefield at a distance of one focal length from the object, will focus parallel waves emanating from the test object at a point lying in the focal plane of the lens. A light detector with a small filtering aperture is then used to measure the intensity variation of the light in the focal or transform plane of the lens. Such measurements require the use of a lens which is highly corrected for all of the common aberrations except chromatic aberration.

Optoelectronic Devices Based on Novel Semiconductor Structures

DTIC Science & Technology

2006-06-14

superlattices 4. TEM study and band -filling effects in quantum-well dots 5. Improvements on tuning ranges and output powers for widely-tunable THz sources...the pump power increases the relative strength for the QW emission in the QWD sample also increases. Eventually at the sufficiently- high pump power ...Ahopelto, Appl. Phys. Lett. 66, 2364 (1995). 5. A monochromatic and high - power THz source tunable in the ranges of 2.7-38.4 ptm and 58.2-3540 ptm for

Fundamental neutron physics beamline at the spallation neutron source at ORNL

DOE PAGES

Fomin, N.; Greene, G. L.; Allen, R. R.; ...

2014-11-04

In this paper, we describe the Fundamental Neutron Physics Beamline (FnPB) facility located at the Spallation Neutron Source at Oak Ridge National Laboratory. The FnPB was designed for the conduct of experiments that investigate scientific issues in nuclear physics, particle physics, astrophysics and cosmology using a pulsed slow neutron beam. Finally, we present a detailed description of the design philosophy, beamline components, and measured fluxes of the polychromatic and monochromatic beams.

Energy distribution measurement of narrow-band ultrashort x-ray beams via K-edge filters subtraction

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

Cardarelli, Paolo; Di Domenico, Giovanni; Marziani, Michele

2012-10-01

The characterization of novel x-ray sources includes the measurement of the photon flux and the energy distribution of the produced beam. The aim of BEATS2 experiment at the SPARC-LAB facility of the INFN National Laboratories of Frascati (Rome, Italy) is to investigate possible medical applications of an x-ray source based on Thomson relativistic back-scattering. This source is expected to produce a pulsed quasi-monochromatic x-ray beam with an instantaneous flux of 10{sup 20} ph/s in pulses 10 ps long and with an average energy of about 20 keV. A direct measurement of energy distribution of this beam is very difficult withmore » traditional detectors because of the extremely high photon flux. In this paper, we present a method for the evaluation of the energy distribution of quasi-monochromatic x-ray beams based on beam filtration with K-edge absorbing foils in the energy range of interest (16-22 keV). The technique was tested measuring the energy distribution of an x-ray beam having a spectrum similar to the expected one (SPARC-LAB Thomson source) by using a tungsten anode x-ray tube properly filtered and powered. The energy distribution obtained has been compared with the one measured with a HPGe detector showing very good agreement.« less

Three-dimensional optical tomographic imaging of supersonic jets through inversion of phase data obtained through the transport-of-intensity equation.

PubMed

Hemanth, Thayyullathil; Rajesh, Langoju; Padmaram, Renganathan; Vasu, R Mohan; Rajan, Kanjirodan; Patnaik, Lalit M

2004-07-20

We report experimental results of quantitative imaging in supersonic circular jets by using a monochromatic light probe. An expanding cone of light interrogates a three-dimensional volume of a supersonic steady-state flow from a circular jet. The distortion caused to the spherical wave by the presence of the jet is determined through our measuring normal intensity transport. A cone-beam tomographic algorithm is used to invert wave-front distortion to changes in refractive index introduced by the flow. The refractive index is converted into density whose cross sections reveal shock and other characteristics of the flow.

Control of the electromagnetic drag using fluctuating light fields

NASA Astrophysics Data System (ADS)

Pastor, Víctor J. López; Marqués, Manuel I.

2018-05-01

An expression for the electromagnetic drag force experienced by an electric dipole in a light field consisting of a monochromatic plane wave with polarization and phase randomly fluctuating is obtained. The expression explicitly considers the transformations of the field and frequency due to the Doppler shift and the change of the polarizability response of the electric dipole. The conditions to be fulfilled by the polarizability of the dipole in order to obtain a positive, a null, and a negative drag coefficient are analytically determined and checked against numerical simulations for the dynamics of a silver nanoparticle. The theoretically predicted diffusive, superdiffusive, and exponentially accelerated dynamical regimes are numerically confirmed.

High Resolution X-Ray Diffraction of Macromolecules with Synchrotron Radiation

NASA Technical Reports Server (NTRS)

Stojanoff, Vivian; Boggon, Titus; Helliwell, John R.; Judge, Russell; Olczak, Alex; Snell, Edward H.; Siddons, D. Peter; Rose, M. Franklin (Technical Monitor)

2000-01-01

We recently combined synchrotron-based monochromatic X-ray diffraction topography methods with triple axis diffractometry and rocking curve measurements: high resolution X-ray diffraction imaging techniques, to better understand the quality of protein crystals. We discuss these methods in the light of results obtained on crystals grown under different conditions. These non destructive techniques are powerful tools in the characterization of the protein crystals and ultimately will allow to improve, develop, and understand protein crystal growth. High resolution X-ray diffraction imaging methods will be discussed in detail in light of recent results obtained on Hen Egg White Lysozyme crystals and other proteins.

Thermodynamic theory of the plasmoelectric effect

DOE PAGES

van de Groep, Jorik; Sheldon, Matthew T.; Atwater, Harry A.; ...

2016-03-18

Resonant metal nanostructures exhibit an optically induced electrostatic potential when illuminated with monochromatic light under off-resonant conditions. This plasmoelectric effect is thermodynamically driven by the increase in entropy that occurs when the plasmonic structure aligns its resonant absorption spectrum with incident illumination by varying charge density. As a result, the elevated steady-state temperature of the nanostructure induced by plasmonic absorption is further increased by a small amount. Here, we study in detail the thermodynamic theory underlying the plasmoelectric effect by analyzing a simplified model system consisting of a single silver nanoparticle. We find that surface potentials as large as 473more » mV are induced under 100 W/m2 monochromatic illumination, as a result of a 11 mK increases in the steady-state temperature of the nanoparticle. Hence, we discuss the applicability of this analysis for realistic experimental geometries, and show that this effect is generic for optical structures in which the resonance is linked to the charge density.« less

An ultrabright and monochromatic electron point source made of a LaB6 nanowire

NASA Astrophysics Data System (ADS)

Zhang, Han; Tang, Jie; Yuan, Jinshi; Yamauchi, Yasushi; Suzuki, Taku T.; Shinya, Norio; Nakajima, Kiyomi; Qin, Lu-Chang

2016-03-01

Electron sources in the form of one-dimensional nanotubes and nanowires are an essential tool for investigations in a variety of fields, such as X-ray computed tomography, flexible displays, chemical sensors and electron optics applications. However, field emission instability and the need to work under high-vacuum or high-temperature conditions have imposed stringent requirements that are currently limiting the range of application of electron sources. Here we report the fabrication of a LaB6 nanowire with only a few La atoms bonded on the tip that emits collimated electrons from a single point with high monochromaticity. The nanostructured tip has a low work function of 2.07 eV (lower than that of Cs) while remaining chemically inert, two properties usually regarded as mutually exclusive. Installed in a scanning electron microscope (SEM) field emission gun, our tip shows a current density gain that is about 1,000 times greater than that achievable with W(310) tips, and no emission decay for tens of hours of operation. Using this new SEM, we acquired very low-noise, high-resolution images together with rapid chemical compositional mapping using a tip operated at room temperature and at 10-times higher residual gas pressure than that required for W tips.

Consumer Perception of the Healthfulness of Ultra-processed Products Featuring Different Front-of-Pack Nutrition Labeling Schemes.

PubMed

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

2017-04-01

To examine the influence of front-of-pack nutrition information on the perception of healthfulness of ultra-processed products across 2 income levels. A between-participants design was used to compare healthfulness perception of ultra-processed products featuring different front-of-pack nutrition information schemes (guideline daily amount system, traffic light system, and monochromatic traffic light system). A total of 300 people (aged 18-70 years, 75% female) from Montevideo, Uruguay, participated in the study; half were middle- or high-income people and the other half were low-income people. Participants were shown the labels of each product and asked to rate their perceived healthfulness and the frequency with which each product should be consumed. Results were analyzed using analysis of variance for statistical significance (P < .05). Low-income participants perceived ultra-processed products to be significantly (P < .05) more healthful than did middle- and high-income participants. The lowest perceived healthfulness scores for low-income participants were obtained for products featuring the colored and monochromatic traffic light system whereas no significant differences (P > .05) among schemes were found for middle- and high-income participants. Nutrition education programs aimed at increasing low-income people's knowledge of the nutritional composition of these products and their potential negative effects on health seem to be necessary. Although the inclusion of semidirective front-of-pack nutrition information decreased the perceived healthfulness of low-income people, it seemed unlikely to influence how they perceive these products. Copyright © 2016 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

A versatile indirect detector design for hard X-ray microimaging

NASA Astrophysics Data System (ADS)

Douissard, P.-A.; Cecilia, A.; Rochet, X.; Chapel, X.; Martin, T.; van de Kamp, T.; Helfen, L.; Baumbach, T.; Luquot, L.; Xiao, X.; Meinhardt, J.; Rack, A.

2012-09-01

Indirect X-ray detectors are of outstanding importance for high resolution imaging, especially at synchrotron light sources: while consisting mostly of components which are widely commercially available, they allow for a broad range of applications in terms of the X-ray energy employed, radiation dose to the detector, data acquisition rate and spatial resolving power. Frequently, an indirect detector consists of a thin-film single crystal scintillator and a high-resolution visible light microscope as well as a camera. In this article, a novel modular-based indirect design is introduced, which offers several advantages: it can be adapted for different cameras, i.e. different sensor sizes, and can be trimmed to work either with (quasi-)monochromatic illumination and the correspondingly lower absorbed dose or with intense white beam irradiation. In addition, it allows for a motorized quick exchange between different magnifications / spatial resolutions. Developed within the European project SCINTAX, it is now commercially available. The characteristics of the detector in its different configurations (i.e. for low dose or for high dose irradiation) as measured within the SCINTAX project will be outlined. Together with selected applications from materials research, non-destructive evaluation and life sciences they underline the potential of this design to make high resolution X-ray imaging widely available.

In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

DOE PAGES

Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; ...

2015-08-25

Here, one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) is high resistance of the cladding to plastic deformation and burst failure, since the deformation and burst behavior governs the cooling efficiency of flow channels and the process of fission product release. To simulate and evaluate the deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisting of a high-resolution video camera, a light filteringmore » unit, and monochromatic light sources. The in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. As the first application, ten (10) candidate cladding materials for ATF, i.e., five FeCrAl alloys and five nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800 °C, while negligible strain rates were measured for higher strength alloys.« less

Green Light-emitting Diodes Light Stimuli during Incubation Enhances Posthatch Growth without Disrupting Normal Eye Development of Broiler Embryos and Hatchlings.

PubMed

Zhang, L; Zhu, X D; Wang, X F; Li, J L; Gao, F; Zhou, G H

2016-11-01

Monochromatic green light-emitting diodes (LED) light stimuli influences the posthatch growth performance of chicks. This study was undertaken with the following objectives: i) to examine whether the green LED light stimuli induces an overheating effect by determining weight loss rate of fertile eggs during incubation period; ii) to look for the development of eyes and other primary organs at different ages of embryos and newly hatched chicks. Arbor Acres fertile broiler eggs (n = 480) were randomly assigned to 3 incubation groups and exposed to continuous white light, green light, or a dark environment (control) from the first day to 19 d of incubation. The light sourced from LED lamps with the intensity of 30 lx at eggshell level. The results showed that either green or white light stimuli during incubation did not significantly affect the weight loss rate of fertile eggs, hatching time, hatchability, chick embryo, or body weight (BW), the weight percentage of heart, liver, and eyes, as well as obvious systematic abnormalities in eye weight, side-to-side, back-to-front, or corneal diameter from 15 d of embryogenesis to 6 d of posthatch (p>0.05). Compared with the dark condition, green light stimuli during incubation tended to increase feed intake (p = 0.080), improved the BW gain of chicks during 0 to 6 day posthatch (p<0.05), and increased the percentage of pectoral muscle to the BW on 3- and 6-day-old chicks. In addition, embryos or chicks in green light had lower weight percentage of yolk retention on 19 d of embryogenesis and 1 d of posthatch in comparison to those in dark or white group (p<0.05). These results suggest that providing 30 lx green LED light stimuli during incubation has no detrimental effect on the development of eyes, heart and liver of embryos and hatchlings, but does have potential benefits in terms of enhancement of the chick growth during the early posthatch stages. In addition, the fertile broiler eggs stimulated with 30 lx green LED light during incubation does not cause an overheating effect.

Virtual monochromatic spectral imaging with fast kilovoltage switching: reduction of metal artifacts at CT.

PubMed

Pessis, Eric; Campagna, Raphaël; Sverzut, Jean-Michel; Bach, Fabienne; Rodallec, Mathieu; Guerini, Henri; Feydy, Antoine; Drapé, Jean-Luc

2013-01-01

With arthroplasty being increasingly used to relieve joint pain, imaging of patients with metal implants can represent a significant part of the clinical work load in the radiologist's daily practice. Computed tomography (CT) plays an important role in the postoperative evaluation of patients who are suspected of having metal prosthesis-related problems such as aseptic loosening, bone resorption or osteolysis, infection, dislocation, metal hardware failure, or periprosthetic bone fracture. Despite advances in detector technology and computer software, artifacts from metal implants can seriously degrade the quality of CT images, sometimes to the point of making them diagnostically unusable. Several factors may help reduce the number and severity of artifacts at multidetector CT, including decreasing the detector collimation and pitch, increasing the kilovolt peak and tube charge, and using appropriate reconstruction algorithms and section thickness. More recently, dual-energy CT has been proposed as a means of reducing beam-hardening artifacts. The use of dual-energy CT scanners allows the synthesis of virtual monochromatic spectral (VMS) images. Monochromatic images depict how the imaged object would look if the x-ray source produced x-ray photons at only a single energy level. For this reason, VMS imaging is expected to provide improved image quality by reducing beam-hardening artifacts.

Measuring Cavitation with Synchrotron X-Rays

NASA Astrophysics Data System (ADS)

Duke, Daniel; Kastengren, Alan; Powell, Chris; X-Ray Fuel Spray Group, Energy Systems Division Team

2012-11-01

Cavitation plays an important role in the formation of sprays from small nozzles such as those found in fuel injection systems. A sharp-edged inlet from the sac into the nozzle of a diesel fuel injector is shown to inititate a strong sheet-like cavitation along the boundary layer of the nozzle throat, which is difficult to measure and can lead to acoustic damage. To investigate this phenomenon, a diagnostic technique capable of mapping the density field of the nozzle through regions of intense cavitation is required. Available visible-light techniques are limited to qualitative observations of the outer extent of cavitation zones. However, brilliant X-rays from a synchrotron source have negligible refraction and are capable of penetrating the full extent of cavitation zones. We present the early results of a novel application of line-of-sight, time-resolved X-ray radiography on a cavitating model nozzle. Experiments were conducted at Sector 7-BM of the Advanced Photon Source. Density and vapor distribution are measured from the quantitative absorption of monochromatic X-rays. The density field can then be tomographically reconstructed from the projections. The density is then validated against a range of compressible and incompressible numerical simulations. This research was performed at the 7-BM beamline of the Advanced Photon Source. We acknowledge the support of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 and the DOE Vehicle Technologies Program (DOE-EERE).

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

Loether, A.; Adams, B. W.; DiCharia, A.

A hard x-ray pump–probe spectrometer using a multi-crystal Bragg reflector is demonstrated at a third generation synchrotron source. This device derives both broadband pump and monochromatic probe pulses directly from a single intense, broadband x-ray pulse centered at 8.767 keV. In conclusion, we present a proof-of-concept experiment which directly measures x-ray induced crystalline lattice strain.

Calibration techniques and results in the soft X-ray and extreme ultraviolet for components of the Extreme Ultraviolet Explorer Satellite

NASA Technical Reports Server (NTRS)

Malina, Roger F.; Jelinsky, Patrick; Bowyer, Stuart

1986-01-01

The calibration facilities and techniques for the Extreme Ultraviolet Explorer (EUVE) from 44 to 2500 A are described. Key elements include newly designed radiation sources and a collimated monochromatic EUV beam. Sample results for the calibration of the EUVE filters, detectors, gratings, collimators, and optics are summarized.

Single and Multiple Scattered Solar Radiation

DTIC Science & Technology

1982-08-30

so that factor can be expected to vary considerably from one scattering point to the next. The monochromatic intensity at the observer due to all of...the single scattering sources within the line-of-sight is obtained by summing over the optical path the product of the source function and the...the observer. Using a dot product 1)etwecen position_ vectors on the unit sphere, it can be Chown that cosA cost coss cost) cos4o + 0 S 0 0 "+ cost

Exposing broiler eggs to green, red and white light during incubation.

PubMed

Archer, G S

2017-07-01

Previous work has shown that exposing broiler eggs to white light during incubation can improve hatchability and post-hatch animal welfare. It was hypothesized that due to how different wavelengths of light can affect avian physiology differently, and how pigmented eggshells filter light that different monochromatic wavelengths would have differential effects on hatchability and post-hatch animal welfare indicators. To determine, we incubated chicken eggs (n=6912) under either no light (dark), green light, red light or white light; the light level was 250 lux. White and red light were observed to increase hatch of fertile (P0.05). Fear response of during isolation and tonic immobility was reduced (P0.05) from dark incubated broilers. All light incubated broilers had lower (P<0.05) plasma corticosterone and higher (P<0.05) plasma serotonin concentrations than dark incubated broilers. These results indicate that white light and red light that is a component of it are possibly the key spectrum to improving hatchability and lower fear and stress susceptibility, whereas green light is not as effective. Incubating broiler eggs under these spectrums could be used to improve hatchery efficiency and post-hatch animal welfare at the same time.

Conversion of visible light to electrical energy - Stable cadmium selenide photoelectrodes in aqueous electrolytes

NASA Technical Reports Server (NTRS)

Wrighton, M. S.; Ellis, A. B.; Kaiser, S. W.

1977-01-01

Stabilization of n-type CdSe to photoanodic dissolution is reported. The stabilization is accomplished by the competitive oxidation of S(--) or S(n)(--) at the CdSe photoanode in an electrochemical cell. Such stabilized cells are shown to sustain the conversion of low energy (not less than 1.7 eV) visible light to electricity with good efficiency and no deterioration of the CdSe photoelectrode or of the electrolyte. The electrolyte undergoes no net chemical change because the oxidation occurring at the photoelectrode is reversed at the cathode. Conversion of monochromatic light at 633 nm to electricity is shown to be up to approximately 9% efficient with output potentials of approximately 0.4 V. Conversion of solar energy to electricity is estimated to be approximately 2% efficient.

Polydopamine-Coated TiO2 Nanotubes for Selective Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde Under Visible Light.

PubMed

Tripathy, Jyotsna; Loget, Gabriel; Altomare, Marco; Schmuki, Patrik

2016-05-01

TiO2 nanotube arrays grown by anodization were coated with thin layers of polydopamine as visible light sensitizer. The PDA-coated TiO2 scaffolds were used as photocatalyst for selective oxidation of benzyl alcohol under monochromatic irradiation at 473 nm. Benzaldehyde was selectively formed and no by-products could be detected. A maximized reaction yield was obtained in O2-saturated acetonitrile. A mechanism is proposed that implies firstly the charge carrier generation in polydopamine as a consequence of visible light absorption. Secondly, photo-promoted electrons are injected in TiO2 conduction band, and subsequently transferred to dissolved O2 to form O*2- radicals. These radicals react with benzyl alcohol and lead to its selective dehydrogenation oxidation towards benzaldehyde.

Prospects for compact high-intensity laser synchrotron x-ray and gamma sources

NASA Astrophysics Data System (ADS)

Pogorelsky, I. V.

1997-03-01

A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high-brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high-brightness electron beam and the high-power CO2 laser may be used for prototype LSS demonstration. In a feasible demonstration experiment, 10-GW, 100-ps CO2 laser beam will be brought to a head-on collision with a 10-ps, 0.5-nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 Å) x-rays of 10-ps pulse duration, with a flux of ˜1019photons/sec, will be produced via linear Compton backscattering. The x-ray spectrum is tunable proportionally to the e-beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 1022 photons/sec level, after the ongoing ATF CO2 laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact "table-top" LSS of monochromatic gamma radiation may become feasible.

Twinkle, Twinkle, Little Laser by Ben Bova

NASA Astrophysics Data System (ADS)

Bova, Ben

2000-03-01

Radio astronomers have had no success in the search for extraterrestrial intelligence (SETI). Astronomers are now studying the heavens for signals that intelligent beings might send using lasers. Laser lights have the advantage of directionality, monochromaticity, and coherence. This research, called "optical SETI," looks for optical or infrared pulses with detectors that can pick up a broad spectrum of frequencies. By confining the search to stars similar to the Sun, scientists hope to find evidence of life other than ours.

A cost analysis of microalgal biomass and biodiesel production in open raceways treating municipal wastewater and under optimum light wavelength.

PubMed

Kang, Zion; Kim, Byung-Hyuk; Ramanan, Rishiram; Choi, Jong-Eun; Yang, Ji-Won; Oh, Hee-Mock; Kim, Hee-Sik

2015-01-01

Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity. Experimental results were then fitted into a model, and cost analysis was performed in comparison with control raceways. Three different microalgal strains, Chlorella vulgaris AG10032, Chlorella sp. JK2, and Scenedesmus sp. JK10, were tested for nutrient removal under different light wavelengths (blue, green, red, and white) using filters in batch cultivation. Blue wavelength showed an average of 27% higher nutrient removal and at least 42% higher chemical oxygen demand removal compared with white light. Naturally, the specific growth rate of microalgae cultivated under blue wavelength was on average 10.8% higher than white wavelength. Similarly, lipid productivity was highest in blue wavelength, at least 46.8% higher than white wavelength, whereas FAME composition revealed a mild increase in oleic and palmitic acid levels. Cost analysis reveals that raceways treating wastewater and using monochromatic wavelength would decrease costs from 2.71 to 0.73 $/kg biomass. We prove that increasing both biomass and lipid productivity is possible through cost-effective approaches, thereby accelerating the commercialization of low-value products from microalgae, like biodiesel.

Dual energy CT: How well can pseudo-monochromatic imaging reduce metal artifacts?

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

Kuchenbecker, Stefan, E-mail: stefan.kuchenbecker@dkfz.de; Faby, Sebastian; Sawall, Stefan

2015-02-15

Purpose: Dual Energy CT (DECT) provides so-called monoenergetic images based on a linear combination of the original polychromatic images. At certain patient-specific energy levels, corresponding to certain patient- and slice-dependent linear combination weights, e.g., E = 160 keV corresponds to α = 1.57, a significant reduction of metal artifacts may be observed. The authors aimed at analyzing the method for its artifact reduction capabilities to identify its limitations. The results are compared with raw data-based processing. Methods: Clinical DECT uses a simplified version of monochromatic imaging by linearly combining the low and the high kV images and by assigning an energymore » to that linear combination. Those pseudo-monochromatic images can be used by radiologists to obtain images with reduced metal artifacts. The authors analyzed the underlying physics and carried out a series expansion of the polychromatic attenuation equations. The resulting nonlinear terms are responsible for the artifacts, but they are not linearly related between the low and the high kV scan: A linear combination of both images cannot eliminate the nonlinearities, it can only reduce their impact. Scattered radiation yields additional noncanceling nonlinearities. This method is compared to raw data-based artifact correction methods. To quantify the artifact reduction potential of pseudo-monochromatic images, they simulated the FORBILD abdomen phantom with metal implants, and they assessed patient data sets of a clinical dual source CT system (100, 140 kV Sn) containing artifacts induced by a highly concentrated contrast agent bolus and by metal. In each case, they manually selected an optimal α and compared it to a raw data-based material decomposition in case of simulation, to raw data-based material decomposition of inconsistent rays in case of the patient data set containing contrast agent, and to the frequency split normalized metal artifact reduction in case of the metal implant. For each case, the contrast-to-noise ratio (CNR) was assessed. Results: In the simulation, the pseudo-monochromatic images yielded acceptable artifact reduction results. However, the CNR in the artifact-reduced images was more than 60% lower than in the original polychromatic images. In contrast, the raw data-based material decomposition did not significantly reduce the CNR in the virtual monochromatic images. Regarding the patient data with beam hardening artifacts and with metal artifacts from small implants the pseudo-monochromatic method was able to reduce the artifacts, again with the downside of a significant CNR reduction. More intense metal artifacts, e.g., as those caused by an artificial hip joint, could not be suppressed. Conclusions: Pseudo-monochromatic imaging is able to reduce beam hardening, scatter, and metal artifacts in some cases but it cannot remove them. In all cases, the CNR is significantly reduced, thereby rendering the method questionable, unless special post processing algorithms are implemented to restore the high CNR from the original images (e.g., by using a frequency split technique). Raw data-based dual energy decomposition methods should be preferred, in particular, because the CNR penalty is almost negligible.« less

Organic light-emitting diodes with direct contact-printed red, green, blue, and white light-emitting layers

NASA Astrophysics Data System (ADS)

Chen, Sun-Zen; Peng, Shiang-Hau; Ting, Tzu-Yu; Wu, Po-Shien; Lin, Chun-Hao; Chang, Chin-Yeh; Shyue, Jing-Jong; Jou, Jwo-Huei

2012-10-01

We demonstrate the feasibility of using direct contact-printing in the fabrication of monochromatic and polychromatic organic light-emitting diodes (OLEDs). Bright devices with red, green, blue, and white contact-printed light-emitting layers with a respective maximum luminance of 29 000, 29 000, 4000, and 18 000 cd/m2 were obtained with sound film integrity by blending a polymeric host into a molecular host. For the red OLED as example, the maximum luminance was decreased from 29 000 to 5000 cd/m2 as only the polymeric host was used, or decreased to 7000 cd/m2 as only the molecular host was used. The markedly improved device performance achieved in the devices with blended hosts may be attributed to the employed polymeric host that contributed a good film-forming character, and the molecular host that contributed a good electroluminescence character.

Melatonin as a chemical indicator of environmental light-dark cycle.

PubMed

Zawilska, J B

1996-01-01

Melatonin (N-acetyl-5-methoxytryptamine) is an evolutionary highly conserved molecule that plays an important role in conveying the clock and calendar information to all living organisms, including man. Melatonin is synthesized in the rhythmic fashion, primarily by the pineal gland, and, to a lesser degree, by extrapineal tissues-namely the retina, the Harderian gland, and the gastrointestinal tract. The rhythm of the hormone production, with maximal levels occurring at night in darkness, is generated by an endogenous circadian clock(s) and is synchronized with the photoperiodic environment to which animals are exposed. This brief outline surveys data on the regulation of rhythmic melatonin biosynthesis by a circadian pacemaker and light (full spectrum white light and monochromatic lights with wavelengths both in the visible and invisible range). Additionally, possible applications of this chronobiotic compound in agriculture and in medicine in the treatment of circadian rhythm sleep disorders are discussed.

Combining shearography and interferometric fringe projection in a single device for complete control of industrial applications

NASA Astrophysics Data System (ADS)

Blain, Pascal; Michel, Fabrice; Piron, Pierre; Renotte, Yvon; Habraken, Serge

2013-08-01

Noncontact optical measurement methods are essential tools in many industrial and research domains. A family of new noncontact optical measurement methods based on the polarization states splitting technique and monochromatic light projection as a way to overcome ambient lighting for in-situ measurement has been developed. Recent works on a birefringent element, a Savart plate, allow one to build a more flexible and robust interferometer. This interferometer is a multipurpose metrological device. On one hand the interferometer can be set in front of a charge-coupled device (CCD) camera. This optical measurement system is called a shearography interferometer and allows one to measure microdisplacements between two states of the studied object under coherent lighting. On the other hand, by producing and shifting multiple sinusoidal Young's interference patterns with this interferometer, and using a CCD camera, it is possible to build a three-dimensional structured light profilometer.

Structured light enables biomimetic swimming and versatile locomotion of photoresponsive soft microrobots

NASA Astrophysics Data System (ADS)

Palagi, Stefano; Mark, Andrew G.; Reigh, Shang Yik; Melde, Kai; Qiu, Tian; Zeng, Hao; Parmeggiani, Camilla; Martella, Daniele; Sanchez-Castillo, Alberto; Kapernaum, Nadia; Giesselmann, Frank; Wiersma, Diederik S.; Lauga, Eric; Fischer, Peer

2016-06-01

Microorganisms move in challenging environments by periodic changes in body shape. In contrast, current artificial microrobots cannot actively deform, exhibiting at best passive bending under external fields. Here, by taking advantage of the wireless, scalable and spatiotemporally selective capabilities that light allows, we show that soft microrobots consisting of photoactive liquid-crystal elastomers can be driven by structured monochromatic light to perform sophisticated biomimetic motions. We realize continuum yet selectively addressable artificial microswimmers that generate travelling-wave motions to self-propel without external forces or torques, as well as microrobots capable of versatile locomotion behaviours on demand. Both theoretical predictions and experimental results confirm that multiple gaits, mimicking either symplectic or antiplectic metachrony of ciliate protozoa, can be achieved with single microswimmers. The principle of using structured light can be extended to other applications that require microscale actuation with sophisticated spatiotemporal coordination for advanced microrobotic technologies.

Light's Darkness

ScienceCinema

Padgett, Miles [University of Glasgow, Glasgow, Scotland

2017-12-09

Optical vortices and orbital angular momentum are currently topical subjects in the optics literature. Although seemingly esoteric, they are, in fact, the generic state of light and arise whenever three or more plane waves interfere. To be observed by eye the light must be monochromatic. Laser speckle is one such example, where the optical energy circulates around each black spot, giving a local orbital angular momentum. This talk with report three on-going studies. First, when considering a volume of interfering waves, the laser specs map out threads of complete darkness embedded in the light. Do these threads form loops? Links? Or even knots? Second, when looking through a rapidly spinning window, the image of the world on the other side is rotated: true or false? Finally, the entanglement of orbital angular momentum states means measuring how the angular position of one photons sets the angular momentum of another: is this an angular version of the EPR (Einstein, Podolsky, and Rosen) paradox?

A cost-effective solution for the reliable determination of cell numbers of microorganisms in liquid culture.

PubMed

Lamb, Jacob J; Eaton-Rye, Julian J; Hohmann-Marriott, Martin F

2013-08-01

The concentration of microorganisms in growth medium is an important parameter in microbiological research. One of the approaches to determine this parameter is based on the physical interaction of small particles with light that results in light scattering. Table-top spectrophotometers can be used to determine the scattering properties of a sample as a change in light transmission. However, a portable, reliable, and maintenance-free instrument that can be built from inexpensive parts could provide new research opportunities. In this report, we show how to build such an instrument. This instrument consists of a low power monochromatic light-emitting diode, a monolithic photodiode, and a microcontroller. We demonstrate that this instrument facilitates the precise determination of cell concentrations for the bacteria Escherichia coli and Pseudomonas aeruginosa as well as the cyanobacterium Synechocystis sp. PCC 6803 and the green alga Chlamydomonas reinhardtii.

Structural Color Model Based on Surface Morphology of MORPHO Butterfly Wing Scale

NASA Astrophysics Data System (ADS)

Huang, Zhongjia; Cai, Congcong; Wang, Gang; Zhang, Hui; Huttula, Marko; Cao, Wei

2016-05-01

Color production through structural coloration is created by micrometer and sub-micrometer surface textures which interfere with visible light. The shiny blue of morpho menelaus is a typical example of structural coloring. Modified from morphology of the morpho scale, a structure of regular windows with two side offsets was constructed on glass substrates. Optical properties of the bioinspired structure were studied through numerical simulations of light scattering. Results show that the structure can generate monochromatic light scattering. Wavelength of scattered light is tunable via changing the spacing between window shelves. Compared to original butterfly model, the modified one possesses larger illumination scopes in azimuthal distributions despite being less in polar directions. Present bionic structure is periodically repeated and is easy to fabricate. It is hoped that the computational materials design work can inspire future experimental realizations of such a structure in photonics applications.

Light adaptation of the unicellular red alga, Cyanidioschyzon merolae, probed by time-resolved fluorescence spectroscopy.

PubMed

Ueno, Yoshifumi; Aikawa, Shimpei; Kondo, Akihiko; Akimoto, Seiji

2015-08-01

Photosynthetic organisms change the quantity and/or quality of their pigment-protein complexes and the interactions among these complexes in response to light conditions. In the present study, we analyzed light adaptation of the unicellular red alga Cyanidioschyzon merolae, whose pigment composition is similar to that of cyanobacteria because its phycobilisomes (PBS) lack phycoerythrin. C. merolae were grown under different light qualities, and their responses were measured by steady-state absorption, steady-state fluorescence, and picosecond time-resolved fluorescence spectroscopies. Cells were cultivated under four monochromatic light-emitting diodes (blue, green, yellow, and red), and changes in pigment composition and energy transfer were observed. Cells grown under blue and green light increased their relative phycocyanin levels compared with cells cultured under white light. Energy-transfer processes to photosystem I (PSI) were sensitive to yellow and red light. The contribution of direct energy transfer from PBS to PSI increased only under yellow light, while red light induced a reduction in energy transfer from photosystem II to PSI and an increase in energy transfer from light-harvesting chlorophyll protein complex I to PSI. Differences in pigment composition, growth, and energy transfer under different light qualities are discussed.

Periprosthetic Artifact Reduction Using Virtual Monochromatic Imaging Derived From Gemstone Dual-Energy Computed Tomography and Dedicated Software.

PubMed

Reynoso, Exequiel; Capunay, Carlos; Rasumoff, Alejandro; Vallejos, Javier; Carpio, Jimena; Lago, Karen; Carrascosa, Patricia

2016-01-01

The aim of this study was to explore the usefulness of combined virtual monochromatic imaging and metal artifact reduction software (MARS) for the evaluation of musculoskeletal periprosthetic tissue. Measurements were performed in periprosthetic and remote regions in 80 patients using a high-definition scanner. Polychromatic images with and without MARS and virtual monochromatic images were obtained. Periprosthetic polychromatic imaging (PI) showed significant differences compared with remote areas among the 3 tissues explored (P < 0.0001). No significant differences were observed between periprosthetic and remote tissues using monochromatic imaging with MARS (P = 0.053 bone, P = 0.32 soft tissue, and P = 0.13 fat). However, such differences were significant using PI with MARS among bone (P = 0.005) and fat (P = 0.02) tissues. All periprosthetic areas were noninterpretable using PI, compared with 11 (9%) using monochromatic imaging. The combined use of virtual monochromatic imaging and MARS reduced periprosthetic artifacts, achieving attenuation levels comparable to implant-free tissue.

Characteristics of light reflected from a dense ionization wave with a tunable velocity.

PubMed

Zhidkov, A; Esirkepov, T; Fujii, T; Nemoto, K; Koga, J; Bulanov, S V

2009-11-20

An optically dense ionization wave (IW) produced by two femtosecond (approximately 10/30 fs) laser pulses focused cylindrically and crossing each other may become an efficient coherent x-ray converter in accordance with the Semenova-Lampe theory. The resulting velocity of a quasiplane IW in the vicinity of pulse intersection changes with the angle between the pulses from the group velocity of ionizing pulses to infinity allowing a tuning of the wavelength of x rays and their bunching. The x-ray spectra after scattering of a lower frequency and long coherent light pulse change from the monochromatic to high order harmoniclike with the duration of the ionizing pulses.

Two solvable problems of planar geometrical optics.

PubMed

Borghero, Francesco; Bozis, George

2006-12-01

In the framework of geometrical optics we consider a two-dimensional transparent inhomogeneous isotropic medium (dispersive or not). We show that (i) for any family belonging to a certain class of planar monoparametric families of monochromatic light rays given in the form f(x,y)=c of any definite color and satisfying a differential condition, all the refractive index profiles n=n(x,y) allowing for the creation of the given family can be found analytically (inverse problem) and that (ii) for any member of a class of two-dimensional refractive index profiles n=n(x,y) satisfying a differential condition, all the compatible families of light rays can be found analytically (direct problem). We present appropriate examples.

Supra-organization and optical anisotropies of the extracellular matrix in the amniotic membrane and limbal stroma before and after explant culture

PubMed Central

Valdetaro, Gisele P.; Aldrovani, Marcela; Padua, Ivan R. M.; Cristovam, Priscila C.; Gomes, José A. P.; Laus, José L.

2016-01-01

In this research we evaluated the supramolecular organizations and the optical anisotropical properties of the de-epithelialized human amniotic membrane and rabbit limbal stroma, before and after explant culture. Birefringence, monochromatic light spectral absorption and linear dichroism of the main extracellular matrix biopolymers, that is, the fibrillar collagens and proteoglycans, were investigated by polarized light microscopy combined with image analysis. Our results demonstrated that the culture procedure–induced stimuli altered the supra-organizational characteristics (in terms of collagens/proteoglycans spatial orientation and ordered-aggregational state) of the amniotic and limbal extracellular matrix, which led to changes in optical anisotropical properties. PMID:28018719

Energy dependence of CP-violation reach for monochromatic neutrino beam

NASA Astrophysics Data System (ADS)

Bernabéu, José; Espinoza, Catalina

2008-06-01

The ultimate goal of future neutrino facilities is the determination of CP violation in neutrino oscillations. Besides | U (e 3) | ≠ 0, this will require precision experiments with a very intense neutrino source and energy control. With this objective in mind, the creation of monochromatic neutrino beams from the electron capture decay of boosted ions by the SPS of CERN has been proposed. We discuss the capabilities of such a facility as a function of the energy of the boost and the baseline for the detector. We compare the physics potential for two different configurations: (I) γ = 90 and γ = 195 (maximum achievable at present SPS) to Frejus; (II) γ = 195 and γ = 440 (maximum achievable at upgraded SPS) to Canfranc. We conclude that the SPS upgrade to 1000 GeV is important to reach a better sensitivity to CP violation iff it is accompanied by a longer baseline.

Pixelated transmission-mode diamond X-ray detector

PubMed Central

Zhou, Tianyi; Ding, Wenxiang; Gaowei, Mengjia; De Geronimo, Gianluigi; Bohon, Jen; Smedley, John; Muller, Erik

2015-01-01

Fabrication and testing of a prototype transmission-mode pixelated diamond X-ray detector (pitch size 60–100 µm), designed to simultaneously measure the flux, position and morphology of an X-ray beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on the front and horizontal stripes on the back of an electronic-grade chemical vapor deposition single-crystal diamond. The bias is rotated through the back horizontal stripes and the current is read out on the front vertical stripes at a rate of ∼1 kHz, which leads to an image sampling rate of ∼30 Hz. This novel signal readout scheme was tested at beamline X28C at the National Synchrotron Light Source (white beam, 5–15 keV) and at beamline G3 at the Cornell High Energy Synchrotron Source (monochromatic beam, 11.3 keV) with incident beam flux ranges from 1.8 × 10−2 to 90 W mm−2. Test results show that the novel detector provides precise beam position (positional noise within 1%) and morphology information (error within 2%), with an additional software-controlled single channel mode providing accurate flux measurement (fluctuation within 1%). PMID:26524304

Beamlines of the Biomedical Imaging and Therapy Facility at the Canadian Light Source - Part 2

NASA Astrophysics Data System (ADS)

Wysokinski, T. W.; Chapman, D.; Adams, G.; Renier, M.; Suortti, P.; Thomlinson, W.

2013-03-01

The BioMedical Imaging and Therapy (BMIT) facility provides a world class facility with unique synchrotron-specific imaging and therapy capabilities. This paper describes Insertion Device (ID) beamline 05ID-2 with the beam terminated in the first experimental hutch: POE-2. The experimental methods available in POE-2 include: Microbeam Radiation Therapy (MRT), Synchrotron Stereotactic Radiation Therapy (SSRT) and absorption imaging (projection and Computed Tomography (CT)). The source for the ID beamline is a multi-pole superconductive 4.3 T wiggler, which can generate ~30 kW of radiative power and deliver dose as high as 3000 Gy/s required for MRT program. The optics in POE-1 hutch prepares either monochromatic or filtered white beam that is used in POE-2. The Double Crystal (DC), bent Laue monochromator will prepare a beam over 10 cm wide at sample point, while spanning an energy range appropriate for imaging studies of animals (20-100+ keV). The experimental hutch will have a flexible positioning system that can handle subjects up to 120 kg. Several different cameras will be available with resolutions ranging from 4 μm to 150 μm. The latest update on the status of 05B1-1 bending magnet (BM) beamline, described in Part 1 [1], is also included.

A projective surgical navigation system for cancer resection

NASA Astrophysics Data System (ADS)

Gan, Qi; Shao, Pengfei; Wang, Dong; Ye, Jian; Zhang, Zeshu; Wang, Xinrui; Xu, Ronald

2016-03-01

Near infrared (NIR) fluorescence imaging technique can provide precise and real-time information about tumor location during a cancer resection surgery. However, many intraoperative fluorescence imaging systems are based on wearable devices or stand-alone displays, leading to distraction of the surgeons and suboptimal outcome. To overcome these limitations, we design a projective fluorescence imaging system for surgical navigation. The system consists of a LED excitation light source, a monochromatic CCD camera, a host computer, a mini projector and a CMOS camera. A software program is written by C++ to call OpenCV functions for calibrating and correcting fluorescence images captured by the CCD camera upon excitation illumination of the LED source. The images are projected back to the surgical field by the mini projector. Imaging performance of this projective navigation system is characterized in a tumor simulating phantom. Image-guided surgical resection is demonstrated in an ex-vivo chicken tissue model. In all the experiments, the projected images by the projector match well with the locations of fluorescence emission. Our experimental results indicate that the proposed projective navigation system can be a powerful tool for pre-operative surgical planning, intraoperative surgical guidance, and postoperative assessment of surgical outcome. We have integrated the optoelectronic elements into a compact and miniaturized system in preparation for further clinical validation.

Fresnel Lenses for Wide-Aperture Optical Receivers

NASA Technical Reports Server (NTRS)

Hemmati, Hamid

2004-01-01

Wide-aperture receivers for freespace optical communication systems would utilize Fresnel lenses instead of conventional telescope lenses, according to a proposal. Fresnel lenses weigh and cost much less than conventional lenses having equal aperture widths. Plastic Fresnel lenses are commercially available in diameters up to 5 m large enough to satisfy requirements for aperture widths of the order of meters for collecting sufficient light in typical long-distance free-space optical communication systems. Fresnel lenses are not yet suitable for high-quality diffraction-limited imaging, especially in polychromatic light. However, optical communication systems utilize monochromatic light, and there is no requirement for high-quality imaging; instead, the basic requirement for an optical receiver is to collect the incoming monochromatic light over a wide aperture and concentrate the light onto a photodetector. Because of lens aberrations and diffraction, the light passing through any lens is focused to a blur circle rather than to a point. Calculations for some representative cases of wide-aperture non-diffraction-limited Fresnel lenses have shown that it should be possible to attain blur-circle diameters of less than 2 mm. Preferably, the blur-circle diameter should match the width of the photodetector. For most high-bandwidth communication applications, the required photodetector diameters would be about 1 mm. In a less-preferable case in which the blur circle was wider than a single photodetector, it would be possible to occupy the blur circle with an array of photodetectors. As an alternative to using a single large Fresnel lens, one could use an array of somewhat smaller lenses to synthesize the equivalent aperture area. Such a configuration might be preferable in a case in which a single Fresnel lens of the requisite large size would be impractical to manufacture, and the blur circle could not be made small enough. For example one could construct a square array of four 5-m-diameter Fresnel lenses to obtain the same light-collecting area as that of a single 10-m-diameter lens. In that case (see figure), the light collected by each Fresnel lens could be collimated, the collimated beams from the four Fresnel lenses could be reflected onto a common offaxis paraboloidal reflector, and the paraboloidal reflector would focus the four beams onto a single photodetector. Alternatively, detected signal from each detector behind each lens would be digitized before summing the signals.

Intersexual variation in the foraging ecology of sexually monochromatic Western Wood-Pewees

Treesearch

Alissa M. Fogg; T. Luke George; Kathryn L. Purcell

2013-01-01

Investigators generally pool observations of males and females in studies of the foraging behavior of sexually monochromatic songbirds. However, such pooling can obscure possible intersexual differences. We compared the foraging behavior of male and female Western Wood-Pewees (Contopus sordidulus), a sexually monochromatic species, in the Sierra...

Berberine cation: A fluorescent chemosensor for alkanes and other low-polarity compounds. An explanation of this phenomenon

PubMed

Cossio; Arrieta; Cebolla; Membrado; Vela; Garriga; Domingo

2000-07-27

Alkanes in the presence of berberine sulfate provide an enhancement of fluorescent signal, which depends on alkane concentration and structure, when the system is irradiated with monochromatic UV light. Computational analysis suggests that an ion-induced dipole between alkanes and berberine sulfate is responsible for this phenomenon. This interaction can properly model the experimentally obtained fluorescent response. The proposed explanation allows other interacting systems to be designed, which have been experimentally confirmed.

Controlling Light Transmission Through Highly Scattering Media Using Semi-Definite Programming as a Phase Retrieval Computation Method.

PubMed

N'Gom, Moussa; Lien, Miao-Bin; Estakhri, Nooshin M; Norris, Theodore B; Michielssen, Eric; Nadakuditi, Raj Rao

2017-05-31

Complex Semi-Definite Programming (SDP) is introduced as a novel approach to phase retrieval enabled control of monochromatic light transmission through highly scattering media. In a simple optical setup, a spatial light modulator is used to generate a random sequence of phase-modulated wavefronts, and the resulting intensity speckle patterns in the transmitted light are acquired on a camera. The SDP algorithm allows computation of the complex transmission matrix of the system from this sequence of intensity-only measurements, without need for a reference beam. Once the transmission matrix is determined, optimal wavefronts are computed that focus the incident beam to any position or sequence of positions on the far side of the scattering medium, without the need for any subsequent measurements or wavefront shaping iterations. The number of measurements required and the degree of enhancement of the intensity at focus is determined by the number of pixels controlled by the spatial light modulator.

Spectral information as an orientation cue in dung beetles.

PubMed

El Jundi, Basil; Foster, James J; Byrne, Marcus J; Baird, Emily; Dacke, Marie

2015-11-01

During the day, a non-uniform distribution of long and short wavelength light generates a colour gradient across the sky. This gradient could be used as a compass cue, particularly by animals such as dung beetles that rely primarily on celestial cues for orientation. Here, we tested if dung beetles can use spectral cues for orientation by presenting them with monochromatic (green and UV) light spots in an indoor arena. Beetles kept their original bearing when presented with a single light cue, green or UV, or when presented with both light cues set 180° apart. When either the UV or the green light was turned off after the beetles had set their bearing in the presence of both cues, they were still able to maintain their original bearing to the remaining light. However, if the beetles were presented with two identical green light spots set 180° apart, their ability to maintain their original bearing was impaired. In summary, our data show that ball-rolling beetles could potentially use the celestial chromatic gradient as a reference for orientation. © 2015 The Author(s).

A compact soft x-ray (0.1-1.2 keV) calibration bench for radiometric measurements using an original versatile Rowland circle grazing incidence monochromator

NASA Astrophysics Data System (ADS)

Hubert, S.

2017-05-01

This paper describes an original Rowland circle grazing incidence spectrometer used as a monochromator for a soft x-ray Manson source in order to calibrate both the source and detectors over the 0.1-1.2 keV spectral range. The originality of the instrument lies on a patented vacuum manipulator which allows the simultaneous boarding of two detectors, one (reference) for measuring the monochromatic radiation and the second to be calibrated. In order to achieve this, the vacuum manipulator is able to interchange, in vacuum, one detector with the other in front of the exit slit of the monochromatizing stage. One purpose of this apparatus was to completely eliminate the intrinsic bremsstrahlung emission of the x-ray diode source and isolate each characteristic line for quantitative detector calibrations. Obtained spectral resolution (Δλ/λ<10-2) and spectral purity (>98%) fully meet this objective. Initially dimensioned to perform calibration of bulky x-ray cameras unfolded on the Laser MégaJoule Facility, other kinds of detector can be obviously calibrated using this instrument. A brief presentation of the first calibration of an x-ray CCD through its quantum efficiency (QE) measurement is included in this paper as example. Comparison with theoretical model for QE and previous measurements at higher energy are finally presented and discussed.

Ultraviolet/visible photodiode of nanostructure Sn-doped ZnO/Si heterojunction

NASA Astrophysics Data System (ADS)

Kheirandish, N.; Mortezaali, A.

2013-05-01

Sn doped ZnO nanostructures deposited on Si substrate with (100) orientation by spray pyrolysis method at temperature 450 °C. Sn/Zn atomic ratio varies from 0% to 5%. The scanning electron microscope measurements showed that size of particles reduce with increasing the doping concentration. The X-ray diffraction analysis revealed formation of the wurtzite phase of ZnO. I-V curves of Sn doped ZnO/Si were investigated in dark and shows diode-like rectifying behavior. Among doped ZnO/Si, sample with atomic ratio of Sn/Zn = 5% is a good candidate to study photodiode properties in UV/visible range. Photoelectric effects have been observed under illumination monochromatic laser light with a wavelength of 325 nm and halogen lamp. Measurements demonstrate that the photodiode has high sensitivity and reproducibility to halogen light respect to laser light.

Differences between wavefront and subjective refraction for infrared light.

PubMed

Teel, Danielle F W; Jacobs, Robert J; Copland, James; Neal, Daniel R; Thibos, Larry N

2014-10-01

To determine the accuracy of objective wavefront refractions for predicting subjective refractions for monochromatic infrared light. Objective refractions were obtained with a commercial wavefront aberrometer (COAS, Wavefront Sciences). Subjective refractions were obtained for 30 subjects with a speckle optometer validated against objective Zernike wavefront refractions on a physical model eye (Teel et al., Design and validation of an infrared Badal optometer for laser speckle, Optom Vis Sci 2008;85:834-42). Both instruments used near-infrared (NIR) radiation (835 nm for COAS, 820 nm for the speckle optometer) to avoid correction for ocular chromatic aberration. A 3-mm artificial pupil was used to reduce complications attributed to higher-order ocular aberrations. For comparison with paraxial (Seidel) and minimum root-mean-square (Zernike) wavefront refractions, objective refractions were also determined for a battery of 29 image quality metrics by computing the correcting lens that optimizes retinal image quality. Objective Zernike refractions were more myopic than subjective refractions for 29 of 30 subjects. The population mean discrepancy was -0.26 diopters (D) (SEM = 0.03 D). Paraxial (Seidel) objective refractions tended to be hyperopically biased (mean discrepancy = +0.20 D, SEM = 0.06 D). Refractions based on retinal image quality were myopically biased for 28 of 29 metrics. The mean bias across all 31 measures was -0.24 D (SEM = 0.03). Myopic bias of objective refractions was greater for eyes with brown irises compared with eyes with blue irises. Our experimental results are consistent with the hypothesis that reflected NIR light captured by the aberrometer originates from scattering sources located posterior to the entrance apertures of cone photoreceptors, near the retinal pigment epithelium. The larger myopic bias for brown eyes suggests that a greater fraction of NIR light is reflected from choroidal melanin in brown eyes compared with blue eyes.

Prize for Industrial Applications of Physics Talk: The Inverse Scattering Problem and the role of measurements in its solution

NASA Astrophysics Data System (ADS)

Wyatt, Philip

2009-03-01

The electromagnetic inverse scattering problem suggests that if a homogeneous and non-absorbing object be illuminated with a monochromatic light source and if the far field scattered light intensity is known at sufficient scattering angles, then, in principle, one could derive the dielectric structure of the scattering object. In general, this is an ill-posed problem and methods must be developed to regularize the search for unique solutions. An iterative procedure often begins with a model of the scattering object, solves the forward scattering problem using this model, and then compares these calculated results with the measured values. Key to any such solution is instrumentation capable of providing adequate data. To this end, the development of the first laser based absolute light scattering photometers is described together with their continuing evolution and some of the remarkable discoveries made with them. For particles much smaller than the wavelength of the incident light (e.g. macromolecules), the inverse scattering problems are easily solved. Among the many solutions derived with this instrumentation are the in situ structure of bacterial cells, new drug delivery mechanisms, the development of new vaccines and other biologicals, characterization of wines, the possibility of custom chemotherapy, development of new polymeric materials, identification of protein crystallization conditions, and a variety discoveries concerning protein interactions. A new form of the problem is described to address bioterrorist threats. Over the many years of development and refinement, one element stands out as essential for the successes that followed: the R and D teams were always directed and executed by physics trained theorists and experimentalists. 14 Ph. D. physicists each made his/her unique contribution to the development of these evolving instruments and the interpretation of their results.

How Can Polarization States of Reflected Light from Snow Surfaces Inform Us on Surface Normals and Ultimately Snow Grain Size Measurements?

NASA Astrophysics Data System (ADS)

Schneider, A. M.; Flanner, M.; Yang, P.; Yi, B.; Huang, X.; Feldman, D.

2016-12-01

The Snow Grain Size and Pollution (SGSP) algorithm is a method applied to Moderate Resolution Imaging Spectroradiometer data to estimate snow grain size from space-borne measurements. Previous studies validate and quantify potential sources of error in this method, but because it assumes flat snow surfaces, however, large scale variations in surface normals can cause biases in its estimates due to its dependence on solar and observation zenith angles. To address these variations, we apply the Monte Carlo method for photon transport using data containing the single scattering properties of different ice crystals to calculate polarization states of reflected monochromatic light at 1500nm from modeled snow surfaces. We evaluate the dependence of these polarization states on solar and observation geometry at 1500nm because multiple scattering is generally a mechanism for depolarization and the ice crystals are relatively absorptive at this wavelength. Using 1500nm thus results in a higher number of reflected photons undergoing fewer scattering events, increasing the likelihood of reflected light having higher degrees of polarization. In evaluating the validity of the model, we find agreement with previous studies pertaining to near-infrared spectral directional hemispherical reflectance (i.e. black-sky albedo) and similarities in measured bidirectional reflectance factors, but few studies exist modeling polarization states of reflected light from snow surfaces. Here, we present novel results pertaining to calculated polarization states and compare dependences on solar and observation geometry for different idealized snow surfaces. If these dependencies are consistent across different ice particle shapes and sizes, then these findings could inform the SGSP algorithm by providing useful relationships between measurable physical quantities and solar and observation geometry to better understand variations in snow surface normals from remote sensing observations.

Study on negative incident photon-to-electron conversion efficiency of quantum dot-sensitized solar cells

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

Li, Chunhui; Wu, Huijue; Zhu, Lifeng

2014-02-15

Recently, negative signals are frequently observed during the measuring process of monochromatic incident photon-to-electron conversion efficiency (IPCE) for sensitized solar cells by DC method. This phenomenon is confusing and hindering the reasonable evaluation of solar cells. Here, cause of negative IPCE values is studied by taking quantum dot-sensitized solar cell (QDSC) as an example, and the accurate measurement method to avoid the negative value is suggested. The negative background signals of QDSC without illumination are found the direct cause of the negative IPCE values by DC method. Ambient noise, significant capacitance characteristics, and uncontrolled electrochemical reaction all can lead tomore » the negative background signals. When the photocurrent response of device under monochromatic light illumination is relatively weak, the actual photocurrent signals will be covered by the negative background signals and the resulting IPCE values will appear negative. To improve the signal-to-noise ratio, quasi-AC method is proposed for IPCE measurement of solar cells with weak photocurrent response based on the idea of replacing the absolute values by the relative values.« less

Demonstration of Numerical Equivalence of Ensemble and Spectral Averaging in Electromagnetic Scattering by Random Particulate Media

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Dlugach, Janna M.; Zakharova, Nadezhda T.

2016-01-01

The numerically exact superposition T-matrix method is used to model far-field electromagnetic scattering by two types of particulate object. Object 1 is a fixed configuration which consists of N identical spherical particles (with N 200 or 400) quasi-randomly populating a spherical volume V having a median size parameter of 50. Object 2 is a true discrete random medium (DRM) comprising the same number N of particles randomly moving throughout V. The median particle size parameter is fixed at 4. We show that if Object 1 is illuminated by a quasi-monochromatic parallel beam then it generates a typical speckle pattern having no resemblance to the scattering pattern generated by Object 2. However, if Object 1 is illuminated by a parallel polychromatic beam with a 10 bandwidth then it generates a scattering pattern that is largely devoid of speckles and closely reproduces the quasi-monochromatic pattern generated by Object 2. This result serves to illustrate the capacity of the concept of electromagnetic scattering by a DRM to encompass fixed quasi-random particulate samples provided that they are illuminated by polychromatic light.

Tomography using monochromatic thermal neutrons with attenuation and phase contrast

NASA Astrophysics Data System (ADS)

Dubus, Francois; Bonse, Ulrich; Biermann, Theodor; Baron, Matthias; Beckmann, Felix; Zawisky, Michael

2002-01-01

Attenuation-contrast tomography with monochromatic thermal neutrons was developed and operated at guide station S18 of the institute Laue-Langevin in Grenoble. From the S18 spectrum the neutron wavelength (lambda) equals 0.18 nm was selected by employing a fore crystal with the silicon 220 reflection at a Bragg angle (Theta) equals 30 degrees. Projections were registered by a position sensitive detector (PSD) consisting of a neutron-to-visible-light converter coupled to a CCD detector. Neutron tomography and its comparison with X-ray tomography is studied. This is of special interest since the cross section for neutron attenuation ((sigma) atom) and the cross section for neutron phase shift (bc) are isotope specific and, in addition, by no means mostly monotonous functions of atomic number Z as are attenuation coefficient ((mu) x) and atomic scattering amplitude (f) in the case of X-rays. Results obtained with n-attenuation tomography will be presented. Possibilities and the setup of an instrument for neutron phase-contrast tomography based on single-crystal neutron interferometry will be described.

Analytical model and figures of merit for filtered Microwave Photonic Links.

PubMed

Gasulla, Ivana; Capmany, José

2011-09-26

The concept of filtered Microwave Photonic Links is proposed in order to provide the most general and versatile description of complex analog photonic systems. We develop a field propagation model where a global optical filter, characterized by its optical transfer function, embraces all the intermediate optical components in a linear link. We assume a non-monochromatic light source characterized by an arbitrary spectral distribution which has a finite linewidth spectrum and consider both intensity modulation and phase modulation with balanced and single detection. Expressions leading to the computation of the main figures of merit concerning the link gain, noise and intermodulation distortion are provided which, to our knowledge, are not available in the literature. The usefulness of this derivation resides in the capability to directly provide performance criteria results for complex links just by substituting in the overall closed-form formulas the numerical or measured optical transfer function characterizing the link. This theory is presented thus as a potential tool for a wide range of relevant microwave photonic application cases which is extendable to multiport radio over fiber systems. © 2011 Optical Society of America

Improving Si solar cell performance using Mn:ZnSe quantum dot-doped PLMA thin film

PubMed Central

2013-01-01

Poly(lauryl methacrylate) (PLMA) thin film doped with Mn:ZnSe quantum dots (QDs) was spin-deposited on the front surface of Si solar cell for enhancing the solar cell efficiency via photoluminescence (PL) conversion. Significant solar cell efficiency enhancements (approximately 5% to 10%) under all-solar-spectrum (AM0) condition were observed after QD-doped PLMA coatings. Furthermore, the real contribution of the PL conversion was precisely assessed by investigating the photovoltaic responses of the QD-doped PLMA to monochromatic and AM0 light sources as functions of QD concentration, combined with reflectance and external quantum efficiency measurements. At a QD concentration of 1.6 mg/ml for example, among the efficiency enhancement of 5.96%, about 1.04% was due to the PL conversion, and the rest came from antireflection. Our work indicates that for the practical use of PL conversion in solar cell performance improvement, cautions are to be taken, as the achieved efficiency enhancement might not be wholly due to the PL conversion. PMID:23787125

Benchtop and Animal Validation of a Projective Imaging System for Potential Use in Intraoperative Surgical Guidance

PubMed Central

Gan, Qi; Wang, Dong; Ye, Jian; Zhang, Zeshu; Wang, Xinrui; Hu, Chuanzhen; Shao, Pengfei; Xu, Ronald X.

2016-01-01

We propose a projective navigation system for fluorescence imaging and image display in a natural mode of visual perception. The system consists of an excitation light source, a monochromatic charge coupled device (CCD) camera, a host computer, a projector, a proximity sensor and a Complementary metal–oxide–semiconductor (CMOS) camera. With perspective transformation and calibration, our surgical navigation system is able to achieve an overall imaging speed higher than 60 frames per second, with a latency of 330 ms, a spatial sensitivity better than 0.5 mm in both vertical and horizontal directions, and a projection bias less than 1 mm. The technical feasibility of image-guided surgery is demonstrated in both agar-agar gel phantoms and an ex vivo chicken breast model embedding Indocyanine Green (ICG). The biological utility of the system is demonstrated in vivo in a classic model of ICG hepatic metabolism. Our benchtop, ex vivo and in vivo experiments demonstrate the clinical potential for intraoperative delineation of disease margin and image-guided resection surgery. PMID:27391764

Atmospheric scattering of middle uv radiation from an internal source.

PubMed

Meier, R R; Lee, J S; Anderson, D E

1978-10-15

A Monte Carlo model has been developed which simulates the multiple-scattering of middle-uv radiation in the lower atmosphere. The source of radiation is assumed to be monochromatic and located at a point. The physical effects taken into account in the model are Rayleigh and Mie scattering, pure absorption by particulates and trace atmospheric gases, and ground albedo. The model output consists of the multiply scattered radiance as a function of look-angle of a detector located within the atmosphere. Several examples are discussed, and comparisons are made with direct-source and single-scattered contributions to the signal received by the detector.

Monochromatic Transmittance/Radiance Computations

DTIC Science & Technology

1974-12-31

In the infrared region, these tran- sitions are normally between various vibration -rotation states. There are usually a large number of possible...energy level of the transition, and Q (e,m.) and Q (0,m.) are respectively the ratio of the vibrational and rotational partition function at...values used are listed in Table 2 (Ref. 2). For source conditions, the vibrational partition function cannot be ignored and has been calculated 4

Pump–probe spectrometer for measuring x-ray induced strain

DOE PAGES

Loether, A.; Adams, B. W.; DiCharia, A.; ...

2016-04-20

A hard x-ray pump–probe spectrometer using a multi-crystal Bragg reflector is demonstrated at a third generation synchrotron source. This device derives both broadband pump and monochromatic probe pulses directly from a single intense, broadband x-ray pulse centered at 8.767 keV. In conclusion, we present a proof-of-concept experiment which directly measures x-ray induced crystalline lattice strain.

Highlights of the new Emission Norm for the Regulation of Light Pollution in Northern Chile

NASA Astrophysics Data System (ADS)

Sanhueza, Pedro

2015-08-01

Due to the need to deal with the new menace of LEDS, which are very blue emitters, and to address other shortcomings regarding scattering and over illumination of the first lighting regulations passed in Chile in 1998 (DS 686/1998), the Chilean Ministry of Environment (MMA) approved new regulations by Presidential decree (DS 043/2012) on May 03, 2013. This new version of the regulations was developed by OPCC in collaboration with the MMA.This new environmental standard includes the following main restrictions:A full-cut-off requirement for general lighting, which means 0.49cd/Klumen at 90º (i.e., no light distribution above horizontal).For sport and recreational activities, an allowed level of 10cd/Klumen at 90º, together with a visor to cut upper-hemisphere emissions.Spectral restrictions divided into three regulated regions of the visible spectrum (as compared to the total light emission between 380 and 780nm): (a) not more than 15% of total light output in the range 300 to 380nm; (b) not more than 15% in the range 380 to 499nm; and (c) not more than 50% in the range 781nm to 1micron.Over illumination restricted to not more than 20% over the Chilean standard (NSEG 9 n71) for minimal levels in public lighting.Billboards with inner sources of illuminations (LED or plasma big screens) must emit no more than 50cd/m2 at night. No spectral restriction is applied.This new lighting regulation has not come into force yet, due to a delay in approving complementary technical protocols. Enforcement is also a critical issue to deal with, given that the institutional environmental framework in Chile is being modified.The OPCC is working with both the Ministry of Public Works and also Ministry of Housing, seeking to go beyond the new lighting regulation by applying a more restrictive approach in terms of spectral restriction, promoting the use of warm white LEDS with a CCT of 2.700 Kº and, in the case of outdoor illumination near professional observatories, monochromatic amber LEDS.

Successful treatment with 308-nm monochromatic excimer light and subsequent tacrolimus 0.03% ointment in refractory plasma cell cheilitis.

PubMed

Yoshimura, Kazuhiro; Nakano, Shunji; Tsuruta, Daisuke; Ohata, Chika; Hashimoto, Takashi

2013-06-01

Plasma cell cheilitis is a chronic inflammatory disease that presents with erythema, erosions, ulcers and occasional nodules within the mucosa, including the lips. It is histopathologically characterized by dense plasma cell infiltration in the lamina propria of the mucous membranes. Several treatments for plasma cell cheilitis have been reported, including topical steroids, topical antibiotics or topical tacrolimus. However, 308-nm monochromatic excimer light (MEL) has never been reported as a treatment option, while it was reported to be very effective in treating erosive oral lichen planus. We report a 62-year-old man who had chronic plasma cell cheilitis on the lower lip, which was refractory to topical and systemic corticosteroid. The lesion and severe pain were significantly improved by the treatment with nine sessions of 308-nm MEL twice per week with a total dose of 1120 mJ/cm(2). However, the lesion gradually worsened after treatment frequency was reduced to once per month. Subsequent tacrolimus 0.03% ointment cleared the lesion completely in a month and no recurrence was observed a year later. Refractory plasma cell cheilitis and concomitant severe pain quickly responded to 308-nm MEL when administrated twice per week. Because the long interval between each MEL treatment seemed ineffective to improve the lesion, appropriate frequency and adequate total dose of MEL treatment may be necessary for a successful treatment. © 2013 Japanese Dermatological Association.

Accuracy of the raw-data-based effective atomic numbers and monochromatic CT numbers for contrast medium with a dual-energy CT technique.

PubMed

Kawahara, Daisuke; Ozawa, Shuichi; Yokomachi, Kazushi; Tanaka, Sodai; Higaki, Toru; Fujioka, Chikako; Suzuki, Tatsuhiko; Tsuneda, Masato; Nakashima, Takeo; Ohno, Yoshimi; Nagata, Yasushi

2018-02-01

To evaluate the accuracy of raw-data-based effective atomic number (Z eff ) values and monochromatic CT numbers for contrast material of varying iodine concentrations, obtained using dual-energy CT. We used a tissue characterization phantom and varying concentrations of iodinated contrast medium. A comparison between the theoretical values of Z eff and that provided by the manufacturer was performed. The measured and theoretical monochromatic CT numbers at 40-130 keV were compared. The average difference between the Z eff values of lung (inhale) inserts in the tissue characterization phantom was 81.3% and the average Z eff difference was within 8.4%. The average difference between the Z eff values of the varying concentrations of iodinated contrast medium was within 11.2%. For the varying concentrations of iodinated contrast medium, the differences between the measured and theoretical monochromatic CT values increased with decreasing monochromatic energy. The Z eff and monochromatic CT numbers in the tissue characterization phantom were reasonably accurate. The accuracy of the raw-data-based Z eff values was higher than that of image-based Z eff values in the tissue-equivalent phantom. The accuracy of Z eff values in the contrast medium was in good agreement within the maximum SD found in the iodine concentration range of clinical dynamic CT imaging. Moreover, the optimum monochromatic energy for human tissue and iodinated contrast medium was found to be 70 keV. Advances in knowledge: The accuracy of the Z eff values and monochromatic CT numbers of the contrast medium created by raw-data-based, dual-energy CT could be sufficient in clinical conditions.

Multimodal ophthalmic imaging using swept source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

NASA Astrophysics Data System (ADS)

Malone, Joseph D.; El-Haddad, Mohamed T.; Tye, Logan A.; Majeau, Lucas; Godbout, Nicolas; Rollins, Andrew M.; Boudoux, Caroline; Tao, Yuankai K.

2016-03-01

Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) benefit clinical diagnostic imaging in ophthalmology by enabling in vivo noninvasive en face and volumetric visualization of retinal structures, respectively. Spectrally encoding methods enable confocal imaging through fiber optics and reduces system complexity. Previous applications in ophthalmic imaging include spectrally encoded confocal scanning laser ophthalmoscopy (SECSLO) and a combined SECSLO-OCT system for image guidance, tracking, and registration. However, spectrally encoded imaging suffers from speckle noise because each spectrally encoded channel is effectively monochromatic. Here, we demonstrate in vivo human retinal imaging using a swept source spectrally encoded scanning laser ophthalmoscope and OCT (SSSESLO- OCT) at 1060 nm. SS-SESLO-OCT uses a shared 100 kHz Axsun swept source, shared scanner and imaging optics, and are detected simultaneously on a shared, dual channel high-speed digitizer. SESLO illumination and detection was performed using the single mode core and multimode inner cladding of a double clad fiber coupler, respectively, to preserve lateral resolution while improving collection efficiency and reducing speckle contrast at the expense of confocality. Concurrent en face SESLO and cross-sectional OCT images were acquired with 1376 x 500 pixels at 200 frames-per-second. Our system design is compact and uses a shared light source, imaging optics, and digitizer, which reduces overall system complexity and ensures inherent co-registration between SESLO and OCT FOVs. En face SESLO images acquired concurrent with OCT cross-sections enables lateral motion tracking and three-dimensional volume registration with broad applications in multivolume OCT averaging, image mosaicking, and intraoperative instrument tracking.

Application of the polychromatic defocus transfer function to multifocal lenses.

PubMed

Schwiegerling, Jim; Choi, Junoh

2008-11-01

To model the performance of multifocal lenses in polychromatic lighting. The defocus transfer function (DTF) is a mathematical technique for illustrating the optical transfer function for all levels of defocus at a given wavelength. A polychromatic version of the DTF is developed that accounts for changes in cutoff frequency, reduction in diffraction efficiency, ocular chromatic aberration, and photoreceptor spectral sensitivity. The differences between the monochromatic and polychromatic DTF are illustrated with a diffractive multifocal intraocular lens. Polychromatic analysis shows an increase in depth of field of diffractive lenses relative to assessment at a single wavelength. The polychromatic DTF is a useful tool for analyzing presbyopia treatments under "white-light" viewing conditions and provides feedback to lens designers on anticipated performance.

Index mismatch aberration correction over long working distances using spatial light modulation.

PubMed

Gjonaj, Bergin; Johnson, Patrick; Bonn, Mischa; Domke, Katrin F

2012-11-20

For many microscopy applications, millimeters-long free working distances (LWD) are required. However, the high resolution and contrast of LWD objectives operated in air are lost when introducing glass and/or liquid with the sample. We propose to use spatial light modulation to correct for such beam aberrations caused by refractive index mismatches. Focusing a monochromatic laser beam with a 10 mm working distance air objective (50×, 0.5 NA) through air, glass, and water, we manage to restore a sharp, intense focus (FWHM<2λ) by adaptive beam phase shaping. Our approach offers a practical and cost-effective route to high resolution and contrast microscopy using LWD air objectives, extending their usage beyond applications in air.

Transforming reflectance spectra into Munsell color space by using prime colors.

PubMed

Romney, A Kimball; Fulton, James T

2006-10-17

Independent researchers have proved mathematically that, given a set of color-matching functions, there exists a unique set of three monochromatic spectral lights that optimizes luminous efficiency and color gamut. These lights are called prime colors. We present a method for transforming reflectance spectra into Munsell color space by using hypothetical absorbance curves based on Gaussian approximations of the prime colors and a simplified version of opponent process theory. The derived color appearance system is represented as a 3D color system that is qualitatively similar to a conceptual representation of the Munsell color system. We illustrate the application of the model and compare it with existing models by using reflectance spectra obtained from 1,269 Munsell color samples.

X-ray diffraction diagnostic design for the National Ignition Facility

NASA Astrophysics Data System (ADS)

Ahmed, Maryum F.; House, Allen; Smith, R. F.; Ayers, Jay; Lamb, Zachary S.; Swift, David W.

2013-09-01

This paper describes the design considerations for Target Diffraction In-Situ (TARDIS), an x-ray diffraction diagnostic at the National Ignition Facility. A crystal sample is ramp-compressed to peak pressures between 10 and 30 Mbar and, during a pressure hold period, is probed with quasi-monochromatic x-rays emanating from a backlighter source foil. The crystal spectrography diffraction lines are recorded onto image plates. The crystal sample, filter, and image plates are packaged into one assembly, allowing for accurate and repeatable target to image plate registration. Unconverted laser light impinges upon the device, generating debris, the effects of which have been mitigated. Dimpled blast shields, high strength steel alloy, and high-z tungsten are used to shield and protect the image plates. A tapered opening was designed to provide adequate thickness of shielding materials without blocking the drive beams or x-ray source from reaching the crystal target. The high strength steel unit serves as a mount for the crystal target and x-ray source foil. A tungsten body contains the imaging components. Inside this sub-assembly, there are three image plates: a 160 degree field of view curved plate directly opposite the target opening and two flat plates for the top and bottom. A polycarbonate frame, coated with the appropriate filter material and embedded with registration features for image plate location, is inserted into the diagnostic body. The target assembly is metrologized and then the diagnostic assembly is attached.

Development of a bunch-by-bunch longitudinal feedback system with a wide dynamic range for the HIGS facility

NASA Astrophysics Data System (ADS)

Wu, W. Z.; Kim, Y.; Li, J. Y.; Teytelman, D.; Busch, M.; Wang, P.; Swift, G.; Park, I. S.; Ko, I. S.; Wu, Y. K.

2011-03-01

Electron beam coupled-bunch instabilities can limit and degrade the performance of storage ring based light sources. A longitudinal feedback system has been developed for the Duke storage ring to suppress multi-bunch beam instabilities which prevent stable, high-current operation of the storage ring based free-electron lasers (FELs) and an FEL driven Compton gamma source, the high intensity gamma-ray source (HIGS) at Duke University. In this work, we report the development of a state-of-the-art second generation longitudinal feedback system which employs a field programmable gate array (FPGA) based processor, and a broadband, high shunt-impedance kicker cavity. With two inputs and two outputs, the kicker cavity was designed with a resonant frequency of 937 MHz, a bandwidth of 97 MHz, and a shunt impedance of 1530 Ω. We also developed an S-matrix based technique to fully characterize the performance of the kicker cavity in the cold test. This longitudinal feedback system has been commissioned and optimized to stabilize high-current electron beams with a wide range of electron beam energies (250 MeV to 1.15 GeV) and a number of electron beam bunch modes, including the single-bunch mode and all possible symmetric bunch modes. This feedback system has become a critical instrument to ensure stable, high-flux operation of HIGS to produce nearly monochromatic, highly polarized Compton gamma-ray beams.

A robust yellow-emitting metallophosphor with electron-injection/-transporting traits for highly efficient white organic light-emitting diodes.

PubMed

Zhou, Guijiang; Yang, Xiaolong; Wong, Wai-Yeung; Wang, Qi; Suo, Si; Ma, Dongge; Feng, Jikang; Wang, Lixiang

2011-10-24

With the aim of endowing triplet emitters in the development of organic light-emitting devices (OLEDs) with electron-injection/-transporting (EI/ET) features, the phenylsulfonyl moiety was introduced into the phenyl ring of a 2-phenylpyridine (Hppy) ligand and the yellow phosphorescent heteroleptic iridium(III) complex 1 was developed. It was shown that the SO(2)Ph unit could provide EI/ET character to 1, as indicated from both electrochemical and computational data. Complex 1 is a promising yellow-emitting material for both monochromatic OLEDs and white OLEDs (WOLEDs). The outstanding electronic traits associated with 1, coupled with careful device design, afforded very attractive electroluminescent performances for two-element WOLEDs, including a low turn-on voltage of less than 3.7 V, a maximum brightness of 48,000 cd m(-2), an external quantum efficiency of 13.0%, a luminance efficiency of 34.7 cd A(-1), and a power efficiency of 24.3 Lm W(-1). In addition, a good color rendering index (CRI) of about 74, a stable white color with a Commission Internationale de L'Eclairage (CIE(x,y)) variation of Δ(x, y) < ±(0.02, 0.02), and a correlated color temperature higher than 5130 K were obtained. These encouraging results indicate the potential of these WOLEDs as good candidates for warm indoor lighting sources, as well as the critical contribution of such key EI/ET properties to triplet emitters to advance new OLED research. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Computational diffraction tomographic microscopy with transport of intensity equation using a light-emitting diode array

NASA Astrophysics Data System (ADS)

Li, Jiaji; Chen, Qian; Zhang, Jialin; Zuo, Chao

2017-10-01

Optical diffraction tomography (ODT) is an effective label-free technique for quantitatively refractive index imaging, which enables long-term monitoring of the internal three-dimensional (3D) structures and molecular composition of biological cells with minimal perturbation. However, existing optical tomographic methods generally rely on interferometric configuration for phase measurement and sophisticated mechanical systems for sample rotation or beam scanning. Thereby, the measurement is suspect to phase error coming from the coherent speckle, environmental vibrations, and mechanical error during data acquisition process. To overcome these limitations, we present a new ODT technique based on non-interferometric phase retrieval and programmable illumination emitting from a light-emitting diode (LED) array. The experimental system is built based on a traditional bright field microscope, with the light source replaced by a programmable LED array, which provides angle-variable quasi-monochromatic illumination with an angular coverage of +/-37 degrees in both x and y directions (corresponding to an illumination numerical aperture of ˜ 0.6). Transport of intensity equation (TIE) is utilized to recover the phase at different illumination angles, and the refractive index distribution is reconstructed based on the ODT framework under first Rytov approximation. The missing-cone problem in ODT is addressed by using the iterative non-negative constraint algorithm, and the misalignment of the LED array is further numerically corrected to improve the accuracy of refractive index quantification. Experiments on polystyrene beads and thick biological specimens show that the proposed approach allows accurate refractive index reconstruction while greatly reduced the system complexity and environmental sensitivity compared to conventional interferometric ODT approaches.

Optical diffraction tomography microscopy with transport of intensity equation using a light-emitting diode array

NASA Astrophysics Data System (ADS)

Li, Jiaji; Chen, Qian; Zhang, Jialin; Zhang, Zhao; Zhang, Yan; Zuo, Chao

2017-08-01

Optical diffraction tomography (ODT) is an effective label-free technique for quantitatively refractive index imaging, which enables long-term monitoring of the internal three-dimensional (3D) structures and molecular composition of biological cells with minimal perturbation. However, existing optical tomographic methods generally rely on interferometric configuration for phase measurement and sophisticated mechanical systems for sample rotation or beam scanning. Thereby, the measurement is suspect to phase error coming from the coherent speckle, environmental vibrations, and mechanical error during data acquisition process. To overcome these limitations, we present a new ODT technique based on non-interferometric phase retrieval and programmable illumination emitting from a light-emitting diode (LED) array. The experimental system is built based on a traditional bright field microscope, with the light source replaced by a programmable LED array, which provides angle-variable quasi-monochromatic illumination with an angular coverage of ±37 degrees in both x and y directions (corresponding to an illumination numerical aperture of ∼0.6). Transport of intensity equation (TIE) is utilized to recover the phase at different illumination angles, and the refractive index distribution is reconstructed based on the ODT framework under first Rytov approximation. The missing-cone problem in ODT is addressed by using the iterative non-negative constraint algorithm, and the misalignment of the LED array is further numerically corrected to improve the accuracy of refractive index quantification. Experiments on polystyrene beads and thick biological specimens show that the proposed approach allows accurate refractive index reconstruction while greatly reduced the system complexity and environmental sensitivity compared to conventional interferometric ODT approaches.

Sex and vision II: color appearance of monochromatic lights.

PubMed

Abramov, Israel; Gordon, James; Feldman, Olga; Chavarga, Alla

2012-09-04

Because cerebral cortex has a very large number of testosterone receptors, we examined the possible sex differences in color appearance of monochromatic lights across the visible spectrum. There is a history of men and women perceiving color differently. However, all of these studies deal with higher cognitive functions which may be culture-biased. We study basic visual functions, such as color appearance, without reference to any objects. We present here a detailed analysis of sex differences in primary chromatic sensations. We tested large groups of young adults with normal vision, including spatial and temporal resolution, and stereopsis. Based on standard color-screening and anomaloscope data, we excluded all color-deficient observers. Stimuli were equi-luminant monochromatic lights across the spectrum. They were foveally-viewed flashes presented against a dark background. The elicited sensations were measured using magnitude estimation of hue and saturation. When the only permitted hue terms are red (R) yellow (Y), green (G), blue (B), alone or in combination, such hue descriptions are language-independent and the hue and saturation values can be used to derive a wide range of color-discrimination functions. There were relatively small but clear and significant, differences between males and females in the hue sensations elicited by almost the entire spectrum. Generally, males required a slightly longer wavelength to experience the same hue as did females. The spectral loci of the unique hues are not correlated with anomaloscope matches; these matches are directly determined by the spectral sensitivities of L- and M-cones (genes for these cones are on the X-chromosomes). Nor are there correlations between loci of pairs of unique hues (R, Y, G, B). Wavelength-discrimination functions derived from the scaling data show that males have a broader range of poorer discrimination in the middle of the spectrum. The precise values for all the data depend on whether Newtonian or Maxwellian optics were used, but the sex differences were the same for both optical systems. As with our associated paper on spatio-temporal vision, there are marked sex differences in color vision. The color-appearances we measured are determined by inputs from thalamic neurons (LGN) to individual neurons in primary visual cortex. This convergence from LGN to cortex is guided by the cortex during embryogenesis. We hypothesize that testosterone plays a major role, somehow leading to different connectivities for males and females: color appearance requires a re-combination and re-weighting of neuronal inputs from the LGN to the cortex, which, as we show, depends on the sex of the participant.

Aging of Non-Visual Spectral Sensitivity to Light in Humans: Compensatory Mechanisms?

PubMed Central

Najjar, Raymond P.; Chiquet, Christophe; Teikari, Petteri; Cornut, Pierre-Loïc; Claustrat, Bruno; Denis, Philippe; Gronfier, Claude

2014-01-01

The deterioration of sleep in the older population is a prevalent feature that contributes to a decrease in quality of life. Inappropriate entrainment of the circadian clock by light is considered to contribute to the alteration of sleep structure and circadian rhythms in the elderly. The present study investigates the effects of aging on non-visual spectral sensitivity to light and tests the hypothesis that circadian disturbances are related to a decreased light transmittance. In a within-subject design, eight aged and five young subjects were exposed at night to 60 minute monochromatic light stimulations at 9 different wavelengths (420–620 nm). Individual sensitivity spectra were derived from measures of melatonin suppression. Lens density was assessed using a validated psychophysical technique. Although lens transmittance was decreased for short wavelength light in the older participants, melatonin suppression was not reduced. Peak of non-visual sensitivity was, however, shifted to longer wavelengths in the aged participants (494 nm) compared to young (484 nm). Our results indicate that increased lens filtering does not necessarily lead to a decreased non-visual sensitivity to light. The lack of age-related decrease in non-visual sensitivity to light may involve as yet undefined adaptive mechanisms. PMID:24465738

Planetary instrument definition and development program: 'Miniature Monochromatic Imager'

NASA Technical Reports Server (NTRS)

Broadfoot, A. L.

1991-01-01

The miniature monochromatic imager (MMI) development work became the basis for the preparation of several instruments which were built and flown on the shuttle STS-39 as well as being used in ground based experiments. The following subject areas are covered: (1) applications of the ICCD to airglow and auroral measurements and (2) a panchromatic spectrograph with supporting monochromatic imagers.

Utilization of coincidence criteria in absolute length measurements by optical interferometry in vacuum and air

NASA Astrophysics Data System (ADS)

Schödel, R.

2015-08-01

Traceability of length measurements to the international system of units (SI) can be realized by using optical interferometry making use of well-known frequencies of monochromatic light sources mentioned in the Mise en Pratique for the realization of the metre. At some national metrology institutes, such as Physikalisch-Technische Bundesanstalt (PTB) in Germany, the absolute length of prismatic bodies (e.g. gauge blocks) is realized by so-called gauge-block interference comparators. At PTB, a number of such imaging phase-stepping interference comparators exist, including specialized vacuum interference comparators, each equipped with three highly stabilized laser light sources. The length of a material measure is expressed as a multiple of each wavelength. The large number of integer interference orders can be extracted by the method of exact fractions in which the coincidence of the lengths resulting from the different wavelengths is utilized as a criterion. The unambiguous extraction of the integer interference orders is an essential prerequisite for correct length measurements. This paper critically discusses coincidence criteria and their validity for three modes of absolute length measurements: 1) measurements under vacuum in which the wavelengths can be identified with the vacuum wavelengths, 2) measurements under air in which the air refractive index is obtained from environmental parameters using an empirical equation, and 3) measurements under air in which the air refractive index is obtained interferometrically by utilizing a vacuum cell placed along the measurement pathway. For case 3), which corresponds to PTB’s Kösters-Comparator for long gauge blocks, the unambiguous determination of integer interference orders related to the air refractive index could be improved by about a factor of ten when an ‘overall dispersion value,’ suggested in this paper, is used as coincidence criterion.

Design of an interferometric system for piston measurements in segmented primary mirrors

NASA Astrophysics Data System (ADS)

Arasa, Josep; Laguarta, Ferran; Pizarro, Carlos; Tomas, Nuria; Pinto, Agusti

2000-10-01

Recently, telescopes with segmented primary mirrors are becoming increasingly popular due to their ability of achieving large apertures without the inconveniences caused by the fabrication and handling of monolithic surfaces with 8m (or over) in diameter. The difference in position of each pair of adjacent segments along the local normal of their interface (called piston hereafter), however, needs to be precisely measured in order to provide a diffraction- limited image. If a system yielding the nanometric accuracy required in piston measurements worked in daylight hours, the resultant saving in observation time would be an important advance on a majority of the state-of-the-art piston measurement systems. An interferometric piston measurement instrument accomplishing such objectives has been designed starting from the usual Michelson configuration at the CD6 (Terrassa, Spain), and its final test has been carried out in the test workbench of the Instituto de Astrofisica de Canarias (IAC, Canary Islands, Spain). Its optical layout relies on projecting the reference arm of the interferometer onto one of the segments of the pair considered, along the direction of the local normal to the surface while the measurement arm is projected onto the interface which divides the pair of segments considered. The field of view and its illumination are calculated to be equivalent in both segments. The lateral shift of the fringes in both interferograms determines the piston error present. A combination of monochromatic and white light is used, in order to remove the (lambda) /2 phase ambiguities present in piston measurements without losing the required resolution in the measurement. In this paper, the optical design of this interferometric piston measurement instrument will be presented. The particular configuration used in the interferometer, the implementation of an imaging system allowing to see both the interface of the segments and the interference fringes, the effect of the extension of the source and the use of both monochromatic and whit light will be discussed. A detailed study of the wavefront errors embedded in the wavefront at different stages of the interferometer is performed. The analysis shows the validity of the design of the instrument, and some experimental results obtained at the test workbench are provided to demonstrate the ability of the instrument to perform nanometric piston measurements under daylight conditions.

Steering and filtering white light with resonant waveguide gratings

NASA Astrophysics Data System (ADS)

Quaranta, Giorgio; Basset, Guillaume; Martin, Olivier J. F.; Gallinet, Benjamin

2017-08-01

A novel thin-film single-layer structure based on resonant waveguide gratings (RWGs) allows to engineer selective color filtering and steering of white light. The unit cell of the structure consists of two adjacent finite-length and cross-talking RWGs, where the former acts as in-coupler and the latter acts as out-coupler. The structure is made by only one nano-imprint lithography replication and one thin film layer deposition, making it fully compatible with up-scalable fabrication processes. We characterize a fabricated optical security element designed to work with the flash and the camera of a smartphone in off-axis light steering configuration, where the pattern is revealed only by placing the smartphone in the proper position. Widespread applications are foreseen in a variety of fields, such as multifocal or monochromatic lenses, solar cells, biosensors, security devices and seethrough optical combiners for near-eye displays.

Full down-conversion of amber-emitting phosphor-converted light-emitting diodes with powder phosphors and a long-wave pass filter.

PubMed

Oh, Jeong Rok; Cho, Sang-Hwan; Park, Hoo Keun; Oh, Ji Hye; Lee, Yong-Hee; Do, Young Rag

2010-05-24

This paper reports the possibility of a facile optical structure to realize a highly efficient monochromatic amber-emitting light-emitting diode (LED) using a powder-based phosphor-converted LED combined with a long-wave pass filter (LWPF). The capping of a blue-reflecting and amber-passing LWPF enhances both the amber emission from the silicate amber phosphor layer and the color purity due to the blocking and recycling of the pumping blue light from the InGaN LED. The enhancement of the luminous efficacy of the amber pc-LED with a LWPF (phosphor concentration 20 wt%, 39.4 lm/W) is 34% over that of an amber pc-LED without a LWPF (phosphor concentration 55 wt%, 29.4 lm/W) at 100 mA and a high color purity (>96%) with Commission International d'Eclairage (CIE) color coordinates of x=0.57 and y=0.42.

Investigation of deep-level defects in Cu(In,Ga)Se2 thin films by two-wavelength excitation photo-capacitance spectroscopy

NASA Astrophysics Data System (ADS)

Hu, Xiaobo; Gupta, Amit; Sakurai, Takeaki; Yamada, Akimasa; Ishizuka, Shogo; Niki, Shigeru; Akimoto, Katsuhiro

2013-10-01

The properties of the defect level located 0.8 eV above the valence band in Cu(In1-x,Gax)Se2 thin films were investigated by a photo-capacitance method using a monochromatic probe light with an energy of 0.7 to 1.8 eV. In addition to the probe light, laser light with a wavelength of 1.55 μm, corresponding to 0.8 eV, was also used to study the saturation effect of the defect level at 0.8 eV. A suppression of electron-hole recombination due to saturation of the defect level was observed at room temperature while no saturation effect was observed at 140 K. The results suggest that the defect level at 0.8 eV acts as a recombination center at least at room temperature.

Cost-Effective Live Cell Density Determination of Liquid Cultured Microorganisms.

PubMed

Kutschera, Alexander; Lamb, Jacob J

2018-02-01

Live monitoring of microorganisms growth in liquid medium is a desired parameter for many research fields. A wildly used approach for determining microbial liquid growth quantification is based on light scattering as the result of the physical interaction of light with microbial cells. These measurements are generally achieved using costly table-top instruments; however, a live, reliable, and straight forward instrument constructed using parts that are inexpensive may provide opportunities for many researchers. Here, such an instrument has been constructed and tested. It consists of modular test tube holding chambers, each with a low power monochromatic light-emitting diode, and a monolithic photodiode. A microcontroller connects to all modular chambers to control the diodes, and send the live data to either an LCD screen, or a computer. This work demonstrate that this modular instrument can determine precise cell concentrations for the bacteria Escherichia coli and Pseudomonas syringae pv. tomato DC3000, as well as Saccharomyces cerevisiae yeast.

Ultrahigh resolution retinal imaging by visible light OCT with longitudinal achromatization

PubMed Central

Chong, Shau Poh; Zhang, Tingwei; Kho, Aaron; Bernucci, Marcel T.; Dubra, Alfredo; Srinivasan, Vivek J.

2018-01-01

Chromatic aberrations are an important design consideration in high resolution, high bandwidth, refractive imaging systems that use visible light. Here, we present a fiber-based spectral/Fourier domain, visible light OCT ophthalmoscope corrected for the average longitudinal chromatic aberration (LCA) of the human eye. Analysis of complex speckles from in vivo retinal images showed that achromatization resulted in a speckle autocorrelation function that was ~20% narrower in the axial direction, but unchanged in the transverse direction. In images from the improved, achromatized system, the separation between Bruch’s membrane (BM), the retinal pigment epithelium (RPE), and the outer segment tips clearly emerged across the entire 6.5 mm field-of-view, enabling segmentation and morphometry of BM and the RPE in a human subject. Finally, cross-sectional images depicted distinct inner retinal layers with high resolution. Thus, with chromatic aberration compensation, visible light OCT can achieve volume resolutions and retinal image quality that matches or exceeds ultrahigh resolution near-infrared OCT systems with no monochromatic aberration compensation. PMID:29675296

Advanced Middle-UV Coherent Optical Sources

DTIC Science & Technology

2013-11-15

by high- resolution triple -axis X-ray diffraction was conducted. As shown in Figure 11, the entire structure is pseudomorphically deposited on the...Achievements: RBS measurements performed on InAlN layers determined the existence of unwanted gallium atoms (contaminants). We found that gallium was...monochromatic image in Fig. 2(b), taken at the left shoulder of the 267-nm emission, corresponds to regions of lower gallium content. We also

Improvement of graphite crystal analyzer for light elements on X-ray fluorescence holography measurement

NASA Astrophysics Data System (ADS)

Happo, Naohisa; Hada, Takuma; Kubota, Atsushi; Ebisu, Yoshihiro; Hosokawa, Shinya; Kimura, Koji; Tajiri, Hiroo; Matsushita, Tomohiro; Hayashi, Kouichi

2018-05-01

Using a graphite crystal analyzer, focused monochromatic fluorescent X-rays can be obtained on an X-ray fluorescence holography (XFH) measurement. To measure the holograms of elements lighter than Ti, we improved a cylindrical-type crystal analyzer and constructed a small C-shaped analyzer. Using the constructed C-shaped analyzer, a Ca Kα hologram of a fluorite single crystal was obtained, from which we reconstructed a clear atomic image. The XFH measurements for the K, Ca, and Sc elements become possible using the presently constructed analyzer.

Direct observation of magnetic domains by Kerr microscopy in a Ni-Mn-Ga magnetic shape-memory alloy

NASA Astrophysics Data System (ADS)

Perevertov, O.; Heczko, O.; Schäfer, R.

2017-04-01

The magnetic domains in a magnetic shape-memory Ni-Mn-Ga alloy were observed by magneto-optical Kerr microscopy using monochromatic blue LED light. The domains were observed for both single- and multivariant ferroelastic states of modulated martensite. The multivariant state with very fine twins was spontaneously formed after transformation from high-temperature austenite. For both cases, bar domains separated by 180∘ domain walls were found and their dynamics was studied. A quasidomain model was applied to explain the domains in the multivariant state.

[A new hypothesis for the treatment of amblyopia: the flicker stimulator].

PubMed

Parrozzani, A; Fedriga, P; Ferrari, E; De Vincentiis, L

1984-01-01

A variety of cells are involved in the pathogenesis of amblyopia : ON, OFF, ON-OFF cells, postsynaptic cells, neurons of striate cortex and the select interest of the macula. The need for stimulation of these cells in treating amblyopia forms the theoretical basis of the Flicker stimulator with red monochromatic light (LED, 655 nm). The authors present a clinical investigation on 35 subjects with anisometropic or strabismic amblyopia, before extensive treatment with classic anti-amblyopic techniques without satisfactory improvement obtaining significant statistical results (p less than 0,001).

Broad-band efficiency calibration of ITER bolometer prototypes using Pt absorbers on SiN membranes.

PubMed

Meister, H; Willmeroth, M; Zhang, D; Gottwald, A; Krumrey, M; Scholze, F

2013-12-01

The energy resolved efficiency of two bolometer detector prototypes for ITER with 4 channels each and absorber thicknesses of 4.5 μm and 12.5 μm, respectively, has been calibrated in a broad spectral range from 1.46 eV up to 25 keV. The calibration in the energy range above 3 eV was performed against previously calibrated silicon photodiodes using monochromatized synchrotron radiation provided by five different beamlines of Physikalische Technische Bundesanstalt at the electron storage rings BESSY II and Metrology Light Source in Berlin. For the measurements in the visible range, a setup was realised using monochromatized halogen lamp radiation and a calibrated laser power meter as reference. The measurements clearly demonstrate that the efficiency of the bolometer prototype detectors in the range from 50 eV up to ≈6 keV is close to unity; at a photon energy of 20 keV the bolometer with the thick absorber detects 80% of the photons, the one with the thin absorber about 50%. This indicates that the detectors will be well capable of measuring the plasma radiation expected from the standard ITER scenario. However, a minimum absorber thickness will be required for the high temperatures in the central plasma. At 11.56 keV, the sharp Pt-L3 absorption edge allowed to cross-check the absorber thickness by fitting the measured efficiency to the theoretically expected absorption of X-rays in a homogeneous Pt-layer. Furthermore, below 50 eV the efficiency first follows the losses due to reflectance expected for Pt, but below 10 eV it is reduced further by a factor of 2 for the thick absorber and a factor of 4 for the thin absorber. Most probably, the different histories in production, storage, and operation led to varying surface conditions and additional loss channels.

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

Vecchio, Alberto; Wickham, Elizabeth D.L.

The Laser Interferometer Space Antenna (LISA) is expected to provide the largest observational sample of binary systems of faint subsolar mass compact objects, in particular, white-dwarfs, whose radiation is monochromatic over most of the LISA observational window. Current astrophysical estimates suggest that the instrument will be able to resolve {approx}10{sup 4} such systems, with a large fraction of them at frequencies > or approx. 3 mHz, where the wavelength of gravitational waves becomes comparable to or shorter than the LISA armlength. This affects the structure of the so-called LISA transfer function which cannot be treated as constant in this frequencymore » range: it introduces characteristic phase and amplitude modulations that depend on the source location in the sky and the emission frequency. Here we investigate the effect of the LISA transfer function on detection and parameter estimation for monochromatic sources. For signal detection we show that filters constructed by approximating the transfer function as a constant (long-wavelength approximation) introduce a negligible loss of signal-to-noise ratio--the fitting factor always exceeds 0.97--for f{<=}10 mHz, therefore in a frequency range where one would actually expect the approximation to fail. For parameter estimation, we conclude that in the range 3 mHz < or approx. f < or approx. 30 mHz the errors associated with parameter measurements differ from {approx_equal}5% up to a factor {approx}10 (depending on the actual source parameters and emission frequency) with respect to those computed using the long-wavelength approximation.« less

Comment on "Collision monochromatization in e+e- colliders"

NASA Astrophysics Data System (ADS)

Shatilov, D.

2018-02-01

Bogomyagkov and Levichev [Phys. Rev. Accel. Beams 20, 051001 (2017), 10.1103/PhysRevAccelBeams.20.051001] have recently reported on monochromatization in collision schemes with crossing angle. From their results, in particular, it may seem that: (1) horizontal dispersion at the IP can provide monochromatization factor Λ ≫1 while retaining Piwinski angle ϕ >1 , (2) production rate in such a scheme for FCC-ee at 62.5 GeV can be larger than that in the nominal crab waist collision, and (3) strong rf focusing can be used for monochromatization purposes. We demonstrate here that the first two statements are not correct, and the last one is very doubtful.

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

Moorhouse, Saul J.; Wu, Yue; O’Hare, Dermot, E-mail: dermot.ohare@chem.ox.ac.uk

A newly developed in situ monochromatic high-energy X-ray diffraction setup was used to investigate the synthesis of MOFs using cation-impregnated polymer resin beads as a ion source. The Co–NDC–DMF (NDC=2,6-naphthalenedicarboxylate; DMF=dimethylformamide) system was investigated, a system which is known to produce at least three distinct frameworks. It was found that the resin-assisted synthesis results in the preferential formation of a topology previously impossible to synthesise in bulk, while the comparable nitrate-salt synthesis appeared to form an alternative phases. It was also found that the resin-assisted synthesis is highly diffusion-controlled. - Graphical abstract: In situ monochromatic high-energy X-ray diffraction study ofmore » a MOF synthesis. - Highlights: • Resin-assisted solvothermal MOF synthesis was studied using in situ diffraction. • Full kinetics of reaction can be obtained from in situ data. • Kinetics show that this resin-assisted synthesis is diffusion controlled. • Resin-assisted synthesis enables the production of an alternative bulk phase.« less

Near infrared photoluminescence properties of porous silicon prepared under the influence of light illumination

NASA Astrophysics Data System (ADS)

Hamadeh, H.; Naddaf, M.; Jazmati, A.

2008-12-01

Porous silicon (PS) has been prepared by anodic etching of boron doped silicon under the influence of monochromatic light illumination. The optical properties of the PS samples have been investigated using temperature dependent photoluminescence (PL) spectroscopy. An overall enhancement of the infrared luminescence yield is caused by the light illumination. In the visible spectral range, changes at the low energy side of the broad PL band were observed. In the near infrared spectral range, a new PL band at 850 nm, which is strongly correlated with light illumination, was detected. The new PL band disappears once blue light is used, whereas an increase in its intensity is observed, when the etching is performed under the illumination of light with wavelengths close to the band gap. By increasing the temperature, the 850 nm transition band grows at the expense of the main near infrared transition at 1100 nm. The recombination characteristics of this PL band are indicative of its extrinsic nature. The macroscopic morphology shows strong dependence on the wavelength of the illumination light. Photoassisted preparation could provide a tool for the control of the optical and structural properties of PS.

Decay pattern of the Pygmy Dipole Resonance in 130Te

NASA Astrophysics Data System (ADS)

Isaak, J.; Beller, J.; Fiori, E.; Krtička, M.; Löher, B.; Pietralla, N.; Romig, C.; Rusev, G.; Savran, D.; Scheck, M.; Silva, J.; Sonnabend, K.; Tonchev, A.; Tornow, W.; Weller, H.; Zweidinger, M.

2014-03-01

The electric dipole strength distribution in 130Te has been investigated using the method of Nuclear Resonance Fluorescence. The experiments were performed at the Darmstadt High Intensity Photon Setup using bremsstrahlung as photon source and at the High Intensity overrightarrow γ -Ray Source, where quasi-monochromatic and polarized photon beams are provided. Average decay properties of 130Te below the neutron separation energy are determined. Comparing the experimental data to the predictions of the statistical model indicate, that nuclear structure effects play an important role even at sufficiently high excitation energies. Preliminary results will be presented.

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, Stanley M.; Sharma, Shiv K.

1988-01-01

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber (13, 13a to 13e) having a metal coating (22, 22a to 22e) on at least a portion of a light transmissive core (17, 17a to 17d). The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the absorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector (16, 16d, 16e) analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode (13e) may function as a working electrode of an electrochemical cell (53) while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface.

Solar Polarimetry and Magnetic Field Measurements

NASA Astrophysics Data System (ADS)

del Toro Iniesta, J. C.

2001-05-01

The magnetic nature of most solar (spatially resolved or unresolved) structures is amply recognized. Magnetic fields of the Sun play a paramount rôle in the overall thermodynamic and dynamic state of our star. The main observable manifestation of solar magnetic fields is the polarization of light either through the Zeeman effect on spectral lines or through the Hanle effect (depolarization by very weak magnetic fields of light previously polarized by scattering). Hence, one can easily understand the increasing importance that polarimetry is experimenting continuously in solar physics. Under the title of this contribution a six-hour course was given during the summer school. Clearly, the limited extension allocated for the notes in these proceedings avoids an extensive account of the several topics discussed: 1) a description of light as an electromagnetic wave and the polarization properties of monochromatic, time-harmonic, plane waves; 2) the polarization properties of polychromatic light and, in particular, of quasi-monochromatic light; 3) the transformations of (partially) polarized light by linear optical systems and a description of the ways we measure the Stokes parameters by spatially and/or temporally modulating the polarimetric signal; 4) a discussion on specific problems relevant to solar polarimetry like seeing-induced and instrumental polarization, or modulation and demodulation, along with a brief description of current solar polarimeters; 5) the vector radiative transfer equation for polarized light and its links to the scalar one for unpolarized light, together with a summary of the Zeeman effect and its consequences on line formation in a magnetized stellar atmosphere; 7) an introduction of the paramount astrophysical problem, i.e., that of finding diagnostics that enable the solar physicist to interpret the observables in terms of the solar atmospheric quantities, including a discussion on contribution and response functions; and 8) a brief outline of inversion techniques as a recommended way to infer values of the vector magnetic field and other thermodynamic and dynamic quantities. Since most of the material presented in the lectures can be found in the literature, I decided to focus these pages to those topics that, in my opinion, need a particular stress and/or do not have received much attention in previous reviews or textbooks. These notes have been written with mostly didactical purposes so that, skipping the customary usage, just a few references will be cited within the text. Instead, a classified (and necessarily incomplete) bibliography is recommended at the end.

Colour influences perception of facial emotions but this effect is impaired in healthy ageing and schizophrenia.

PubMed

Silver, Henry; Bilker, Warren B

2015-01-01

Social cognition is commonly assessed by identification of emotions in facial expressions. Presence of colour, a salient feature of stimuli, might influence emotional face perception. We administered 2 tests of facial emotion recognition, the Emotion Recognition Test (ER40) using colour pictures and the Penn Emotional Acuity Test using monochromatic pictures, to 37 young healthy, 39 old healthy and 37 schizophrenic men. Among young healthy individuals recognition of emotions was more accurate and faster in colour than in monochromatic pictures. Compared to the younger group, older healthy individuals revealed impairment in identification of sad expressions in colour but not monochromatic pictures. Schizophrenia patients showed greater impairment in colour than monochromatic pictures of neutral and sad expressions and overall total score compared to both healthy groups. Patients showed significant correlations between cognitive impairment and perception of emotion in colour but not monochromatic pictures. Colour enhances perception of general emotional clues and this contextual effect is impaired in healthy ageing and schizophrenia. The effects of colour need to be considered in interpreting and comparing studies of emotion perception. Coloured face stimuli may be more sensitive to emotion processing impairments but less selective for emotion-specific information than monochromatic stimuli. This may impact on their utility in early detection of impairments and investigations of underlying mechanisms.

Towards equation of state of dark energy from quasar monitoring: Reverberation strategy

NASA Astrophysics Data System (ADS)

Czerny, B.; Hryniewicz, K.; Maity, I.; Schwarzenberg-Czerny, A.; Życki, P. T.; Bilicki, M.

2013-08-01

Context. High-redshift quasars can be used to constrain the equation of state of dark energy. They can serve as a complementary tool to supernovae Type Ia, especially at z > 1. Aims: The method is based on the determination of the size of the broad line region (BLR) from the emission line delay, the determination of the absolute monochromatic luminosity either from the observed statistical relation or from a model of the formation of the BLR, and the determination of the observed monochromatic flux from photometry. This allows the luminosity distance to a quasar to be obtained, independently from its redshift. The accuracy of the measurements is, however, a key issue. Methods: We modeled the expected accuracy of the measurements by creating artificial quasar monochromatic lightcurves and responses from the BLR under various assumptions about the variability of a quasar, BLR extension, distribution of the measurements in time, accuracy of the measurements, and the intrinsic line variability. Results: We show that the five-year monitoring of a single quasar based on the Mg II line should give an accuracy of 0.06-0.32 mag in the distance modulus which will allow new constraints to be put on the expansion rate of the Universe at high redshifts. Successful monitoring of higher redshift quasars based on C IV lines requires proper selection of the objects to avoid sources with much higher levels of the intrinsic variability of C IV compared to Mg II.

Treatment of Bell's Palsy Using Monochromatic Infrared Energy: A Report of 2 Cases.

PubMed

Ng, Shu Yan; Chu, Ming Him E

2014-06-01

The purpose of the study is to describe the use of monochromatic infrared energy (MIRE) therapy in the management of 2 patients with Bell's palsy. Two patients presented to a chiropractic clinic with Bell's palsy that was diagnosed by a medical physician. Both patients were treated using MIRE. The acute patient was a 32-year-old male. He presented with left facial palsy 1 day before the consultation. He was unable to puff the left cheek and close the left eyelid. He had difficulty raising the left eyebrow. The chronic case was a 46-year-old lady. Prior to the first consultation, she was treated with corticosteroid and electro-acupuncture for one and a half years, with incomplete recovery. When first seen, the left corner of mouth drooped and she had difficulty raising her left eyebrow. Monochromatic infrared energy therapy, emitting 890 nm infrared light, was placed on the post-auricular area, pre-auricular area, the temple and mandibular area of the affected side. Each treatment lasted 30 minutes. Photographs were taken every week to document changes. The acute case received 19 treatments in 6 weeks. He reported an improvement of 95%. The chronic case received a total of 45 treatments in 9 months. She rated an improvement of 50%. At the conclusion of treatment, she was able to close her left eyelid and puff her left cheek but still could not raise her left eyebrow. These 2 patients seemed to respond to a different degree to the MIRE therapy. As 71% of patients with Bell's palsy recover uneventfully without any treatment, the present study describes the course of care but cannot confirm the effectiveness of MIRE therapy in the management of Bell's palsy.

Treatment of Bell's Palsy Using Monochromatic Infrared Energy: A Report of 2 Cases

PubMed Central

Ng, Shu Yan; Chu, Ming Him E.

2014-01-01

Objective The purpose of the study is to describe the use of monochromatic infrared energy (MIRE) therapy in the management of 2 patients with Bell's palsy. Clinical features Two patients presented to a chiropractic clinic with Bell's palsy that was diagnosed by a medical physician. Both patients were treated using MIRE. The acute patient was a 32-year-old male. He presented with left facial palsy 1 day before the consultation. He was unable to puff the left cheek and close the left eyelid. He had difficulty raising the left eyebrow. The chronic case was a 46-year-old lady. Prior to the first consultation, she was treated with corticosteroid and electro-acupuncture for one and a half years, with incomplete recovery. When first seen, the left corner of mouth drooped and she had difficulty raising her left eyebrow. Intervention and outcome Monochromatic infrared energy therapy, emitting 890 nm infrared light, was placed on the post-auricular area, pre-auricular area, the temple and mandibular area of the affected side. Each treatment lasted 30 minutes. Photographs were taken every week to document changes. The acute case received 19 treatments in 6 weeks. He reported an improvement of 95%. The chronic case received a total of 45 treatments in 9 months. She rated an improvement of 50%. At the conclusion of treatment, she was able to close her left eyelid and puff her left cheek but still could not raise her left eyebrow. Conclusion These 2 patients seemed to respond to a different degree to the MIRE therapy. As 71% of patients with Bell's palsy recover uneventfully without any treatment, the present study describes the course of care but cannot confirm the effectiveness of MIRE therapy in the management of Bell's palsy. PMID:25685117

Techniques of noninvasive optical tomographic imaging

NASA Astrophysics Data System (ADS)

Rosen, Joseph; Abookasis, David; Gokhler, Mark

2006-01-01

Recently invented methods of optical tomographic imaging through scattering and absorbing media are presented. In one method, the three-dimensional structure of an object hidden between two biological tissues is recovered from many noisy speckle pictures obtained on the output of a multi-channeled optical imaging system. Objects are recovered from many speckled images observed by a digital camera through two stereoscopic microlens arrays. Each microlens in each array generates a speckle image of the object buried between the layers. In the computer each image is Fourier transformed jointly with an image of the speckled point-like source captured under the same conditions. A set of the squared magnitudes of the Fourier-transformed pictures is accumulated to form a single average picture. This final picture is again Fourier transformed, resulting in the three-dimensional reconstruction of the hidden object. In the other method, the effect of spatial longitudinal coherence is used for imaging through an absorbing layer with different thickness, or different index of refraction, along the layer. The technique is based on synthesis of multiple peak spatial degree of coherence. This degree of coherence enables us to scan simultaneously different sample points on different altitudes, and thus decreases the acquisition time. The same multi peak degree of coherence is also used for imaging through the absorbing layer. Our entire experiments are performed with a quasi-monochromatic light source. Therefore problems of dispersion and inhomogeneous absorption are avoided.

Laser-induced differential normalized fluorescence method for cancer diagnosis

DOEpatents

Vo-Dinh, Tuan; Panjehpour, Masoud; Overholt, Bergein F.

1996-01-01

An apparatus and method for cancer diagnosis are disclosed. The diagnostic method includes the steps of irradiating a tissue sample with monochromatic excitation light, producing a laser-induced fluorescence spectrum from emission radiation generated by interaction of the excitation light with the tissue sample, and dividing the intensity at each wavelength of the laser-induced fluorescence spectrum by the integrated area under the laser-induced fluorescence spectrum to produce a normalized spectrum. A mathematical difference between the normalized spectrum and an average value of a reference set of normalized spectra which correspond to normal tissues is calculated, which provides for amplifying small changes in weak signals from malignant tissues for improved analysis. The calculated differential normalized spectrum is correlated to a specific condition of a tissue sample.

Laser-induced differential normalized fluorescence method for cancer diagnosis

DOEpatents

Vo-Dinh, T.; Panjehpour, M.; Overholt, B.F.

1996-12-03

An apparatus and method for cancer diagnosis are disclosed. The diagnostic method includes the steps of irradiating a tissue sample with monochromatic excitation light, producing a laser-induced fluorescence spectrum from emission radiation generated by interaction of the excitation light with the tissue sample, and dividing the intensity at each wavelength of the laser-induced fluorescence spectrum by the integrated area under the laser-induced fluorescence spectrum to produce a normalized spectrum. A mathematical difference between the normalized spectrum and an average value of a reference set of normalized spectra which correspond to normal tissues is calculated, which provides for amplifying small changes in weak signals from malignant tissues for improved analysis. The calculated differential normalized spectrum is correlated to a specific condition of a tissue sample. 5 figs.

Effects of Infrared Laser Radiation on the In Vitro Isomerization of All-Trans Retinal to 11-Cis Retinal

PubMed Central

Liegner, J.; Taboada, J.; Tsin, A. T. C.

2015-01-01

The in vitro effect of infrared laser light on the isomerization of all-trans retinal dissolved in an ether/hexane and also an ethanol solvent was studied. Pulsed laser energy at 1064 nm was used to drive the molecular reconfiguration of all-trans retinal to 11-cis retinal. High pressure liquid chromatography (HPLC) was used to quantify the conversion. Overall isomerization was minimal (0.2 percent to 1.0 percent), yet, a significant difference in isomerization due to pulsed infrared laser energy over non-modulated monochromatic laser light was detected (up to 168 percent difference). Potentially, pulsed laser radiation tuned to the ethylenic stretch frequency of the C11=C12 bond of retinal may induce rotational changes to the chromophore. PMID:26321787

Two-dimensional simulation of eccentric photorefraction images for ametropes: factors influencing the measurement.

PubMed

Wu, Yifei; Thibos, Larry N; Candy, T Rowan

2018-05-07

Eccentric photorefraction and Purkinje image tracking are used to estimate refractive state and eye position simultaneously. Beyond vision screening, they provide insight into typical and atypical visual development. Systematic analysis of the effect of refractive error and spectacles on photorefraction data is needed to gauge the accuracy and precision of the technique. Simulation of two-dimensional, double-pass eccentric photorefraction was performed (Zemax). The inward pass included appropriate light sources, lenses and a single surface pupil plane eye model to create an extended retinal image that served as the source for the outward pass. Refractive state, as computed from the luminance gradient in the image of the pupil captured by the model's camera, was evaluated for a range of refractive errors (-15D to +15D), pupil sizes (3 mm to 7 mm) and two sets of higher-order monochromatic aberrations. Instrument calibration was simulated using -8D to +8D trial lenses at the spectacle plane for: (1) vertex distances from 3 mm to 23 mm, (2) uncorrected and corrected hyperopic refractive errors of +4D and +7D, and (3) uncorrected and corrected astigmatism of 4D at four different axes. Empirical calibration of a commercial photorefractor was also compared with a wavefront aberrometer for human eyes. The pupil luminance gradient varied linearly with refractive state for defocus less than approximately 4D (5 mm pupil). For larger errors, the gradient magnitude saturated and then reduced, leading to under-estimation of refractive state. Additional inaccuracy (up to 1D for 8D of defocus) resulted from spectacle magnification in the pupil image, which would reduce precision in situations where vertex distance is variable. The empirical calibration revealed a constant offset between the two clinical instruments. Computational modelling demonstrates the principles and limitations of photorefraction to help users avoid potential measurement errors. Factors that could cause clinically significant errors in photorefraction estimates include high refractive error, vertex distance and magnification effects of a spectacle lens, increased higher-order monochromatic aberrations, and changes in primary spherical aberration with accommodation. The impact of these errors increases with increasing defocus. © 2018 The Authors Ophthalmic & Physiological Optics © 2018 The College of Optometrists.

Choice of Grating Orientation for Evaluation of Peripheral Vision

PubMed Central

Venkataraman, Abinaya Priya; Winter, Simon; Rosén, Robert; Lundström, Linda

2016-01-01

ABSTRACT Purpose Peripheral resolution acuity depends on the orientation of the stimuli. However, it is uncertain if such a meridional effect also exists for peripheral detection tasks because they are affected by optical errors. Knowledge of the quantitative differences in acuity for different grating orientations is crucial for choosing the appropriate stimuli for evaluations of peripheral resolution and detection tasks. We assessed resolution and detection thresholds for different grating orientations in the peripheral visual field. Methods Resolution and detection thresholds were evaluated for gratings of four different orientations in eight different visual field meridians in the 20-deg visual field in white light. Detection measurements in monochromatic light (543 nm; bandwidth, 10 nm) were also performed to evaluate the effects of chromatic aberration on the meridional effect. A combination of trial lenses and adaptive optics system was used to correct the monochromatic lower- and higher-order aberrations. Results For both resolution and detection tasks, gratings parallel to the visual field meridian had better threshold compared with the perpendicular gratings, whereas the two oblique gratings had similar thresholds. The parallel and perpendicular grating acuity differences for resolution and detection tasks were 0.16 logMAR and 0.11 logMAD, respectively. Elimination of chromatic errors did not affect the meridional preference in detection acuity. Conclusions Similar to peripheral resolution, detection also shows a meridional effect that appears to have a neural origin. The threshold difference seen for parallel and perpendicular gratings suggests the use of two oblique gratings as stimuli in alternative forced-choice procedures for peripheral vision evaluation to reduce measurement variation. PMID:26889822

Choice of Grating Orientation for Evaluation of Peripheral Vision.

PubMed

Venkataraman, Abinaya Priya; Winter, Simon; Rosén, Robert; Lundström, Linda

2016-06-01

Peripheral resolution acuity depends on the orientation of the stimuli. However, it is uncertain if such a meridional effect also exists for peripheral detection tasks because they are affected by optical errors. Knowledge of the quantitative differences in acuity for different grating orientations is crucial for choosing the appropriate stimuli for evaluations of peripheral resolution and detection tasks. We assessed resolution and detection thresholds for different grating orientations in the peripheral visual field. Resolution and detection thresholds were evaluated for gratings of four different orientations in eight different visual field meridians in the 20-deg visual field in white light. Detection measurements in monochromatic light (543 nm; bandwidth, 10 nm) were also performed to evaluate the effects of chromatic aberration on the meridional effect. A combination of trial lenses and adaptive optics system was used to correct the monochromatic lower- and higher-order aberrations. For both resolution and detection tasks, gratings parallel to the visual field meridian had better threshold compared with the perpendicular gratings, whereas the two oblique gratings had similar thresholds. The parallel and perpendicular grating acuity differences for resolution and detection tasks were 0.16 logMAR and 0.11 logMAD, respectively. Elimination of chromatic errors did not affect the meridional preference in detection acuity. Similar to peripheral resolution, detection also shows a meridional effect that appears to have a neural origin. The threshold difference seen for parallel and perpendicular gratings suggests the use of two oblique gratings as stimuli in alternative forced-choice procedures for peripheral vision evaluation to reduce measurement variation.

Bichromatic Sisyphus Cooling

NASA Astrophysics Data System (ADS)

Cashen, M.; Yatsenko, L.; Metcalf, H.

2001-05-01

Sisyphus cooling arises when the conservative dipole force of a monochromatic optical standing wave (SW) is modified by optical pumping among multiple ground state sublevels at low intensity(J. Dalibard and C. Cohen-Tannoudji, J. Opt. Soc. B6), 2023 (1989)., or among dressed state manifolds at high intensity(A. Aspect et al., Phys. Rev. Lett. 57), 1688 (1986). As part of our ongoing exploration of optical forces in non-monochromatic light, we have discovered a new type of Sisyphus cooling in a two-level atom where the optical pumping is driven by a second SW produced as a sideband from weak frequency modulation. Each beam of the carrier's SW has a Rabi frequency Ωc ~ 20 γ and is tuned below atomic resonance by δc ~ -38 γ. Thus the light shift at the antinodes is ω_c^ls ~ 8.6 γ. For the sideband, Ωs ~ 1.4 γ and δs ~ +1 γ so ω_s^ls ~ 1 γ. The resulting forces satisfy Fc > 8 F_s. By contrast, the excitation rate γ_s^p > 2 γ_c^p. We choose the relative spatial phase of the SW's to be π, so moving atoms are most likely to be excited at the red-tuned carrier nodes, and thus they climb more hills than they descend. We observe transverse cooling of a beam of He metastables when δc < 0 and heating otherwise, in contrast to Ref. 3 because here the excitation is at the nodes of the high intensity carrier SW. We also observe channeling of the slow atoms in the carrier's SW.

Three-dimensional polarization states of monochromatic light fields.

PubMed

Azzam, R M A

2011-11-01

The 3×1 generalized Jones vectors (GJVs) [E(x) E(y) E(z)](t) (t indicates the transpose) that describe the linear, circular, and elliptical polarization states of an arbitrary three-dimensional (3-D) monochromatic light field are determined in terms of the geometrical parameters of the 3-D vibration of the time-harmonic electric field. In three dimensions, there are as many distinct linear polarization states as there are points on the surface of a hemisphere, and the number of distinct 3-D circular polarization states equals that of all two-dimensional (2-D) polarization states on the Poincaré sphere, of which only two are circular states. The subset of 3-D polarization states that results from the superposition of three mutually orthogonal x, y, and z field components of equal amplitude is considered as a function of their relative phases. Interesting contours of equal ellipticity and equal inclination of the normal to the polarization ellipse with respect to the x axis are obtained in 2-D phase space. Finally, the 3×3 generalized Jones calculus, in which elastic scattering (e.g., by a nano-object in the near field) is characterized by the 3-D linear transformation E(s)=T E(i), is briefly introduced. In such a matrix transformation, E(i) and E(s) are the 3×1 GJVs of the incident and scattered waves and T is the 3×3 generalized Jones matrix of the scatterer at a given frequency and for given directions of incidence and scattering.

Bragg x-ray optics for imaging spectroscopy of plasma microsources.

PubMed

Pikuz, T A; Ya Faenov, A; Pikuz, S A; Romanova, V M; Shelkovenko, T A

1995-01-01

Bragg x-ray optics based on crystals with transmission and reflection properties bent on cylindrical or spherical surfaces are discussed. Applications of such optics for obtaining one- and two-dimensional monochromatic images of different plasma sources in the wide spectral range 1-20 Å are described. Samples of spectra obtained with spectral resolution of up to λ/Δλ ~ 10,000 and spatial resolution of up to 18 μm are presented.

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

Kinzey, Bruce R.; Myer, Michael

This report describes the process and results of a demonstration of solid-state lighting (SSL) technology in a residential street lighting application, under the U.S. Department of Energy GATEWAY Solid-State Lighting Technology Demonstration Program. In this project, eight 100W (nominal) high-pressure sodium cobra head fixtures were replaced with a like number of LED street light luminaires manufactured by Leotek, Inc. The Leotek product achieved an estimated payback in the Lija Loop installation of about 20 years for replacement scenarios and a much shorter 7.6 years for new installations. Much of the associated energy savings (55%) supporting these payback periods, however, weremore » achieved by reducing average horizontal photopic illuminance a similar amount (53%). Examined from a different perspective, the measured performance suggests that the Leotek product is at approximate parity with the HPS cobra head in terms of average delivered photopic illumination for a given power consumption. HPS comprises the second most efficacious street lighting technology available, exceeded only by low pressure sodium (LPS). LPS technology is not considered suitable for most street lighting applications due to its monochromatic spectral output and poor color rendering ability; therefore, this LED product is performing at an efficiency level comparable to its primary competition in this application.« less

Can AERONET data be used to accurately model the monochromatic beam and circumsolar irradiances under cloud-free conditions in desert environment?

NASA Astrophysics Data System (ADS)

Eissa, Y.; Blanc, P.; Wald, L.; Ghedira, H.

2015-12-01

Routine measurements of the beam irradiance at normal incidence include the irradiance originating from within the extent of the solar disc only (DNIS), whose angular extent is 0.266° ± 1.7 %, and from a larger circumsolar region, called the circumsolar normal irradiance (CSNI). This study investigates whether the spectral aerosol optical properties of the AERONET stations are sufficient for an accurate modelling of the monochromatic DNIS and CSNI under cloud-free conditions in a desert environment. The data from an AERONET station in Abu Dhabi, United Arab Emirates, and the collocated Sun and Aureole Measurement instrument which offers reference measurements of the monochromatic profile of solar radiance were exploited. Using the AERONET data both the radiative transfer models libRadtran and SMARTS offer an accurate estimate of the monochromatic DNIS, with a relative root mean square error (RMSE) of 6 % and a coefficient of determination greater than 0.96. The observed relative bias obtained with libRadtran is +2 %, while that obtained with SMARTS is -1 %. After testing two configurations in SMARTS and three in libRadtran for modelling the monochromatic CSNI, libRadtran exhibits the most accurate results when the AERONET aerosol phase function is presented as a two-term Henyey-Greenstein phase function. In this case libRadtran exhibited a relative RMSE and a bias of respectively 27 and -24 % and a coefficient of determination of 0.882. Therefore, AERONET data may very well be used to model the monochromatic DNIS and the monochromatic CSNI. The results are promising and pave the way towards reporting the contribution of the broadband circumsolar irradiance to standard measurements of the beam irradiance.

Evaluation of blue light exposure to beta brainwaves on simulated night driving

NASA Astrophysics Data System (ADS)

Purawijaya, Dandri Aly; Fitri, Lulu Lusianti; Suprijanto

2015-09-01

Numbers of night driving accident in Indonesia since 2010 are exponentially rising each year with total of loss more than 50 billion rupiah. One of the causes that contribute to night driving accident is drowsiness. Drowsiness is affected by circadian rhythm resulted from the difference of blue light quality and quantity between night and day. Blue light may effect on human physiology through non-visual pathway by suppressing melatonin hormone suppression that influence drowsiness. Meanwhile, the production of hormones and other activities in brain generate bioelectrical activity such as brainwaves and can be recorded using Electroencephalograph (EEG). Therefore, this research objective is to evaluate the effect of blue light exposure to beta brainwave emergence during night driving simulation to a driver. This research was conducted to 4 male subjects who are able to drive and have a legitimate car driving license. The driving simulator was done using SCANIA Truck Driving Simulator on freeform driving mode in dark environment. Subjects drove for total 32 minutes. The data collections were taken in 2 days with 16 minutes for each day. The 16 minutes were divided again into 8 minutes adaptation in dark and 8 minutes for driving either in blue light exposure or in total darkness. While driving the simulation, subjects' brainwaves were recorded using EEG EMOTIV 14 Channels, exposed by LED monochromatic blue light with 160 Lux from source and angle 45o and sat 1 m in front of the screen. Channels used on this research were for visual (O1; O2), cognition (F3; F4; P7; P8), and motor (FC5; FC6). EEG brainwave result was filtered with EEGLab to obtain beta waves at 13 - 30 Hz frequencies. Results showed that beta waves response to blue light varied for each subject. Blue light exposure either increased or decreased beta waves in 2 minutes pattern and maintaining beta waves on cognition and motor area in 3 out of 4 subjects. Meanwhile, blue light exposure did not maintain and induce beta waves fluctuation on visual area of another 2 subjects. The conclusion of this research is that blue light exposure affected the pattern of beta waves on frontal, parietal, premotor cortex and visual lobes.

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

Hartemann, F V; Albert, F; Anderson, S G

Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabledmore » by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).« less

Approximate Stokes Drift Profiles in Deep Water

NASA Astrophysics Data System (ADS)

Breivik, Øyvind; Janssen, Peter A. E. M.; Bidlot, Jean-Raymond

2014-09-01

A deep-water approximation to the Stokes drift velocity profile is explored as an alternative to the monochromatic profile. The alternative profile investigated relies on the same two quantities required for the monochromatic profile, viz the Stokes transport and the surface Stokes drift velocity. Comparisons with parametric spectra and profiles under wave spectra from the ERA-Interim reanalysis and buoy observations reveal much better agreement than the monochromatic profile even for complex sea states. That the profile gives a closer match and a more correct shear has implications for ocean circulation models since the Coriolis-Stokes force depends on the magnitude and direction of the Stokes drift profile and Langmuir turbulence parameterizations depend sensitively on the shear of the profile. The alternative profile comes at no added numerical cost compared to the monochromatic profile.

Discriminating colors through a red filter by protanopes and colour normals.

PubMed

Diaconu, Vasile; Sullivan, David; Bouchard, Jean F; Vucea, Valentina

2010-01-01

Individuals with color vision deficiency have difficulties in differentiating colour in their daily activities. Through certain coloured filters, dichromats may report an improvement of their capacity to differentiate colors, but it is not known if this is achieved by means of a chromatic mechanism. The present study attempts to explain the mechanism by which a coloured filter can produce a beneficial effect in dichromatic visual perception and what is the nature of this improvement. Four male protanopes and four normal trichromats (two males and two females) participated in the present study. We evaluated the effect of the red filter (with a spectral transmittance similar to that of the X-Chrom filter) on the detection thresholds for monochromatic light stimuli from 420 to 660 nm in 20 nm steps. The increment spectral sensitivity functions were measured for 1.2 degrees diameter test flashes presented for 300 ms on a 60-cd m(-2) illuminant C background using an optical bench with a monochromator, for both filter and no filter conditions. The capacity to correctly name green, yellow and red for the monochromatic lights of 550, 575 and 625 nm presented for 300 ms on a 60 cd m(-2) illuminant C background screen was also evaluated with and without the red filter. The spectral sensitivity data suggest that, the use of a red filter improves the protanope's capacity to detect long wavelength light stimuli. The results on the colors naming procedure demonstrate that the red filter modifies colour perception in normal and protanope subjects. In normals, only the red color perception is preserved, and typical colour perception for the green and the yellow is lost. Without the filter, all the protanopes demonstrated a residual colour perception for red and green colours. Through the red filter only red colour perception remains. A red filter does not improve the protanopic red-green perception, but it does improve the ability of the protanope to detect long-wavelength light. This improvement seems to arise by means of the luminance mechanism.

Dumb and Lazy? A Comparison of Color Learning and Memory Retrieval in Drones and Workers of the Buff-Tailed Bumblebee, Bombus terrestris, by Means of PER Conditioning

PubMed Central

Lichtenstein, Leonie; Sommerlandt, Frank M. J.; Spaethe, Johannes

2015-01-01

More than 100 years ago, Karl von Frisch showed that honeybee workers learn and discriminate colors. Since then, many studies confirmed the color learning capabilities of females from various hymenopteran species. Yet, little is known about visual learning and memory in males despite the fact that in most bee species males must take care of their own needs and must find rewarding flowers to obtain food. Here we used the proboscis extension response (PER) paradigm to study the color learning capacities of workers and drones of the bumblebee, Bombus terrestris. Light stimuli were paired with sucrose reward delivered to the insects’ antennae and inducing a reflexive extension of the proboscis. We evaluated color learning (i.e. conditioned PER to color stimuli) in absolute and differential conditioning protocols and mid-term memory retention was measured two hours after conditioning. Different monochromatic light stimuli in combination with neutral density filters were used to ensure that the bumblebees could only use chromatic and not achromatic (e.g. brightness) information. Furthermore, we tested if bees were able to transfer the learned information from the PER conditioning to a novel discrimination task in a Y-maze. Both workers and drones were capable of learning and discriminating between monochromatic light stimuli and retrieved the learned stimulus after two hours. Drones performed as well as workers during conditioning and in the memory test, but failed in the transfer test in contrast to workers. Our data clearly show that bumblebees can learn to associate a color stimulus with a sugar reward in PER conditioning and that both workers and drones reach similar acquisition and mid-term retention performances. Additionally, we provide evidence that only workers transfer the learned information from a Pavlovian to an operant situation. PMID:26230643

Dumb and Lazy? A Comparison of Color Learning and Memory Retrieval in Drones and Workers of the Buff-Tailed Bumblebee, Bombus terrestris, by Means of PER Conditioning.

PubMed

Lichtenstein, Leonie; Sommerlandt, Frank M J; Spaethe, Johannes

2015-01-01

More than 100 years ago, Karl von Frisch showed that honeybee workers learn and discriminate colors. Since then, many studies confirmed the color learning capabilities of females from various hymenopteran species. Yet, little is known about visual learning and memory in males despite the fact that in most bee species males must take care of their own needs and must find rewarding flowers to obtain food. Here we used the proboscis extension response (PER) paradigm to study the color learning capacities of workers and drones of the bumblebee, Bombus terrestris. Light stimuli were paired with sucrose reward delivered to the insects' antennae and inducing a reflexive extension of the proboscis. We evaluated color learning (i.e. conditioned PER to color stimuli) in absolute and differential conditioning protocols and mid-term memory retention was measured two hours after conditioning. Different monochromatic light stimuli in combination with neutral density filters were used to ensure that the bumblebees could only use chromatic and not achromatic (e.g. brightness) information. Furthermore, we tested if bees were able to transfer the learned information from the PER conditioning to a novel discrimination task in a Y-maze. Both workers and drones were capable of learning and discriminating between monochromatic light stimuli and retrieved the learned stimulus after two hours. Drones performed as well as workers during conditioning and in the memory test, but failed in the transfer test in contrast to workers. Our data clearly show that bumblebees can learn to associate a color stimulus with a sugar reward in PER conditioning and that both workers and drones reach similar acquisition and mid-term retention performances. Additionally, we provide evidence that only workers transfer the learned information from a Pavlovian to an operant situation.

Application of principal component analysis to multispectral-multimodal optical image analysis for malaria diagnostics.

PubMed

Omucheni, Dickson L; Kaduki, Kenneth A; Bulimo, Wallace D; Angeyo, Hudson K

2014-12-11

Multispectral imaging microscopy is a novel microscopic technique that integrates spectroscopy with optical imaging to record both spectral and spatial information of a specimen. This enables acquisition of a large and more informative dataset than is achievable in conventional optical microscopy. However, such data are characterized by high signal correlation and are difficult to interpret using univariate data analysis techniques. In this work, the development and application of a novel method which uses principal component analysis (PCA) in the processing of spectral images obtained from a simple multispectral-multimodal imaging microscope to detect Plasmodium parasites in unstained thin blood smear for malaria diagnostics is reported. The optical microscope used in this work has been modified by replacing the broadband light source (tungsten halogen lamp) with a set of light emitting diodes (LEDs) emitting thirteen different wavelengths of monochromatic light in the UV-vis-NIR range. The LEDs are activated sequentially to illuminate same spot of the unstained thin blood smears on glass slides, and grey level images are recorded at each wavelength. PCA was used to perform data dimensionality reduction and to enhance score images for visualization as well as for feature extraction through clusters in score space. Using this approach, haemozoin was uniquely distinguished from haemoglobin in unstained thin blood smears on glass slides and the 590-700 spectral range identified as an important band for optical imaging of haemozoin as a biomarker for malaria diagnosis. This work is of great significance in reducing the time spent on staining malaria specimens and thus drastically reducing diagnosis time duration. The approach has the potential of replacing a trained human eye with a trained computerized vision system for malaria parasite blood screening.

Dark Light, Rod Saturation, and the Absolute and Incremental Sensitivity of Mouse Cone Vision

PubMed Central

Naarendorp, Frank; Esdaille, Tricia M.; Banden, Serenity M.; Andrews-Labenski, John; Gross, Owen P.; Pugh, Edward N.

2012-01-01

Visual thresholds of mice for the detection of small, brief targets were measured with a novel behavioral methodology in the dark and in the presence of adapting lights spanning ∼8 log10 units of intensity. To help dissect the contributions of rod and cone pathways, both wild-type mice and mice lacking rod (Gnat1−/−) or cone (Gnat2cpfl3) function were studied. Overall, the visual sensitivity of mice was found to be remarkably similar to that of the human peripheral retina. Rod absolute threshold corresponded to 12-15 isomerized pigment molecules (R*) in image fields of 800 to 3000 rods. Rod “dark light” (intrinsic retinal noise in darkness) corresponded to that estimated previously from single-cell recordings, 0.012R*s−1rod−1, indicating that spontaneous thermalisomerizations are responsible. Psychophysical rod saturation was measured for the first time in a nonhman species and found to be very similar to that of the human rod monochromat. Cone threshold corresponded to ∼5 R* cone−1 in an image field of 280 cones. Cone dark light was equivalent to ∼5000 R*s−1 cone−1, consistent with primate single-cell data but 100-fold higher than predicted by recent measurements of the rate of thermal isomerization of mouse cone opsins, indicating that nonopsin sources of noise determine cone threshold. The new, fully automated behavioral method is based on the ability of mice to learn to interrupt spontaneous wheel running on the presentation of a visual cue and provides an efficient and highly reliable means of examining visual function in naturally behaving normal and mutant mice. PMID:20844144

1,4-Dihydropyrrolo[3,2-b]pyrroles as a Single Component Photoactive Layer: A New Paradigm for Broadband Detection.

PubMed

Canjeevaram Balasubramanyam, Ram Kumar; Kandjani, Ahmad E; Harrison, Christopher J; Abdul Haroon Rashid, Syed Sulthan Alaudeen; Sabri, Ylias M; Bhargava, Suresh K; Narayan, Ramanuj; Basak, Pratyay; Ippolito, Samuel J

2017-08-23

Single component organic photodetectors capable of broadband light sensing represent a paradigm shift for designing flexible and inexpensive optoelectronic devices. The present study demonstrates the application of a new quadrupolar 1,4-dihydropyrrolo[3,2-b]pyrrole derivative with spectral sensitivity across 350-830 nm as a potential broadband organic photodetector (OPD) material. The amphoteric redox characteristics evinced from the electrochemical studies are exploited to conceptualize a single component OPD with ITO and Al as active electrodes. The photodiode showed impressive broadband photoresponse to monochromatic light sources of 365, 470, 525, 589, 623, and 830 nm. Current density-voltage (J-V) and transient photoresponse studies showed stable and reproducible performance under continuous on/off modulations. The devices operating in reverse bias at 6 V displayed broad spectral responsivity (R) and very good detectivity (D*) peaking a maximum 0.9 mA W -1 and 1.9 × 10 10 Jones (at 623 nm and 500 μW cm -2 ) with a fast rise and decay times of 75 and 140 ms, respectively. Low dark current densities ranging from 1.8 × 10 -10 Acm -2 at 1 V to 7.2 × 10 -9 A cm -2 at 6 V renders an operating range to amplify the photocurrent signal, spectral responsivity, and detectivity. Interestingly, the fabricated OPDs display a self-operational mode which is rarely reported for single component organic systems.

Biological applications and effects of optical masers

NASA Astrophysics Data System (ADS)

Ham, William T., Jr.; Mueller, Harold A.; Williams, Ray C.; Geeraets, Walter J.; Ruffolo, John J., Jr.

1988-02-01

Research experiments and projects pertaining to the ocular hazards of lasers and other optical sources are reviewed and discussed in some detail. Early studies to determine threshold retinal damage in the rabbit from ruby and neodymium lasers are described and followed by more elaborate experiments with monkeys using the He;Ne laser. A comparison between threshold retinal lesions in human volunteers, monkeys and rabbits is given. Retinal damage in the rhesus monkey is evaluated in terms of visual acuity. Quantitative data on solar retinitis as determined in the rhesus monkey are provided and the effects of wavelength on light toxicity are evaluated for eight monochromatic laser lines. Experiments performed at Los Alamos to evaluate the ocular effects and hazards of picosecond and nanosecond pulses of radiation from CO2 and HF lasers are described. A list of published papers describing the above research is included. The HF laser effects on the rabbit cornea were very similar to those caused by exposure to the CO2 laser. The energy from the CO2 and HF lasers is completely absorbed in the superficial layers of the cornea, creating a sharp sonic or shock wave which can disrupt the epithelial cells but does not penetrate to the stroma.

Initial studies of the bidirectional reflectance distribution function of carbon nanotube structures for stray light control applications

NASA Astrophysics Data System (ADS)

Butler, James J.; Georgiev, Georgi T.; Tveekrem, June L.; Quijada, Manuel; Getty, Stephanie; Hagopian, John G.

2010-10-01

The Bidirectional Reflectance Distribution Function (BRDF) at visible and near-infrared wavelengths of Multi-Wall Carbon NanoTubes (MWCNTs) grown on substrate materials are reported. The BRDF measurements were performed in the Diffuser Calibration Laboratory (DCaL) at NASA's Goddard Space Flight Center, and results at 500nm and 900nm are reported here. In addition, the 8° Directional/Hemispherical Reflectance of the samples is reported from the ultraviolet to shortwave infrared. The 8° Directional/Hemispherical Reflectance was measured in the Optics Branch at NASA's Goddard Space Flight Center. The BRDF was measured at 0° and 45° incident angles and from -80° to +80° scatter angles using a monochromatic source. The optical scatter properties of the samples as represented by their BRDF were found to be strongly influenced by the choice of substrate. As a reference, the optical scattering properties of the carbon nanotubes are compared to the BRDF of Aeroglaze Z306TM and Rippey Ultrapol IVTM, a well-known black paint and black appliqué, respectively. The possibility, promise, and challenges of employing carefully engineered carbon nanotubes in straylight control applications particularly for spaceflight instrumentation is also discussed.

Novel anti-microbial therapies for dental plaque-related diseases.

PubMed

Allaker, Robert P; Douglas, C W Ian

2009-01-01

Control of dental plaque-related diseases has traditionally relied on non-specific removal of plaque by mechanical means. As our knowledge of oral disease mechanisms increases, future treatment is likely to be more targeted, for example at small groups of organisms, single species or at key virulence factors they produce. The aim of this review is to consider the current status as regards novel treatment approaches. Maintenance of oral hygiene often includes use of chemical agents; however, increasing problems of resistance to synthetic antimicrobials have encouraged the search for alternative natural products. Plants are the source of more than 25% of prescription and over-the-counter preparations, and the potential of natural agents for oral prophylaxis will therefore be considered. Targeted approaches may be directed at the black-pigmented anaerobes associated with periodontitis. Such pigments provide an opportunity for targeted phototherapy with high-intensity monochromatic light. Studies to date have demonstrated selective killing of Porphyromonas gingivalis and Prevotella intermedia in biofilms. Functional inhibition approaches, including the use of protease inhibitors, are also being explored to control periodontitis. Replacement therapy by which a resident pathogen is replaced with a non-pathogenic bacteriocin-producing variant is currently under development with respect to Streptococcus mutans and dental caries.

Virtual taphonomy using synchrotron tomographic microscopy reveals cryptic features and internal structure of modern and fossil plants

PubMed Central

Smith, Selena Y.; Collinson, Margaret E.; Rudall, Paula J.; Simpson, David A.; Marone, Federica; Stampanoni, Marco

2009-01-01

While more commonly applied in zoology, synchrotron radiation X-ray tomographic microscopy (SRXTM) is well-suited to nondestructive study of the morphology and anatomy of both fossil and modern plants. SRXTM uses hard X-rays and a monochromatic light source to provide high-resolution data with little beam-hardening, resulting in slice data with clear boundaries between materials. Anatomy is readily visualized, including various planes of section from a single specimen, as clear as in traditional histological sectioning at low magnifications. Thus, digital sectioning of rare or difficult material is possible. Differential X-ray attenuation allows visualization of different layers or chemistries to enable virtual 3-dimensional (3D) dissections of material. Virtual potential fossils can be visualized and digital tissue removal reveals cryptic underlying morphology. This is essential for fossil identification and for comparisons between assemblages where fossils are preserved by different means. SRXTM is a powerful approach for botanical studies using morphology and anatomy. The ability to gain search images in both 2D and 3D for potential fossils gives paleobotanists a tool—virtual taphonomy—to improve our understanding of plant evolution and paleobiogeography. PMID:19574457

Enhancement of collective atomic recoil lasing due to pump phase modulation

NASA Astrophysics Data System (ADS)

Robb, G. R. M.; Burgess, R. T. L.; Firth, W. J.

2008-10-01

We investigate the effect of a phase-modulated pump beam on collective backscattering [also termed collective atomic recoil lasing (CARL)] by a cold, collisionless atomic gas. We show using a numerical analysis that different regimes can be identified in which the atomic dynamics evolves in a qualitatively different manner during the light-atom interaction, depending on the magnitude of the pump modulation frequency. Our results also demonstrate that phase-modulating the pump field can substantially enhance the backscattered field intensity relative to the case of a monochromatic pump which has been used in CARL experiments to date.

Propagation of partially coherent fields through planar dielectric boundaries using angle-impact Wigner functions I. Two dimensions.

PubMed

Petruccelli, Jonathan C; Alonso, Miguel A

2007-09-01

We examine the angle-impact Wigner function (AIW) as a computational tool for the propagation of nonparaxial quasi-monochromatic light of any degree of coherence past a planar boundary between two homogeneous media. The AIWs of the reflected and transmitted fields in two dimensions are shown to be given by a simple ray-optical transformation of the incident AIW plus a series of corrections in the form of differential operators. The radiometric and leading six correction terms are studied for Gaussian Schell-model fields of varying transverse width, transverse coherence, and angle of incidence.

An Open-path Laser Transmissometer for Atmospheric Extinction Measurements

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

Chandran, P. M. Satheesh; Krishnakumar, C. P.; Varma, Ravi

2011-10-20

A transmissometer is an optical instrument which measures transmitted intensity of monochromatic light over a fixed pathlength. Prototype of a simple laser transmissometer has been developed for transmission (or extinction) measurements through suspended absorbers and scatterers in the atmosphere over tens of meters. Instrument consists of a continuous green diode pumped solid state laser, transmission optics, photodiode detectors and A/D data acquisition components. A modulated laser beam is transmitted and subsequently reflected and returned to the unit by a retroreflecting mirror assembly placed several tens of meters away. Results from an open-path field measurement of the instrument are described.

Achromatical Optical Correlator

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin; Liu, Hua-Kuang

1989-01-01

Signal-to-noise ratio exceeds that of monochromatic correlator. Achromatical optical correlator uses multiple-pinhole diffraction of dispersed white light to form superposed multiple correlations of input and reference images in output plane. Set of matched spatial filters made by multiple-exposure holographic process, each exposure using suitably-scaled input image and suitable angle of reference beam. Recording-aperture mask translated to appropriate horizontal position for each exposure. Noncoherent illumination suitable for applications involving recognition of color and determination of scale. When fully developed achromatical correlators will be useful for recognition of patterns; for example, in industrial inspection and search for selected features in aerial photographs.

Ultra-directional source of longitudinal acoustic waves based on a two-dimensional solid/solid phononic crystal

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

Morvan, B.; Tinel, A.; Sainidou, R.

2014-12-07

Phononic crystals (PC) can be used to control the dispersion properties of acoustic waves, which are essential to direct their propagation. We use a PC-based two-dimensional solid/solid composite to demonstrate experimentally and theoretically the spatial filtering of a monochromatic non-directional wave source and its emission in a surrounding water medium as an ultra-directional beam with narrow angular distribution. The phenomenon relies on square-shaped equifrequency contours (EFC) enabling self-collimation of acoustic waves within the phononic crystal. Additionally, the angular width of collimated beams is controlled via the EFC size-shrinking when increasing frequency.

Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy

PubMed Central

Hindle, Francis; Yang, Chun; Mouret, Gael; Cuisset, Arnaud; Bocquet, Robin; Lampin, Jean-François; Blary, Karine; Peytavit, Emilien; Akalin, Tahsin; Ducournau, Guillaume

2009-01-01

A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements. PMID:22291552

Recent searches for continuous gravitational waves

NASA Astrophysics Data System (ADS)

Riles, Keith

2017-12-01

Gravitational wave astronomy opened dramatically in September 2015 with the LIGO discovery of a distant and massive binary black hole coalescence. The more recent discovery of a binary neutron star merger, followed by a gamma ray burst (GRB) and a kilonova, reinforces the excitement of this new era, in which we may soon see other sources of gravitational waves, including continuous, nearly monochromatic signals. Potential continuous wave (CW) sources include rapidly spinning galactic neutron stars and more exotic possibilities, such as emission from axion Bose Einstein “clouds” surrounding black holes. Recent searches in Advanced LIGO data are presented, and prospects for more sensitive future searches are discussed.

Abnormal hypothalamic response to light in seasonal affective disorder.

PubMed

Vandewalle, Gilles; Hébert, Marc; Beaulieu, Catherine; Richard, Laurence; Daneault, Véronique; Garon, Marie-Lou; Leblanc, Jean; Grandjean, Didier; Maquet, Pierre; Schwartz, Sophie; Dumont, Marie; Doyon, Julien; Carrier, Julie

2011-11-15

Vulnerability to the reduction in natural light associated with fall/winter is generally accepted as the main trigger of seasonal affective disorder (SAD), whereas light therapy is a treatment of choice of the disorder. However, the relationship between exposure to light and mood regulation remains unclear. As compared with green light, blue light was shown to acutely modulate emotion brain processing in healthy individuals. Here, we investigated the impact of light on emotion brain processing in patients with SAD and healthy control subjects and its relationship with retinal light sensitivity. Fourteen symptomatic untreated patients with SAD (34.5 ± 8.2 years; 9 women) and 16 healthy control subjects (32.3 ± 7.7 years; 11 women) performed an auditory emotional task in functional magnetic resonance imaging during the fall/winter season, while being exposed to alternating blue and green monochromatic light. Scotopic and photopic retinal light sensitivities were then evaluated with electroretinography. Blue light enhanced responses to auditory emotional stimuli in the posterior hypothalamus in patients with SAD, whereas green light decreased these responses. These effects of blue and green light were not observed in healthy control subjects, despite similar retinal sensitivity in SAD and control subjects. These results point to the posterior hypothalamus as the neurobiological substrate involved in specific aspects of SAD, including a distinctive response to light and altered emotional responses. Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Hydrogen as an atomic beam standard

NASA Technical Reports Server (NTRS)

Peters, H. E.

1972-01-01

After a preliminary discussion of feasibility, new experimental work with a hydrogen beam is described. A space focused magnetic resonance technique with separated oscillatory fields is used with a monochromatic beam of cold hydrogen atoms which are selected from a higher temperature source. The first resonance curves and other experimental results are presented. These results are interpreted from the point of view of accuracy potential and frequency stability, and are compared with hydrogen maser and cesium beam capabilities.

Photonic band gap effect and structural color from silver nanoparticle gelatin emulsion

NASA Astrophysics Data System (ADS)

Kok, Mang Hin; Ma, Rui; Lee, Jeffrey Chi Wai; Tam, Wing Yim; Chan, C. T.; Sheng, Ping; Cheah, Kok Wai

2005-10-01

We have fabricated planar structures of silver nanoparticles in monochromatic gelatin emulsion with a continuous spacing ranging from 0.15-0.40 micron using a two-beam interference of a single laser source. Our planar holograms display a colorful “rainbow” pattern and photonic bandgaps covering the visible and IR ranges. We model the planar silver nanoparticle-gelatin composite system using an effective medium approach and good agreement is obtained between theory and experiment.

Towards a Table-Top Laser Driven XUV/X-Ray Source

DTIC Science & Technology

2015-08-27

irradiated with intense ultra-short laser pulses. Bright monochromatic x- rays and broadband XUV emissions...as   evidenced  in  nature  by  the  sun,  stars,  and   gamma   ray  bursters.  In  laboratory  conditions,   bright...N.   Nerush,   I.   Yu.   Kostyukov,   B.   F.   Shen,   and   K.   U.   Akli;   "Energy partition,   gamma   ray

Photoperiodism of Male Offspring Production in the Water Flea Daphnia pulex.

PubMed

Toyota, Kenji; Sato, Tomomi; Tatarazako, Norihisa; Iguchi, Taisen

2017-08-01

Photoperiodism is a biological seasonal timing system utilized to regulate development and reproduction in organisms. The freshwater micro-crustacean Daphnia pulex displays environmental sex determination, the precise physiological mechanisms of which are largely unknown due to the lack of an experimental system to induce female or male offspring production by alterations of the rearing environment. We recently found that D. pulex, WTN6 strain, produces female or male offspring in response to long-day or short-day conditions, respectively. Taking advantage of this system, here we report the photoperiodic response curve for male offspring production, showing 12 hours as natural critical daylength (50% incidence of male-producing mothers), and that male offspring inducibility is highly sensitive to photoperiodic alterations. By using monochromatic light emitting diode (LED) devices, we found that the effective wavelength is red-light (627 nm), which stably induces male offspring production. This suggests that the red-light photoreceptor may be decisive in the primary step of sex determination process in this strain. Our findings provide the first insights into photoperiodism and red-light as key factors in triggering male offspring production in daphnids.

Suns-VOC characteristics of high performance kesterite solar cells

NASA Astrophysics Data System (ADS)

Gunawan, Oki; Gokmen, Tayfun; Mitzi, David B.

2014-08-01

Low open circuit voltage (VOC) has been recognized as the number one problem in the current generation of Cu2ZnSn(Se,S)4 (CZTSSe) solar cells. We report high light intensity and low temperature Suns-VOC measurement in high performance CZTSSe devices. The Suns-VOC curves exhibit bending at high light intensity, which points to several prospective VOC limiting mechanisms that could impact the VOC, even at 1 sun for lower performing samples. These VOC limiting mechanisms include low bulk conductivity (because of low hole density or low mobility), bulk or interface defects, including tail states, and a non-ohmic back contact for low carrier density CZTSSe. The non-ohmic back contact problem can be detected by Suns-VOC measurements with different monochromatic illuminations. These limiting factors may also contribute to an artificially lower JSC-VOC diode ideality factor.

Polariton excitation in epsilon-near-zero slabs: Transient trapping of slow light

NASA Astrophysics Data System (ADS)

Ciattoni, Alessandro; Marini, Andrea; Rizza, Carlo; Scalora, Michael; Biancalana, Fabio

2013-05-01

We numerically investigate the propagation of a spatially localized and quasimonochromatic electromagnetic pulse through a slab with a Lorentz dielectric response in the epsilon-near-zero regime, where the real part of the permittivity vanishes at the pulse carrier frequency. We show that the pulse is able to excite a set of virtual polariton modes supported by the slab, with the excitation undergoing a generally slow damping due to absorption and radiation leakage. Our numerical and analytical approaches indicate that in its transient dynamics the electromagnetic field displays the very same enhancement of the field component perpendicular to the slab, as in the monochromatic regime. The transient trapping is inherently accompanied by a significantly reduced group velocity ensuing from the small dielectric permittivity, thus providing an alternative platform for achieving control and manipulation of slow light.

Experimental realization of a CMOS-compatible optical directed priority encoder using cascaded micro-ring resonators

NASA Astrophysics Data System (ADS)

Xiao, Huifu; Li, Dezhao; Liu, Zilong; Han, Xu; Chen, Wenping; Zhao, Ting; Tian, Yonghui; Yang, Jianhong

2018-03-01

In this paper, we propose and experimentally demonstrate an integrated optical device that can implement the logical function of priority encoding from a 4-bit electrical signal to a 2-bit optical signal. For the proof of concept, the thermo-optic modulation scheme is adopted to tune each micro-ring resonator (MRR). A monochromatic light with the working wavelength is coupled into the input port of the device through a lensed fiber, and the four input electrical logic signals regarded as pending encode signals are applied to the micro-heaters above four MRRs to control the working states of the optical switches. The encoding results are directed to the output ports in the form of light. At last, the logical function of priority encoding with an operation speed of 10 Kbps is demonstrated successfully.

The change in color matches with retinal angle of incidence of the colorimeter beams.

PubMed

Alpern, M; Kitahara, H; Fielder, G H

1987-01-01

Differences between W.D.W. chromaticities of monochromatic lights obtained with all colorimeter beams incident on the retina "off-axis" and those found for lights striking the retina normally have been studied throughout the visible spectrum on 4 normal trichromats. The results are inconsistent with: (i) the assumption in Weale's theories of the Stiles-Crawford hue shift that the sets of absorption spectra of the visual pigments catching normally and obliquely incident photons are identical, and (ii) "self-screening" explanations for the change in color with angle of incidence on the retina. The color matching functions of a protanomalous trichromat are inconsistent with the hypothesis that the absorption spectra of the visual pigments catching normally incident photons in his retina are those catching obliquely incident photons in the normal retina.

Add/drop filters based on SiC technology for optical interconnects

NASA Astrophysics Data System (ADS)

Vieira, M.; Vieira, M. A.; Louro, P.; Fantoni, A.; Silva, V.

2014-03-01

In this paper we demonstrate an add/drop filter based on SiC technology. Tailoring of the channel bandwidth and wavelength is experimentally demonstrated. The concept is extended to implement a 1 by 4 wavelength division multiplexer with channel separation in the visible range. The device consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure. Several monochromatic pulsed lights, separately or in a polychromatic mixture illuminated the device. Independent tuning of each channel is performed by steady state violet bias superimposed either from the front and back sides. Results show that, front background enhances the light-to-dark sensitivity of the long and medium wavelength channels and quench strongly the others. Back violet background has the opposite behaviour. This nonlinearity provides the possibility for selective removal or addition of wavelengths. An optoelectronic model is presented and explains the light filtering properties of the add/drop filter, under different optical bias conditions.

Relativistic spin-orbit interactions of photons and electrons

NASA Astrophysics Data System (ADS)

Smirnova, D. A.; Travin, V. M.; Bliokh, K. Y.; Nori, F.

2018-04-01

Laboratory optics, typically dealing with monochromatic light beams in a single reference frame, exhibits numerous spin-orbit interaction phenomena due to the coupling between the spin and orbital degrees of freedom of light. Similar phenomena appear for electrons and other spinning particles. Here we examine transformations of paraxial photon and relativistic-electron states carrying the spin and orbital angular momenta (AM) under the Lorentz boosts between different reference frames. We show that transverse boosts inevitably produce a rather nontrivial conversion from spin to orbital AM. The converted part is then separated between the intrinsic (vortex) and extrinsic (transverse shift or Hall effect) contributions. Although the spin, intrinsic-orbital, and extrinsic-orbital parts all point in different directions, such complex behavior is necessary for the proper Lorentz transformation of the total AM of the particle. Relativistic spin-orbit interactions can be important in scattering processes involving photons, electrons, and other relativistic spinning particles, as well as when studying light emitted by fast-moving bodies.

Improvements In The Calculation Of White Light Modulation Transfer Function (MTF) In Japan Optical Engineering Research Association (JOERA)

NASA Astrophysics Data System (ADS)

Minami, Setsuo; Ogawa, Ryota

1980-09-01

Consequences of the working project formed in JOERA (JAPAN OPTICAL ENGINEERING RESEARCH ASSOCIATION) from 1976 to 1978 are to be reported. The question, "What is the most reasonable number of mesh divides of entrance pupil to get monochromatic OTF and the most economical sampling method of spectral wavelengths to calculate White Light MTF?" is important in the actual stage of designing to optimize the conflict relationship between numerical accuracy and computing time. We have examined the spectral characteristics of OTF using some typical lenses such as photographic telephoto lens and wide angled retrofocus lens, cleared the structure of the White Light MTF, and found some techniques to get the reasonable numerical results. As a result of trial experiments to get coincidence between measurements and calculat-ions, the standard filter, which should be added to the MTF lens tester and whose spectral transmittance should be installed in the calculation, are proposed.

Low-intensity red and infrared lasers on XPA and XPC gene expression

NASA Astrophysics Data System (ADS)

Fonseca, A. S.; Magalhães, L. A. G.; Mencalha, A. L.; Ferreira-Machado, S. C.; Geller, M.; Paoli, F.

2014-09-01

Laser devices emit monochromatic, coherent, and highly collimated intense beams of light that are useful for a number of biomedical applications. However, for low-intensity lasers, possible adverse effects of laser light on DNA are still controversial. In this work, the expression of XPA and XPC genes in skin and muscle tissue exposed to low-intensity red and infrared lasers was evaluated. Skin and muscle tissue of Wistar rats were exposed to low-intensity red and infrared lasers at different fluences in continuous mode emission. Skin and muscle tissue samples were withdrawn for total RNA extraction, cDNA synthesis, and evaluation of actin gene expression by quantitative polymerase chain reaction. Data obtained show that laser radiation alters the expression of XPA and XPC mRNA differently in skin and muscle tissue of Wistar rats, depending on physical (fluence and wavelength) and biological (tissue) parameters. Laser light could modify expression of genes related to the nucleotide excision repair pathway at fluences and wavelengths used in clinical protocols.

Dose comparison between conventional and quasi-monochromatic systems for diagnostic radiology

NASA Astrophysics Data System (ADS)

Baldelli, P.; Taibi, A.; Tuffanelli, A.; Gambaccini, M.

2004-09-01

Several techniques have been introduced in the last year to reduce the dose to the patient by minimizing the risk of tumour induced by radiation. In this work the radiological potential of dose reduction in quasi-monochromatic spectra produced via mosaic crystal Bragg diffraction has been evaluated, and a comparison with conventional spectra has been performed for four standard examinations: head, chest, abdomen and lumbar sacral spine. We have simulated quasi-monochromatic x-rays with the Shadow code, and conventional spectra with the Spectrum Processor. By means of the PCXMC software, we have simulated four examinations according to parameters established by the European Guidelines, and calculated absorbed dose for principal organs and the effective dose. Simulations of quasi-monochromatic laminar beams have been performed without anti-scatter grid, because of their inherent scatter geometry, and compared with simulations with conventional beams with anti-scatter grids. Results have shown that the dose reduction due to the introduction of quasi-monochromatic x-rays depends on different parameters related to the quality of the beam, the organ composition and the anti-scatter grid. With parameters chosen in this study a significant dose reduction can be achieved for two out of four kinds of examination.

Metacontrast masking is processed before grapheme-color synesthesia.

PubMed

Bacon, Michael Patrick; Bridgeman, Bruce; Ramachandran, Vilayanur S

2013-01-01

We investigated the physiological mechanism of grapheme-color synesthesia using metacontrast masking. A metacontrast target is rendered invisible by a mask that is delayed by about 60 ms; the target and mask do not overlap in space or time. Little masking occurs, however, if the target and mask are simultaneous. This effect must be cortical, because it can be obtained dichoptically. To compare the data for synesthetes and controls, we developed a metacontrast design in which nonsynesthete controls showed weaker dichromatic masking (i.e., the target and mask were in different colors) than monochromatic masking. We accomplished this with an equiluminant target, mask, and background for each observer. If synesthetic color affected metacontrast, synesthetes should show monochromatic masking more similar to the weak dichromatic masking among controls, because synesthetes could add their synesthetic color to the monochromatic condition. The target-mask pairs used for each synesthete were graphemes that elicited strong synesthetic colors. We found stronger monochromatic than dichromatic U-shaped metacontrast for both synesthetes and controls, with optimal masking at an asynchrony of 66 ms. The difference in performance between the monochromatic and dichromatic conditions in the synesthetes indicates that synesthesia occurs at a later processing stage than does metacontrast masking.

Sensitivity and specificity of monochromatic photography of the ocular fundus in differentiating optic nerve head drusen and optic disc oedema: optic disc drusen and oedema.

PubMed

Gili, Pablo; Flores-Rodríguez, Patricia; Yangüela, Julio; Orduña-Azcona, Javier; Martín-Ríos, María Dolores

2013-03-01

Evaluation of the efficacy of monochromatic photography of the ocular fundus in differentiating optic nerve head drusen (ONHD) and optic disc oedema (ODE). Sixty-six patients with ONHD, 31 patients with ODE and 70 healthy subjects were studied. Colour and monochromatic fundus photography with different filters (green, red and autofluorescence) were performed. The results were analysed blindly by two observers. The sensitivity, specificity and interobserver agreement (k) of each test were assessed. Colour photography offers 65.5 % sensitivity and 100 % specificity for the diagnosis of ONHD. Monochromatic photography improves sensitivity and specificity and provides similar results: green filter (71.20 % sensitivity, 96.70 % specificity), red filter (80.30 % sensitivity, 96.80 % specificity), and autofluorescence technique (87.8 % sensitivity, 100 % specificity). The interobserver agreement was good with all techniques used: autofluorescence (k = 0.957), green filter (k = 0.897), red filter (k = 0.818) and colour (k = 0.809). Monochromatic fundus photography permits ONHD and ODE to be differentiated, with good sensitivity and very high specificity. The best results were obtained with autofluorescence and red filter study.

Improved sensitivity in patients with peripheral neuropathy: effects of monochromatic infrared photo energy.

PubMed

DeLellis, Salvatore L; Carnegie, Dale H; Burke, Thomas J

2005-01-01

The medical records of 1,047 patients (mean age, 73 years) with established peripheral neuropathy were examined to determine whether treatment with monochromatic infrared photo energy was associated with increased foot sensitivity to the 5.07 Semmes-Weinstein monofilament. The peripheral neuropathy in 790 of these patients (75%) was due to diabetes mellitus. Before treatment with monochromatic infrared photo energy, of the ten tested sites (five on each foot), a mean +/- SD of 7.9 +/- 2.4 sites were insensitive to the 5.07 Semmes-Weinstein monofilament, and 1,033 patients exhibited loss of protective sensation. After treatment, the mean +/- SD number of insensate sites on both feet was 2.3 +/- 2.4, an improvement of 71%. Only 453 of 1,033 patients (43.9%) continued to have loss of protective sensation after treatment. Therefore, monochromatic infrared photo energy treatment seems to be associated with significant clinical improvement in foot sensation in patients, primarily Medicare aged, with peripheral neuropathy. Because insensitivity to the 5.07 Semmes-Weinstein monofilament has been reported to be a major risk factor for diabetic foot wounds, the use of monochromatic infrared photo energy may be associated with a reduced incidence of diabetic foot wounds and amputations.

Far-field interference of a neutron white beam and the applications to noninvasive phase-contrast imaging

NASA Astrophysics Data System (ADS)

Pushin, D. A.; Sarenac, D.; Hussey, D. S.; Miao, H.; Arif, M.; Cory, D. G.; Huber, M. G.; Jacobson, D. L.; LaManna, J. M.; Parker, J. D.; Shinohara, T.; Ueno, W.; Wen, H.

2017-04-01

The phenomenon of interference plays a crucial role in the field of precision measurement science. Wave-particle duality has expanded the well-known interference effects of electromagnetic waves to massive particles. The majority of the wave-particle interference experiments require a near monochromatic beam which limits its applications due to the resulting low intensity. Here we demonstrate white beam interference in the far-field regime using a two-phase-grating neutron interferometer and its application to phase-contrast imaging. The functionality of this interferometer is based on the universal moiré effect that allows us to improve upon the standard Lau setup. Interference fringes were observed with monochromatic and polychromatic neutron beams for both continuous and pulsed beams. Far-field neutron interferometry allows for the full utilization of intense neutron sources for precision measurements of gradient fields. It also overcomes the alignment, stability, and fabrication challenges associated with the more familiar perfect-crystal neutron interferometer, as well as avoids the loss of intensity due to the absorption analyzer grating requirement in Talbot-Lau interferometer.

The capabilities of monochromatic EC neutrino beams with the SPS upgrade

NASA Astrophysics Data System (ADS)

Espinoza, C.; Bernabéu, J.

2008-05-01

The goal for future neutrino facilities is the determination of the U(e3) mixing and CP violation in neutrino oscillations. This will require precision experiments with a very intense neutrino source and energy control. With this objective in mind, the creation of monochromatic neutrino beams from the electron capture decay of boosted ions by the SPS of CERN has been proposed. We discuss the capabilities of such a facility as a function of the energy of the boost and the baseline for the detector. We conclude that the SPS upgrade to 1000 GeV is crucial to reach a better sensitivity to CP violation iff it is accompanied by a longer baseline. We compare the physics potential for two different configurations: I) γ = 90 and γ = 195 (maximum achievable at present SPS) to Frejus; II) γ = 195 and γ = 440 (maximum achievable at upgraded SPS) to Canfranc. The main conclusion is that, whereas the gain in the determination of U(e3) is rather modest, setup II provides much better sensitivity to CP violation.

Coherent Light induced in Optical Fiber by a Charged Particle

NASA Astrophysics Data System (ADS)

Artru, Xavier; Ray, Cédric

2016-07-01

Coherent light production in an optical fiber by a charged particle (named PIGL, for particle-induced guided, light) is reviewed. From the microscopic point of view, light is emitted by transient electric dipoles induced in the fiber medium by the Coulomb field of the particle. The phenomenon can also considered as the capture of virtual photons of the particle field by the fiber. Two types of captures are distinguished. Type-I takes place in a uniform part of the fiber; then the photon keeps its longitudinal momentum pz . Type-II takes place near an end or in a non-uniform part of the fiber; then pz is not conserved. Type-I PIGL is not affected by background lights external to the fiber. At grazing incidence it becomes nearly monochromatic. Its circular polarization depends on the angular momentum of the particle about the fiber and on the relative velocity between the particle and the guided wave. A general formula for the yield of Type-II radiation, based on the reciprocity theorem, is proposed. This radiation can be assisted by metallic objects stuck to the fiber, via plasmon excitation. A periodic structure leads to a guided Smith-Purcell radiation. Applications of PIGL in beam diagnostics are considered.

Traceable calibration of ultraviolet meters used with broadband, extended sources.

PubMed

Coleman, A J; Collins, M; Saunders, J E

2000-01-01

A calibration system has been developed to provide increased accuracy in the measurement of the irradiance responsivity appropriate for UV meters used with broadband, extended sources of the type employed in phototherapy. The single wavelength responsivity of the test meter is obtained in the wavelength range 250-400 nm by intercomparison with a transfer standard meter in a narrow, monochromatic beam. Traceability to primary standard irradiance scales is provided via the National Measurement System with a best uncertainty of 7% (at 95% confidence). The effective responsivity of the test meter, when used with broadband extended sources, is calculated using the measured spectral and angular response of the meter and tabulated data on the spectral and spatial characteristics of the source radiance. The uncertainty in the effective responsivity, independent of the source variability, is estimated to be 10% (at 95% confidence). The advantages of this calibration system over existing approaches are discussed.

Accuracies of the synthesized monochromatic CT numbers and effective atomic numbers obtained with a rapid kVp switching dual energy CT scanner

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

Goodsitt, Mitchell M.; Christodoulou, Emmanuel G.; Larson, Sandra C.

2011-04-15

Purpose: This study was performed to investigate the accuracies of the synthesized monochromatic images and effective atomic number maps obtained with the new GE Discovery CT750 HD CT scanner. Methods: A Gammex-RMI model 467 tissue characterization phantom and the CT number linearity section of a Phantom Laboratory Catphan 600 phantom were scanned using the dual energy (DE) feature on the GE CT750 HD scanner. Synthesized monochromatic images at various energies between 40 and 120 keV and effective atomic number (Z{sub eff}) maps were generated. Regions of interest were placed within these images/maps to measure the average monochromatic CT numbers andmore » average Z{sub eff} of the materials within these phantoms. The true Z{sub eff} values were either supplied by the phantom manufacturer or computed using Mayneord's equation. The linear attenuation coefficients for the true CT numbers were computed using the NIST XCOM program with the input of manufacturer supplied elemental compositions and densities. The effects of small variations in the assumed true densities of the materials were also investigated. Finally, the effect of body size on the accuracies of the synthesized monochromatic CT numbers was investigated using a custom lumbar section phantom with and without an external fat-mimicking ring. Results: Other than the Z{sub eff} of the simulated lung inserts in the tissue characterization phantom, which could not be measured by DECT, the Z{sub eff} values of all of the other materials in the tissue characterization and Catphan phantoms were accurate to 15%. The accuracies of the synthesized monochromatic CT numbers of the materials in both phantoms varied with energy and material. For the 40-120 keV range, RMS errors between the measured and true CT numbers in the Catphan are 8-25 HU when the true CT numbers were computed using the nominal plastic densities. These RMS errors improve to 3-12 HU for assumed true densities within the nominal density {+-}0.02 g/cc range. The RMS errors between the measured and true CT numbers of the tissue mimicking materials in the tissue characterization phantom over the 40-120 keV range varied from about 6 HU-248 HU and did not improve as dramatically with small changes in assumed true density. Conclusions: Initial tests indicate that the Z{sub eff} values computed with DECT on this scanner are reasonably accurate; however, the synthesized monochromatic CT numbers can be very inaccurate, especially for dense tissue mimicking materials at low energies. Furthermore, the synthesized monochromatic CT numbers of materials still depend on the amount of the surrounding tissues especially at low keV, demonstrating that the numbers are not truly monochromatic. Further research is needed to develop DE methods that produce more accurate synthesized monochromatic CT numbers.« less

Action spectra of photosystems II and I and quantum yield of photosynthesis in leaves in State 1.

PubMed

Laisk, Agu; Oja, Vello; Eichelmann, Hillar; Dall'Osto, Luca

2014-02-01

The spectral global quantum yield (YII, electrons/photons absorbed) of photosystem II (PSII) was measured in sunflower leaves in State 1 using monochromatic light. The global quantum yield of PSI (YI) was measured using low-intensity monochromatic light flashes and the associated transmittance change at 810nm. The 810-nm signal change was calibrated based on the number of electrons generated by PSII during the flash (4·O2 evolution) which arrived at the PSI donor side after a delay of 2ms. The intrinsic quantum yield of PSI (yI, electrons per photon absorbed by PSI) was measured at 712nm, where photon absorption by PSII was small. The results were used to resolve the individual spectra of the excitation partitioning coefficients between PSI (aI) and PSII (aII) in leaves. For comparison, pigment-protein complexes for PSII and PSI were isolated, separated by sucrose density ultracentrifugation, and their optical density was measured. A good correlation was obtained for the spectral excitation partitioning coefficients measured by these different methods. The intrinsic yield of PSI was high (yI=0.88), but it absorbed only about 1/3 of quanta; consequently, about 2/3 of quanta were absorbed by PSII, but processed with the low intrinsic yield yII=0.63. In PSII, the quantum yield of charge separation was 0.89 as detected by variable fluorescence Fv/Fm, but 29% of separated charges recombined (Laisk A, Eichelmann H and Oja V, Photosynth. Res. 113, 145-155). At wavelengths less than 580nm about 30% of excitation is absorbed by pigments poorly connected to either photosystem, most likely carotenoids bound in pigment-protein complexes. Copyright © 2013 Elsevier B.V. All rights reserved.

Holographic imaging with a Shack-Hartmann wavefront sensor.

PubMed

Gong, Hai; Soloviev, Oleg; Wilding, Dean; Pozzi, Paolo; Verhaegen, Michel; Vdovin, Gleb

2016-06-27

A high-resolution Shack-Hartmann wavefront sensor has been used for coherent holographic imaging, by computer reconstruction and propagation of the complex field in a lensless imaging setup. The resolution of the images obtained with the experimental data is in a good agreement with the diffraction theory. Although a proper calibration with a reference beam improves the image quality, the method has a potential for reference-less holographic imaging with spatially coherent monochromatic and narrowband polychromatic sources in microscopy and imaging through turbulence.

Studying the Physics and Operation of Multi-Terminal Near-Micron and Sub-Micron Length, Hot Electron Semiconductor Devices.

DTIC Science & Technology

1988-02-15

Reprint 4 is a broad discussion of the consequences of the intracollisional field effect . In reprint 5, the uniform field momentum and energy balance...been submitted for publication. An extensive discussion of the effects of nonparabolicity on the moment equations is near completion. A study of the... effect . These effects are discussed later. A . Self-Energy Corrections I n the presence of a strong monochromatic source, one, in general, would

SU-E-I-40: Phantom Research On Monochromatic Images Taken by Dual CBCT with Multiple Energy Sets

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

Gao, R; Shandong University, Jinan, Shandong; Wang, H

Purpose: To evaluate the quality of monochromatic images at the same virtual monochromatic energy using dual cone-beam computed tomography (CBCT) with either kV/kV or MV/kV or MV/MV energy sets. Methods: CT images of Catphan 504 phantom were acquired using four different KV and MV settings: 80kV, 140kV, 4MV, 6MV. Three sets of monochromatic images were calculated: 80kV-140kV, 140kV-4MV and 4MV-6MV. Each set of CBCT images were reconstructed from the same selected virtual monochromatic energy of 1MeV. Contrast-to-Noise Ratios (CNRs) were calculated and compared between each pair of images with different energy sets. Results: Between kV/MV and MV/MV images, the CNRsmore » are comparable for all inserts. However, differences of CNRs were observed between the kV/kV and kV/MV images. Delrin’s CNR ratio between kV/kV image and kV/MV image is 1.634. LDPE’s (Low-Density Polyethylene) CNR ratio between kV/kV and kV/MV images is 0.509. Polystyrene’s CNR ratio between kV/kV image and kV/MV image is 2.219. Conclusion: Preliminary results indicated that the CNRs calculated from CBCT images reconstructed from either kV/MV projections or MV/MV projections for the same selected virtual monochromatic energy may be comparable.« less

VIIRS/J1 polarization narrative

NASA Astrophysics Data System (ADS)

Waluschka, Eugene; McCorkel, Joel; McIntire, Jeff; Moyer, David; McAndrew, Brendan; Brown, Steven W.; Lykke, Keith R.; Young, James B.; Fest, Eric; Butler, James; Wang, Tung R.; Monroy, Eslim O.; Turpie, Kevin; Meister, Gerhard; Thome, Kurtis J.

2015-09-01

The polarization sensitivity of the Visible/NearIR (VISNIR) bands in the Joint Polar Satellite Sensor 1 (J1) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was measured using a broadband source. While polarization sensitivity for bands M5-M7, I1, and I2 was less than 2.5 %, the maximum polarization sensitivity for bands M1, M2, M3, and M4 was measured to be 6.4 %, 4.4 %, 3.1 %, and 4.3 %, respectively with a polarization characterization uncertainty of less than 0.38%. A detailed polarization model indicated that the large polarization sensitivity observed in the M1 to M4 bands is mainly due to the large polarization sensitivity introduced at the leading and trailing edges of the newly manufactured VISNIR bandpass focal plane filters installed in front of the VISNIR detectors. This was confirmed by polarization measurements of bands M1 and M4 bands using monochromatic light. Discussed are the activities leading up to and including the two polarization tests, some discussion of the polarization model and the model results, the role of the focal plane filters, the polarization testing of the Aft-Optics-Assembly, the testing of the polarizers at the National Aeronautics and Space Administration's (NASA) Goddard center and at the National Institute of Science and Technology (NIST) facility and the use of NIST's Traveling Spectral Irradiance and Radiance responsivity Calibrations using Uniform Sources (T-SIRCUS) for polarization testing and associated analyses and results.

Unbiased Estimation of Refractive State of Aberrated Eyes

PubMed Central

Martin, Jesson; Vasudevan, Balamurali; Himebaugh, Nikole; Bradley, Arthur; Thibos, Larry

2011-01-01

To identify unbiased methods for estimating the target vergence required to maximize visual acuity based on wavefront aberration measurements. Experiments were designed to minimize the impact of confounding factors that have hampered previous research. Objective wavefront refractions and subjective acuity refractions were obtained for the same monochromatic wavelength. Accommodation and pupil fluctuations were eliminated by cycloplegia. Unbiased subjective refractions that maximize visual acuity for high contrast letters were performed with a computer controlled forced choice staircase procedure, using 0.125 diopter steps of defocus. All experiments were performed for two pupil diameters (3mm and 6mm). As reported in the literature, subjective refractive error does not change appreciably when the pupil dilates. For 3 mm pupils most metrics yielded objective refractions that were about 0.1D more hyperopic than subjective acuity refractions. When pupil diameter increased to 6 mm, this bias changed in the myopic direction and the variability between metrics also increased. These inaccuracies were small compared to the precision of the measurements, which implies that most metrics provided unbiased estimates of refractive state for medium and large pupils. A variety of image quality metrics may be used to determine ocular refractive state for monochromatic (635nm) light, thereby achieving accurate results without the need for empirical correction factors. PMID:21777601

Adaptive optics with a magnetic deformable mirror: applications in the human eye

NASA Astrophysics Data System (ADS)

Fernandez, Enrique J.; Vabre, Laurent; Hermann, Boris; Unterhuber, Angelika; Povazay, Boris; Drexler, Wolfgang

2006-10-01

A novel deformable mirror using 52 independent magnetic actuators (MIRAO 52, Imagine Eyes) is presented and characterized for ophthalmic applications. The capabilities of the device to reproduce different surfaces, in particular Zernike polynomials up to the fifth order, are investigated in detail. The study of the influence functions of the deformable mirror reveals a significant linear response with the applied voltage. The correcting device also presents a high fidelity in the generation of surfaces. The ranges of production of Zernike polynomials fully cover those typically found in the human eye, even for the cases of highly aberrated eyes. Data from keratoconic eyes are confronted with the obtained ranges, showing that the deformable mirror is able to compensate for these strong aberrations. Ocular aberration correction with polychromatic light, using a near Gaussian spectrum of 130 nm full width at half maximum centered at 800 nm, in five subjects is accomplished by simultaneously using the deformable mirror and an achromatizing lens, in order to compensate for the monochromatic and chromatic aberrations, respectively. Results from living eyes, including one exhibiting 4.66 D of myopia and a near pathologic cornea with notable high order aberrations, show a practically perfect aberration correction. Benefits and applications of simultaneous monochromatic and chromatic aberration correction are finally discussed in the context of retinal imaging and vision.

COMPARISON OF RETINAL PATHOLOGY VISUALIZATION IN MULTISPECTRAL SCANNING LASER IMAGING.

PubMed

Meshi, Amit; Lin, Tiezhu; Dans, Kunny; Chen, Kevin C; Amador, Manuel; Hasenstab, Kyle; Muftuoglu, Ilkay Kilic; Nudleman, Eric; Chao, Daniel; Bartsch, Dirk-Uwe; Freeman, William R

2018-03-16

To compare retinal pathology visualization in multispectral scanning laser ophthalmoscope imaging between the Spectralis and Optos devices. This retrospective cross-sectional study included 42 eyes from 30 patients with age-related macular degeneration (19 eyes), diabetic retinopathy (10 eyes), and epiretinal membrane (13 eyes). All patients underwent retinal imaging with a color fundus camera (broad-spectrum white light), the Spectralis HRA-2 system (3-color monochromatic lasers), and the Optos P200 system (2-color monochromatic lasers). The Optos image was cropped to a similar size as the Spectralis image. Seven masked graders marked retinal pathologies in each image within a 5 × 5 grid that included the macula. The average area with detected retinal pathology in all eyes was larger in the Spectralis images compared with Optos images (32.4% larger, P < 0.0001), mainly because of better visualization of epiretinal membrane and retinal hemorrhage. The average detection rate of age-related macular degeneration and diabetic retinopathy pathologies was similar across the three modalities, whereas epiretinal membrane detection rate was significantly higher in the Spectralis images. Spectralis tricolor multispectral scanning laser ophthalmoscope imaging had higher rate of pathology detection primarily because of better epiretinal membrane and retinal hemorrhage visualization compared with Optos bicolor multispectral scanning laser ophthalmoscope imaging.

Rectennas at optical frequencies: How to analyze the response

NASA Astrophysics Data System (ADS)

Joshi, Saumil; Moddel, Garret

2015-08-01

Optical rectennas, antenna-coupled diode rectifiers that receive optical-frequency electromagnetic radiation and convert it to DC output, have been proposed for use in harvesting electromagnetic radiation from a blackbody source. The operation of these devices is qualitatively different from that of lower-frequency rectennas, and their design requires a new approach. To that end, we present a method to determine the rectenna response to high frequency illumination. It combines classical circuit analysis with classical and quantum-based photon-assisted tunneling response of a high-speed diode. We demonstrate the method by calculating the rectenna response for low and high frequency monochromatic illumination, and for radiation from a blackbody source. Such a blackbody source can be a hot body generating waste heat, or radiation from the sun.

Inelastic neutron scattering experiments with the monochromatic imaging mode of the RITA-II spectrometer

NASA Astrophysics Data System (ADS)

Bahl, C. R. H.; Lefmann, K.; Abrahamsen, A. B.; Rønnow, H. M.; Saxild, F.; Jensen, T. B. S.; Udby, L.; Andersen, N. H.; Christensen, N. B.; Jakobsen, H. S.; Larsen, T.; Häfliger, P. S.; Streule, S.; Niedermayer, Ch.

2006-05-01

Recently a monochromatic multiple data taking mode has been demonstrated for diffraction experiments using a RITA type cold neutron spectrometer with a multi-bladed analyser and a position-sensitive detector. Here, we show how this mode can be used in combination with a flexible radial collimator to perform real inelastic neutron scattering experiments. We present the results from inelastic powder, single crystal dispersion and single crystal constant energy mapping experiments. The advantages and complications of performing these experiments are discussed along with a comparison between the imaging mode and the traditional monochromatic focussing mode.

Thickness determination of thin solid films by angle-resolved X-ray fluorescence spectrometry using monochromatized synchrotron radiation

NASA Astrophysics Data System (ADS)

Schmitt, W.; Drotbohm, P.; Rothe, J.; Hormes, J.; Ottermann, C. R.; Bange, K.

1995-05-01

Thickness measurements by the method of angle-resolved, self-ratio X-ray fluorescence spectrometry (AR/SR/XFS) have been carried out on thin solid films using monochromatized synchrotron radiation at the Bonn storage ring ELSA. Synchrotron radiation was monochromatized by means of a double-crystal monochromator and fluorescence radiation was detected by a Si(Li) semiconductor detector. The results for sample systems consisting of Au on Si, Cr on SiO2 and TiO2 on alkali-free glass are very satisfactory and agree well with results obtained by other methods.

Pupillary behavior in relation to wavelength and age

PubMed Central

Lobato-Rincón, Luis-Lucio; Cabanillas-Campos, Maria del Carmen; Bonnin-Arias, Cristina; Chamorro-Gutiérrez, Eva; Murciano-Cespedosa, Antonio; Sánchez-Ramos Roda, Celia

2014-01-01

Pupil light reflex can be used as a non-invasive ocular predictor of cephalic autonomic nervous system integrity. Spectral sensitivity of the pupil's response to light has, for some time, been an interesting issue. It has generally, however, only been investigated with the use of white light and studies with monochromatic wavelengths are scarce. This study investigates the effects of wavelength and age within three parameters of the pupil light reflex (amplitude of response, latency, and velocity of constriction) in a large sample of younger and older adults (N = 97), in mesopic conditions. Subjects were exposed to a single light stimulus at four different wavelengths: white (5600°K), blue (450 nm), green (510 nm), and red (600 nm). Data was analyzed appropriately, and, when applicable, using the General Linear Model (GLM), Randomized Complete Block Design (RCBD), Student's t-test and/or ANCOVA. Across all subjects, pupillary response to light had the greatest amplitude and shortest latency in white and green light conditions. In regards to age, older subjects (46–78 years) showed an increased latency in white light and decreased velocity of constriction in green light compared to younger subjects (18–45 years old). This study provides data patterns on parameters of wavelength-dependent pupil reflexes to light in adults and it contributes to the large body of pupillometric research. It is hoped that this study will add to the overall evaluation of cephalic autonomic nervous system integrity. PMID:24795595

Astronomy and Cancer Research: X-Rays and Nanotechnology from Black Holes to Cancer Therapy

NASA Astrophysics Data System (ADS)

Pradhan, Anil K.; Nahar, Sultana N.

It seems highly unlikely that any connection is to be found between astronomy and medicine. But then it also appears to be obvious: X-rays. However, that is quite superficial because the nature of X-rays in the two disciplines is quite different. Nevertheless, we describe recent research on exactly that kind of link. Furthermore, the linkage lies in atomic physics, and via spectroscopy which is a vital tool in astronomy and may also be equally valuable in biomedical research. This review begins with the physics of black hole environments as viewed through X-ray spectroscopy. It is then shown that similar physics can be applied to spectroscopic imaging and therapeutics using heavy-element (high-Z) moieties designed to target cancerous tumors. X-ray irradiation of high-Z nanomaterials as radiosensitizing agents should be extremely efficient for therapy and diagnostics (theranostics). However, broadband radiation from conventional X-ray sources (such as CT scanners) results in vast and unnecessary radiation exposure. Monochromatic X-ray sources are expected to be considerably more efficient. We have developed a new and comprehensive methodology—Resonant Nano-Plasma Theranostics (RNPT)—that encompasses the use of monochromatic X-ray sources and high-Z nanoparticles. Ongoing research entails theoretical computations, numerical simulations, and in vitro and in vivo biomedical experiments. Stemming from basic theoretical studies of Kα resonant photoabsorption and fluorescence in all elements of the Periodic Table, we have established a comprehensive multi-disciplinary program involving researchers from physics, chemistry, astronomy, pathology, radiation oncology and radiology. Large-scale calculations necessary for theory and modeling are done at a variety of computational platforms at the Ohio Supercomputer Center. The final goal is the implementation of RNPT for clinical applications.

Biophysical and medical safety basis of laser emission

NASA Astrophysics Data System (ADS)

Paltsev, Yu.; Levina, A.

1996-01-01

Laser equipment may inflict serious losses to human health if safety norms established by relevant standards and other documentation are not properly observed. It is explained by physical properties of laser emission (LE) which differs from general light sources by quantitative behavior of such parameters as the degrees of coherence, monochromaticity, brightness, polarization. Thus, biological effects due to laser emission, as a rule, are more expressed comparing with other types of emission from other spontaneous light sources. LE effects biological tissues through the density of energy flow and impulse duration. It is common knowledge nowadays that LE biological action is assessed by two criteria: physical parameters and absorptive properties of tissues exposed to rays. LE causes the greatest danger to the eyes due to their specific structure. The next target organ vulnerable to LE is skin. Pathological changes of skin depend on the LE power, time of exposure, wave length, and the extent of skin pigmentation. Along with different kinds of damage directly in the tissues exposed to rays, LE may cause changes in organs and body systems subject to indirect exposure. It is important that these changes may develop due to low intensity levels of LE that do not cause local damage. National and international standards on LE safety are based on maximum allowable levels (MAL) of exposure. It has been generally accepted that the main MAL criterion is LE threshold minimal exposure which causes damage to retina, eyes, and skin. As distinct from foreign safety standards, hygienic norms and regulations are in force in the Russian Federation where additional co-efficients along with standard generally accepted MAL values have been introduced for the persons who are subject to occupational regular exposure to lasers. This approach has been chosen after the results of follow-up and health studies of these occupational contingents have been analyzed, and experiments on laboratory animals assessed.

Dispersed Fringe Sensing Analysis - DFSA

NASA Technical Reports Server (NTRS)

Sigrist, Norbert; Shi, Fang; Redding, David C.; Basinger, Scott A.; Ohara, Catherine M.; Seo, Byoung-Joon; Bikkannavar, Siddarayappa A.; Spechler, Joshua A.

2012-01-01

Dispersed Fringe Sensing (DFS) is a technique for measuring and phasing segmented telescope mirrors using a dispersed broadband light image. DFS is capable of breaking the monochromatic light ambiguity, measuring absolute piston errors between segments of large segmented primary mirrors to tens of nanometers accuracy over a range of 100 micrometers or more. The DFSA software tool analyzes DFS images to extract DFS encoded segment piston errors, which can be used to measure piston distances between primary mirror segments of ground and space telescopes. This information is necessary to control mirror segments to establish a smooth, continuous primary figure needed to achieve high optical quality. The DFSA tool is versatile, allowing precise piston measurements from a variety of different optical configurations. DFSA technology may be used for measuring wavefront pistons from sub-apertures defined by adjacent segments (such as Keck Telescope), or from separated sub-apertures used for testing large optical systems (such as sub-aperture wavefront testing for large primary mirrors using auto-collimating flats). An experimental demonstration of the coarse-phasing technology with verification of DFSA was performed at the Keck Telescope. DFSA includes image processing, wavelength and source spectral calibration, fringe extraction line determination, dispersed fringe analysis, and wavefront piston sign determination. The code is robust against internal optical system aberrations and against spectral variations of the source. In addition to the DFSA tool, the software package contains a simple but sophisticated MATLAB model to generate dispersed fringe images of optical system configurations in order to quickly estimate the coarse phasing performance given the optical and operational design requirements. Combining MATLAB (a high-level language and interactive environment developed by MathWorks), MACOS (JPL s software package for Modeling and Analysis for Controlled Optical Systems), and DFSA provides a unique optical development, modeling and analysis package to study current and future approaches to coarse phasing controlled segmented optical systems.

Shadow-free single-pixel imaging

NASA Astrophysics Data System (ADS)

Li, Shunhua; Zhang, Zibang; Ma, Xiao; Zhong, Jingang

2017-11-01

Single-pixel imaging is an innovative imaging scheme and receives increasing attention in recent years, for it is applicable for imaging at non-visible wavelengths and imaging under weak light conditions. However, as in conventional imaging, shadows would likely occur in single-pixel imaging and sometimes bring negative effects in practical uses. In this paper, the principle of shadows occurrence in single-pixel imaging is analyzed, following which a technique for shadows removal is proposed. In the proposed technique, several single-pixel detectors are used to detect the backscattered light at different locations so that the shadows in the reconstructed images corresponding to each detector shadows are complementary. Shadow-free reconstruction can be derived by fusing the shadow-complementary images using maximum selection rule. To deal with the problem of intensity mismatch in image fusion, we put forward a simple calibration. As experimentally demonstrated, the technique is able to reconstruct monochromatic and full-color shadow-free images.

Tropism in azalea and lily flowers

NASA Astrophysics Data System (ADS)

Shimizu, M.; Tomita-Yokotani, K.; Nakamura, T.; Yamashita, M.

Tropic responses were examined in azalea Rhododendrom pulchrum and lily Lilium cv. 'Casablanca' flowers. Orientation of the flowers in these two species depicts several up/down characteristics, such as angle of the corolla opening, alignment or configuration of a specific petal at the top, plus direction in the curved tip of the pistil and stamen. Gravity was found to be the prime factor, with light as a secondary signal that determines gravitropism in the pistil of the azalea. Within the azalea, sedimented amyloplasts were observed throughout the cells along the inner layers below the epidermis. In lily flowers, no sedimented amyloplasts were found in style cells, and phototropic responses caused upward bending of the pistil. Responses of lily pistils to monochromatic light were consistent with the action spectrum for phototropism in the shoots of monocotyledonous plants. We discuss how these features may increase the fitness for pollination in these two species.

Panretinal, high-resolution color photography of the mouse fundus.

PubMed

Paques, Michel; Guyomard, Jean-Laurent; Simonutti, Manuel; Roux, Michel J; Picaud, Serge; Legargasson, Jean-François; Sahel, José-Alain

2007-06-01

To analyze high-resolution color photographs of the mouse fundus. A contact fundus camera based on topical endoscopy fundus imaging (TEFI) was built. Fundus photographs of C57 and Balb/c mice obtained by TEFI were qualitatively analyzed. High-resolution digital imaging of the fundus, including the ciliary body, was routinely obtained. The reflectance and contrast of retinal vessels varied significantly with the amount of incident and reflected light and, thus, with the degree of fundus pigmentation. The combination of chromatic and spherical aberration favored blue light imaging, in term of both field and contrast. TEFI is a small, low-cost system that allows high-resolution color fundus imaging and fluorescein angiography in conscious mice. Panretinal imaging is facilitated by the presence of the large rounded lens. TEFI significantly improves the quality of in vivo photography of retina and ciliary process of mice. Resolution is, however, affected by chromatic aberration, and should be improved by monochromatic imaging.

Role of pigmentation in protecting Aspergillus niger conidiospores against pulsed light radiation.

PubMed

Esbelin, Julia; Mallea, Sabine; Ram, Arthur F; Carlin, Frédéric

2013-01-01

The photoprotective potential of fungus pigments was investigated by irradiating conidiospores of three Aspergillus niger strains possessing the same genetic background, but differing in their degree of pigmentation with pulsed light (PL) and monochromatic (254 nm) UV-C radiation. Spores of A. niger MA93.1 and JHP1.1 presenting, respectively, a fawn and a white pigmentation were more sensitive to PL and continuous UV-C radiation than the wild-type A. niger strain N402 possessing a dark pigment. Both spores of the dark A. niger N402 and the fawn-color mutant were equally resistant to moist heat at 56°C while spores of the white-color mutant were highly sensitive. These results indicate that melanin protects pigmented spores of A. niger from PL. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.

Selective photodestruction of alpha-amino acids. [in carbonaceous chondrites and chemical evolution experiments

NASA Technical Reports Server (NTRS)

Levi, N.; Lawless, J. G.

1978-01-01

A problem encountered in the analysis of amino acids in chemical evolution experiments and in extracts of meteorites is the large number present. A method for selectively destroying the alpha-amino acids, with only the beta- and gamma-amino acids remaining in the solution, is described. The amino acids used were racemic, with one milliliter of solution containing 0.0000025 mol of each acid irradiated in a 1-cm quartz cell having 254-nm monochromatic light in the presence of CuCl2. Excess H2S was added to precipitate the Cu (2+) as CuS. A gas chromatographic analysis was used to observe that irradiation with 254-nm light in the presence of Cu (2+) destroyed all the amino acids except the beta and the gamma types. It is concluded that with such a procedure, complex mixtures of amino acids can be simplified to make identification by GC mass spectrometry easier.

Estimating chlorophyll content and bathymetry of Lake Tahoe using AVIRIS data

NASA Technical Reports Server (NTRS)

Hamilton, Michael K.; Davis, Curtiss O.; Rhea, W. J.; Pilorz, Stuart H.; Carder, Kendall L.

1993-01-01

Data on chlorophyll content and bathymetry of Lake Tahoe obtained on August 9, 1990 by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) are compared to concurrent in situ surface and in-water measurements. Measured parameters included profiles of percent transmission of monochromatic light, stimulated chlorophyll fluorescence, photosynthetically available radiation, spectral upwelling and downwelling irradiance, and upwelling radiance. Several analyses were performed illustrating the utility of the AVIRIS over a dark water scene. Image-derived chlorophyll concentration compared extremely well with that measured with bottle samples. A bathymetry map of the shallow parts of the lake was constructed which compares favorably with published lake soundings.