Streak camera measurements of laser pulse temporal dispersion in short graded-index optical fibers

International Nuclear Information System (INIS)

Lerche, R.A.; Phillips, G.E.

1981-01-01

Streak camera measurements were used to determine temporal dispersion in short (5 to 30 meter) graded-index optical fibers. Results show that 50-ps, 1.06-μm and 0.53-μm laser pulses can be propagated without significant dispersion when care is taken to prevent propagation of energy in fiber cladding modes

Soft x-ray streak cameras

International Nuclear Information System (INIS)

Stradling, G.L.

1988-01-01

This paper is a discussion of the development and of the current state of the art in picosecond soft x-ray streak camera technology. Accomplishments from a number of institutions are discussed. X-ray streak cameras vary from standard visible streak camera designs in the use of an x-ray transmitting window and an x-ray sensitive photocathode. The spectral sensitivity range of these instruments includes portions of the near UV and extends from the subkilovolt x- ray region to several tens of kilovolts. Attendant challenges encountered in the design and use of x-ray streak cameras include the accommodation of high-voltage and vacuum requirements, as well as manipulation of a photocathode structure which is often fragile. The x-ray transmitting window is generally too fragile to withstand atmospheric pressure, necessitating active vacuum pumping and a vacuum line of sight to the x-ray signal source. Because of the difficulty of manipulating x-ray beams with conventional optics, as is done with visible light, the size of the photocathode sensing area, access to the front of the tube, the ability to insert the streak tube into a vacuum chamber and the capability to trigger the sweep with very short internal delay times are issues uniquely relevant to x-ray streak camera use. The physics of electron imaging may place more stringent limitations on the temporal and spatial resolution obtainable with x-ray photocathodes than with the visible counterpart. Other issues which are common to the entire streak camera community also concern the x-ray streak camera users and manufacturers

MULTIMODAL IMAGING OF ANGIOID STREAKS ASSOCIATED WITH TURNER SYNDROME.

Science.gov (United States)

Chiu, Bing Q; Tsui, Edmund; Hussnain, Syed Amal; Barbazetto, Irene A; Smith, R Theodore

2018-02-13

To report multimodal imaging in a novel case of angioid streaks in a patient with Turner syndrome with 10-year follow-up. Case report of a patient with Turner syndrome and angioid streaks followed at Bellevue Hospital Eye Clinic from 2007 to 2017. Fundus photography, fluorescein angiography, and optical coherence tomography angiography were obtained. Angioid streaks with choroidal neovascularization were noted in this patient with Turner syndrome without other systemic conditions previously correlated with angioid streaks. We report a case of angioid streaks with choroidal neovascularization in a patient with Turner syndrome. We demonstrate that angioid streaks, previously associated with pseudoxanthoma elasticum, Ehlers-Danlos syndrome, Paget disease of bone, and hemoglobinopathies, may also be associated with Turner syndrome, and may continue to develop choroidal neovascularization, suggesting the need for careful ophthalmic examination in these patients.

Development of a Data Reduction Algorithm for Optical Wide Field Patrol (OWL) II: Improving Measurement of Lengths of Detected Streaks

Science.gov (United States)

Park, Sun-Youp; Choi, Jin; Roh, Dong-Goo; Park, Maru; Jo, Jung Hyun; Yim, Hong-Suh; Park, Young-Sik; Bae, Young-Ho; Park, Jang-Hyun; Moon, Hong-Kyu; Choi, Young-Jun; Cho, Sungki; Choi, Eun-Jung

2016-09-01

As described in the previous paper (Park et al. 2013), the detector subsystem of optical wide-field patrol (OWL) provides many observational data points of a single artificial satellite or space debris in the form of small streaks, using a chopper system and a time tagger. The position and the corresponding time data are matched assuming that the length of a streak on the CCD frame is proportional to the time duration of the exposure during which the chopper blades do not obscure the CCD window. In the previous study, however, the length was measured using the diagonal of the rectangle of the image area containing the streak; the results were quite ambiguous and inaccurate, allowing possible matching error of positions and time data. Furthermore, because only one (position, time) data point is created from one streak, the efficiency of the observation decreases. To define the length of a streak correctly, it is important to locate the endpoints of a streak. In this paper, a method using a differential convolution mask pattern is tested. This method can be used to obtain the positions where the pixel values are changed sharply. These endpoints can be regarded as directly detected positional data, and the number of data points is doubled by this result.

Electro-optical design of a long slit streak tube

Science.gov (United States)

Tian, Liping; Tian, Jinshou; Wen, Wenlong; Chen, Ping; Wang, Xing; Hui, Dandan; Wang, Junfeng

2017-11-01

A small size and long slit streak tube with high spatial resolution was designed and optimized. Curved photocathode and screen were adopted to increase the photocathode working area and spatial resolution. High physical temporal resolution obtained by using a slit accelerating electrode. Deflection sensitivity of the streak tube was improved by adopting two-folded deflection plates. The simulations indicate that the photocathode effective working area can reach 30mm × 5mm. The static spatial resolution is higher than 40lp/mm and 12lp/mm along scanning and slit directions respectively while the physical temporal resolution is higher than 60ps. The magnification is 0.75 and 0.77 in scanning and slit directions. And also, the deflection sensitivity is as high as 37mm/kV. The external dimension of the streak tube are only ∅74mm×231mm. Thus, it can be applied to laser imaging radar system for large field of view and high range precision detection.

Optical Spectroscopy

DEFF Research Database (Denmark)

Thyrhaug, Erling

The work presented in this thesis is broadly concerned with how complexation reactions and molecular motion can be characterized with the standard techniques in optical spectroscopy. The thesis aims to show a relatively broad range of methods for probing physico-chemical properties in fluorophore...... information about chemical equilibria, kinetics and molecular motion by monitoring changes in optical properties of the system. The five presented research projects are largely unrelated to each other both in aim and in what property is probed, however they are all connected in that they are fluorophore...... reactions by optical spectroscopy. In project 1 simple steady-state absorption and fluorescence spectroscopy is used to determine the stoichiometries and equilibrium constants in the inclusion complex formation between cyclodextrins and derivatives of the water-insoluble oligo(phenylene vinylene) in aqueous...

Wind Streaks on Earth; Exploration and Interpretation

Science.gov (United States)

Cohen-Zada, Aviv Lee; Blumberg, Dan G.; Maman, Shimrit

2015-04-01

Wind streaks, one of the most common aeolian features on planetary surfaces, are observable on the surface of the planets Earth, Mars and Venus. Due to their reflectance properties, wind streaks are distinguishable from their surroundings, and they have thus been widely studied by remote sensing since the early 1970s, particularly on Mars. In imagery, these streaks are interpreted as the presence - or lack thereof - of small loose particles on the surface deposited or eroded by wind. The existence of wind streaks serves as evidence for past or present active aeolian processes. Therefore, wind streaks are thought to represent integrative climate processes. As opposed to the comprehensive and global studies of wind streaks on Mars and Venus, wind streaks on Earth are understudied and poorly investigated, both geomorphologically and by remote sensing. The aim of this study is, thus, to fill the knowledge gap about the wind streaks on Earth by: generating a global map of Earth wind streaks from modern high-resolution remotely sensed imagery; incorporating the streaks in a geographic information system (GIS); and overlaying the GIS layers with boundary layer wind data from general circulation models (GCMs) and data from the ECMWF Reanalysis Interim project. The study defines wind streaks (and thereby distinguishes them from other aeolian features) based not only on their appearance in imagery but more importantly on their surface appearance. This effort is complemented by a focused field investigation to study wind streaks on the ground and from a variety of remotely sensed images (both optical and radar). In this way, we provide a better definition of the physical and geomorphic characteristics of wind streaks and acquire a deeper knowledge of terrestrial wind streaks as a means to better understand global and planetary climate and climate change. In a preliminary study, we detected and mapped over 2,900 wind streaks in the desert regions of Earth distributed in

Optical Spectroscopy Measurements of Shock Waves Driven by Intense Z-Pinch Radiation

International Nuclear Information System (INIS)

Asay, J.; Bernard, M.; Bailey, J.E.; Carlson, A.L.; Chandler, G.A.; Hall, C.A.; Hanson, D.; Johnston, R.; Lake, P.; Lawrence, J.

1999-01-01

Z-pinches created using the Z accelerator generate approximately220 TW, 1.7 MJ radiation pulses that heat large (approximately10 cm 3 ) hohlraums to 100-150 eV temperatures for times of order 10 nsec. We are performing experiments exploiting this intense radiation to drive shock waves for equation of state studies. The shock pressures are typically 1-10 Mbar with 10 nsec duration in 6-mm-diameter samples. In this paper we demonstrate the ability to perform optical spectroscopy measurements on shocked samples located in close proximity to the z-pinch. These experiments are particularly well suited to optical spectroscopy measurements because of the relatively large sample size and long duration. The optical emission is collected using fiber optics and recorded with a streaked spectrograph. Other diagnostics include VISAR and active shock breakout measurements of the shocked sample and a suite of diagnostics that characterize the radiation drive. Our near term goal is to use the spectral emission to obtain the temperature of the shocked material. Longer term objectives include the examination of deviations of the spectrum from blackbody, line emission from lower density regions, determination of kinetic processes in molecular systems, evaluation of phase transitions such as the onset of metalization in transparent materials, and characterization of the plasma formed when the shock exits the rear surface. An initial set of data illustrating both the potential and the challenge of these measurements is described

Aluminum-coated optical fibers as efficient infrared timing fiducial photocathodes for synchronizing x-ray streak cameras

International Nuclear Information System (INIS)

Koch, J.A.; MacGowan, B.J.

1991-01-01

The timing fiducial system at the Nova Two-Beam Facility allows time-resolved x-ray and optical streak camera data from laser-produced plasmas to be synchronized to within 30 ps. In this system, an Al-coated optical fiber is inserted into an aperture in the cathode plate of each streak camera. The coating acts as a photocathode for a low-energy pulse of 1ω (λ = 1.054 μm) light which is synchronized to the main Nova beam. The use of the fundamental (1ω) for this fiducial pulse has been found to offer significant advantages over the use of the 2ω second harmonic (λ = 0.53 μm). These advantages include brighter signals, greater reliability, and a higher relative damage threshold, allowing routine use without fiber replacement. The operation of the system is described, and experimental data and interpretations are discussed which suggest that the electron production in the Al film is due to thermionic emission. The results of detailed numerical simulations of the relevant thermal processes, undertaken to model the response of the coated fiber to 1ω laser pulses, are also presented, which give qualitative agreement with experimental data. Quantitative discrepancies between the modeling results and the experimental data are discussed, and suggestions for further research are given

Picosecond x-ray streak cameras

Science.gov (United States)

Averin, V. I.; Bryukhnevich, Gennadii I.; Kolesov, G. V.; Lebedev, Vitaly B.; Miller, V. A.; Saulevich, S. V.; Shulika, A. N.

1991-04-01

The first multistage image converter with an X-ray photocathode (UMI-93 SR) was designed in VNIIOFI in 1974 [1]. The experiments carried out in IOFAN pointed out that X-ray electron-optical cameras using the tube provided temporal resolution up to 12 picoseconds [2]. The later work has developed into the creation of the separate streak and intensifying tubes. Thus, PV-003R tube has been built on base of UMI-93SR design, fibre optically connected to PMU-2V image intensifier carrying microchannel plate.

Picosecond Streaked K-Shell Spectroscopy of Near Solid-Density Aluminum Plasmas

Science.gov (United States)

Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; Mileham, C.; Froula, D. H.; Golovkin, I. E.

2016-10-01

The thermal x-ray emission from rapidly heated solid targets containing a buried-aluminum layer was measured. The targets were driven by high-contrast 1 ω or 2 ω laser pulses at focused intensities up to 1 ×1019W/Wcm2 cm2 . A streaked x-ray spectrometer recorded the Al Heα and lithium-like satellite lines with 2-ps temporal resolution and moderate resolving power (E/E ΔE 700). Time-integrated measurements over the same spectral range were used to correct the streaked data for variations in photocathode sensitivity. Line widths and intensity ratios from the streaked data were interpreted using a collisional radiative atomic model to provide the average plasma conditions in the buried layer as a function of time. It was observed that the resonance line tends toward lower photon energies at high electron densities. The measured shifts will be compared to predicted shifts from Stark-operator calculations at the inferred plasma conditions. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944, the office of Fusion Energy Sciences Award Number DE-SC0012317, and the Stewardship Science Graduate Fellowship Grant Number DE-NA0002135.

Design of microcontroller based system for automation of streak camera

International Nuclear Information System (INIS)

Joshi, M. J.; Upadhyay, J.; Deshpande, P. P.; Sharma, M. L.; Navathe, C. P.

2010-01-01

A microcontroller based system has been developed for automation of the S-20 optical streak camera, which is used as a diagnostic tool to measure ultrafast light phenomenon. An 8 bit MCS family microcontroller is employed to generate all control signals for the streak camera. All biasing voltages required for various electrodes of the tubes are generated using dc-to-dc converters. A high voltage ramp signal is generated through a step generator unit followed by an integrator circuit and is applied to the camera's deflecting plates. The slope of the ramp can be changed by varying values of the capacitor and inductor. A programmable digital delay generator has been developed for synchronization of ramp signal with the optical signal. An independent hardwired interlock circuit has been developed for machine safety. A LABVIEW based graphical user interface has been developed which enables the user to program the settings of the camera and capture the image. The image is displayed with intensity profiles along horizontal and vertical axes. The streak camera was calibrated using nanosecond and femtosecond lasers.

Design of microcontroller based system for automation of streak camera.

Science.gov (United States)

Joshi, M J; Upadhyay, J; Deshpande, P P; Sharma, M L; Navathe, C P

2010-08-01

A microcontroller based system has been developed for automation of the S-20 optical streak camera, which is used as a diagnostic tool to measure ultrafast light phenomenon. An 8 bit MCS family microcontroller is employed to generate all control signals for the streak camera. All biasing voltages required for various electrodes of the tubes are generated using dc-to-dc converters. A high voltage ramp signal is generated through a step generator unit followed by an integrator circuit and is applied to the camera's deflecting plates. The slope of the ramp can be changed by varying values of the capacitor and inductor. A programmable digital delay generator has been developed for synchronization of ramp signal with the optical signal. An independent hardwired interlock circuit has been developed for machine safety. A LABVIEW based graphical user interface has been developed which enables the user to program the settings of the camera and capture the image. The image is displayed with intensity profiles along horizontal and vertical axes. The streak camera was calibrated using nanosecond and femtosecond lasers.

Design of microcontroller based system for automation of streak camera

Energy Technology Data Exchange (ETDEWEB)

Joshi, M. J.; Upadhyay, J.; Deshpande, P. P.; Sharma, M. L.; Navathe, C. P. [Laser Electronics Support Division, RRCAT, Indore 452013 (India)

2010-08-15

A microcontroller based system has been developed for automation of the S-20 optical streak camera, which is used as a diagnostic tool to measure ultrafast light phenomenon. An 8 bit MCS family microcontroller is employed to generate all control signals for the streak camera. All biasing voltages required for various electrodes of the tubes are generated using dc-to-dc converters. A high voltage ramp signal is generated through a step generator unit followed by an integrator circuit and is applied to the camera's deflecting plates. The slope of the ramp can be changed by varying values of the capacitor and inductor. A programmable digital delay generator has been developed for synchronization of ramp signal with the optical signal. An independent hardwired interlock circuit has been developed for machine safety. A LABVIEW based graphical user interface has been developed which enables the user to program the settings of the camera and capture the image. The image is displayed with intensity profiles along horizontal and vertical axes. The streak camera was calibrated using nanosecond and femtosecond lasers.

Improved approach to characterizing and presenting streak camera performance

International Nuclear Information System (INIS)

Wiedwald, J.D.; Jones, B.A.

1985-01-01

The performance of a streak camera recording system is strongly linked to the technique used to amplify, detect and quantify the streaked image. At the Lawrence Livermore National Laboratory (LLNL) streak camera images have been recorded both on film and by fiber-optically coupling to charge-coupled devices (CCD's). During the development of a new process for recording these images (lens coupling the image onto a cooled CCD) the definitions of important performance characteristics such as resolution and dynamic range were re-examined. As a result of this development, these performance characteristics are now presented to the streak camera user in a more useful format than in the past. This paper describes how these techniques are used within the Laser Fusion Program at LLNL. The system resolution is presented as a modulation transfer function, including the seldom reported effects that flare and light scattering have at low spatial frequencies. Data are presented such that a user can adjust image intensifier gain and pixel averaging to optimize the useful dynamic range in any particular application

A time-resolved image sensor for tubeless streak cameras

Science.gov (United States)

Yasutomi, Keita; Han, SangMan; Seo, Min-Woong; Takasawa, Taishi; Kagawa, Keiichiro; Kawahito, Shoji

2014-03-01

This paper presents a time-resolved CMOS image sensor with draining-only modulation (DOM) pixels for tube-less streak cameras. Although the conventional streak camera has high time resolution, the device requires high voltage and bulky system due to the structure with a vacuum tube. The proposed time-resolved imager with a simple optics realize a streak camera without any vacuum tubes. The proposed image sensor has DOM pixels, a delay-based pulse generator, and a readout circuitry. The delay-based pulse generator in combination with an in-pixel logic allows us to create and to provide a short gating clock to the pixel array. A prototype time-resolved CMOS image sensor with the proposed pixel is designed and implemented using 0.11um CMOS image sensor technology. The image array has 30(Vertical) x 128(Memory length) pixels with the pixel pitch of 22.4um. .

Precise measurement of a subpicosecond electron single bunch by the femtosecond streak camera

International Nuclear Information System (INIS)

Uesaka, M.; Ueda, T.; Kozawa, T.; Kobayashi, T.

1998-01-01

Precise measurement of a subpicosecond electron single bunch by the femtosecond streak camera is presented. The subpicosecond electron single bunch of energy 35 MeV was generated by the achromatic magnetic pulse compressor at the S-band linear accelerator of nuclear engineering research laboratory (NERL), University of Tokyo. The electric charge per bunch and beam size are 0.5 nC and the horizontal and vertical beam sizes are 3.3 and 5.5 mm (full width at half maximum; FWHM), respectively. Pulse shape of the electron single bunch is measured via Cherenkov radiation emitted in air by the femtosecond streak camera. Optical parameters of the optical measurement system were optimized based on much experiment and numerical analysis in order to achieve a subpicosecond time resolution. By using the optimized optical measurement system, the subpicosecond pulse shape, its variation for the differents rf phases in the accelerating tube, the jitter of the total system and the correlation between measured streak images and calculated longitudinal phase space distributions were precisely evaluated. This measurement system is going to be utilized in several subpicosecond analyses for radiation physics and chemistry. (orig.)

Initial tests of the dual-sweep streak camera system planned for APS particle-beam diagnostics

International Nuclear Information System (INIS)

Lumpkin, A.; Yang, B.; Gai, W.; Cieslik, W.

1995-01-01

Initial tests of a dual-sweep streak system planned for use on the Advanced Photon Source (APS) have been performed using assets of the Argonne Wakefield Accelerator (AWA) facility. The short light pulses from the photoelectric injector drive laser in both the visible (λ=496 nm, Δt∼1.5 ps (FWHM)), and the ultraviolet (λ=248 nm, Δt∼5 ps (FWHM)) were used. Both a UV-visible S20 photocathode streak tube and a UV-to-x-ray Au photocathode streak tube were tested. Calibration data with an etalon were also obtained. A sample of dual-sweep streak data using optical synchrotron radiation on the APS injector synchrotron is also presented

Streaking into middle school science: The Dell Streak pilot project

Science.gov (United States)

Austin, Susan Eudy

A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the Streak could be used as an effective instructional tool, and if it could be considered an effective instructional resource for reviewing and preparing for the science assessments. A mixed method research design was used for the study to analyze both quantitative and qualitative results to determine if the Dell Streaks' utilization could achieve the following: 1. instructional strategies would change, 2. it would be an effective instructional tool, and 3. a comparison of the students' test scores and benchmark assessments' scores would provide statistically significant difference. Through the use of an ANOVA it was determined a statistically significant difference had occurred. A Post Hoc analysis was conducted to identify where the difference occurred. Finally a T-test determined was there was no statistically significance difference between the mean End-of-Grade tests and four quarterly benchmark scores of the control and the experimental groups. Qualitative research methods were used to gather results to determine if the Streaks were an effective instructional tool. Classroom observations identified that the teacher's teaching styles and new instructional strategies were implemented throughout the pilot project. Students had an opportunity to complete a questionnaire three times during the pilot project. Results revealed what the students liked about using the devices and the challenges they were facing. The teacher completed a reflective questionnaire throughout the pilot project and offered valuable reflections about the use of the devices in an educational setting. The reflection data supporting the case study was drawn

Optical imaging and spectroscopy

CERN Document Server

Brady, David J

2009-01-01

An essential reference for optical sensor system design This is the first text to present an integrated view of the optical and mathematical analysis tools necessary to understand computational optical system design. It presents the foundations of computational optical sensor design with a focus entirely on digital imaging and spectroscopy. It systematically covers: Coded aperture and tomographic imaging Sampling and transformations in optical systems, including wavelets and generalized sampling techniques essential to digital system analysis Geometric, wave, and statis

Optical Spectroscopy and Imaging of Correlated Spin Orbit Phases

Science.gov (United States)

2016-06-14

Unlimited UU UU UU UU 14-06-2016 15-Mar-2013 14-Mar-2016 Final Report: Optical Spectroscopy and Imaging of Correlated Spin-Orbit Phases The views...Box 12211 Research Triangle Park, NC 27709-2211 Ultrafast optical spectroscopy , nonlinear optical spectroscopy , iridates, cuprates REPORT...California Blvd. Pasadena, CA 91125 -0001 ABSTRACT Number of Papers published in peer-reviewed journals: Final Report: Optical Spectroscopy and

Triton's streaks as windblown dust

Science.gov (United States)

Sagan, Carl; Chyba, Christopher

1990-01-01

Explanations for the surface streaks observed by Voyager 2 on Triton's southern hemisphere are discussed. It is shown that, despite Triton's tenuous atmosphere, low-cohesion dust trains with diameters of about 5 micron or less may be carried into suspension by aeolian surface shear stress, given expected geostrophic wind speeds of about 10 m/s. For geyser-like erupting dust plumes, it is shown that dust-settling time scales and expected wind velocities can produce streaks with length scales in good agreement with those of the streaks. Thus, both geyserlike eruptions or direct lifting by surface winds appear to be viable mechanisms for the origin of the streaks.

Spectroscopy and optical diagnostics for gases

CERN Document Server

Hanson, Ronald K; Goldenstein, Christopher S

2016-01-01

This text provides an introduction to the science that governs the interaction of light and matter (in the gas phase). It provides readers with the basic knowledge to exploit the light-matter interaction to develop quantitative tools for gas analysis (i.e. optical diagnostics) and understand and interpret the results of spectroscopic measurements. The authors pair the basics of gas‐phase spectroscopy with coverage of key optical diagnostic techniques utilized by practicing engineers and scientists to measure fundamental flow‐field properties. The text is organized to cover three sub‐topics of gas‐phase spectroscopy: (1) spectral line positions, (2) spectral line strengths, and (3) spectral lineshapes by way of absorption, emission, and scattering interactions. The latter part of the book describes optical measurement techniques and equipment. Key subspecialties include laser induced fluorescence, tunable laser absorption spectroscopy, and wavelength modulation spectroscopy. It is ideal for students an...

STREAK CAMERA MEASUREMENTS OF THE APS PC GUN DRIVE LASER

Energy Technology Data Exchange (ETDEWEB)

Dooling, J. C.; Lumpkin, A. H.

2017-06-25

We report recent pulse-duration measurements of the APS PC Gun drive laser at both second harmonic and fourth harmonic wavelengths. The drive laser is a Nd:Glass-based chirped pulsed amplifier (CPA) operating at an IR wavelength of 1053 nm, twice frequency-doubled to obtain UV output for the gun. A Hamamatsu C5680 streak camera and an M5675 synchroscan unit are used for these measurements; the synchroscan unit is tuned to 119 MHz, the 24th subharmonic of the linac s-band operating frequency. Calibration is accomplished both electronically and optically. Electronic calibration utilizes a programmable delay line in the 119 MHz rf path. The optical delay uses an etalon with known spacing between reflecting surfaces and is coated for the visible, SH wavelength. IR pulse duration is monitored with an autocorrelator. Fitting the streak camera image projected profiles with Gaussians, UV rms pulse durations are found to vary from 2.1 ps to 3.5 ps as the IR varies from 2.2 ps to 5.2 ps.

Nonlinear streak computation using boundary region equations

Energy Technology Data Exchange (ETDEWEB)

Martin, J A; Martel, C, E-mail: juanangel.martin@upm.es, E-mail: carlos.martel@upm.es [Depto. de Fundamentos Matematicos, E.T.S.I Aeronauticos, Universidad Politecnica de Madrid, Plaza Cardenal Cisneros 3, 28040 Madrid (Spain)

2012-08-01

The boundary region equations (BREs) are applied for the simulation of the nonlinear evolution of a spanwise periodic array of streaks in a flat plate boundary layer. The well-known BRE formulation is obtained from the complete Navier-Stokes equations in the high Reynolds number limit, and provides the correct asymptotic description of three-dimensional boundary layer streaks. In this paper, a fast and robust streamwise marching scheme is introduced to perform their numerical integration. Typical streak computations present in the literature correspond to linear streaks or to small-amplitude nonlinear streaks computed using direct numerical simulation (DNS) or the nonlinear parabolized stability equations (PSEs). We use the BREs to numerically compute high-amplitude streaks, a method which requires much lower computational effort than DNS and does not have the consistency and convergence problems of the PSE. It is found that the flow configuration changes substantially as the amplitude of the streaks grows and the nonlinear effects come into play. The transversal motion (in the wall normal-streamwise plane) becomes more important and strongly distorts the streamwise velocity profiles, which end up being quite different from those of the linear case. We analyze in detail the resulting flow patterns for the nonlinearly saturated streaks and compare them with available experimental results. (paper)

Improving the off-axis spatial resolution and dynamic range of the NIF X-ray streak cameras (invited)

Energy Technology Data Exchange (ETDEWEB)

MacPhee, A. G., E-mail: macphee2@llnl.gov; Hatch, B. W.; Bell, P. M.; Bradley, D. K.; Datte, P. S.; Landen, O. L.; Palmer, N. E.; Piston, K. W.; Rekow, V. V. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); Dymoke-Bradshaw, A. K. L.; Hares, J. D. [Kentech Instruments Ltd., Isis Building, Howbery Park, Wallingford, Oxfordshire OX10 8BD (United Kingdom); Hassett, J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627 (United States); Meadowcroft, A. L. [AWE Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Hilsabeck, T. J.; Kilkenny, J. D. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

2016-11-15

We report simulations and experiments that demonstrate an increase in spatial resolution of the NIF core diagnostic x-ray streak cameras by at least a factor of two, especially off axis. A design was achieved by using a corrector electron optic to flatten the field curvature at the detector plane and corroborated by measurement. In addition, particle in cell simulations were performed to identify the regions in the streak camera that contribute the most to space charge blurring. These simulations provide a tool for convolving synthetic pre-shot spectra with the instrument function so signal levels can be set to maximize dynamic range for the relevant part of the streak record.

Improving the off-axis spatial resolution and dynamic range of the NIF X-ray streak cameras (invited).

Science.gov (United States)

MacPhee, A G; Dymoke-Bradshaw, A K L; Hares, J D; Hassett, J; Hatch, B W; Meadowcroft, A L; Bell, P M; Bradley, D K; Datte, P S; Landen, O L; Palmer, N E; Piston, K W; Rekow, V V; Hilsabeck, T J; Kilkenny, J D

2016-11-01

We report simulations and experiments that demonstrate an increase in spatial resolution of the NIF core diagnostic x-ray streak cameras by at least a factor of two, especially off axis. A design was achieved by using a corrector electron optic to flatten the field curvature at the detector plane and corroborated by measurement. In addition, particle in cell simulations were performed to identify the regions in the streak camera that contribute the most to space charge blurring. These simulations provide a tool for convolving synthetic pre-shot spectra with the instrument function so signal levels can be set to maximize dynamic range for the relevant part of the streak record.

Laser-based terahertz-field-driven streak camera for the temporal characterization of ultrashort processes

Energy Technology Data Exchange (ETDEWEB)

Schuette, Bernd

2011-09-15

In this work, a novel laser-based terahertz-field-driven streak camera is presented. It allows for a pulse length characterization of femtosecond (fs) extreme ultraviolet (XUV) pulses by a cross-correlation with terahertz (THz) pulses generated with a Ti:sapphire laser. The XUV pulses are emitted by a source of high-order harmonic generation (HHG) in which an intense near-infrared (NIR) fs laser pulse is focused into a gaseous medium. The design and characterization of a high-intensity THz source needed for the streak camera is also part of this thesis. The source is based on optical rectification of the same NIR laser pulse in a lithium niobate crystal. For this purpose, the pulse front of the NIR beam is tilted via a diffraction grating to achieve velocity matching between NIR and THz beams within the crystal. For the temporal characterization of the XUV pulses, both HHG and THz beams are focused onto a gas target. The harmonic radiation creates photoelectron wavepackets which are then accelerated by the THz field depending on its phase at the time of ionization. This principle adopted from a conventional streak camera and now widely used in attosecond metrology. The streak camera presented here is an advancement of a terahertz-field-driven streak camera implemented at the Free Electron Laser in Hamburg (FLASH). The advantages of the laser-based streak camera lie in its compactness, cost efficiency and accessibility, while providing the same good quality of measurements as obtained at FLASH. In addition, its flexibility allows for a systematic investigation of streaked Auger spectra which is presented in this thesis. With its fs time resolution, the terahertz-field-driven streak camera thereby bridges the gap between attosecond and conventional cameras. (orig.)

Laser-based terahertz-field-driven streak camera for the temporal characterization of ultrashort processes

International Nuclear Information System (INIS)

Schuette, Bernd

2011-09-01

In this work, a novel laser-based terahertz-field-driven streak camera is presented. It allows for a pulse length characterization of femtosecond (fs) extreme ultraviolet (XUV) pulses by a cross-correlation with terahertz (THz) pulses generated with a Ti:sapphire laser. The XUV pulses are emitted by a source of high-order harmonic generation (HHG) in which an intense near-infrared (NIR) fs laser pulse is focused into a gaseous medium. The design and characterization of a high-intensity THz source needed for the streak camera is also part of this thesis. The source is based on optical rectification of the same NIR laser pulse in a lithium niobate crystal. For this purpose, the pulse front of the NIR beam is tilted via a diffraction grating to achieve velocity matching between NIR and THz beams within the crystal. For the temporal characterization of the XUV pulses, both HHG and THz beams are focused onto a gas target. The harmonic radiation creates photoelectron wavepackets which are then accelerated by the THz field depending on its phase at the time of ionization. This principle adopted from a conventional streak camera and now widely used in attosecond metrology. The streak camera presented here is an advancement of a terahertz-field-driven streak camera implemented at the Free Electron Laser in Hamburg (FLASH). The advantages of the laser-based streak camera lie in its compactness, cost efficiency and accessibility, while providing the same good quality of measurements as obtained at FLASH. In addition, its flexibility allows for a systematic investigation of streaked Auger spectra which is presented in this thesis. With its fs time resolution, the terahertz-field-driven streak camera thereby bridges the gap between attosecond and conventional cameras. (orig.)

XIX International Youth School on Coherent Optics and Optical Spectroscopy

International Nuclear Information System (INIS)

2016-01-01

The XIX International Youth School on Coherent Optics and Optical Spectroscopy (COOS2015) was held in Kazan, Russia, from October 5 to October 7 at the Nikolai Lobachevsky Scientific Library of Kazan Federal University. The School follows the global tendency toward comprehensive studies of matter properties and its interaction with electromagnetic fields. Since 1997 more than 100 famous scientists from USA, Germany, Ukraine, Belarussia and Russia had plenary lecture presentations. This is the right place, where over 1000 young scientists had an opportunity to participate in hot discussions regarding the latest scientific news. Many young people have submitted interesting reports on photonics, quantum electronics, laser physics, quantum optics, traditional optical and laser spectroscopy, non-linear optics, material science and nanotechnology. Here we are publishing the full-size papers prepared from the most interesting lectures and reports selected by the Program Committee of the School. (paper)

Notes on the IMACON 500 streak camera system

International Nuclear Information System (INIS)

Clendenin, J.E.

1985-01-01

The notes provided are intended to supplement the instruction manual for the IMACON 500 streak camera system. The notes cover the streak analyzer, instructions for timing the streak camera, and calibration

Principles of laser spectroscopy and quantum optics

CERN Document Server

Berman, Paul R

2011-01-01

Principles of Laser Spectroscopy and Quantum Optics is an essential textbook for graduate students studying the interaction of optical fields with atoms. It also serves as an ideal reference text for researchers working in the fields of laser spectroscopy and quantum optics. The book provides a rigorous introduction to the prototypical problems of radiation fields interacting with two- and three-level atomic systems. It examines the interaction of radiation with both atomic vapors and condensed matter systems, the density matrix and the Bloch vector, and applications involving linear absorptio

Cheap streak camera based on the LD-S-10 intensifier tube

Science.gov (United States)

Dashevsky, Boris E.; Krutik, Mikhail I.; Surovegin, Alexander L.

1992-01-01

Basic properties of a new streak camera and its test results are reported. To intensify images on its screen, we employed modular G1 tubes, the LD-A-1.0 and LD-A-0.33, enabling magnification of 1.0 and 0.33, respectively. If necessary, the LD-A-0.33 tube may be substituted by any other image intensifier of the LDA series, the choice to be determined by the size of the CCD matrix with fiber-optical windows. The reported camera employs a 12.5- mm-long CCD strip consisting of 1024 pixels, each 12 X 500 micrometers in size. Registered radiation was imaged on a 5 X 0.04 mm slit diaphragm tightly connected with the LD-S- 10 fiber-optical input window. Electrons escaping the cathode are accelerated in a 5 kV electric field and focused onto a phosphor screen covering a fiber-optical plate as they travel between deflection plates. Sensitivity of the latter was 18 V/mm, which implies that the total deflecting voltage was 720 V per 40 mm of the screen surface, since reversed-polarity scan pulses +360 V and -360 V were applied across the deflection plate. The streak camera provides full scan times over the screen of 15, 30, 50, 100, 250, and 500 ns. Timing of the electrically or optically driven camera was done using a 10 ns step-controlled-delay (0 - 500 ns) circuit.

A novel simultaneous streak and framing camera without principle errors

Science.gov (United States)

Jingzhen, L.; Fengshan, S.; Ningwen, L.; Xiangdong, G.; Bin, H.; Qingyang, W.; Hongyi, C.; Yi, C.; Xiaowei, L.

2018-02-01

A novel simultaneous streak and framing camera with continuous access, the perfect information of which is far more important for the exact interpretation and precise evaluation of many detonation events and shockwave phenomena, has been developed. The camera with the maximum imaging frequency of 2 × 106 fps and the maximum scanning velocity of 16.3 mm/μs has fine imaging properties which are the eigen resolution of over 40 lp/mm in the temporal direction and over 60 lp/mm in the spatial direction and the framing frequency principle error of zero for framing record, and the maximum time resolving power of 8 ns and the scanning velocity nonuniformity of 0.136%~-0.277% for streak record. The test data have verified the performance of the camera quantitatively. This camera, simultaneously gained frames and streak with parallax-free and identical time base, is characterized by the plane optical system at oblique incidence different from space system, the innovative camera obscura without principle errors, and the high velocity motor driven beryllium-like rotating mirror, made of high strength aluminum alloy with cellular lateral structure. Experiments demonstrate that the camera is very useful and reliable to take high quality pictures of the detonation events.

HOMES - Holographic Optical Method for Exoplanet Spectroscopy

Data.gov (United States)

National Aeronautics and Space Administration — HOMES (Holographic Optical Method for Exoplanet Spectroscopy) is a space telescope that employs a double dispersion architecture, using a holographic optical element...

Persistence of Smectic-A Oily Streaks into the Nematic Phase by UV Irradiation of Reactive Mesogens

Directory of Open Access Journals (Sweden)

Ines Gharbi

2017-12-01

Full Text Available Thin smectic liquid crystal films with competing boundary conditions (planar and homeotropic at opposing surfaces form well-known striated structures known as “oily streaks”, which are a series of hemicylindrical caps that run perpendicular to the easy axis of the planar substrate. The streaks vanish on heating into the nematic phase, where the film becomes uniform and exhibits hybrid alignment. On adding sufficient reactive mesogen and polymerizing, the oily streak texture is maintained on heating through the entire nematic phase until reaching the bulk isotropic phase, above which the texture vanishes. Depending on the liquid crystal thickness, the oily streak structure may be retrieved after cooling, which demonstrates the strong impact of the polymer backbone on the liquid crystal texture. Polarizing optical, atomic force, and scanning electron microscopy data are presented.

Large-grazing-angle, multi-image Kirkpatrick-Baez microscope as the front end to a high-resolution streak camera for OMEGA

International Nuclear Information System (INIS)

Gotchev, O.V.; Hayes, L.J.; Jaanimagi, P.A.; Knauer, J.P.; Marshall, F.J.; Meyerhofer, D.D.

2003-01-01

A high-resolution x-ray microscope with a large grazing angle has been developed, characterized, and fielded at the Laboratory for Laser Energetics. It increases the sensitivity and spatial resolution in planar direct-drive hydrodynamic stability experiments, relevant to inertial confinement fusion research. It has been designed to work as the optical front end of the PJX - a high-current, high-dynamic-range x-ray streak camera. Optical design optimization, results from numerical ray tracing, mirror-coating choice, and characterization have been described previously [O. V. Gotchev, et al., Rev. Sci. Instrum. 74, 2178 (2003)]. This work highlights the optics' unique mechanical design and flexibility and considers certain applications that benefit from it. Characterization of the microscope's resolution in terms of its modulation transfer function over the field of view is shown. Recent results from hydrodynamic stability experiments, diagnosed with the optic and the PJX, are provided to confirm the microscope's advantages as a high-resolution, high-throughput x-ray optical front end for streaked imaging

Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

Science.gov (United States)

Redding, Brandon; Schwab, Mark J.; Pan, Yong-le

2015-01-01

The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field. PMID:26247952

Noise and detection in ''optical'' modulation spectroscopy

International Nuclear Information System (INIS)

Montelatici, V.

1975-01-01

The measuring techniques suitable for ''optical'' modulation spectroscopy are analyzed and source of noise identified. The choice of optical detector is for photoelectrical devices. It is shown that the shot noise of phototubes is the most important noise source

Angioid streaks in a case of Camurati–Engelmann disease

Directory of Open Access Journals (Sweden)

Betül Tugcu

2017-01-01

Full Text Available Camurati–Engelmann disease (CED is a rare autosomal dominant disease with various phenotypic expressions. The hallmark of the disease is bilateral symmetric diaphyseal hyperostosis of the long bones with progressive involvement of the metaphysis. Ocular manifestations occur rarely and mainly result from bony overgrowth of the orbit and optic canal stenosis. We report a case of CED showing angioid streaks (ASs in both fundi with no macular involvement and discuss the possible theories of the pathogenesis of AS in this disease.

Resonant Optical Gradient Force Interaction for Nano-Imaging and-Spectroscopy

Science.gov (United States)

2016-07-19

New J. Phys. 18 (2016) 053042 doi:10.1088/1367-2630/18/5/053042 PAPER Resonant optical gradient force interaction for nano-imaging and -spectroscopy...HonghuaUYang andMarkus BRaschke Department of Physics , Department of Chemistry, and JILA,University of Colorado, Boulder, CO80309,USA E-mail...honghua.yang@colorado.edu andmarkus.raschke@colorado.edu Keywords:nano spectroscopy, optical force, near-field optics Abstract The optical gradient force

Traveling wave deflector design for femtosecond streak camera

International Nuclear Information System (INIS)

Pei, Chengquan; Wu, Shengli; Luo, Duan; Wen, Wenlong; Xu, Junkai; Tian, Jinshou; Zhang, Minrui; Chen, Pin; Chen, Jianzhong; Liu, Rong

2017-01-01

In this paper, a traveling wave deflection deflector (TWD) with a slow-wave property induced by a microstrip transmission line is proposed for femtosecond streak cameras. The pass width and dispersion properties were simulated. In addition, the dynamic temporal resolution of the femtosecond camera was simulated by CST software. The results showed that with the proposed TWD a femtosecond streak camera can achieve a dynamic temporal resolution of less than 600 fs. Experiments were done to test the femtosecond streak camera, and an 800 fs dynamic temporal resolution was obtained. Guidance is provided for optimizing a femtosecond streak camera to obtain higher temporal resolution.

Traveling wave deflector design for femtosecond streak camera

Energy Technology Data Exchange (ETDEWEB)

Pei, Chengquan; Wu, Shengli [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi’an 710049 (China); Luo, Duan [Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wen, Wenlong [Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); Xu, Junkai [Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Tian, Jinshou, E-mail: tianjs@opt.ac.cn [Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006 (China); Zhang, Minrui; Chen, Pin [Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Jianzhong [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi’an 710049 (China); Liu, Rong [Xi' an Technological University, Xi' an 710021 (China)

2017-05-21

In this paper, a traveling wave deflection deflector (TWD) with a slow-wave property induced by a microstrip transmission line is proposed for femtosecond streak cameras. The pass width and dispersion properties were simulated. In addition, the dynamic temporal resolution of the femtosecond camera was simulated by CST software. The results showed that with the proposed TWD a femtosecond streak camera can achieve a dynamic temporal resolution of less than 600 fs. Experiments were done to test the femtosecond streak camera, and an 800 fs dynamic temporal resolution was obtained. Guidance is provided for optimizing a femtosecond streak camera to obtain higher temporal resolution.

Brillouin micro-spectroscopy through aberrations via sensorless adaptive optics

Science.gov (United States)

Edrei, Eitan; Scarcelli, Giuliano

2018-04-01

Brillouin spectroscopy is a powerful optical technique for non-contact viscoelastic characterizations which has recently found applications in three-dimensional mapping of biological samples. Brillouin spectroscopy performances are rapidly degraded by optical aberrations and have therefore been limited to homogenous transparent samples. In this work, we developed an adaptive optics (AO) configuration designed for Brillouin scattering spectroscopy to engineer the incident wavefront and correct for aberrations. Our configuration does not require direct wavefront sensing and the injection of a "guide-star"; hence, it can be implemented without the need for sample pre-treatment. We used our AO-Brillouin spectrometer in aberrated phantoms and biological samples and obtained improved precision and resolution of Brillouin spectral analysis; we demonstrated 2.5-fold enhancement in Brillouin signal strength and 1.4-fold improvement in axial resolution because of the correction of optical aberrations.

Large-Grazing-Angle, Multi-Image Kirkpatrick-Baez Microscope as the Front End to a High-Resolution Streak Camera for OMEGA

International Nuclear Information System (INIS)

Gotchev, O.V.; Hayes, L.J.; Jaanimagi, P.A.; Knauer, J.P.; Marshall, F.J.; Meyerhofer, D. D.

2003-01-01

(B204)A new, high-resolution x-ray microscope with a large grazing angle has been developed, characterized, and fielded at the Laboratory for Laser Energetics. It increases the sensitivity and spatial resolution in planar direct-drive hydrodynamic stability experiments, relevant to inertial confinement fusion (ICF) research. It has been designed to work as the optical front end of the PJX-a high-current, high-dynamic-range x-ray streak camera. Optical design optimization, results from numerical ray tracing, mirror-coating choice, and characterization have been described previously [O. V. Gotchev, et al./Rev. Sci. Instrum. 74, 2178 (2003)]. This work highlights the optics' unique mechanical design and flexibility and considers certain applications that benefit from it. Characterization of the microscope's resolution in terms of its modulation transfer function (MTF) over the field of view is shown. Recent results from hydrodynamic stability experiments, diagnosed with the optic and the PJX, are provided to confirm the microscope's advantages as a high-resolution, high-throughput x-ray optical front end for streaked imaging

Ultra fast x-ray streak camera

International Nuclear Information System (INIS)

Coleman, L.W.; McConaghy, C.F.

1975-01-01

A unique ultrafast x-ray sensitive streak camera, with a time resolution of 50psec, has been built and operated. A 100A thick gold photocathode on a beryllium vacuum window is used in a modified commerical image converter tube. The X-ray streak camera has been used in experiments to observe time resolved emission from laser-produced plasmas. (author)

Dynamic range studies of the RCA streak tube in the LLL streak camera

International Nuclear Information System (INIS)

Thomas, S.W.; Phillips, G.E.

1979-01-01

As indicated by tests on several cameras, the dynamic range of the Lawrence Livermore Laboratory streak-camera system appears to be about two orders of magnitude greater than those reported for other systems for 10- to 200-ps pulses. The lack of a fine mesh grid in the RCA streak tube used in these cameras probably contributes to a lower system dynamic noise and therefore raises the dynamic range. A developmental tube with a mesh grid was tested and supports this conjecture. Order-of-magnitude variations in input slit width do not affect the spot size on the phosphor or the dynamic range of the RCA tube. (author)

Optical spectroscopy for food and beverages control

Science.gov (United States)

Mignani, Anna Grazia; Ciaccheri, Leonardo; Mencaglia, Andrea Azelio

2011-08-01

A selection of spectroscopy-based, fiber optic and micro-optic devices is presented. They have been designed and tested for monitoring the quality and safety of typical foodstuffs. The VIS-NIR spectra, considered as product fingerprints, allowed to discriminating the geographic region of production and to detecting nutritional and nutraceutic indicators.

Supraconductor magnet for optical spectroscopy

International Nuclear Information System (INIS)

Levy, G.; Buhler, S.

1985-01-01

A superconductive magnet system for optic spectroscopy has been built. It includes an elaborate support structure, a LN2/LHe cryostat with its supplies and controls and a superconductive magnet of the split pole type equipped with a superconductive switch. A vertically introduced sample in the LHe bath, on request subcooled down to 2.2K is observed through two optical passages. Magnet characteristics are as follows : - clear bore 35mm - clear split 20mm - central field 6.33 Teslas - homogeneity over 10mm D.S.V.: 1% [fr

Streak-photographic investigation of shock wave emission after laser-induced plasma formation in water

Science.gov (United States)

Noack, Joachim; Vogel, Alfred

1995-05-01

The shock wave emission after dielectric breakdown in water was investigated to assess potential shock wave effects in plasma mediated tissue ablation and intraocular photodisruption. Of particular interest was the dependence of shock wave pressure as a function of distance from the plasma for different laser pulse energies. We have generated plasmas in water with a Nd:YAG laser system delivering pulses of 6 ns duration. The pulses, with energies between 0.4 and 36 mJ (approximately equals 180 times threshold), were focused into a cuvette containing distilled water. The shock wave was visualized with streak photography combined with a schlieren technique. An important advantage of this technique is that the shock position as a function of time can directly be obtained from a single streak and hence a single event. Other methods (e.g. flash photography or passage time measurements between fixed locations) in contrast rely on reproducible events. Using the shock wave speed obtained from the streak images, shock wave peak pressures were calculated providing detailed information on the propagation of the shock. The shock peak pressure as a function of distance r from the optical axis was found to decrease faster than 1/r2 in regions up to distances of 100-150 micrometers . For larger distances it was found to be roughly proportional to 1/r. The scaling law for maximum shock pressure p, at a given distance was found to be proportional to the square root of the laser pulse energy E for distances of 50-200 micrometers from the optical axis.

Streaking tremor in Cascadia

Science.gov (United States)

Vidale, J. E.; Ghosh, A.; Sweet, J. R.; Creager, K. C.; Wech, A.; Houston, H.

2009-12-01

Details of tremor deep in subduction zones is damnably difficult to glimpse because of the lack of crisp initial arrivals, low waveform coherence, uncertain focal mechanisms, and the probability of simultaneous activity across extended regions. Yet such details hold out the best hope to illuminate the unknown mechanisms underlying episodic tremor and slip. Attacking this problem with brute force, we pointed a small, very dense seismic array down at the migration path of a good-sized episodic tremor and slip (ETS) event. In detail, it was an 84-element, 1300-m-aperture temporary seismic array in northern Washington, and the migration path of the May 2008 ETS event was 30-40 km directly underneath. Our beamforming technique tracked the time, incident angle, and azimuth of tremor radiation in unprecedented detail. We located the tremor by assuming it occurs on the subduction interface, estimated relative tremor moment released by each detected tremor window, and mapped it on the interface [Ghosh et al., GRL, 2009]. Fortunately for our ability to image it, the tremor generally appears to emanate from small regions, and we were surprised by how steadily the regions migrated with time. For the first time in Cascadia, we found convergence-parallel transient streaks of tremor migrating at velocities of several tens of km/hr, with movement in both up- and down-dip directions. Similar patterns have been seen in Japan [Shelly, G3, 2007]. This is in contrast to the long-term along-strike marching of tremor at 10 km/day. These streaks tend to propagate steadily and often repeat the same track on the interface multiple times. They light up persistent moment patches on the interface by a combination of increased amplitude and longer residence time within the patches. The up- and down-dip migration dominates the 2 days of tremor most clearly imaged by our array. The tendency of the streaks to fill in bands is the subject of the presentation of Ghosh et al. here. The physical

Optical Fiber Sensing Based on Reflection Laser Spectroscopy

Directory of Open Access Journals (Sweden)

Gianluca Gagliardi

2010-03-01

Full Text Available An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

Optical spectroscopy techniques can accurately distinguish benign and malignant renal tumours.

Science.gov (United States)

Couapel, Jean-Philippe; Senhadji, Lotfi; Rioux-Leclercq, Nathalie; Verhoest, Grégory; Lavastre, Olivier; de Crevoisier, Renaud; Bensalah, Karim

2013-05-01

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: There is little known about optical spectroscopy techniques ability to evaluate renal tumours. This study shows for the first time the ability of Raman and optical reflectance spectroscopy to distinguish benign and malignant renal tumours in an ex vivo environment. We plan to develop this optical assistance in the operating room in the near future. To evaluate the ability of Raman spectroscopy (RS) and optical reflectance spectroscopy (ORS) to distinguish benign and malignant renal tumours at surgery. Between March and October 2011, RS and ORS spectra were prospectively acquired on surgical renal specimens removed for suspicion of renal cell carcinoma (RCC). Optical measurements were done immediately after surgery. Optical signals were normalised to ensure comparison between spectra. Initial and final portions of each spectrum were removed to avoid artefacts. A support vector machine (SVM) was built and tested using a leave-one-out cross-validation. Classification scores, including accuracy, sensitivity and specificity were calculated on the entire population and in patients with tumours of 700 optical spectra were obtained and submitted to SVM classification. The SVM could recognise benign and malignant renal tumours with an accuracy of 96% (RS) and 88% (ORS) in the whole population and with an accuracy of 93% (RS) and 95% (ORS) in the present subset of small renal tumours (Benign and malignant renal tumours can be accurately discriminated by a combination of RS and ORS. In vivo experiments are needed to further assess the value of optical spectroscopy techniques. © 2012 BJU International.

Compact streak camera for the shock study of solids by using the high-pressure gas gun

Science.gov (United States)

Nagayama, Kunihito; Mori, Yasuhito

1993-01-01

For the precise observation of high-speed impact phenomena, a compact high-speed streak camera recording system has been developed. The system consists of a high-pressure gas gun, a streak camera, and a long-pulse dye laser. The gas gun installed in our laboratory has a muzzle of 40 mm in diameter, and a launch tube of 2 m long. Projectile velocity is measured by the laser beam cut method. The gun is capable of accelerating a 27 g projectile up to 500 m/s, if helium gas is used as a driver. The system has been designed on the principal idea that the precise optical measurement methods developed in other areas of research can be applied to the gun study. The streak camera is 300 mm in diameter, with a rectangular rotating mirror which is driven by an air turbine spindle. The attainable streak velocity is 3 mm/microsecond(s) . The size of the camera is rather small aiming at the portability and economy. Therefore, the streak velocity is relatively slower than the fast cameras, but it is possible to use low-sensitivity but high-resolution film as a recording medium. We have also constructed a pulsed dye laser of 25 - 30 microsecond(s) in duration. The laser can be used as a light source of observation. The advantage for the use of the laser will be multi-fold, i.e., good directivity, almost single frequency, and so on. The feasibility of the system has been demonstrated by performing several experiments.

Raman Spectroscopy with simple optic components

International Nuclear Information System (INIS)

Mendoza, Mario; Cunya, Eduardo; Olivera, Paula

2014-01-01

Raman Spectroscopy is .a high resolution photonics technique that provides chemical and structural information of almost any material, organic or inorganic compound. In this report we describe the implementation of a system based on the principle of Raman scattering, developed to analyze solid samples. The spectrometer integrates an optical bench coupled to an optical fiber and a green laser source of 532 nm. The spectrometer was tested obtaining the Naphthalene and the Yellow 74 Pigment Raman patterns. (authors).

Multislit streak photography for plasma dynamics studies

International Nuclear Information System (INIS)

Tou, T.Y.; Lee, S.

1988-01-01

A microscope slide with several transparent slits installed in a streak camera is used to record time-resolved two-dimensional information when a curved luminous plasma sheath traverses these slits. Applying this method to the plasma focus experiment, the axial run-down trajectory and the shapes of the plasma sheath at various moments can be obtained from a single streak photograph

A compact large-format streak tube for imaging lidar

Science.gov (United States)

Hui, Dandan; Luo, Duan; Tian, Liping; Lu, Yu; Chen, Ping; Wang, Junfeng; Sai, Xiaofeng; Wen, Wenlong; Wang, Xing; Xin, Liwei; Zhao, Wei; Tian, Jinshou

2018-04-01

The streak tubes with a large effective photocathode area, large effective phosphor screen area, and high photocathode radiant sensitivity are essential for improving the field of view, depth of field, and detectable range of the multiple-slit streak tube imaging lidar. In this paper, a high spatial resolution, large photocathode area, and compact meshless streak tube with a spherically curved cathode and screen is designed and tested. Its spatial resolution reaches 20 lp/mm over the entire Φ28 mm photocathode working area, and the simulated physical temporal resolution is better than 30 ps. The temporal distortion in our large-format streak tube, which is shown to be a non-negligible factor, has a minimum value as the radius of curvature of the photocathode varies. Furthermore, the photocathode radiant sensitivity and radiant power gain reach 41 mA/W and 18.4 at the wavelength of 550 nm, respectively. Most importantly, the external dimensions of our streak tube are no more than Φ60 mm × 110 mm.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

Science.gov (United States)

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.; Hartig, K. C.; Phillips, M. C.

2018-06-01

Rapid, in-field, and non-contact isotopic analysis of solid materials is extremely important to a large number of applications, such as nuclear nonproliferation monitoring and forensics, geochemistry, archaeology, and biochemistry. Presently, isotopic measurements for these and many other fields are performed in laboratory settings. Rapid, in-field, and non-contact isotopic analysis of solid material is possible with optical spectroscopy tools when combined with laser ablation. Laser ablation generates a transient vapor of any solid material when a powerful laser interacts with a sample of interest. Analysis of atoms, ions, and molecules in a laser-produced plasma using optical spectroscopy tools can provide isotopic information with the advantages of real-time analysis, standoff capability, and no sample preparation requirement. Both emission and absorption spectroscopy methods can be used for isotopic analysis of solid materials. However, applying optical spectroscopy to the measurement of isotope ratios from solid materials presents numerous challenges. Isotope shifts arise primarily due to variation in nuclear charge distribution caused by different numbers of neutrons, but the small proportional nuclear mass differences between nuclei of various isotopes lead to correspondingly small differences in optical transition wavelengths. Along with this, various line broadening mechanisms in laser-produced plasmas and instrumental broadening generated by the detection system are technical challenges frequently encountered with emission-based optical diagnostics. These challenges can be overcome by measuring the isotope shifts associated with the vibronic emission bands from molecules or by using the techniques of laser-based absorption/fluorescence spectroscopy to marginalize the effect of instrumental broadening. Absorption and fluorescence spectroscopy probe the ground state atoms existing in the plasma when it is cooler, which inherently provides narrower

Betting Decision Under Break-Streak Pattern: Evidence from Casino Gaming.

Science.gov (United States)

Fong, Lawrence Hoc Nang; So, Amy Siu Ian; Law, Rob

2016-03-01

Cognitive bias is prevalent among gamblers, especially those with gambling problems. Grounded in the heuristics theories, this study contributes to the literature by examining a cognitive bias triggered by the break streak pattern in the casino setting. We postulate that gamblers tend to bet on the latest outcome when there is a break-streak pattern. Moreover, three determinants of the betting decision under break-streak pattern, including the streak length of the alternative outcome, the frequency of the latest outcome, and gender, were identified and examined in this study. A non-participatory observational study was conducted among the Cussec gamblers in a casino in Macao. An analysis of 1229 bets confirms our postulation, particularly when the streak of the alternative outcome is long, the latest outcome is frequent, and the gamblers are females. The findings provide meaningful implications for casino management and public policymakers regarding the minimization of gambling harm.

Picosecond X-ray streak camera dynamic range measurement

Energy Technology Data Exchange (ETDEWEB)

Zuber, C., E-mail: celine.zuber@cea.fr; Bazzoli, S.; Brunel, P.; Gontier, D.; Raimbourg, J.; Rubbelynck, C.; Trosseille, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Fronty, J.-P.; Goulmy, C. [Photonis SAS, Avenue Roger Roncier, BP 520, 19106 Brive Cedex (France)

2016-09-15

Streak cameras are widely used to record the spatio-temporal evolution of laser-induced plasma. A prototype of picosecond X-ray streak camera has been developed and tested by Commissariat à l’Énergie Atomique et aux Énergies Alternatives to answer the Laser MegaJoule specific needs. The dynamic range of this instrument is measured with picosecond X-ray pulses generated by the interaction of a laser beam and a copper target. The required value of 100 is reached only in the configurations combining the slowest sweeping speed and optimization of the streak tube electron throughput by an appropriate choice of high voltages applied to its electrodes.

Two-color mid-infrared spectroscopy of optically doped semiconductors

International Nuclear Information System (INIS)

Forcales, M.; Klik, M.A.J.; Vinh, N.Q.; Phillips, J.; Wells, J-P.R.; Gregorkiewicz, T.

2003-01-01

Optical doping is an attractive method to tailor photonic properties of semiconductor matrices for development of solid-state electroluminescent structures. For practical applications, thermal stability of emission obtained from these materials is required. Thermal processes can be conveniently investigated by two-color spectroscopy in the visible and the mid-infrared. Free-electron laser is a versatile high-brilliance source of radiation in the latter spectral range. In this contribution, we briefly review some of the results obtained recently by the two-color spectroscopy with a free-electron laser in different semiconductors optically doped with rare earth and transition metal ions. Effects leading to both enhancement and quenching of emission from optical dopants will be presented. For InP:Yb, Si:Er, and Si:Cu activation of particular optically induced non-radiative recombination paths will be shown. For Si:Er and Si:Ag, observation of a low temperature optical memory effect will be reported

Transition due to streamwise streaks in a supersonic flat plate boundary layer

Science.gov (United States)

Paredes, Pedro; Choudhari, Meelan M.; Li, Fei

2016-12-01

Transition induced by stationary streaks undergoing transient growth in a supersonic flat plate boundary layer flow is studied using numerical computations. While the possibility of strong transient growth of small-amplitude stationary perturbations in supersonic boundary layer flows has been demonstrated in previous works, its relation to laminar-turbulent transition cannot be established within the framework of linear disturbances. Therefore, this paper investigates the nonlinear evolution of initially linear optimal disturbances that evolve into finite amplitude streaks in the downstream region, and then studies the modal instability of those streaks as a likely cause for the onset of bypass transition. The nonmodal evolution of linearly optimal stationary perturbations in a supersonic, Mach 3 flat plate boundary layer is computed via the nonlinear plane-marching parabolized stability equations (PSE) for stationary perturbations, or equivalently, the perturbation form of parabolized Navier-Stokes equations. To assess the effect of the nonlinear finite-amplitude streaks on transition, the linear form of plane-marching PSE is used to investigate the instability of the boundary layer flow modified by the spanwise periodic streaks. The onset of transition is estimated using an N -factor criterion based on modal amplification of the secondary instabilities of the streaks. In the absence of transient growth disturbances, first mode instabilities in a Mach 3, zero pressure gradient boundary layer reach N =10 at Rex≈107 . However, secondary instability modes of the stationary streaks undergoing transient growth are able to achieve the same N -factor at Rex<2 ×106 when the initial streak amplitude is sufficiently large. In contrast to the streak instabilities in incompressible flows, subharmonic instability modes with twice the fundamental spanwise wavelength of the streaks are found to have higher amplification ratios than the streak instabilities at fundamental

Sweep devices for picosecond image-converter streak cameras

International Nuclear Information System (INIS)

Cunin, B.; Miehe, J.A.; Sipp, B.; Schelev, M.Ya.; Serduchenko, J.N.; Thebault, J.

1979-01-01

Four different sweep devices based on microwave tubes, avalanche transistors, krytrons, and laser-triggered spark gaps are treated in detail. These control circuits are developed for picosecond image-converter cameras and generate sweep pulses providing streak speeds in the range of 10 7 to 5x10 10 cm/sec with maximum time resolution better than 10 -12 sec. Special low-jitter triggering schemes reduce the jitter to less than 5x10 -11 sec. Some problems arising in the construction and matching of the sweep devices and image-streak tube are discussed. Comparative parameters of nanosecond switching elements are presented. The results described can be used by other authors involved in streak camera development

Design of neutron streak camera for fusion diagnostics

International Nuclear Information System (INIS)

Wang, C.L.; Kalibjian, R.; Singh, M.S.

1982-06-01

The D-T burn time for advanced laser-fusion targets is calculated to be very short, 2 . Each fission fragment leaving the cathode generates 400 secondary electrons that are all < 20 eV. These electrons are focussed to a point with an extractor and an anode, and are then purified with an electrostatic deflector. The electron beam is streaked and detected with the standard streak camera techniques. Careful shielding is needed for x-rays from the fusion target and general background. It appears that the neutron streak camera can be a viable and unique tool for studying temporal history of fusion burns in D-T plasmas of a few keV ion temperature

Optical spectroscopy using gas-phase femtosecond laser filamentation.

Science.gov (United States)

Odhner, Johanan; Levis, Robert

2014-01-01

Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.

A New Optical Design for Imaging Spectroscopy

Science.gov (United States)

Thompson, K. L.

2002-05-01

We present an optical design concept for imaging spectroscopy, with some advantages over current systems. The system projects monochromatic images onto the 2-D array detector(s). Faint object and crowded field spectroscopy can be reduced first using image processing techniques, then building the spectrum, unlike integral field units where one must first extract the spectra, build data cubes from these, then reconstruct the target's integrated spectral flux. Like integral field units, all photons are detected simultaneously, unlike tunable filters which must be scanned through the wavelength range of interest and therefore pay a sensitivity pentalty. Several sample designs are presented, including an instrument optimized for measuring intermediate redshift galaxy cluster velocity dispersions, one designed for near-infrared ground-based adaptive optics, and one intended for space-based rapid follow-up of transient point sources such as supernovae and gamma ray bursts.

Triggered streak and framing rotating-mirror cameras

International Nuclear Information System (INIS)

Huston, A.E.; Tabrar, A.

1975-01-01

A pulse motor has been developed which enables a mirror to be rotated to speeds in excess of 20,000 rpm with 10 -4 s. High-speed cameras of both streak and framing type have been assembled which incorporate this mirror drive, giving streak writing speeds up to 2,000ms -1 , and framing speeds up to 500,000 frames s -1 , in each case with the capability of triggering the camera from the event under investigation. (author)

Orientation tuning of contrast masking caused by motion streaks.

Science.gov (United States)

Apthorp, Deborah; Cass, John; Alais, David

2010-08-01

We investigated whether the oriented trails of blur left by fast-moving dots (i.e., "motion streaks") effectively mask grating targets. Using a classic overlay masking paradigm, we varied mask contrast and target orientation to reveal underlying tuning. Fast-moving Gaussian blob arrays elevated thresholds for detection of static gratings, both monoptically and dichoptically. Monoptic masking at high mask (i.e., streak) contrasts is tuned for orientation and exhibits a similar bandwidth to masking functions obtained with grating stimuli (∼30 degrees). Dichoptic masking fails to show reliable orientation-tuned masking, but dichoptic masks at very low contrast produce a narrowly tuned facilitation (∼17 degrees). For iso-oriented streak masks and grating targets, we also explored masking as a function of mask contrast. Interestingly, dichoptic masking shows a classic "dipper"-like TVC function, whereas monoptic masking shows no dip and a steeper "handle". There is a very strong unoriented component to the masking, which we attribute to transiently biased temporal frequency masking. Fourier analysis of "motion streak" images shows interesting differences between dichoptic and monoptic functions and the information in the stimulus. Our data add weight to the growing body of evidence that the oriented blur of motion streaks contributes to the processing of fast motion signals.

Angioid streaks, clinical course, complications, and current therapeutic management

Directory of Open Access Journals (Sweden)

Ilias Georgalas

2008-12-01

Full Text Available Ilias Georgalas1, Dimitris Papaconstantinou2, Chrysanthi Koutsandrea2, George Kalantzis2, Dimitris Karagiannis2, Gerasimos Georgopoulos2, Ioannis Ladas21Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, NHS, Athens, Greece; 2Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, University of Athens, Athens, GreeceAbstract: Angioid streaks are visible irregular crack-like dehiscences in Bruch’s membrane that are associated with atrophic degeneration of the overlying retinal pigmented epithelium. Angioid streaks may be associated with pseudoxanthoma elasticum, Paget’s disease, sickle-cell anemia, acromegaly, Ehlers–Danlos syndrome, and diabetes mellitus, but also appear in patients without any systemic disease. Patients with angioid streaks are generally asymptomatic, unless the lesions extend towards the foveola or develop complications such as traumatic Bruch’s membrane rupture or macular choroidal neovascularization (CNV. The visual prognosis in patients with CNV secondary to angioid streaks if untreated, is poor and most treatment modalities, until recently, have failed to limit the devastating impact of CNV in central vision. However, it is likely that treatment with antivascular endothelial growth factor, especially in treatment-naive eyes to yield favorable results in the future and this has to be investigated in future studies.Keywords: angioid streaks, pseudoxanthoma elasticum, choroidal neovascularization

Earth aeolian wind streaks: Comparison to wind data from model and stations

Science.gov (United States)

Cohen-Zada, A. L.; Maman, S.; Blumberg, D. G.

2017-05-01

Wind streak is a collective term for a variety of aeolian features that display distinctive albedo surface patterns. Wind streaks have been used to map near-surface winds and to estimate atmospheric circulation patterns on Mars and Venus. However, because wind streaks have been studied mostly on Mars and Venus, much of the knowledge regarding the mechanism and time frame of their formation and their relationship to the atmospheric circulation cannot be verified. This study aims to validate previous studies' results by a comparison of real and modeled wind data with wind streak orientations as measured from remote-sensing images. Orientations of Earth wind streaks were statistically correlated to resultant drift direction (RDD) values calculated from reanalysis and wind data from 621 weather stations. The results showed good agreement between wind streak orientations and reanalysis RDD (r = 0.78). A moderate correlation was found between the wind streak orientations and the weather station data (r = 0.47); a similar trend was revealed on a regional scale when the analysis was performed by continent, with r ranging from 0.641 in North America to 0.922 in Antarctica. At sites where wind streak orientations did not correspond to the RDDs (i.e., a difference of 45°), seasonal and diurnal variations in the wind flow were found to be responsible for deviation from the global pattern. The study thus confirms that Earth wind streaks were formed by the present wind regime and they are indeed indicative of the long-term prevailing wind direction on global and regional scales.

Optical Two-Dimensional Spectroscopy of Disordered Semiconductor Quantum Wells and Quantum Dots

Energy Technology Data Exchange (ETDEWEB)

Cundiff, Steven T. [Univ. of Colorado, Boulder, CO (United States)

2016-05-03

This final report describes the activities undertaken under grant "Optical Two-Dimensional Spectroscopy of Disordered Semiconductor Quantum Wells and Quantum Dots". The goal of this program was to implement optical 2-dimensional Fourier transform spectroscopy and apply it to electronic excitations, including excitons, in semiconductors. Specifically of interest are quantum wells that exhibit disorder due to well width fluctuations and quantum dots. In both cases, 2-D spectroscopy will provide information regarding coupling among excitonic localization sites.

Fabry-Perot interferometry using an image-intensified rotating-mirror streak camera

International Nuclear Information System (INIS)

Seitz, W.L.; Stacy, H.L.

1983-01-01

A Fabry-Perot velocity interferometer system is described that uses a modified rotating mirror streak camera to recrod the dynamic fringe positions. A Los Alamos Model 72B rotating-mirror streak camera, equipped with a beryllium mirror, was modified to include a high aperture (f/2.5) relay lens and a 40-mm image-intensifier tube such that the image normally formed at the film plane of the streak camera is projected onto the intensifier tube. Fringe records for thin (0.13 mm) flyers driven by a small bridgewire detonator obtained with a Model C1155-01 Hamamatsu and Model 790 Imacon electronic streak cameras are compared with those obtained with the image-intensified rotating-mirror streak camera (I 2 RMC). Resolution comparisons indicate that the I 2 RMC gives better time resolution than either the Hamamatsu or the Imacon for total writing times of a few microseconds or longer

Approaches to diagnosis and detection of cassava brown streak ...

African Journals Online (AJOL)

Cassava brown streak disease (CBSD) has been a problem in the East African coastal cassava growing areas for more than 70 years. The disease is caused by successful infection with Cassava Brown Streak Virus (CBSV) (Family, Potyviridae: Genus, Ipomovirus). Diagnosis of CBSD has for long been primarily leaf ...

Two-dimensional spectroscopy at infrared and optical frequencies

OpenAIRE

Hochstrasser, Robin M.

2007-01-01

This Perspective on multidimensional spectroscopy in the optical and infrared spectral regions focuses on the principles and the scientific and technical challenges facing these new fields. The methods hold great promise for advances in the visualization of time-dependent structural changes in complex systems ranging from liquids to biological assemblies, new materials, and fundamental physical processes. The papers in this special feature on multidimensional spectroscopy in chemistry, physic...

Characterization results from several commercial soft X-ray streak cameras

Science.gov (United States)

Stradling, G. L.; Studebaker, J. K.; Cavailler, C.; Launspach, J.; Planes, J.

The spatio-temporal performance of four soft X-ray streak cameras has been characterized. The objective in evaluating the performance capability of these instruments is to enable us to optimize experiment designs, to encourage quantitative analysis of streak data and to educate the ultra high speed photography and photonics community about the X-ray detector performance which is available. These measurements have been made collaboratively over the space of two years at the Forge pulsed X-ray source at Los Alamos and at the Ketjak laser facility an CEA Limeil-Valenton. The X-ray pulse lengths used for these measurements at these facilities were 150 psec and 50 psec respectively. The results are presented as dynamically-measured modulation transfer functions. Limiting temporal resolution values were also calculated. Emphasis is placed upon shot noise statistical limitations in the analysis of the data. Space charge repulsion in the streak tube limits the peak flux at ultra short experiments duration times. This limit results in a reduction of total signal and a decrease in signal to no ise ratio in the streak image. The four cameras perform well with 20 1p/mm resolution discernable in data from the French C650X, the Hadland X-Chron 540 and the Hamamatsu C1936X streak cameras. The Kentech X-ray streak camera has lower modulation and does not resolve below 10 1p/mm but has a longer photocathode.

Postprocessing method to clean up streaks due to noisy detectors

International Nuclear Information System (INIS)

Tuy, H.K.; Mattson, R.A.

1990-01-01

This paper reports that occasionally, one of the thousands of detectors in a CT scanner will intermittently produce erroneous data, creating streaks in the reconstructed image. The authors propose a method to identify and clean up the streaks automatically. To find the rays along which the data values are bad, a binary image registering the edges of the original image is created. Forward projection is applied to the binary image to single out edges along rays. Data along views containing the identified bad rays are estimated by means of forward projecting the original image. Back projection of the negative of the estimated convolved data along these views onto the streaky image will remove streaks from the image. Image enhancement is achieved by means of back projecting the convolved data estimated from the image after the streak removal along views of bad rays

Dual-modal cancer detection based on optical pH sensing and Raman spectroscopy.

Science.gov (United States)

Kim, Soogeun; Lee, Seung Ho; Min, Sun Young; Byun, Kyung Min; Lee, Soo Yeol

2017-10-01

A dual-modal approach using Raman spectroscopy and optical pH sensing was investigated to discriminate between normal and cancerous tissues. Raman spectroscopy has demonstrated the potential for in vivo cancer detection. However, Raman spectroscopy has suffered from strong fluorescence background of biological samples and subtle spectral differences between normal and disease tissues. To overcome those issues, pH sensing is adopted to Raman spectroscopy as a dual-modal approach. Based on the fact that the pH level in cancerous tissues is lower than that in normal tissues due to insufficient vasculature formation, the dual-modal approach combining the chemical information of Raman spectrum and the metabolic information of pH level can improve the specificity of cancer diagnosis. From human breast tissue samples, Raman spectra and pH levels are measured using fiber-optic-based Raman and pH probes, respectively. The pH sensing is based on the dependence of pH level on optical transmission spectrum. Multivariate statistical analysis is performed to evaluate the classification capability of the dual-modal method. The analytical results show that the dual-modal method based on Raman spectroscopy and optical pH sensing can improve the performance of cancer classification. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Raman spectroscopy of optical properties in CdS thin films

Directory of Open Access Journals (Sweden)

Trajić J.

2015-01-01

Full Text Available Properties of CdS thin films were investigated applying atomic force microscopy (AFM and Raman spectroscopy. CdS thin films were prepared by using thermal evaporation technique under base pressure 2 x 10-5 torr. The quality of these films was investigated by AFM spectroscopy. We apply Raman scattering to investigate optical properties of CdS thin films, and reveal existence of surface optical phonon (SOP mode at 297 cm-1. Effective permittivity of mixture were modeled by Maxwell - Garnet approximation. [Projekat Ministarstva nauke Republike Srbije, br. 45003

Control of Vascular Streak Dieback Disease of Cocoa with Flutriafol Fungicides

Directory of Open Access Journals (Sweden)

Febrilia Nur'aini

2014-12-01

Full Text Available Vascular streak dieback caused by the fungus Oncobasidium theobromae is one of the important diseases in cocoa crop in Indonesia. One approach to control the disease is by using fungicides. The aim of this research was to determine the effect of class triazole fungicides to the intensity of the vascular streak dieback disease on cocoa seedling phase, immature and mature cocoa. Experiments were conducted in Kotta Blater, PTPN XII and Kaliwining, Indonesian  Coffee and Cocoa Research Institute. Flutriafol 250 g/l with a concentration 0,05%, 0,1% and 0,15% foliar sprayed on cocoa seedlings, immature and mature cocoa. Active compound combination of Azoxystrobin and Difenoconazole with 0,1% concentration used as a comparation fungicides. The result showed that Flutriafol with 0,05%, 0,1% and 0,15% concentration and Azoxystrobin & Difenoconazol with 0,1% concentration could suppress the vascular streak dieback disease on seedlings. On immature plants, the application of Flutriafol was not effectively suppress the vascular streak dieback disease whereas the fungicide comparison could suppress with the efficacy level of 46.22%. On mature plants,both of fungicides could not suppress the vascular streak dieback disease. Key words: Fungicide, cocoa, vascular streak dieback, triazole, flutriafol, azoxystrobin+difenoconazol

Soft x-ray streak camera for laser fusion applications

International Nuclear Information System (INIS)

Stradling, G.L.

1981-04-01

This thesis reviews the development and significance of the soft x-ray streak camera (SXRSC) in the context of inertial confinement fusion energy development. A brief introduction of laser fusion and laser fusion diagnostics is presented. The need for a soft x-ray streak camera as a laser fusion diagnostic is shown. Basic x-ray streak camera characteristics, design, and operation are reviewed. The SXRSC design criteria, the requirement for a subkilovolt x-ray transmitting window, and the resulting camera design are explained. Theory and design of reflector-filter pair combinations for three subkilovolt channels centered at 220 eV, 460 eV, and 620 eV are also presented. Calibration experiments are explained and data showing a dynamic range of 1000 and a sweep speed of 134 psec/mm are presented. Sensitivity modifications to the soft x-ray streak camera for a high-power target shot are described. A preliminary investigation, using a stepped cathode, of the thickness dependence of the gold photocathode response is discussed. Data from a typical Argus laser gold-disk target experiment are shown

Laparoscopic Removal of Streak Gonads in Turner Syndrome.

Science.gov (United States)

Mandelberger, Adrienne; Mathews, Shyama; Andikyan, Vaagn; Chuang, Linus

To demonstrate the skills necessary for complete resection of bilateral streak gonads in Turner syndrome. Video case presentation with narration highlighting the key techniques used. The video was deemed exempt from formal review by our institutional review board. Turner syndrome is a form of gonadal dysgenesis that affects 1 in 2500 live births. Patients often have streak gonads and may present with primary amenorrhea or premature ovarian failure. Patients with a mosaic karyotype that includes a Y chromosome are at increased risk for gonadoblastoma and subsequent transformation into malignancy. Gonadectomy is recommended for these patients, typically at adolescence. Streak gonads can be difficult to identify, and tissue margins are often in close proximity to critical retroperitoneal structures. Resection can be technically challenging and requires a thorough understanding of retroperitoneal anatomy and precise dissection techniques to ensure complete removal. Laparoscopic approach to bilateral salpingo-oophorectomy of streak gonads. Retroperitoneal dissection and ureterolysis are performed, with the aid of the Ethicon Harmonic Ace, to ensure complete gonadectomy. Careful and complete resection of gonadal tissue in the hands of a skilled laparoscopic surgeon is key for effective cancer risk reduction surgery in Turner syndrome mosaics. Copyright © 2016 AAGL. Published by Elsevier Inc. All rights reserved.

Electronic structure of antiferromagnetic UN and UPtGe single crystals from optical and magneto-optical spectroscopy

International Nuclear Information System (INIS)

Marutzky, M.

2006-01-01

In this thesis the study of the magneto-optical Kerr effect and the determination of the optical constants by means of ellipsometry and Fourier-transformation infrared spectroscopy of UN and UPtGe is described. In UPtGe an optical anisotropy was detected over a spectral range from 6 meV to 32 eV. (HSI)

Optical Spectroscopy to Guide Photodynamic Therapy of Head and Neck Tumors

NARCIS (Netherlands)

Robinson, Dominic J.; Karakullukcu, M. Baris; Kruijt, Bastiaan; Kanick, Stephen Chad; van Veen, Robert P. L.; Amelink, Arjen; Sterenborg, Henricus J. C. M.; Witjes, Max J. H.; Tan, I. Bing

2010-01-01

In contrast to other interstitial applications of photodynamic therapy (PDT), optical guidance or monitoring in the head and neck is at a very early stage of development. The present paper reviews the use of optical approaches, in particular optical spectroscopy, that have been used or have the

Stabilization of the hypersonic boundary layer by finite-amplitude streaks

Science.gov (United States)

Ren, Jie; Fu, Song; Hanifi, Ardeshir

2016-02-01

Stabilization of two-dimensional disturbances in hypersonic boundary layer flows by finite-amplitude streaks is investigated using nonlinear parabolized stability equations. The boundary-layer flows at Mach numbers 4.5 and 6.0 are studied in which both first and second modes are supported. The streaks considered here are driven either by the so-called optimal perturbations (Klebanoff-type) or the centrifugal instability (Görtler-type). When the streak amplitude is in an appropriate range, i.e., large enough to modulate the laminar boundary layer but low enough to not trigger secondary instability, both first and second modes can effectively be suppressed.

Optical frequency comb Faraday rotation spectroscopy

Science.gov (United States)

Johansson, Alexandra C.; Westberg, Jonas; Wysocki, Gerard; Foltynowicz, Aleksandra

2018-05-01

We demonstrate optical frequency comb Faraday rotation spectroscopy (OFC-FRS) for broadband interference-free detection of paramagnetic species. The system is based on a femtosecond doubly resonant optical parametric oscillator and a fast-scanning Fourier transform spectrometer (FTS). The sample is placed in a DC magnetic field parallel to the light propagation. Efficient background suppression is implemented via switching the direction of the field on consecutive FTS scans and subtracting the consecutive spectra, which enables long-term averaging. In this first demonstration, we measure the entire Q- and R-branches of the fundamental band of nitric oxide in the 5.2-5.4 µm range and achieve good agreement with a theoretical model.

Effects of Hot Streak Shape on Rotor Heating in a High-Subsonic Single-Stage Turbine

Science.gov (United States)

Dorney, Daniel J.; Gundy-Burlet, Karen L.; Norvig, Peter (Technical Monitor)

1999-01-01

Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location (clocking) of the hot streak relative to the first-stage vane airfoils can be used to minimize the adverse effects of the hot streak. The effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have also been evaluated. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine operating in high subsonic flow. In addition to a simulation of the baseline turbine, simulations have been performed for circular and elliptical hot streaks of varying sizes in an effort to represent different combustor designs. The predicted results for the baseline simulation show good agreement with the available experimental data. The results of the hot streak simulations indicate: that a) elliptical hot streaks mix more rapidly than circular hot streaks, b) for small hot streak surface area the average rotor temperature is not a strong function of hot streak temperature ratio or shape, and c) hot streaks with larger surface area interact with the secondary flows at the rotor hub endwall, generating an additional high temperature region.

Precision Spectroscopy, Diode Lasers, and Optical Frequency Measurement Technology

Science.gov (United States)

Hollberg, Leo (Editor); Fox, Richard (Editor); Waltman, Steve (Editor); Robinson, Hugh

1998-01-01

This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

Improvements in Off-Center Focusing in an X-ray Streak Camera

International Nuclear Information System (INIS)

McDonald, J W; Weber, F; Holder, J P; Bell, P M

2003-01-01

Due to the planar construction of present x-ray streak tubes significant off-center defocusing is observed in both static and dynamic images taken with one-dimensional resolution slits. Based on the streak tube geometry curved photocathodes with radii of curvature ranging from 3.5 to 18 inches have been fabricated. We report initial off-center focusing performance data on the evaluation of these ''improved'' photocathodes in an X-ray streak camera and an update on the theoretical simulations to predict the optimum cathode curvature

Diving-related visual loss in the setting of angioid streaks: report of two cases.

Science.gov (United States)

Angulo Bocco, Maria I; Spielberg, Leigh; Coppens, Greet; Catherine, Janet; Verougstraete, Claire; Leys, Anita M

2012-01-01

The purpose of this study was to report diving-related visual loss in the setting of angioid streaks. Observational case reports of two patients with angioid streaks suffering sudden visual loss immediately after diving. Two young adult male patients presented with visual loss after diving headfirst. Funduscopy revealed angioid streaks, peau d'orange, subretinal hemorrhages, and ruptures of Bruch membrane. Choroidal neovascularization developed during follow-up. Both patients had an otherwise uneventful personal and familial medical history. In patients with angioid streaks, diving headfirst can lead to subretinal hemorrhages and traumatic ruptures in Bruch membrane and increase the risk of maculopathy. Ophthalmologists should caution patients with angioid streaks against diving headfirst.

Dual-modal cancer detection based on optical pH sensing and Raman spectroscopy

Science.gov (United States)

Kim, Soogeun; Lee, Seung Ho; Min, Sun Young; Byun, Kyung Min; Lee, Soo Yeol

2017-10-01

A dual-modal approach using Raman spectroscopy and optical pH sensing was investigated to discriminate between normal and cancerous tissues. Raman spectroscopy has demonstrated the potential for in vivo cancer detection. However, Raman spectroscopy has suffered from strong fluorescence background of biological samples and subtle spectral differences between normal and disease tissues. To overcome those issues, pH sensing is adopted to Raman spectroscopy as a dual-modal approach. Based on the fact that the pH level in cancerous tissues is lower than that in normal tissues due to insufficient vasculature formation, the dual-modal approach combining the chemical information of Raman spectrum and the metabolic information of pH level can improve the specificity of cancer diagnosis. From human breast tissue samples, Raman spectra and pH levels are measured using fiber-optic-based Raman and pH probes, respectively. The pH sensing is based on the dependence of pH level on optical transmission spectrum. Multivariate statistical analysis is performed to evaluate the classification capability of the dual-modal method. The analytical results show that the dual-modal method based on Raman spectroscopy and optical pH sensing can improve the performance of cancer classification.

Optical characterization of semiconductors infrared, Raman, and photoluminescence spectroscopy

CERN Document Server

Perkowitz, Sidney

1993-01-01

This is the first book to explain, illustrate, and compare the most widely used methods in optics: photoluminescence, infrared spectroscopy, and Raman scattering. Written with non-experts in mind, the book develops the background needed to understand the why and how of each technique, but does not require special knowledge of semiconductors or optics. Each method is illustrated with numerous case studies. Practical information drawn from the authors experience is given to help establish optical facilities, including commercial sources for equipment, and experimental details. For industrial sci

Optical Biopsy Using Tissue Spectroscopy and Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Norman S Nishioka

2003-01-01

Full Text Available ‘Optical biopsy’ or ‘optical diagnostics’ is a technique whereby light energy is used to obtain information about the structure and function of tissues without disrupting them. In fluorescence spectroscopy, light energy (usually provided by a laser is used to excite tissues and the resulting fluorescence provides information about the target tissue. Its major gastrointestinal application has been in the evaluation of colonic polyps, in which it can reliably distinguish malignant from benign lesions. Optical coherence tomography (OCT has been used in the investigation of Barrett’s epithelium (and dysplasia, although a variety of other applications are feasible. For example, OCT could assist in the identification and staging of mucosal and submucosal neoplasms, the grading of inflammation in the stomach and intestine, the diagnosis of biliary tumours and the assessment of villous architecture. OCT differs from endoscopic ultrasound, a complementary modality, in that it has a much higher resolution but lesser depth of penetration. The images correlate with the histopathological appearance of tissues, and the addition of Doppler methods may enable it to evaluate the vascularity of tumours and the amount of blood flow in varices. Refinements in these new optical techniques will likely make them valuable in clinical practice, although their specific roles have yet to be determined.

Spectroscopy of Molecules in Extreme Rotational States Using AN Optical Centrifuge

Science.gov (United States)

Mullin, Amy S.; Toro, Carlos; Echibiri, Geraldine; Liu, Qingnan

2012-06-01

Our lab has developed a high-power optical centrifuge that is capable of trapping and spinning large number densities of molecules into extreme rotational states. By coupling this device with high resolution transient IR absorption spectroscopy, we measure the time-resolved behavior and energy profiles of individual ro-vibrational states of molecules in very high rotational states. Recent results will be discussed on the spectroscopy of new rotational states, collisional dynamics in the optical centrifuge, spatially-dependent energy profiles and possibilities for new chemistry induced by centrifugal forces.

Overall comparison of subpicosecond electron beam diagnostics by the polychromator, the interferometer and the femtosecond streak camera

CERN Document Server

Watanabe, T; Yoshimatsu, T; Sasaki, S; Sugiyama, Y; Ishi, K; Shibata, Y; Kondo, Y; Yoshii, K; Ueda, T; Uesaka, M

2002-01-01

Measurements of longitudinal bunch length of subpicosecond and picosecond electron beams have been performed by three methods with three radiation sources at the 35 MeV S-band twin liner accelerators at Nuclear Engineering Research Laboratory, University of Tokyo. The methods we adopt are the femtosecond streak camera with a nondispersive reflective optics, the coherent transition radiation (CTR) Michelson interferometer and the 10 ch polychromator that detects the spectrum of CTR and coherent diffraction radiation (CDR). The measurements by the two CTR methods were independently done with the streak camera and their results were consistent with one another. As a result, the reliability of the polychromator for the diagnostics of less than picosecond electron bunch and the usefulness of the diagnostics for the single shot measurement were verified. Furthermore, perfect nondestructive diagnostics for subpicosecond bunches was performed utilizing CDR interferometry. Then the good agreement between CDR interfero...

Validation of interventional fiber optic spectroscopy with MR Spectroscopy, MAS-NMR spectroscopy, high-performance thin-layer chromatography, and histopathology for accurate hepatic fat quantification

NARCIS (Netherlands)

Nachabé, R.; Hoorn, J.W.A. van der; Molengraaf, R. van de; Lamerichs, R.; Pikkemaat, J.; Sio, C.F.; Hendriks, B.H.W.; Sterenborg, H.J.C.M.

2012-01-01

Objectives: To validate near-infrared (NIR)-based optical spectroscopy measurements of hepatic fat content using a minimally invasive needle-like probe with integrated optical fibers, enabling real-time feedback during percutaneous interventions. The results were compared with magnetic resonance

Optical trapping and Raman spectroscopy of solid particles.

Science.gov (United States)

Rkiouak, L; Tang, M J; Camp, J C J; McGregor, J; Watson, I M; Cox, R A; Kalberer, M; Ward, A D; Pope, F D

2014-06-21

The heterogeneous interactions of gas molecules on solid particles are crucial in many areas of science, engineering and technology. Such interactions play a critical role in atmospheric chemistry and in heterogeneous catalysis, a key technology in the energy and chemical industries. Investigating heterogeneous interactions upon single levitated particles can provide significant insight into these important processes. Various methodologies exist for levitating micron sized particles including: optical, electrical and acoustic techniques. Prior to this study, the optical levitation of solid micron scale particles has proved difficult to achieve over timescales relevant to the above applications. In this work, a new vertically configured counter propagating dual beam optical trap was optimized to levitate a range of solid particles in air. Silica (SiO2), α-alumina (Al2O3), titania (TiO2) and polystyrene were stably trapped with a high trapping efficiency (Q = 0.42). The longest stable trapping experiment was conducted continuously for 24 hours, and there are no obvious constraints on trapping time beyond this period. Therefore, the methodology described in this paper should be of major benefit to various research communities. The strength of the new technique is demonstrated by the simultaneous levitation and spectroscopic interrogation of silica particles by Raman spectroscopy. In particular, the adsorption of water upon silica was investigated under controlled relative humidity environments. Furthermore, the collision and coagulation behaviour of silica particles with microdroplets of sulphuric acid was followed using both optical imaging and Raman spectroscopy.

Ultrafast chiroptical spectroscopy: Monitoring optical activity in quick time

Directory of Open Access Journals (Sweden)

Hanju Rhee

2011-12-01

Full Text Available Optical activity spectroscopy provides rich structural information of biologically important molecules in condensed phases. However, a few intrinsic problems of conventional method based on electric field intensity measurement scheme prohibited its extension to time domain technique. We have recently developed new types of optical activity spectroscopic methods capable of measuring chiroptical signals with femtosecond pulses. It is believed that these novel approaches will be applied to a variety of ultrafast chiroptical studies.

Spatiotemporal mechanical variation reveals critical role for rho kinase during primitive streak morphogenesis.

Science.gov (United States)

Henkels, Julia; Oh, Jaeho; Xu, Wenwei; Owen, Drew; Sulchek, Todd; Zamir, Evan

2013-02-01

Large-scale morphogenetic movements during early embryo development are driven by complex changes in biochemical and biophysical factors. Current models for amniote primitive streak morphogenesis and gastrulation take into account numerous genetic pathways but largely ignore the role of mechanical forces. Here, we used atomic force microscopy (AFM) to obtain for the first time precise biomechanical properties of the early avian embryo. Our data reveal that the primitive streak is significantly stiffer than neighboring regions of the epiblast, and that it is stiffer than the pre-primitive streak epiblast. To test our hypothesis that these changes in mechanical properties are due to a localized increase of actomyosin contractility, we inhibited actomyosin contractility via the Rho kinase (ROCK) pathway using the small-molecule inhibitor Y-27632. Our results using several different assays show the following: (1) primitive streak formation was blocked; (2) the time-dependent increase in primitive streak stiffness was abolished; and (3) convergence of epiblast cells to the midline was inhibited. Taken together, our data suggest that actomyosin contractility is necessary for primitive streak morphogenesis, and specifically, ROCK plays a critical role. To better understand the underlying mechanisms of this fundamental process, future models should account for the findings presented in this study.

Remote in-situ laser-induced breakdown spectroscopy using optical fibers

Science.gov (United States)

Marquardt, Brian James

The following dissertation describes the development of methods for performing remote Laser-Induced Breakdown Spectroscopy (LIBS) using optical fibers. Studies were performed to determine the optimal excitation and collection parameters for remote LIBS measurements of glasses, soils and paint. A number of fiber-optic LIBS probes were developed and used to characterize various samples by plasma emission spectroscopy. A novel method for launching high-power laser pulses into optical fibers without causing catastrophic failure is introduced. A systematic study of a number of commercially available optical fibers was performed to determine which optical fibers were best suited for delivering high-power laser pulses. The general design of an all fiber-optic LIBS probe is described and applied to the determination of Pb in soil. A fiber-optic probe was developed for the microanalysis of solid samples remotely by LIBS, Raman spectroscopy and Raman imaging. The design of the probe allows for real-time sample imaging in-situ using coherent imaging fibers. This allows for precise atomic emission and Raman measurements to be performed remotely on samples in hostile or inaccessible environments. A novel technique was developed for collecting spectral plasma images using an acousto-optic tunable filter (AOTF). The spatial and temporal characteristics of the plasma were studied as a function of delay time. From the plasma images the distribution of Pb emission could be determined and fiber-optic designs could be optimized for signal collection. The performance of a two fiber LIBS probe is demonstrated for the determination of the amount of lead in samples of dry paint. It is shown that dry paint samples can be analyzed for their Pb content in-situ using a fiber-optic LIBS probe with detection limits well below the levels currently regulated by the Consumer Products Safety Commission. It is also shown that these measurements can be performed on both latex and enamel paints, and

Quantum optics, molecular spectroscopy and low-temperaturespectroscopy: general discussion

Czech Academy of Sciences Publication Activity Database

Orrit, M.; Evans, G.; Cordes, T.; Kratochvílová, Irena

2015-01-01

Roč. 184, Sep (2015), 275-303 ISSN 1359-6640 R&D Projects: GA TA ČR TA04020156 Institutional support: RVO:68378271 Keywords : quantum optics * molecular spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.544, year: 2015

Structured photocathodes for improved high-energy x-ray efficiency in streak cameras

Energy Technology Data Exchange (ETDEWEB)

Opachich, Y. P., E-mail: opachiyp@nv.doe.gov; Huffman, E.; Koch, J. A. [National Security Technologies, LLC, Livermore, California 94551 (United States); Bell, P. M.; Bradley, D. K.; Hatch, B.; Landen, O. L.; MacPhee, A. G.; Nagel, S. R. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Chen, N.; Gopal, A.; Udin, S. [Nanoshift LLC, Emeryville, California 94608 (United States); Feng, J. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Hilsabeck, T. J. [General Atomics, San Diego, California 92121 (United States)

2016-11-15

We have designed and fabricated a structured streak camera photocathode to provide enhanced efficiency for high energy X-rays (1–12 keV). This gold coated photocathode was tested in a streak camera and compared side by side against a conventional flat thin film photocathode. Results show that the measured electron yield enhancement at energies ranging from 1 to 10 keV scales well with predictions, and that the total enhancement can be more than 3×. The spatial resolution of the streak camera does not show degradation in the structured region. We predict that the temporal resolution of the detector will also not be affected as it is currently dominated by the slit width. This demonstration with Au motivates exploration of comparable enhancements with CsI and may revolutionize X-ray streak camera photocathode design.

Scanning, non-contact, hybrid broadband diffuse optical spectroscopy and diffuse correlation spectroscopy system.

Science.gov (United States)

Johansson, Johannes D; Mireles, Miguel; Morales-Dalmau, Jordi; Farzam, Parisa; Martínez-Lozano, Mar; Casanovas, Oriol; Durduran, Turgut

2016-02-01

A scanning system for small animal imaging using non-contact, hybrid broadband diffuse optical spectroscopy (ncDOS) and diffuse correlation spectroscopy (ncDCS) is presented. The ncDOS uses a two-dimensional spectrophotometer retrieving broadband (610-900 nm) spectral information from up to fifty-seven source-detector distances between 2 and 5 mm. The ncDCS data is simultaneously acquired from four source-detector pairs. The sample is scanned in two dimensions while tracking variations in height. The system has been validated with liquid phantoms, demonstrated in vivo on a human fingertip during an arm cuff occlusion and on a group of mice with xenoimplanted renal cell carcinoma.

Characteristics of uranium oxide cathode for neutron streak camera

International Nuclear Information System (INIS)

Niki, H.; Itoga, K.; Yamanaka, M.; Yamanaka, T.; Yamanaka, C.

1986-01-01

In laser fusion research, time-resolved neutron measurements require 20ps resolution in order to obtain the time history of the D-T burn. Uranium oxide was expected to be a sensitive material as a cathode of a neutron streak camera because of its large fission cross section. The authors report their measurements of some characteristics of the uranium oxide cathode connected to a conventional streak tube. 14 MeV neutron signal were observed as the bright spots on a TV monitor using a focus mode opration. Detection efficiency was ∼ 1 x 10 -6 for 1 μm thick cathode. Each signal consisted of more than several tens of components, which were corresponding to the secondary electrons dragged out from the cathode by a fission fragment. Time resolution is thought to be limited mainly by the transit time spread of the secondary electrons. 14ps resolution was obtained by a streak mode operation for a single fission event

Slope streaks on Mars: A new “wet” mechanism

Science.gov (United States)

Kreslavsky, Mikhail A.; Head, James W.

2009-06-01

Slope steaks are one of the most intriguing modern phenomena observed on Mars. They have been mostly interpreted as some specific type of granular flow. We propose another mechanism for slope streak formation on Mars. It involves natural seasonal formation of a modest amount of highly concentrated chloride brines within a seasonal thermal skin, and runaway propagation of percolation fronts. Given the current state of knowledge of temperature regimes and the composition and structure of the surface layer in the slope streak regions, this mechanism is consistent with the observational constraints; it requires an assumption that a significant part of the observed chlorine to be in form of calcium and ferric chloride, and a small part of the observed hydrogen to be in form of water ice. This "wet" mechanism has a number of appealing advantages in comparison to the widely accepted "dry" granular flow mechanism. Potential tests for the "wet" mechanism include better modeling of the temperature regime and observations of the seasonality of streak formation.

Pea Streak Virus Recorded in Europe

Czech Academy of Sciences Publication Activity Database

Sarkisova, Tatiana; Bečková, M.; Fránová, Jana; Petrzik, Karel

2016-01-01

Roč. 52, č. 3 (2016), s. 164-166 ISSN 1212-2580 R&D Projects: GA MZe QH71145 Institutional support: RVO:60077344 Keywords : Pea streak virus * alfalfa * carlavirus * partial sequence Subject RIV: EE - Microbiology, Virology Impact factor: 0.742, year: 2016

Polarized light in optics and spectroscopy

CERN Document Server

Kliger, David S

1990-01-01

This comprehensive introduction to polarized light provides students and researchers with the background and the specialized knowledge needed to fully utilize polarized light. It provides a basic introduction to the interaction of light with matter for those unfamiliar with photochemistry and photophysics. An in-depth discussion of polarizing optics is also given. Different analytical techniques are introduced and compared and introductions to the use of polarized light in various forms of spectroscopy are provided.Key Features* Starts at a basic level and develops tools for resear

Optical fiber strain sensor using fiber resonator based on frequency comb Vernier spectroscopy

DEFF Research Database (Denmark)

Zhang, Liang; Lu, Ping; Chen, Li

2012-01-01

A novel (to our best knowledge) optical fiber strain sensor using a fiber ring resonator based on frequency comb Vernier spectroscopy is proposed and demonstrated. A passively mode-locked optical fiber laser is employed to generate a phased-locked frequency comb. Strain applied to the optical fib...

Fiber-optic Raman spectroscopy for in vivo diagnosis of gastric dysplasia.

Science.gov (United States)

Wang, Jianfeng; Lin, Kan; Zheng, Wei; Ho, Khek Yu; Teh, Ming; Yeoh, Khay Guan; Huang, Zhiwei

2016-06-23

This study aims to assess the clinical utility of a rapid fiber-optic Raman spectroscopy technique developed for enhancing in vivo diagnosis of gastric precancer during endoscopic examination. We have developed a real-time fiber-optic Raman spectroscopy system capable of simultaneously acquiring both fingerprint (FP) (i.e., 800-1800 cm(-1)) and high-wavenumber (HW) (i.e., 2800-3600 cm(-1)) Raman spectra from gastric tissue in vivo at endoscopy. A total of 5792 high-quality in vivo FP/HW Raman spectra (normal (n = 5160); dysplasia (n = 155), and adenocarcinoma (n = 477)) were acquired in real-time from 441 tissue sites (normal (n = 396); dysplasia (n = 11), and adenocarcinoma (n = 34)) of 191 gastric patients (normal (n = 172); dysplasia (n = 6), and adenocarcinoma (n = 13)) undergoing routine endoscopic examinations. Partial least squares discriminant analysis (PLS-DA) together with leave-one-patient-out cross validation (LOPCV) were implemented to develop robust spectral diagnostic models. The FP/HW Raman spectra differ significantly between normal, dysplasia and adenocarcinoma of the stomach, which can be attributed to changes in proteins, lipids, nucleic acids, and the bound water content. PLS-DA and LOPCV show that the fiber-optic FP/HW Raman spectroscopy provides diagnostic sensitivities of 96.0%, 81.8% and 88.2%, and specificities of 86.7%, 95.3% and 95.6%, respectively, for the classification of normal, dysplastic and cancerous gastric tissue, superior to either the FP or HW Raman techniques alone. Further dichotomous PLS-DA analysis yields a sensitivity of 90.9% (10/11) and specificity of 95.9% (380/396) for the detection of gastric dysplasia using FP/HW Raman spectroscopy, substantiating its clinical advantages over white light reflectance endoscopy (sensitivity: 90.9% (10/11), and specificity: 51.0% (202/396)). This work demonstrates that the fiber-optic FP/HW Raman spectroscopy technique has great promise for enhancing in vivo diagnosis of gastric

Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles Using Optical Nanofibers: A Review

Science.gov (United States)

Morrissey, Michael J.; Deasy, Kieran; Frawley, Mary; Kumar, Ravi; Prel, Eugen; Russell, Laura; Truong, Viet Giang; Chormaic, Síle Nic

2013-01-01

The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining interest in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication, and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization, and optical trapping schemes. Next, a natural extension of this work to molecules is introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for specific applications. PMID:23945738

Electrical and optical spectroscopy for quantitative screening of hepatic steatosis in donor livers

Energy Technology Data Exchange (ETDEWEB)

McLaughlin, B L; Wilkinson, T D; Robertson, P A [Engineering Department, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 OFA (United Kingdom); Wells, A C; Watson, C J E [University Department of Surgery, Addenbrooke' s Hospital, Box 202, Level 9, Hills Road, Cambridge CB2 OCQ (United Kingdom); Virtue, S; Vidal-Puig, A, E-mail: mclaugb@gmail.co [Department of Clinical Biochemistry, University of Cambridge, Addenbrooke' s Hospital, Hills Road, Cambridge CB2 2QR (United Kingdom)

2010-11-21

Macro-steatosis in deceased donor livers is increasingly prevalent and is associated with poor or non-function of the liver upon reperfusion. Current assessment of the extent of steatosis depends upon the macroscopic assessment of the liver by the surgeon and histological examination, if available. In this paper we demonstrate electrical and optical spectroscopy techniques which quantitatively characterize fatty infiltration in liver tissue. Optical spectroscopy showed a correlation coefficient of 0.85 in humans when referenced to clinical hematoxylin and eosin (H and E) sections in 20 human samples. With further development, an optical probe may provide a comprehensive measure of steatosis across the liver at the time of procurement.

Optical spectroscopy of ten extragalactic radiosources

International Nuclear Information System (INIS)

Rawlings, S.; Riley, J.M.; Saunders, R.

1989-01-01

We present optical spectroscopy of ten objects associated with extra-galactic radiosources, using the University of Hawaii 2.2-m telescope. Redshifts are measured for four radiogalaxies (B20217 + 36A + B, 3C73, 0648 + 19A, 0648 + 19B) and for a galaxy which is probably associated with a double radio-source with highly unusual properties (0951 + 37); existing redshifts are confirmed for two radiogalaxies (4C39.04, 4C40.08); and a tentative redshift of z=2.87 measured for the quasar 3C82. (author)

Detection, Occurrence, and Survey of Rice Stripe and Black-Streaked Dwarf Diseases in Zhejiang Province, China

OpenAIRE

Heng-mu ZHANG; Hua-di WANG; Jian YANG; Michael J ADAMS; Jian-ping CHEN

2013-01-01

The major viral diseases that occur on rice plants in Zhejiang Province, eastern China, are stripe and rice black-streaked dwarf diseases. Rice stripe disease is only caused by rice stripe tenuivirus (RSV), while rice black-streaked dwarf disease can be caused by rice black-streaked dwarf fijivirus (RBSDV) and/or southern rice black-streaked dwarf fijivirus (SRBSDV). Here we review the characterization of these viruses, methods for their detection, and extensive surveys showing their occurren...

Novel technique for addressing streak artifact in gated dual-source MDCT angiography utilizing ECG-editing

Energy Technology Data Exchange (ETDEWEB)

Meyer, Laura T.; Boll, Daniel T. [Duke University Medical Center, Department of Radiology, Box 3808, Durham, NC (United States)

2008-11-15

Streak artifact is an important source of image degradation in computed tomographic imaging. In coronary MDCT angiography, streak artifact from pacemaker leads in the SVC can render segments of the right coronary artery uninterpretable. With current technology in clinical practice, there is no effective way to eliminate streak artifact in coronary MDCT angiography entirely. We propose a technique to minimize the impact of streak artifact in retrospectively gated coronary MDCT angiography by utilizing small shifts in the reconstruction window. In our experience, previously degraded portions of the coronary vasculature were able to be well evaluated using this technique. (orig.)

The effect of wall temperature distribution on streaks in compressible turbulent boundary layer

Science.gov (United States)

Zhang, Zhao; Tao, Yang; Xiong, Neng; Qian, Fengxue

2018-05-01

The thermal boundary condition at wall is very important for the compressible flow due to the coupling of the energy equation, and a lot of research works about it were carried out in past decades. In most of these works, the wall was assumed as adiabatic or uniform isothermal surface; the flow over a thermal wall with some special temperature distribution was seldom studied. Lagha studied the effect of uniform isothermal wall on the streaks, and pointed out that higher the wall temperature is, the longer the streak (POF, 2011, 23, 015106). So, we designed streamwise stripes of wall temperature distribution on the compressible turbulent boundary layer at Mach 3.0 to learn the effect on the streaks by means of direct numerical simulation in this paper. The mean wall temperature is equal to the adiabatic case approximately, and the width of the temperature stripes is in the same order as the width of the streaks. The streak patterns in near-wall region with different temperature stripes are shown in the paper. Moreover, we find that there is a reduction of friction velocity with the wall temperature stripes when compared with the adiabatic case.

The origin and structure of streak-like instabilities in laminar boundary layer flames

Science.gov (United States)

Gollner, Michael; Miller, Colin; Tang, Wei; Finney, Mark

2017-11-01

Streamwise streaks are consistently observed in wildland fires, at the base of pool fires, and in other heated flows within a boundary layer. This study examines both the origin of these structures and their role in influencing some of the macroscopic properties of the flow. Streaks were reproduced and characterized via experiments on stationary heated strips and liquid and gas-fueled burners in laminar boundary layer flows, providing a framework to develop theory based on both observed and measured physical phenomena. The incoming boundary layer was established as the controlling mechanism in forming streaks, which are generated by pre-existing coherent structures, while the amplification of streaks was determined to be compatible with quadratic growth of Rayleigh-Taylor Instabilities, providing credence to the idea that the downstream growth of streaks is strongly tied to buoyancy. These local instabilities were also found to affect macroscopic properties of the flow, including heat transfer to the surface, indicating that a two-dimensional assumption may fail to adequately describe heat and mass transfer during flame spread and other reacting boundary layer flows. This work was supported by NSF (CBET-1554026) and the USDA-FS (13-CS-11221637-124).

Nondipole effects in attosecond photoelectron streaking

DEFF Research Database (Denmark)

Spiewanowski, Maciek; Madsen, Lars Bojer

2012-01-01

The influence of nondipole terms on the time delay in photoionization by an extreme-ultraviolet attosecond pulse in the presence of a near-infrared femtosecond laser pulse from 1s, 2s, and 2p states in hydrogen is investigated. In this attosecond photoelectron streaking process, the relative...

Oxygenation level and hemoglobin concentration in experimental tumor estimated by diffuse optical spectroscopy

Science.gov (United States)

Orlova, A. G.; Kirillin, M. Yu.; Volovetsky, A. B.; Shilyagina, N. Yu.; Sergeeva, E. A.; Golubiatnikov, G. Yu.; Turchin, I. V.

2017-07-01

Using diffuse optical spectroscopy the level of oxygenation and hemoglobin concentration in experimental tumor in comparison with normal muscle tissue of mice have been studied. Subcutaneously growing SKBR-3 was used as a tumor model. Continuous wave fiber probe diffuse optical spectroscopy system was employed. Optical properties extraction approach was based on diffusion approximation. Decreased blood oxygen saturation level and increased total hemoglobin content were demonstrated in the neoplasm. The main reason of such differences between tumor and norm was significant elevation of deoxyhemoglobin concentration in SKBR-3. The method can be useful for diagnosis of tumors as well as for study of blood flow parameters of tumor models with different angiogenic properties.

Force-detected nanoscale absorption spectroscopy in water at room temperature using an optical trap

Science.gov (United States)

Parobek, Alexander; Black, Jacob W.; Kamenetska, Maria; Ganim, Ziad

2018-04-01

Measuring absorption spectra of single molecules presents a fundamental challenge for standard transmission-based instruments because of the inherently low signal relative to the large background of the excitation source. Here we demonstrate a new approach for performing absorption spectroscopy in solution using a force measurement to read out optical excitation at the nanoscale. The photoinduced force between model chromophores and an optically trapped gold nanoshell has been measured in water at room temperature. This photoinduced force is characterized as a function of wavelength to yield the force spectrum, which is shown to be correlated to the absorption spectrum for four model systems. The instrument constructed for these measurements combines an optical tweezer with frequency domain absorption spectroscopy over the 400-800 nm range. These measurements provide proof-of-principle experiments for force-detected nanoscale spectroscopies that operate under ambient chemical conditions.

Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy

Science.gov (United States)

Neuman, Keir C.; Nagy, Attila

2012-01-01

Single-molecule force spectroscopy has emerged as a powerful tool to investigate the forces and motions associated with biological molecules and enzymatic activity. The most common force spectroscopy techniques are optical tweezers, magnetic tweezers and atomic force microscopy. These techniques are described and illustrated with examples highlighting current capabilities and limitations. PMID:18511917

Streak camera imaging of single photons at telecom wavelength

Science.gov (United States)

Allgaier, Markus; Ansari, Vahid; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Donohue, John Matthew; Czerniuk, Thomas; Aßmann, Marc; Bayer, Manfred; Brecht, Benjamin; Silberhorn, Christine

2018-01-01

Streak cameras are powerful tools for temporal characterization of ultrafast light pulses, even at the single-photon level. However, the low signal-to-noise ratio in the infrared range prevents measurements on weak light sources in the telecom regime. We present an approach to circumvent this problem, utilizing an up-conversion process in periodically poled waveguides in Lithium Niobate. We convert single photons from a parametric down-conversion source in order to reach the point of maximum detection efficiency of commercially available streak cameras. We explore phase-matching configurations to apply the up-conversion scheme in real-world applications.

Performance of Laser Megajoule’s x-ray streak camera

Energy Technology Data Exchange (ETDEWEB)

Zuber, C., E-mail: celine.zuber@cea.fr; Bazzoli, S.; Brunel, P.; Burillo, M.; Gontier, D.; Moreau, I.; Oudot, G.; Rubbelynck, C.; Soullié, G.; Stemmler, P.; Trosseille, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Fronty, J. P.; Goulmy, C. [Photonis France SAS, Avenue Roger Roncier, BP 520, 19106 Brive Cedex (France)

2016-11-15

A prototype of a picosecond x-ray streak camera has been developed and tested by Commissariat à l’Énergie Atomique et aux Énergies Alternatives to provide plasma-diagnostic support for the Laser Megajoule. We report on the measured performance of this streak camera, which almost fulfills the requirements: 50-μm spatial resolution over a 15-mm field in the photocathode plane, 17-ps temporal resolution in a 2-ns timebase, a detection threshold lower than 625 nJ/cm{sup 2} in the 0.05–15 keV spectral range, and a dynamic range greater than 100.

Optical emission and mass spectroscopy of plasma processes in reactive DC pulsed magnetron sputtering of aluminium oxide

Czech Academy of Sciences Publication Activity Database

Novotný, Michal; Bulíř, Jiří; Pokorný, Petr; Bočan, Jiří; Fitl, Přemysl; Lančok, Ján; Musil, Jindřich

2010-01-01

Roč. 12, č. 3 (2010), 697-700 ISSN 1454-4164 R&D Projects: GA AV ČR IAA100100718; GA AV ČR KAN400100653; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : reactive magnetron sputtering * alumina * plasma spectroscopy * mass spectroscopy * optical emission spectroscopy Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.412, year: 2010

Streak artifacts on Kidney CT: Ionic vs nonionic contrast media

International Nuclear Information System (INIS)

Cho, Eun Ok; Kim, Won Hong; Jung, Myung Suk; Kim, Yong Hoon; Hur, Gham

1993-01-01

The authors reviewed findings of enhanced abdominal computed tomography (CT) scans to know the difference between a higher dose of conventional ionic contrast media(iothalamate meglumine) and a lower dose of a new, nonionic contrast material(ioversol). One hundred adult patients were divided into two groups. Each group consisted of 50 patients. Iothalamate meglumine and ioversol were intravenously administered in each group. The radio of the male to female in the former was 28:22, and the latter 29:21. We examine the degree of renal streak artifact and measure the Hounsfield number of urine in renal collecting system. There were significant differences of the degree of the streak artifact depending upon the osmolality of contrast media used and that was related with urine CT number(P value<0.005). We authors conclude that nonionic low osmolar contrast media is prone to cause streak artifacts and distortions of renal image than conventional ionic high osmolar contrast media

POD analysis of the instability mode of a low-speed streak in a laminar boundary layer

Science.gov (United States)

Deng, Si-Chao; Pan, Chong; Wang, Jin-Jun; Rinoshika, Akira

2017-12-01

The instability of one single low-speed streak in a zero-pressure-gradient laminar boundary layer is investigated experimentally via both hydrogen bubble visualization and planar particle image velocimetry (PIV) measurement. A single low-speed streak is generated and destabilized by the wake of an interference wire positioned normal to the wall and in the upstream. The downstream development of the streak includes secondary instability and self-reproduction process, which leads to the generation of two additional streaks appearing on either side of the primary one. A proper orthogonal decomposition (POD) analysis of PIV measured velocity field is used to identify the components of the streak instability in the POD mode space: for a sinuous/varicose type of POD mode, its basis functions present anti-symmetric/symmetric distributions about the streak centerline in the streamwise component, and the symmetry condition reverses in the spanwise component. It is further shown that sinuous mode dominates the turbulent kinematic energy (TKE) through the whole streak evolution process, the TKE content first increases along the streamwise direction to a saturation value and then decays slowly. In contrast, varicose mode exhibits a sustained growth of the TKE content, suggesting an increasing competition of varicose instability against sinuous instability.

Fiber scintillator/streak camera detector for burn history measurement in inertial confinement fusion experiment

International Nuclear Information System (INIS)

Miyanaga, N.; Ohba, N.; Fujimoto, K.

1997-01-01

To measure the burn history in an inertial confinement fusion experiment, we have developed a new neutron detector based on plastic scintillation fibers. Twenty-five fiber scintillators were arranged in a geometry compensation configuration by which the time-of-flight difference of the neutrons is compensated by the transit time difference of light passing through the fibers. Each fiber scintillator is spliced individually to an ultraviolet optical fiber that is coupled to a streak camera. We have demonstrated a significant improvement of sensitivity compared with the usual bulk scintillator coupled to a bundle of the same ultraviolet fibers. copyright 1997 American Institute of Physics

Noise-Immune Cavity-Enhanced Optical Frequency Comb Spectroscopy

Science.gov (United States)

Rutkowski, Lucile; Khodabakhsh, Amir; Johanssson, Alexandra C.; Foltynowicz, Aleksandra

2015-06-01

We present noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS), a recently developed technique for sensitive, broadband, and high resolution spectroscopy. In NICE-OFCS an optical frequency comb (OFC) is locked to a high finesse cavity and phase-modulated at a frequency precisely equal to (a multiple of) the cavity free spectral range. Since each comb line and sideband is transmitted through a separate cavity mode in exactly the same way, any residual frequency noise on the OFC relative to the cavity affects each component in an identical manner. The transmitted intensity contains a beat signal at the modulation frequency that is immune to frequency-to-amplitude noise conversion by the cavity, in a way similar to continuous wave noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS). The light transmitted through the cavity is detected with a fast-scanning Fourier-transform spectrometer (FTS) and the NICE-OFCS signal is obtained by fast Fourier transform of the synchronously demodulated interferogram. Our NICE-OFCS system is based on an Er:fiber femtosecond laser locked to a cavity with a finesse of ˜9000 and a fast-scanning FTS equipped with a high-bandwidth commercial detector. We measured NICE-OFCS signals from the 3νb{1}+νb{3} overtone band of CO_2 around 1.57 μm and achieved absorption sensitivity 6.4×10-11cm-1 Hz-1/2 per spectral element, corresponding to a minimum detectable CO_2 concentration of 25 ppb after 330 s integration time. We will describe the principles of the technique and its technical implementation, and discuss the spectral lineshapes of the NICE-OFCS signals. A. Khodabakhsh, C. Abd Alrahman, and A. Foltynowicz, Opt. Lett. 39, 5034-5037 (2014). J. Ye, L. S. Ma, and J. L. Hall, J. Opt. Soc. Am. B 15, 6-15 (1998). A. Khodabakhsh, A. C. Johansson, and A. Foltynowicz, Appl. Phys. B (2015) doi:10.1007/s00340-015-6010-7.

High-Resolution Two-Dimensional Optical Spectroscopy of Electron Spins

Directory of Open Access Journals (Sweden)

M. Salewski

2017-08-01

Full Text Available Multidimensional coherent optical spectroscopy is one of the most powerful tools for investigating complex quantum mechanical systems. While it was conceived decades ago in magnetic resonance spectroscopy using microwaves and radio waves, it has recently been extended into the visible and UV spectral range. However, resolving MHz energy splittings with ultrashort laser pulses still remains a challenge. Here, we analyze two-dimensional Fourier spectra for resonant optical excitation of resident electrons to localized trions or donor-bound excitons in semiconductor nanostructures subject to a transverse magnetic field. Particular attention is devoted to Raman coherence spectra, which allow one to accurately evaluate tiny splittings of the electron ground state and to determine the relaxation times in the electron spin ensemble. A stimulated steplike Raman process induced by a sequence of two laser pulses creates a coherent superposition of the ground-state doublet which can be retrieved only optically because of selective excitation of the same subensemble with a third pulse. This provides the unique opportunity to distinguish between different complexes that are closely spaced in energy in an ensemble. The related experimental demonstration is based on photon-echo measurements in an n-type CdTe/(Cd,MgTe quantum-well structure detected by a heterodyne technique. The difference in the sub-μeV range between the Zeeman splittings of donor-bound electrons and electrons localized at potential fluctuations can be resolved even though the homogeneous linewidth of the optical transitions is larger by 2 orders of magnitude.

The LLL compact 10-ps streak camera

International Nuclear Information System (INIS)

Thomas, S.W.; Houghton, J.W.; Tripp, G.R.; Coleman, L.W.

1975-01-01

The 10-ps streak camera has been redesigned to simplify its operation, reduce manufacturing costs, and improve its appearance. The electronics have been simplified, a film indexer added, and a contacted slit has been evaluated. Data support a 10-ps resolution. (author)

Communication: atomic force detection of single-molecule nonlinear optical vibrational spectroscopy.

Science.gov (United States)

Saurabh, Prasoon; Mukamel, Shaul

2014-04-28

Atomic Force Microscopy (AFM) allows for a highly sensitive detection of spectroscopic signals. This has been first demonstrated for NMR of a single molecule and recently extended to stimulated Raman in the optical regime. We theoretically investigate the use of optical forces to detect time and frequency domain nonlinear optical signals. We show that, with proper phase matching, the AFM-detected signals closely resemble coherent heterodyne-detected signals. Applications are made to AFM-detected and heterodyne-detected vibrational resonances in Coherent Anti-Stokes Raman Spectroscopy (χ((3))) and sum or difference frequency generation (χ((2))).

X-ray streak camera for observation of tightly pinched relativistic electron beams

International Nuclear Information System (INIS)

Johnson, D.J.

1977-01-01

A pinhole camera is coupled with a Pilot-B scintillator and image-intensified TRW streak camera to study pinched electron beam profiles via observation of anode target bremsstrahlung. Streak intensification is achieved with an EMI image intensifier operated at a gain of up to 10 6 which allows optimizing the pinhole configuration so that resolution is simultaneously limited by photon-counting statistics and pinhole geometry. The pinhole used is one-dimensional and is fabricated by inserting uranium shims with hyperbolic curved edges between two 5-cm-thick lead blocks. The loss of spatial resolution due to the x-ray transmission through the perimeter of the pinhole is calculated and a streak photograph of a Gamble I pinched beam interacting with a brass anode is presented

Synchronization of streak and framing camera measurements of an intense relativistic electron beam propagating through gas

International Nuclear Information System (INIS)

Weidman, D.J.; Murphy, D.P.; Myers, M.C.; Meger, R.A.

1994-01-01

The expansion of the radius of a 5 MeV, 20 kA, 40 ns electron beam from SuperIBEX during propagation through gas is being measured. The beam is generated, conditions, equilibrated, and then passed through a thin foil that produces Cherenkov light, which is recorded by a streak camera. At a second location, the beam hits another Cherenkov emitter, which is viewed by a framing camera. Measurements at these two locations can provide a time-resolved measure of the beam expansion. The two measurements, however, must be synchronized with each other, because the beam radius is not constant throughout the pulse due to variations in beam current and energy. To correlate the timing of the two diagnostics, several shots have been taken with both diagnostics viewing Cherenkov light from the same foil. Experimental measurements of the Cherenkov light from one foil viewed by both diagnostics will be presented to demonstrate the feasibility of correlating the diagnostics with each other. Streak camera data showing the optical fiducial, as well as the final correlation of the two diagnostics, will also be presented. Preliminary beam radius measurements from Cherenkov light measured at two locations will be shown

Development and Optical Testing of the Camera, Hand Lens, and Microscope Probe with Scannable Laser Spectroscopy (CHAMP-SLS)

Science.gov (United States)

Mungas, Greg S.; Gursel, Yekta; Sepulveda, Cesar A.; Anderson, Mark; La Baw, Clayton; Johnson, Kenneth R.; Deans, Matthew; Beegle, Luther; Boynton, John

2008-01-01

Conducting high resolution field microscopy with coupled laser spectroscopy that can be used to selectively analyze the surface chemistry of individual pixels in a scene is an enabling capability for next generation robotic and manned spaceflight missions, civil, and military applications. In the laboratory, we use a range of imaging and surface preparation tools that provide us with in-focus images, context imaging for identifying features that we want to investigate at high magnification, and surface-optical coupling that allows us to apply optical spectroscopic analysis techniques for analyzing surface chemistry particularly at high magnifications. The camera, hand lens, and microscope probe with scannable laser spectroscopy (CHAMP-SLS) is an imaging/spectroscopy instrument capable of imaging continuously from infinity down to high resolution microscopy (resolution of approx. 1 micron/pixel in a final camera format), the closer CHAMP-SLS is placed to a feature, the higher the resultant magnification. At hand lens to microscopic magnifications, the imaged scene can be selectively interrogated with point spectroscopic techniques such as Raman spectroscopy, microscopic Laser Induced Breakdown Spectroscopy (micro-LIBS), laser ablation mass-spectrometry, Fluorescence spectroscopy, and/or Reflectance spectroscopy. This paper summarizes the optical design, development, and testing of the CHAMP-SLS optics.

Combination of optical spectroscopy and electrical impedancemetry for nutrition behavior characterizations

Science.gov (United States)

Perchik, Alexey; Pavlov, Konstantin; Vilenskii, Maksim; Popov, Mikhail

2017-07-01

Unhealthy nutrition trends determination technique is described. Combination of optical spectroscopy and electrical impedancemetry will lead to development of a healthcare device that will predict unhealthy eating habits and decrease risk factors of diseases development.

C.C.D. readout of a picosecond streak camera with an intensified C.C.D

International Nuclear Information System (INIS)

Lemonier, M.; Richard, J.C.; Cavailler, C.; Mens, A.; Raze, G.

1984-08-01

This paper deals with a digital streak camera readout device. The device consists in a low light level television camera made of a solid state C.C.D. array coupled to an image intensifier associated to a video-digitizer coupled to a micro-computer system. The streak camera images are picked-up as a video signal, digitized and stored. This system allows the fast recording and the automatic processing of the data provided by the streak tube

rf streak camera based ultrafast relativistic electron diffraction.

Science.gov (United States)

Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Tran, T

2009-01-01

We theoretically and experimentally investigate the possibility of using a rf streak camera to time resolve in a single shot structural changes at the sub-100 fs time scale via relativistic electron diffraction. We experimentally tested this novel concept at the UCLA Pegasus rf photoinjector. Time-resolved diffraction patterns from thin Al foil are recorded. Averaging over 50 shots is required in order to get statistics sufficient to uncover a variation in time of the diffraction patterns. In the absence of an external pump laser, this is explained as due to the energy chirp on the beam out of the electron gun. With further improvements to the electron source, rf streak camera based ultrafast electron diffraction has the potential to yield truly single shot measurements of ultrafast processes.

Micro-optical instrumentation for process spectroscopy

Science.gov (United States)

Crocombe, Richard A.; Flanders, Dale C.; Atia, Walid

2004-12-01

Traditional laboratory ultraviolet/visible/near-infrared spectroscopy instruments are tabletop-sized pieces of equipment that exhibit very high performance, but are generally too large and costly to be widely distributed for process control applications or used as spectroscopic sensors. Utilizing a unique, and proven, micro-optical technology platform origi-nally developed, qualified and deployed in the telecommunications industry, we have developed a new class of spectro-scopic micro-instrumentation that has laboratory quality resolution and spectral range, with superior speed and robust-ness. The fundamentally lower cost and small form factor of the technology will enable widespread use in process moni-toring and control. This disruption in the ground rules of spectroscopic analysis in these processes is enabled by the re-placement of large optics and detector arrays with a high-finesse, high-speed micro electro mechanical system (MEMS) tunable filter and a single detector, that enable the manufacture of a high performance and extremely rugged spectrome-ter in the footprint of a credit card. Specific process monitoring and control applications discussed in the paper include pharmaceutical, gas sensing and chemical processing applications.

Optical re-injection in cavity-enhanced absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Leen, J. Brian, E-mail: b.leen@lgrinc.com; O’Keefe, Anthony [Los Gatos Research, 67 E. Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)

2014-09-15

Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

Differential Optical-absorption Spectroscopy (doas) System For Urban Atmospheric-pollution Monitoring

OpenAIRE

Edner, H; Ragnarson, P; Spannare, S; Svanberg, Sune

1993-01-01

We describe a fully computer-controlled differential optical absorption spectroscopy system for atmospheric air pollution monitoring. A receiving optical telescope can sequentially tune in to light beams from a number of distant high-pressure Xe lamp light sources to cover the area of a medium-sized city. A beam-finding servosystem and automatic gain control permit unattended long-time monitoring. Using an astronomical code, we can also search and track celestial sources. Selected wavelength ...

Atomic and Molecular Data for Optical Stellar Spectroscopy

OpenAIRE

Heiter, U.; Lind, K.; Asplund, M.; Barklem, P. S.; Bergemann, M.; Magrini, L.; Masseron, T.; Mikolaitis, Š.; Pickering, J. C.; Ruffoni, M. P.

2015-01-01

High-precision spectroscopy of large stellar samples plays a crucial role for several topical issues in astrophysics. Examples include studying the chemical structure and evolution of the Milky Way galaxy, tracing the origin of chemical elements, and characterizing planetary host stars. Data are accumulating from instruments that obtain high-quality spectra of stars in the ultraviolet, optical and infrared wavelength regions on a routine basis. These instruments are located at ground-based 2-...

X-ray streak crystal spectography

International Nuclear Information System (INIS)

Kauffman, R.L.; Brown, T.; Medecki, H.

1983-01-01

We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11 0 to 38 0 and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/δE > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given

Microprocessor-controlled wide-range streak camera

Science.gov (United States)

Lewis, Amy E.; Hollabaugh, Craig

2006-08-01

Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storage using flash-based storage media. The camera's user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized.

Microprocessor-controlled, wide-range streak camera

International Nuclear Information System (INIS)

Amy E. Lewis; Craig Hollabaugh

2006-01-01

Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storage using flash-based storage media. The camera's user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized

Linear and nonlinear optical spectroscopy: Spectral, temporal and spatial resolution

DEFF Research Database (Denmark)

Hvam, Jørn Marcher

1997-01-01

Selected linear and nonlinear optical spectroscopies are being described with special emphasis on the possibility of obtaining simultaneous spectral, temporal and spatial resolution. The potential of various experimental techniques is being demonstrated by specific examples mostly taken from inve...... investigations of the electronic, and opto-electronic, properties of semiconductor nanostructures....

Two-color spatial and temporal temperature measurements using a streaked soft x-ray imager

Energy Technology Data Exchange (ETDEWEB)

Moore, A. S., E-mail: alastair.moore@physics.org; Ahmed, M. F.; Soufli, R.; Pardini, T.; Hibbard, R. L.; Bailey, C. G.; Bell, P. M.; Hau-Riege, S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); Benstead, J.; Morton, J.; Guymer, T. M.; Garbett, W. J.; Rubery, M. S.; Skidmore, J. W. [Directorate Science and Technology, AWE Aldermaston, Reading RG7 4PR (United Kingdom); Bedzyk, M.; Shoup, M. J.; Regan, S. P.; Agliata, T.; Jungquist, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Schmidt, D. W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); and others

2016-11-15

A dual-channel streaked soft x-ray imager has been designed and used on high energy-density physics experiments at the National Ignition Facility. This streaked imager creates two images of the same x-ray source using two slit apertures and a single shallow angle reflection from a nickel mirror. Thin filters are used to create narrow band pass images at 510 eV and 360 eV. When measuring a Planckian spectrum, the brightness ratio of the two images can be translated into a color-temperature, provided that the spectral sensitivity of the two images is well known. To reduce uncertainty and remove spectral features in the streak camera photocathode from this photon energy range, a thin 100 nm CsI on 50 nm Al streak camera photocathode was implemented. Provided that the spectral shape is well-known, then uncertainties on the spectral sensitivity limits the accuracy of the temperature measurement to approximately 4.5% at 100 eV.

Cavity-enhanced Raman spectroscopy with optical feedback cw diode lasers for gas phase analysis and spectroscopy.

Science.gov (United States)

Salter, Robert; Chu, Johnny; Hippler, Michael

2012-10-21

A variant of cavity-enhanced Raman spectroscopy (CERS) is introduced, in which diode laser radiation at 635 nm is coupled into an external linear optical cavity composed of two highly reflective mirrors. Using optical feedback stabilisation, build-up of circulating laser power by 3 orders of magnitude occurs. Strong Raman signals are collected in forward scattering geometry. Gas phase CERS spectra of H(2), air, CH(4) and benzene are recorded to demonstrate the potential for analytical applications and fundamental molecular studies. Noise equivalent limits of detection in the ppm by volume range (1 bar sample) can be achieved with excellent linearity with a 10 mW excitation laser, with sensitivity increasing with laser power and integration time. The apparatus can be operated with battery powered components and can thus be very compact and portable. Possible applications include safety monitoring of hydrogen gas levels, isotope tracer studies (e.g., (14)N/(15)N ratios), observing isotopomers of hydrogen (e.g., radioactive tritium), and simultaneous multi-component gas analysis. CERS has the potential to become a standard method for sensitive gas phase Raman spectroscopy.

Streaked x-ray spectrometer having a discrete selection of Bragg geometries for Omega

Energy Technology Data Exchange (ETDEWEB)

Millecchia, M.; Regan, S. P.; Bahr, R. E.; Romanofsky, M.; Sorce, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States)

2012-10-15

The streaked x-ray spectrometer (SXS) is used with streak cameras [D. H. Kalantar, P. M. Bell, R. L. Costa, B. A. Hammel, O. L. Landen, T. J. Orzechowski, J. D. Hares, and A. K. L. Dymoke-Bradshaw, in 22nd International Congress on High-Speed Photography and Photonics, edited by D. L. Paisley and A. M. Frank (SPIE, Bellingham, WA, 1997), Vol. 2869, p. 680] positioned with a ten-inch manipulator on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] and OMEGA EP [L. J. Waxer et al., Presented at CLEO/QELS 2008, San Jose, CA, 4-9 May 2008 (Paper JThB1)] for time-resolved, x-ray spectroscopy of laser-produced plasmas in the 1.4- to 20-keV photon-energy range. These experiments require measuring a portion of this photon-energy range to monitor a particular emission or absorption feature of interest. The SXS relies on a pinned mechanical reference system to create a discrete set of Bragg reflection geometries for a variety of crystals. A wide selection of spectral windows is achieved accurately and efficiently using this technique. It replaces the previous spectrometer designs that had a continuous Bragg angle adjustment and required a tedious alignment calibration procedure. The number of spectral windows needed for the SXS was determined by studying the spectral ranges selected by OMEGA users over the last decade. These selections are easily configured in the SXS using one of the 25 discrete Bragg reflection geometries and one of the six types of Bragg crystals, including two curved crystals.

Streak cameras and their applications

International Nuclear Information System (INIS)

Bernet, J.M.; Imhoff, C.

1987-01-01

Over the last several years, development of various measurement techniques in the nanosecond and pico-second range has led to increased reliance on streak cameras. This paper will present the main electronic and optoelectronic performances of the Thomson-CSF TSN 506 cameras and their associated devices used to build an automatic image acquisition and processing system (NORMA). A brief survey of the diversity and the spread of the use of high speed electronic cinematography will be illustrated by a few typical applications [fr

Spectroscopy for Dummies

DEFF Research Database (Denmark)

Lindvold, Lars René

This presentation will give short introduction to the most pertinent topics of optical spectroscopy. The following topics will be discussed: • The origin of spectra in UV, VIS and IR spectral range • Spectroscopic methods like absorption, luminescence and Raman • Wavelength dispersive optical...... components • Materials for use optical spectroscopy • Spectrometer geometries • Detectors for use in spectrometer • Practical examples of optical spectroscopy The objective of this presentation is to give the audience a good feel for the range of possibilities that optical spectroscopy can provide....

An Optical and Terahertz Instrumentation System at the FAST LINAC at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Thurman-Keup, R. [Fermilab; Lumpkin, A. H. [Fermilab; Thangaraj, J. [Fermilab

2017-08-01

FAST is a facility at Fermilab that consists of a photoinjector, two superconducting capture cavities, one superconducting ILC-style cryomodule, and a small ring for studying non-linear, integrable beam optics called IOTA. This paper discusses the layout for the optical transport system that provides optical radiation to an externally located streak camera for bunch length measurements, and THz radiation to a Martin-Puplett interferometer, also for bunch length measurements. It accepts radiation from two synchrotron radiation ports in a chicane bunch compressor and a diffraction/transition radiation screen downstream of the compressor. It also has the potential to access signal from a transition radiation screen or YAG screen after the spectrometer magnet for measurements of energy-time correlations. Initial results from both the streak camera and Martin-Puplett will be presented.

Optical Emission Spectroscopy of Plasma in Hybrid Pulsed Laser Deposition System

Czech Academy of Sciences Publication Activity Database

Novotný, Michal; Jelínek, Miroslav; Bulíř, Jiří; Lančok, Ján; Jastrabík, Lubomír; Zelinger, Zdeněk

2002-01-01

Roč. 52, Suppl. D (2002), s. 292-298 ISSN 0011-4626 R&D Projects: GA AV ČR IAA1010110 Keywords : optical emission spectroscopy * pulsed laser deposition * RF discharge Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.311, year: 2002

Process control with optical emission spectroscopy in triode ion plating

International Nuclear Information System (INIS)

Salmenoja, K.; Korhonen, A.S.; Sulonen, M.S.

1985-01-01

Physical vapor deposition (PVD) techniques used to prepare, e.g., hard TiN, HfN, or ZrN coatings include a great variety of processes ranging from reactive evaporation to sputtering and ion plating. In ion plating one effective way to enhance ionization is to use a negatively biased hot filament. The use of an electron emitting filament brings an extra variable to be taken into account in developing the process control. In addition, proper control of the evaporation source is critical in ensuring reproducible results. With optical emission spectroscopy (OES) it should be possible to control the coating process more accurately. The stoichiometry and the composition of the growing coating may then be ensured effectively in subsequent runs. In this work the application of optical emission spectroscopy for process control in triode ion plating is discussed. The composition of the growing coating is determined experimentally using the relative intensities of specific emission lines. Changes in the evaporation rate and the gas flow can be seen directly from emission line intensities. Even the so-called poisoning of the evaporation source with reactive gas can be detected. Several experimental runs were carried out and afterwards the concentration profiles of the deposited coatings were checked with the nuclear resonance broadening (NRB) method. The results show the usefulness of emission spectroscopy in discharge control

Genetic Analysis of Streaked and Abnormal Floret Mutant st-fon

Directory of Open Access Journals (Sweden)

De-xi CHEN

2013-07-01

Full Text Available A double mutant with streaked leaf and abnormal floret was found and temporarily named streaked leaf and floral organ number mutant (st-fon. For this mutant, besides white streak appeared on culm, leaves and panicles, the number of floral organs increased and florets cracked. The extreme phenotype was that several small florets grew from one floret or branch rachis in small florets extended and developed into panicles. By using transmission electron microscope to observe the ultrastructure of white histocytes of leaves at the seedling stage, the white tissues which showed abnormal plastids, lamellas and thylakoids could not develop into normal chloroplast, and the development of chloroplast was blocked at the early growth stage of plastid. Scanning electron microscope and paraffin section were also used to observe the development of floral organs, and the results indicated that the development of floral meristem was out of order and unlimited, whereas in the twisty leaves, vascular bundle sheath cells grew excessively, or some bubbly cells increased. Genetic analyses carried out by means of cross and backcross with four normal-leaf-color materials revealed that the mutant is of cytoplasm inheritance.

In-plane spectroscopy with optical fibers and liquid-filled APEX™ glass microcuvettes

International Nuclear Information System (INIS)

Gaillard, William R; Tantawi, Khalid Hasan; Williams, John D; Waddell, Emanuel; Fedorov, Vladimir

2013-01-01

Chemical etching and laser drilling of microstructural glass results in opaque or translucent sidewalls, limiting the optical analysis of glass microfluidic devices to top down or non-planar topologies. These non-planar observation topologies prevent each layer of a multilayered device from being independently optically addressed. However, novel photosensitive glass processing techniques in APEX™ have resulted in microfabricated glass structures with transparent sidewalls. Toward the goal of a transparent multilayered glass microfluidic device, this study demonstrates the ability to perform spectroscopy with optical fibers and microcuvettes fabricated in photosensitive APEX™ glass. (technical note)

Extreme Spectroscopy: In situ nuclear materials behavior from optical data

Energy Technology Data Exchange (ETDEWEB)

Guimbretiere, G.; Canizares, A.; Raimboux, N.; Omnee, R.; Duval, F.; Ammar, M.R.; Simon, P. [CNRS - UPR3079 CEMHTI, Universite d' Orleans, 45071Orleans cedex 2 (France); Desgranges, L.; Mohun, R. [CEA, DEN, DEC, F-13108 Saint-Paul-Lez-Durance (France); Jegou, C.; Magnin, M. [CEA/DTCD/SECM/LMPA, Marcoule 30207 Bagnols Sur Ceze (France); Clavier, N.; Dacheux, N. [ICSM-UMR5257 CEA/CNRS/UM2/ENSCM, Marcoule, BP17171, 30207 Bagnols sur Ceze (France)

2015-07-01

In the nuclear industry, materials are regularly exposed to high temperature or/and irradiation and a better knowledge and understanding of their behavior under such extreme conditions is a key-point for improvements and further developments. Nowadays, Raman spectroscopy begins to be well known as a promising technique in the post mortem and remote characterization of nuclear materials exposed to extreme conditions. On this topic, at ANIMMA 2013 conference, we have presented some results about its implementation in the study of model or real nuclear fuel. However, the strength of Raman spectroscopy as in situ characterization tool is mainly its ability to be implemented remotely through optical fibers. Aware of this, implementation of other optical techniques can be considered in order to gain information not only on the structural dynamics of materials but also on the electronic charge carrier populations. In this paper, we propose to present our last advances in Raman characterization of nuclear materials and enlarge to the in situ use of complementary optical spectroscopies. Emphasis will be made on the information that can be gained to the behavior of the model fuel depleted UO{sub 2} under extreme conditions of high temperature and ionic irradiation: - In Situ Raman identification of the radiolysis alteration products of UO{sub 2} in contact with water under ionic irradiation. - In Situ Raman recording of the damaged dynamic of UO{sub 2} under inert atmosphere. - In Situ Raman and photo-luminescence study of virgin and damaged UO2 at high temperature. - In Situ study of electronic charge carriers' behavior in U{sub x}Th{sub 1-x}O{sub 2} solid solutions by mean of Iono- and Thermo- luminescence under and post- ionic irradiation. (authors)

Analyses of Twelve New Whole Genome Sequences of Cassava Brown Streak Viruses and Ugandan Cassava Brown Streak Viruses from East Africa: Diversity, Supercomputing and Evidence for Further Speciation

Science.gov (United States)

Ndunguru, Joseph; Sseruwagi, Peter; Tairo, Fred; Stomeo, Francesca; Maina, Solomon; Djinkeng, Appolinaire; Kehoe, Monica; Boykin, Laura M.

2015-01-01

Cassava brown streak disease is caused by two devastating viruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) which are frequently found infecting cassava, one of sub-Saharan Africa’s most important staple food crops. Each year these viruses cause losses of up to $100 million USD and can leave entire families without their primary food source, for an entire year. Twelve new whole genomes, including seven of CBSV and five of UCBSV were uncovered in this research, doubling the genomic sequences available in the public domain for these viruses. These new sequences disprove the assumption that the viruses are limited by agro-ecological zones, show that current diagnostic primers are insufficient to provide confident diagnosis of these viruses and give rise to the possibility that there may be as many as four distinct species of virus. Utilizing NGS sequencing technologies and proper phylogenetic practices will rapidly increase the solution to sustainable cassava production. PMID:26439260

Analyses of Twelve New Whole Genome Sequences of Cassava Brown Streak Viruses and Ugandan Cassava Brown Streak Viruses from East Africa: Diversity, Supercomputing and Evidence for Further Speciation.

Directory of Open Access Journals (Sweden)

Joseph Ndunguru

Full Text Available Cassava brown streak disease is caused by two devastating viruses, Cassava brown streak virus (CBSV and Ugandan cassava brown streak virus (UCBSV which are frequently found infecting cassava, one of sub-Saharan Africa's most important staple food crops. Each year these viruses cause losses of up to $100 million USD and can leave entire families without their primary food source, for an entire year. Twelve new whole genomes, including seven of CBSV and five of UCBSV were uncovered in this research, doubling the genomic sequences available in the public domain for these viruses. These new sequences disprove the assumption that the viruses are limited by agro-ecological zones, show that current diagnostic primers are insufficient to provide confident diagnosis of these viruses and give rise to the possibility that there may be as many as four distinct species of virus. Utilizing NGS sequencing technologies and proper phylogenetic practices will rapidly increase the solution to sustainable cassava production.

Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties.

Science.gov (United States)

Vishwanath, Karthik; Chang, Kevin; Klein, Daniel; Deng, Yu Feng; Chang, Vivide; Phelps, Janelle E; Ramanujam, Nimmi

2011-02-01

Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.

Avoiding acidic region streaking in two-dimensional gel ...

Indian Academy of Sciences (India)

Supplementary figure 6. 2DE gel images ... Number of acidic streaks. Fedyunin et al. 2012. 4.02. 6. Zuo et al. 2000. 2.54. 9. Valenete et ... CE, 3rd 2009 Proteasomal protein degradation in ... Nandakumar MP, Shen J, Raman B and Marten MR.

Atomic and molecular phases through attosecond streaking

DEFF Research Database (Denmark)

Baggesen, Jan Conrad; Madsen, Lars Bojer

2011-01-01

phase of the atomic or molecular ionization matrix elements from the two states through the interference from the two channels. The interference may change the phase of the photoelectron streaking signal within the envelope of the infrared field, an effect to be accounted for when reconstructing short...... pulses from the photoelectron signal and in attosecond time-resolved measurements....

Frequency stabilization of a 1083 nm fiber laser to {sup 4}He transition lines with optical heterodyne saturation spectroscopies

Energy Technology Data Exchange (ETDEWEB)

Gong, W.; Peng, X., E-mail: xiangpeng@pku.edu.cn; Li, W.; Guo, H., E-mail: hongguo@pku.edu.cn [State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics Engineering and Computer Science, Center for Quantum Information Technology, and Center for Computational Science and Engineering (CCSE), Peking University, Beijing 100871 (China)

2014-07-15

Two kinds of optical heterodyne saturation spectroscopies, namely, frequency modulation spectroscopy (FMS) and modulation transfer spectroscopy (MTS), are demonstrated for locking a fiber laser to the transition lines of metastable {sup 4}He atoms around 1083 nm. The servo-loop error signals of FMS and MTS for stabilizing laser frequency are optimized by studying the dependence of the peak-to-peak amplitude and slope on the optical power of pump and probe beams. A comparison of the stabilization performances of FMS/MTS and polarization spectroscopy (PS) is presented, which shows that MTS exhibits relatively superior performance with the least laser frequency fluctuation due to its flat-background dispersive signal, originated from the four-wave mixing process. The Allan deviation of the stabilized laser frequency is 5.4 × 10{sup −12}@100 s with MTS for data acquired in 1000 s, which is sufficiently applicable for fields like laser cooling, optical pumping, and optical magnetometry.

Corrosion product characterisation by fibre optic raman spectroscopy

International Nuclear Information System (INIS)

Guzonas, D.A.; Rochefort, P.A.; Turner, C.W.

1998-01-01

Fibre optic Raman spectroscopy has been used to characterise secondary-side deposits removed from CANDU steam generators. The deposits examined were in the form of powders, millimetre-sized flakes, and deposits on the surfaces of pulled steam generator tubes. The compositions of the deposits obtained using Raman spectroscopy are similar to the compositions obtained using other ex-situ analytical techniques. A semi-quantitative estimate of amounts of the major components can be obtained from the spectra. It was noted that the signal-to-noise ratio of the Raman spectra decreased as the amount of magnetite in the deposit increased, as a result of absorption of the laser light by the magnetite. The conversion of magnetite to hematite by the laser beam was observed when high laser powers were used. The Raman spectra of larger flake samples clearly illustrate the inhomogeneous nature of the deposits. (author)

Microprocessor-controlled, wide-range streak camera

Energy Technology Data Exchange (ETDEWEB)

Amy E. Lewis, Craig Hollabaugh

2006-09-01

Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storage using flash-based storage media. The camera’s user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized.

Isotopic analysis using optical spectroscopy (1963)

International Nuclear Information System (INIS)

Gerstenkorn, S.

1963-01-01

The isotopic displacement in the atomic lines of certain elements (H, He, Li, Ne, Sr, Hg, Pb, U, Pu) is used for dosing these elements isotopically. The use of the Fabry-Perot photo-electric interference spectrometer is shown to be particularly adapted for this sort of problem: in each case we give on the one hand the essential results obtained with this apparatus, and on the other hand the results previously obtained with a conventional apparatus (grating, photographic plate). These results together give an idea of the possibilities of optical spectroscopy: in the best case, the precision which may be expected is of the order of 1 to 2 per cent for isotopes whose concentration is about 1 per cent. (author) [fr

Numerical Investigation on the Influence of Hot Streak Temperature Ratio in a High-Pressure Stage of Vaneless Counter-Rotating Turbine

Directory of Open Access Journals (Sweden)

Zhao Qingjun

2007-01-01

Full Text Available The results of recent studies have shown that combustor exit temperature distortion can cause excessive heat load of high-pressure turbine (HPT rotor blades. The heating of HPT rotor blades can lead to thermal fatigue and degrade turbine performance. In order to explore the influence of hot streak temperature ratio on the temperature distributions of HPT airfoil surface, three-dimensional multiblade row unsteady Navier-Stokes simulations have been performed in a vaneless counter-rotating turbine (VCRT. The hot streak temperature ratios from 1.0 (without hot streak to 2.4 were used in these numerical simulations, including 1.0, 1.2, 1.6, 2.0, and 2.4 temperature ratios. The hot streak is circular in shape with a diameter equal to 25% of the span. The center of the hot streak is located at 50% of span and 0% of pitch (the leading edge of the HPT stator vane. The predicted results show that the hot streak is relatively unaffected as it migrates through the HPT stator. The hot streak mixes with the vane wake and convects towards the pressure surface (PS of the HPT rotor when it moves over the vane surface of the HPT stator. The heat load of the HPT rotor increases with the increase of the hot streak temperature ratio. The existence of the inlet temperature distortion induces a thin layer of cooler air in the HPT rotor, which separates the PS of the HPT rotor from the hotter fluid. The numerical results also indicating the migration characteristics of the hot streak in the HPT rotor are predominated by the combined effects of secondary flow and buoyancy. The combined effects that induce the high-temperature fluid migrate towards the hub on the HPT rotor. The effect of the secondary flow on the hotter fluid increases as the hot streak temperature ratio is increased. The influence of buoyancy is directly proportional to the hot streak temperature ratio. The predicted results show that the increase of the hot streak temperature ratio trends to increase

From Selenium- to Tellurium-Based Glass Optical Fibers for Infrared Spectroscopies

Directory of Open Access Journals (Sweden)

Jacques Lucas

2013-05-01

Full Text Available Chalcogenide glasses are based on sulfur, selenium and tellurium elements, and have been studied for several decades regarding different applications. Among them, selenide glasses exhibit excellent infrared transmission in the 1 to 15 µm region. Due to their good thermo-mechanical properties, these glasses could be easily shaped into optical devices such as lenses and optical fibers. During the past decade of research, selenide glass fibers have been proved to be suitable for infrared sensing in an original spectroscopic method named Fiber Evanescent Wave Spectroscopy (FEWS. FEWS has provided very nice and promising results, for example for medical diagnosis. Then, some sophisticated fibers, also based on selenide glasses, were developed: rare-earth doped fibers and microstructured fibers. In parallel, the study of telluride glasses, which can have transmission up to 28 µm due to its atom heaviness, has been intensified thanks to the DARWIN mission led by the European Space Agency (ESA. The development of telluride glass fiber enables a successful observation of CO2 absorption band located around 15 µm. In this paper we review recent results obtained in the Glass and Ceramics Laboratory at Rennes on the development of selenide to telluride glass optical fibers, and their use for spectroscopy from the mid to the far infrared ranges.

Radiation-induced defects in chalcogenide glasses characterized by combined optical spectroscopy, XPS and PALS methods

International Nuclear Information System (INIS)

Shpotyuk, O.; Kovalskiy, A.; Jain, H.; Golovchak, R.; Zurawska, A.

2007-01-01

Temperature-dependent optical absorption spectroscopy, high-resolution X-ray photoelectron spectroscopy and positron annihilation lifetimes spectroscopy are utilized to understand radiation-induced changes in Ge-Sb-S chalcogenide glasses. Theoretically predicted topological scheme of γ-induced coordination defect formation in stoichiometric Ge 23.5 Sb 11.8 S 64.7 glass composition is supported by these measurements. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Optical biopsy of breast tissue using differential path-length spectroscopy

International Nuclear Information System (INIS)

Veen, Robert L P van; Amelink, Arjen; Menke-Pluymers, Marian; Pol, Carmen van der; Sterenborg, Henricus J C M

2005-01-01

Differential path-length spectroscopy (DPS) was used to determine the local optical properties of breast tissue in vivo. DPS measurements were made on healthy and malignant breast tissue using a fibre-optic needle probe, and were correlated to the histological outcome of core-needle biopsies taken from the same location as the measurements. DPS yields information on the local tissue blood content, the local blood oxygenation, the average micro-vessel diameter, the β-carotene concentration and the scatter slope. Our data show that malignant breast tissue is characterized by a significant decrease in tissue oxygenation and a higher blood content compared to normal breast tissue

Optical Spectroscopy and Multiphoton Imaging for the Diagnosis and Characterization of Hyperplasias in the Mouse Mammary Gland

National Research Council Canada - National Science Library

Skala, Melissa C

2007-01-01

.... Optical spectroscopy, in vivo and in vitro microscopy studies indicate that optical methods show great promise for the early diagnosis of cancer, and may potentially provide biologically relevant...

Metastable argon atom density in complex argon/acetylene plasmas determined by means of optical absorption and emission spectroscopy

International Nuclear Information System (INIS)

Sushkov, Vladimir; Herrendorf, Ann-Pierra; Hippler, Rainer

2016-01-01

Optical emission and absorption spectroscopy has been utilized to investigate the instability of acetylene-containing dusty plasmas induced by growing nano-particles. The density of Ar(1s 5 ) metastable atoms was derived by two methods: tunable diode laser absorption spectroscopy and with the help of the branching ratio method of emitted spectral lines. Results of the two techniques agree well with each other. The density of Ar(1s 3 ) metastable atoms was also measured by means of optical emission spectroscopy. The observed growth instability leads to pronounced temporal variations of the metastable and other excited state densities. An analysis of optical line ratios provides evidence for a depletion of free electrons during the growth cycle but no indication for electron temperature variations. (paper)

Raman Spectroscopy with simple optic components; Espectrometria Raman con componentes opticos simples

Energy Technology Data Exchange (ETDEWEB)

Mendoza, Mario; Cunya, Eduardo; Olivera, Paula [Direccion de Investigacion y Desarrollo, Instituto Peruano de Energia Nuclear, Lima (Peru)

2014-07-01

Raman Spectroscopy is .a high resolution photonics technique that provides chemical and structural information of almost any material, organic or inorganic compound. In this report we describe the implementation of a system based on the principle of Raman scattering, developed to analyze solid samples. The spectrometer integrates an optical bench coupled to an optical fiber and a green laser source of 532 nm. The spectrometer was tested obtaining the Naphthalene and the Yellow 74 Pigment Raman patterns. (authors).

Non-invasive optical monitoring of the newborn piglet brain using continuous-wave and frequency-domain spectroscopy

International Nuclear Information System (INIS)

Fantini, S.; Franceschini, M.A.; Gratton, E.; Hueber, D.; Rosenfeld, W.; Maulik, D.; Stubblefield, P.G.; Stankovic, M.R.

1999-01-01

We have used continuous-wave (CW) and frequency-domain spectroscopy to investigate the optical properties of the newborn piglet brain in vivo and non-invasively. Three anaesthetized, intubated, ventilated and instrumented newborn piglets were placed into a stereotaxic instrument for optimal experimental stability, reproducible probe-to-scalp optical contact and 3D adjustment of the optical probe. By measuring the absolute values of the brain absorption and reduced scattering coefficients at two wavelengths (758 and 830 nm), frequency-domain spectroscopy provided absolute readings (in contrast to the relative readings of CW spectroscopy) of cerebral haemoglobin concentration and saturation during experimentally induced perturbations in cerebral haemodynamics and oxygenation. Such perturbations included a modulation of the inspired oxygen concentration, transient brain asphyxia, carotid artery occlusion and terminal brain asphyxia. The baseline cerebral haemoglobin saturation and concentration, measured with frequency-domain spectroscopy, were about 60% and 42 μM respectively. The cerebral saturation values ranged from a minimum of 17% (during transient brain asphyxia) to a maximum of 80% (during recovery from transient brain asphyxia). To analyse the CW optical data, we have (a) derived a mathematical relationship between the cerebral optical properties and the differential pathlength factor and (b) introduced a method based on the spatial dependence of the detected intensity (dc slope method). The analysis of the cerebral optical signals associated with the arterial pulse and with respiration demonstrates that motion artefacts can significantly affect the intensity recorded from a single optode pair. Motion artefacts can be strongly reduced by combining data from multiple optodes to provide relative readings in the dc slope method. We also report significant biphasic changes (initial decrease and successive increase) in the reduced scattering coefficient measured

The ECM moves during primitive streak formation--computation of ECM versus cellular motion.

Directory of Open Access Journals (Sweden)

Evan A Zamir

2008-10-01

Full Text Available Galileo described the concept of motion relativity--motion with respect to a reference frame--in 1632. He noted that a person below deck would be unable to discern whether the boat was moving. Embryologists, while recognizing that embryonic tissues undergo large-scale deformations, have failed to account for relative motion when analyzing cell motility data. A century of scientific articles has advanced the concept that embryonic cells move ("migrate" in an autonomous fashion such that, as time progresses, the cells and their progeny assemble an embryo. In sharp contrast, the motion of the surrounding extracellular matrix scaffold has been largely ignored/overlooked. We developed computational/optical methods that measure the extent embryonic cells move relative to the extracellular matrix. Our time-lapse data show that epiblastic cells largely move in concert with a sub-epiblastic extracellular matrix during stages 2 and 3 in primitive streak quail embryos. In other words, there is little cellular motion relative to the extracellular matrix scaffold--both components move together as a tissue. The extracellular matrix displacements exhibit bilateral vortical motion, convergence to the midline, and extension along the presumptive vertebral axis--all patterns previously attributed solely to cellular "migration." Our time-resolved data pose new challenges for understanding how extracellular chemical (morphogen gradients, widely hypothesized to guide cellular trajectories at early gastrulation stages, are maintained in this dynamic extracellular environment. We conclude that models describing primitive streak cellular guidance mechanisms must be able to account for sub-epiblastic extracellular matrix displacements.

Spectroscopy and photophysics of self-organized zinc porphyrin nanolayers. 1. Optical spectroscopy of excitonic interactions involving the soret band

NARCIS (Netherlands)

Donker, H.; Koehorst, R.B.M.; Schaafsma, T.J.

2005-01-01

The photophysical properties of excited singlet states of zinc tetra-(p-octylphenyl)-porphyrin in 5-25-nm-thick films spin-coated onto quartz slides have been investigated by optical spectroscopy. Analysis of the polarized absorption spectra using a dipole-dipole exciton model with two mutually

Optical spectroscopy versus mass spectrometry: The race for fieldable isotopic analysis

International Nuclear Information System (INIS)

Barshick, C.M.; Young, J.P.; Shaw, R.W.

1995-01-01

Several techniques have been developed to provide on-site isotopic analyses, including decay-counting and mass spectrometry, as well as methods that rely on the accessibility of optical transitions for isotopic selectivity (e.g., laser-induced fluorescence and optogalvanic spectroscopy). The authors have been investigating both mass spectrometry and optogalvanic spectroscopy for several years. Although others have considered these techniques for isotopic analysis, the authors have focussed on the use of a dc glow discharge for atomization and ionization, and a demountable discharge cell for rapid sample exchange. The authors' goal is a fieldable instrument that provides useful uranium isotope ratio information

An optical and dielectric spectroscopy study of Er.sup.3+./sup.-doped KTaO.sub.3./sub..

Czech Academy of Sciences Publication Activity Database

Trepakov, Vladimír; Skvortsov, A.; Poletaev, N.; Potůček, Zdeněk; Nuzhnyy, Dmitry; Jastrabík, Lubomír; Dejneka, Alexandr

2011-01-01

Roč. 248, č. 12 (2011), s. 2908-2915 ISSN 0370-1972 R&D Projects: GA ČR GC202/09/J017; GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100522 Keywords : Er 3+ centres * IR spectroscopy * optical absorption photoluminescence * potassium tantalate * THz spectroscopy Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.316, year: 2011

A pilot study on the use of optical spectroscopy to detection of liver fibrosis

International Nuclear Information System (INIS)

Fabila, A; La Rosa, J. de; Stolik, S.; Escobedo, C.; Suarez Alvarez, K.; Lopez Navarrete, G.

2012-01-01

In this paper we present the preliminary study to evaluate the use of optical spectroscopy as a tool to detect liver fibrosis. In vivo fluorescence and diffuse reflectance spectra were acquired from male rats in which fibrosis were induced by means of carbon tetrachloride. Spectral measurements were obtained using a portable system with an excitation source of 365 nm and a fiber-optic probe. The livers from rats with fibrosis showed an increase in fluorescence and diffuse reflectance intensity when compared to normal liver tissue. A support vector machine discrimination algorithm based on fluorescence and diffuse reflectance intensities at 493 and 365 nm was developed. This algorithm yields a sensitivity and specificity of 88% and 94%, respectively, in differentiating fibrotic liver from normal liver tissue. the results obtained in this study suggest that optical spectroscopy could be worthy of further exploration in patients. (Author)

FOREX-A Fiber Optics Diagnostic System For Study Of Materials At High Temperatures And Pressures

Science.gov (United States)

Smith, D. E.; Roeske, F.

1983-03-01

We have successfully fielded a Fiber Optics Radiation EXperiment system (FOREX) designed for measuring material properties at high temperatures and pressures on an underground nuclear test. The system collects light from radiating materials and transmits it through several hundred meters of optical fibers to a recording station consisting of a streak camera with film readout. The use of fiber optics provides a faster time response than can presently be obtained with equalized coaxial cables over comparable distances. Fibers also have significant cost and physical size advantages over coax cables. The streak camera achieves a much higher information density than an equivalent oscilloscope system, and it also serves as the light detector. The result is a wide bandwidth high capacity system that can be fielded at a relatively low cost in manpower, space, and materials. For this experiment, the streak camera had a 120 ns time window with a 1.2 ns time resolution. Dynamic range for the system was about 1000. Beam current statistical limitations were approximately 8% for a 0.3 ns wide data point at one decade above the threshold recording intensity.

A Demographic Model to Evaluate Population Declines in the Endangered Streaked Horned Lark

Directory of Open Access Journals (Sweden)

Alaine F. Camfield

2011-12-01

Full Text Available The Streaked Horned Lark (Eremophila alpestris strigata is listed as endangered by the State of Washington, USA and by Canada under the Species at Risk Act and is also classified as a federal candidate for listing under the Endangered Species Act in the USA. A substantial portion of Streaked Horned Lark habitat has been lost or degraded, and range contraction has occurred in Oregon, Washington, and British Columbia. We estimate the vital rates (fecundity, adult and juvenile survival and population growth rate (λ for Streaked Horned Larks breeding in Washington, USA and conduct a Life-Stage Simulation Analysis (LSA to evaluate which vital rate has the greatest influence on λ. We simulated changes in the three vital rates to examine how much they would need to be adjusted either independently or in concert to achieve a stable Streaked Horned Lark population (λ = 1. We also evaluated which fecundity component (the number of fledglings per egg laid or renesting interval had the greatest impact on λ. The estimate of population growth suggests that Streaked Horned Larks in Washington are declining rapidly (λ = 0.62 ± 0.10 and that local breeding sites are not sustainable without immigration. The LSA results indicate that adult survival had the greatest influence on λ, followed by juvenile survival and fecundity. However, increases in vital rates led to λ = 1 only when adult survival was raised from 0.47 to 0.85, juvenile survival from 0.17 to 0.58, and fecundity from 0.91 to 3.09. Increases in breeding success and decreases in the renesting interval influenced λ similarly; however, λ did not reach 1 even when breeding success was raised to 100% or renesting intervals were reduced to 1 day. Only when all three vital rates were increased simultaneously did λ approach 1 without requiring highly unrealistic increases in each vital rate. We conclude that conservation activities need to target all or multiple vital rates to be successful. The

Radiation-induced defects in chalcogenide glasses characterized by combined optical spectroscopy, XPS and PALS methods

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, O. [Institute of Physics of Jan Dlugosz University, 13/15 al. Armii Krajowej, Czestochowa 42201 (Poland); Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States); Lviv Institute of Materials of SRC ' ' Carat' ' , 202, Stryjska str., 79031 Lviv (Ukraine); Kovalskiy, A.; Jain, H. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States); Golovchak, R. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States); Lviv Institute of Materials of SRC ' ' Carat' ' , 202, Stryjska str., 79031 Lviv (Ukraine); Zurawska, A. [Opole University of Technology, 75, Ozimska str., Opole 45370 (Poland)

2007-03-15

Temperature-dependent optical absorption spectroscopy, high-resolution X-ray photoelectron spectroscopy and positron annihilation lifetimes spectroscopy are utilized to understand radiation-induced changes in Ge-Sb-S chalcogenide glasses. Theoretically predicted topological scheme of {gamma}-induced coordination defect formation in stoichiometric Ge{sub 23.5}Sb{sub 11.8}S{sub 64.7} glass composition is supported by these measurements. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Multi-modal approach using Raman spectroscopy and optical coherence tomography for the discrimination of colonic adenocarcinoma from normal colon

Science.gov (United States)

Ashok, Praveen C.; Praveen, Bavishna B.; Bellini, Nicola; Riches, Andrew; Dholakia, Kishan; Herrington, C. Simon

2013-01-01

We report a multimodal optical approach using both Raman spectroscopy and optical coherence tomography (OCT) in tandem to discriminate between colonic adenocarcinoma and normal colon. Although both of these non-invasive techniques are capable of discriminating between normal and tumour tissues, they are unable individually to provide both the high specificity and high sensitivity required for disease diagnosis. We combine the chemical information derived from Raman spectroscopy with the texture parameters extracted from OCT images. The sensitivity obtained using Raman spectroscopy and OCT individually was 89% and 78% respectively and the specificity was 77% and 74% respectively. Combining the information derived using the two techniques increased both sensitivity and specificity to 94% demonstrating that combining complementary optical information enhances diagnostic accuracy. These data demonstrate that multimodal optical analysis has the potential to achieve accurate non-invasive cancer diagnosis. PMID:24156073

Streak electronic camera with slow-scanning storage tube used in the field of high-speed cineradiography

International Nuclear Information System (INIS)

Marilleau, J.; Bonnet, L.; Garcin, G.; Guix, R.; Loichot, R.

The cineradiographic machine designed for measurements in the field of detonics consists of a linear accelerator associated with a braking target, a scintillator and a remote controlled electronic camera. The quantum factor of X-ray detection and the energetic efficiency of the scintillator are given. The electronic camera is built upon a deflection-converter tube (RCA C. 73 435 AJ) coupled by optical fibres to a photosensitive storage tube (TH-CSF Esicon) used in a slow-scanning process with electronic recording of the information. The different parts of the device are described. Some capabilities such as data processing numerical outputs, measurements and display are outlined. A streak cineradiogram of a typical implosion experiment is given [fr

Two-dimensional optical correlation spectroscopy applied to liquid/glass dynamics

OpenAIRE

Lazonder, Kees; Pshenichnikov, Maxim S.; Wiersma, Douwe A.; Corkum, Paul; Jonas, David M.; Miller, R.J. Dwayne.; Weiner, Andrew M.

2007-01-01

Correlation spectroscopy was used to study the effects of temperature and phase changes on liquid and glass solvent dynamics. By assessing the eccentricity of the elliptic shape of a 2D optical correlation spectrum the value of the underlying frequency-frequency correlation function can be retrieved through a very simple relationship. This method yielded both intuitive clues and a quantitative measure of the dynamics of the system.

Bilateral choroidal neovascularization response to unilateral intravitreal Ranibizumab injection in a patient with angioid streaks

Directory of Open Access Journals (Sweden)

Otacílio de Oliveira Maia Júnior

2013-08-01

Full Text Available Report of a 48 year-old male with bilateral decrease in vision due to choroidal neovascularization secondary to angioid streaks. Best corrected visual acuity was 20/80 in the right eye and counting fingers at 2 meters on the left eye. Patient underwent intravitreal injection of Ranibizumab (Lucentis in the eye with worse visual acuity. Fifteen days after treatment patient reported better visual acuity on the fellow eye, which was measured to be 20/25. Treatment result was evaluated with visual acuity and optical coherence tomography. The effect of ranibizumab was observed in the treated eye, but the fellow eye had complete resolution of the choroidal neovascularization complex. This result may be a response to systemic absorption of the medication.

A high spatio-temporal resolution optical pyrometer at the ORION laser facility.

Science.gov (United States)

Floyd, Emma; Gumbrell, Edward T; Fyrth, Jim; Luis, James D; Skidmore, Jonathan W; Patankar, Siddharth; Giltrap, Samuel; Smith, Roland

2016-11-01

A streaked pyrometer has been designed to measure the temperature of ≈100 μm diameter heated targets in the warm dense matter region. The diagnostic has picosecond time resolution. Spatial resolution is limited by the streak camera to 4 μm in one dimension; the imaging system has superior resolution of 1 μm. High light collection efficiency means that the diagnostic can transmit a measurable quantity of thermal emission at temperatures as low as 1 eV to the detector. This is achieved through the use of an f/1.4 objective, and a minimum number of reflecting and refracting surfaces to relay the image over 8 m with no vignetting over a 0.4 mm field of view with 12.5× magnification. All the system optics are highly corrected, to allow imaging with minimal aberrations over a broad spectral range. The detector is a highly sensitive Axis Photonique streak camera with a P820PSU streak tube. For the first time, two of these cameras have been absolutely calibrated at 1 ns and 2 ns sweep speeds under full operational conditions and over 8 spectral bands between 425 nm and 650 nm using a high-stability picosecond white light source. Over this range the cameras had a response which varied between 47 ± 8 and 14 ± 4 photons/count. The calibration of the optical imaging system makes absolute temperature measurements possible. Color temperature measurements are also possible due to the wide spectral range over which the system is calibrated; two different spectral bands can be imaged onto different parts of the photocathode of the same streak camera.

A new streaked soft x-ray imager for the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Benstead, J., E-mail: james.benstead@awe.co.uk; Morton, J.; Guymer, T. M.; Garbett, W. J.; Rubery, M. S.; Skidmore, J. W. [AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Moore, A. S.; Ahmed, M. F.; Soufli, R.; Pardini, T.; Hibbard, R. L.; Bailey, C. G.; Bell, P. M.; Hau-Riege, S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Bedzyk, M.; Shoup, M. J.; Reagan, S.; Agliata, T.; Jungquist, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Schmidt, D. W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); and others

2016-05-15

A new streaked soft x-ray imager has been designed for use on high energy-density (HED) physics experiments at the National Ignition Facility based at the Lawrence Livermore National Laboratory. This streaked imager uses a slit aperture, single shallow angle reflection from a nickel mirror, and soft x-ray filtering to, when coupled to one of the NIF’s x-ray streak cameras, record a 4× magnification, one-dimensional image of an x-ray source with a spatial resolution of less than 90 μm. The energy band pass produced depends upon the filter material used; for the first qualification shots, vanadium and silver-on-titanium filters were used to gate on photon energy ranges of approximately 300–510 eV and 200–400 eV, respectively. A two-channel version of the snout is available for x-ray sources up to 1 mm and a single-channel is available for larger sources up to 3 mm. Both the one and two-channel variants have been qualified on quartz wire and HED physics target shots.

Time domain diffuse optical spectroscopy: In vivo quantification of collagen in breast tissue

Science.gov (United States)

Taroni, Paola; Pifferi, Antonio; Quarto, Giovanna; Farina, Andrea; Ieva, Francesca; Paganoni, Anna Maria; Abbate, Francesca; Cassano, Enrico; Cubeddu, Rinaldo

2015-05-01

Time-resolved diffuse optical spectroscopy provides non-invasively the optical characterization of highly diffusive media, such as biological tissues. Light pulses are injected into the tissue and the effects of light propagation on re-emitted pulses are interpreted with the diffusion theory to assess simultaneously tissue absorption and reduced scattering coefficients. Performing spectral measurements, information on tissue composition and structure is derived applying the Beer law to the measured absorption and an empiric approximation to Mie theory to the reduced scattering. The absorption properties of collagen powder were preliminarily measured in the range of 600-1100 nm using a laboratory set-up for broadband time-resolved diffuse optical spectroscopy. Optical projection images were subsequently acquired in compressed breast geometry on 218 subjects, either healthy or bearing breast lesions, using a portable instrument for optical mammography that operates at 7 wavelengths selected in the range 635-1060 nm. For all subjects, tissue composition was estimated in terms of oxy- and deoxy-hemoglobin, water, lipids, and collagen. Information on tissue microscopic structure was also derived. Good correlation was obtained between mammographic breast density (a strong risk factor for breast cancer) and an optical index based on collagen content and scattering power (that accounts mostly for tissue collagen). Logistic regression applied to all optically derived parameters showed that subjects at high risk for developing breast cancer for their high breast density can effectively be identified based on collagen content and scattering parameters. Tissue composition assessed in breast lesions with a perturbative approach indicated that collagen and hemoglobin content are significantly higher in malignant lesions than in benign ones.

Relationships between early spring wheat streak mosaic severity levels and grain yield: Implications for management decisions

Science.gov (United States)

Wheat streak mosaic (WSM) caused by Wheat streak mosaic virus, which is transmitted by the wheat curl mite (Aceria tosichella), is a major yield-limiting disease in the Texas High Plains. In addition to its impact on grain production, the disease reduces water-use efficiency by affecting root develo...

Molecular characterization of Banana streak virus isolate from Musa Acuminata in China.

Science.gov (United States)

Zhuang, Jun; Wang, Jian-Hua; Zhang, Xin; Liu, Zhi-Xin

2011-12-01

Banana streak virus (BSV), a member of genus Badnavirus, is a causal agent of banana streak disease throughout the world. The genetic diversity of BSVs from different regions of banana plantations has previously been investigated, but there are relatively few reports of the genetic characteristic of episomal (non-integrated) BSV genomes isolated from China. Here, the complete genome, a total of 7722bp (GenBank accession number DQ092436), of an isolate of Banana streak virus (BSV) on cultivar Cavendish (BSAcYNV) in Yunnan, China was determined. The genome organises in the typical manner of badnaviruses. The intergenic region of genomic DNA contains a large stem-loop, which may contribute to the ribosome shift into the following open reading frames (ORFs). The coding region of BSAcYNV consists of three overlapping ORFs, ORF1 with a non-AUG start codon and ORF2 encoding two small proteins are individually involved in viral movement and ORF3 encodes a polyprotein. Besides the complete genome, a defective genome lacking the whole RNA leader region and a majority of ORF1 and which encompasses 6525bp was also isolated and sequenced from this BSV DNA reservoir in infected banana plants. Sequence analyses showed that BSAcYNV has closest similarity in terms of genome organization and the coding assignments with an BSV isolate from Vietnam (BSAcVNV). The corresponding coding regions shared identities of 88% and -95% at nucleotide and amino acid levels, respectively. Phylogenetic analysis also indicated BSAcYNV shared the closest geographical evolutionary relationship to BSAcVNV among sequenced banana streak badnaviruses.

Cassava brown streak disease in Rwanda, the associated viruses and disease phenotypes.

Science.gov (United States)

Munganyinka, E; Ateka, E M; Kihurani, A W; Kanyange, M C; Tairo, F; Sseruwagi, P; Ndunguru, J

2018-02-01

Cassava brown streak disease (CBSD) was first observed on cassava ( Manihot esculenta ) in Rwanda in 2009. In 2014 eight major cassava-growing districts in the country were surveyed to determine the distribution and variability of symptom phenotypes associated with CBSD, and the genetic diversity of cassava brown streak viruses. Distribution of the CBSD symptom phenotypes and their combinations varied greatly between districts, cultivars and their associated viruses. The symptoms on leaf alone recorded the highest (32.2%) incidence, followed by roots (25.7%), leaf + stem (20.3%), leaf + root (10.4%), leaf + stem + root (5.2%), stem + root (3.7%), and stem (2.5%) symptoms. Analysis by RT-PCR showed that single infections of Ugandan cassava brown streak virus (UCBSV) were most common (74.2% of total infections) and associated with all the seven phenotypes studied. Single infections of Cassava brown streak virus (CBSV) were predominant (15.3% of total infections) in CBSD-affected plants showing symptoms on stems alone. Mixed infections (CBSV + UCBSV) comprised 10.5% of total infections and predominated in the combinations of leaf + stem + root phenotypes. Phylogenetic analysis and the estimates of evolutionary divergence, using partial sequences (210 nt) of the coat protein gene, revealed that in Rwanda there is one type of CBSV and an indication of diverse UCBSV. This study is the first to report the occurrence and distribution of both CBSV and UCBSV based on molecular techniques in Rwanda.

Assessment of high precision, high accuracy Inductively Coupled Plasma-Optical Emission Spectroscopy to obtain concentration uncertainties less than 0.2% with variable matrix concentrations

International Nuclear Information System (INIS)

Rabb, Savelas A.; Olesik, John W.

2008-01-01

The ability to obtain high precision, high accuracy measurements in samples with complex matrices using High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy (HP-ICP-OES) was investigated. The Common Analyte Internal Standard (CAIS) procedure was incorporated into the High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy method to correct for matrix-induced changes in emission intensity ratios. Matrix matching and standard addition approaches to minimize matrix-induced errors when using High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy were also assessed. The High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy method was tested with synthetic solutions in a variety of matrices, alloy standard reference materials and geological reference materials

Optical spectroscopy: current advances and future applications in cancer diagnostics and therapy

NARCIS (Netherlands)

Evers, Daniel; Evers, D.J.; Hendriks, B.; Lucassen, G.W.; Lucassen, Gerald; Ruers, Theo J.M.

2012-01-01

Optical spectroscopy (OS) is a tissue-sensing technique that could enhance cancer diagnosis and treatment in the near future. With OS, tissue is illuminated with a selected light spectrum. Different tissue types can be distinguished from each other based on specific changes in the reflected light

On the investigation of electronic defect states in ZnO thin films by space charge spectroscopy with optical excitation

Science.gov (United States)

Schmidt, Matthias; Wenckstern, Holger von; Pickenhain, Rainer; Grundmann, Marius

2012-09-01

Electronic defect states in a n-type conducting zinc oxide thin film sample were investigated by means of space charge spectroscopy focussing on levels in the midgap region as well as on hole traps. To overcome the experimental difficulties arising from the wide bandgap and the lack of p-type conduction, optical excitation was employed to measure the emission of trapped charge carriers from these levels. Therefore - besides deep-level transient spectroscopy measurements - photo-capacitance, optically chopped photo-current, minority carrier transient spectroscopy, and optical capacitance-voltage experiments were conducted. In doing so, a midgap level labelled T4, and hole traps labelled TH1 and TH2 were detected. In the case of T4 and TH1 the photo-ionisation cross-section spectra were determined.

Opportunities for sub-laser-cycle spectroscopy in condensed phase

International Nuclear Information System (INIS)

Ivanov, Misha; Smirnova, Olga

2013-01-01

Highlights: ► We discuss how sub-cycle attosecond spectroscopy can be extended from gas to condensed phase. ► We show that attosecond streaking measurements can be applied to bound electrons. ► We discuss time-resolving the formation of band structure in laser fields. - Abstract: To a large extent, progress of attosecond spectroscopy in the gas phase has been driven by designing approaches where time-resolution is not limited by the pulse duration. Instead, the time resolution comes from exploiting the sensitivity of electronic response to the oscillations of the electric field in the laser pulse and attosecond control over these oscillations. This paper discusses perspectives and opportunities for transporting the ideas of sub-cycle spectroscopy from gas to condensed phase

Implementation of a lock-in amplifier for optical spectroscopy measurement

International Nuclear Information System (INIS)

Homs, R.; Puron, E.

2012-01-01

The experimental set-up of an optical spectroscopy measurement based on virtual instrumentation is presented. A lock-in amplifier has been implemented by applying digital signal processing techniques to a PC-based data acquisition board. The application was developed in C++, on top of open source Qt/Qwt graphical framework. The emission spectral of reference light sources were measured in order to calibrate and validate the system. (Author)

A maize resistance gene functions against bacterial streak disease in rice.

Science.gov (United States)

Zhao, Bingyu; Lin, Xinghua; Poland, Jesse; Trick, Harold; Leach, Jan; Hulbert, Scot

2005-10-25

Although cereal crops all belong to the grass family (Poacea), most of their diseases are specific to a particular species. Thus, a given cereal species is typically resistant to diseases of other grasses, and this nonhost resistance is generally stable. To determine the feasibility of transferring nonhost resistance genes (R genes) between distantly related grasses to control specific diseases, we identified a maize R gene that recognizes a rice pathogen, Xanthomonas oryzae pv. oryzicola, which causes bacterial streak disease. Bacterial streak is an important disease of rice in Asia, and no simply inherited sources of resistance have been identified in rice. Although X. o. pv. oryzicola does not cause disease on maize, we identified a maize gene, Rxo1, that conditions a resistance reaction to a diverse collection of pathogen strains. Surprisingly, Rxo1 also controls resistance to the unrelated pathogen Burkholderia andropogonis, which causes bacterial stripe of sorghum and maize. The same gene thus controls resistance reactions to both pathogens and nonpathogens of maize. Rxo1 has a nucleotide-binding site-leucine-rich repeat structure, similar to many previously identified R genes. Most importantly, Rxo1 functions after transfer as a transgene to rice, demonstrating the feasibility of nonhost R gene transfer between cereals and providing a valuable tool for controlling bacterial streak disease.

Realization of an optical multi and mono-channel analyzer, associated to a streak camera. Application to metrology of picosecond low intensity luminous pulses

International Nuclear Information System (INIS)

Roth, J.M.

1985-02-01

An electronic system including a low light level television tube (Nocticon) to digitize images from streak cameras is studied and realized. Performances (sensibility, signal-to-noise ratio) are studied and compared with a multi-channel analyzer using a linear network of photodiodes. It is applied to duration and amplitude measurement of short luminous pulses [fr

traits and resistance to maize streak virus disease in kenya

African Journals Online (AJOL)

African Crop Science Journal, Vol. 14. No. 4, pp. ... Kenya Agricultural Research Institute, Muguga-South, P.O. Box 30148, Nairobi, Kenya .... streak disease has been identified in various maize recycling and development of pure-lines at.

Spectroscopy of molecules in very high rotational states using an optical centrifuge.

Science.gov (United States)

Yuan, Liwei; Toro, Carlos; Bell, Mack; Mullin, Amy S

2011-01-01

We have developed a high power optical centrifuge for measuring the spectroscopy of molecules in extreme rotational states. The optical centrifuge has a pulse energy that is more than 2 orders of magnitude greater than in earlier instruments. The large pulse energy allows us to drive substantial number densities of molecules to extreme rotational states in order to measure new spectroscopic transitions that are not accessible with traditional methods. Here we demonstrate the use of the optical centrifuge for measuring IR transitions of N2O from states that have been inaccessible until now. In these studies, the optical centrifuge drives N2O molecules into states with J ~ 200 and we use high resolution transient IR probing to measure the appearance of population in states with J = 93-99 that result from collisional cooling of the centrifuged molecules. High resolution Doppler broadened line profile measurements yield information about the rotational and translational energy distributions in the optical centrifuge.

Light field driven streak-camera for single-shot measurements of the temporal profile of XUV-pulses from a free-electron laser; Lichtfeld getriebene Streak-Kamera zur Einzelschuss Zeitstrukturmessung der XUV-Pulse eines Freie-Elektronen Lasers

Energy Technology Data Exchange (ETDEWEB)

Fruehling, Ulrike

2009-10-15

The Free Electron Laser in Hamburg (FLASH) is a source for highly intense ultra short extreme ultraviolet (XUV) light pulses with pulse durations of a few femtoseconds. Due to the stochastic nature of the light generation scheme based on self amplified spontaneous emission (SASE), the duration and temporal profile of the XUV pulses fluctuate from shot to shot. In this thesis, a THz-field driven streak-camera capable of single pulse measurements of the XUV pulse-profile has been realized. In a first XUV-THz pump-probe experiment at FLASH, the XUV-pulses are overlapped in a gas target with synchronized THz-pulses generated by a new THz-undulator. The electromagnetic field of the THz light accelerates photoelectrons produced by the XUV-pulses with the resulting change of the photoelectron momenta depending on the phase of the THz field at the time of ionisation. This technique is intensively used in attosecond metrology where near infrared streaking fields are employed for the temporal characterisation of attosecond XUV-Pulses. Here, it is adapted for the analysis of pulse durations in the few femtosecond range by choosing a hundred times longer far infrared streaking wavelengths. Thus, the gap between conventional streak cameras with typical resolutions of hundreds of femtoseconds and techniques with attosecond resolution is filled. Using the THz-streak camera, the time dependent electric field of the THz-pulses was sampled in great detail while on the other hand the duration and even details of the time structure of the XUV-pulses were characterized. (orig.)

ANTIOXIDANT EFFECTS OF L-SERINE AGAINST FATTY STREAK FORMATION IN HYPERCHOLESTEROLEMIC ANIMALS

Directory of Open Access Journals (Sweden)

Ahmad Movahedian

2010-12-01

Full Text Available   Abstract INTRODUCTION: Peroxidation of blood lipoproteins is regarded as a key event in the development of atherosclerosis. Evidence suggests that oxidative modification of amino acids in low-density lipoprotein (LDL particles leads to its convert into an atherogenic form, which is taken up by macrophages. Therefore the reduction of oxidative modification of lipoproteins by increasing plasma antioxidant capacity may prevent cardiovascular disease. methods: In this study, the antioxidant and anti-fatty streak effects of L-serine were investigated in hypercholesterolemic rabbits. Rabbits were randomly divided into three groups which were fed high-cholesterol diet (hypercholesterolemic control group, high-cholesterol + L-serine diet (treatment group, and normal diet (control for twelve weeks and then blood samples were obtained to measure plasma cholesterol, triglyceride (TG, high-density lipoprotein (HDL, low-density lipoprotein (LDL, antioxidant capacity (AC, malondialdehyde (MDA, and conjugated dienes (CDS. Right and left coronary arteries were also obtained for histological evaluation. results: No significant difference was observed in plasma cholesterol, TG, HDL, LDL and CDS levels between treatment and hypercholesterolemic control groups (P>0.05. The levels of plasma MDA and AC were 0.29‌ µM and 56%, respectively in the treatment group which showed a significant change in comparison with hypercholesterolemic control groups (P<0.05. The mean size of produced fatty streak also showed significant reduction in the treatment group compared to the hypercholesterolemic group (P<0.05. CONCLUSIONS: The results showed that L-serine has antioxidant and anti-fatty streak effects without any influence on plasma lipid levels in hypercholesterolemic rabbits.     Keywords: Atherosclerosis, cholesterol, L-serine, antioxidant, lipids, fatty streak.

Cassava brown streak disease effects on leaf metabolites and ...

African Journals Online (AJOL)

Cassava brown streak disease effects on leaf metabolites and pigment accumulation. ... Total reducing sugar and starch content also dropped significantly (-30 and -60%, respectively), much as NASE 14 maintained a relatively higher amount of carbohydrates. Leaf protein levels were significantly reduced at a rate of 0.07 ...

Controlling the optical path length in turbid media using differential path-length spectroscopy: fiber diameter dependence

NARCIS (Netherlands)

Kaspers, O. P.; Sterenborg, H. J. C. M.; Amelink, A.

2008-01-01

We have characterized the path length for the differential path-length spectroscopy (DPS) fiber optic geometry for a wide range of optical properties and for fiber diameters ranging from 200 mu m to 1000 mu m. Phantom measurements show that the path length is nearly constant for scattering

Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

DEFF Research Database (Denmark)

Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga

2010-01-01

The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

Two-Photon Vibrational Spectroscopy using local optical fields of gold and silver nanostructures

Science.gov (United States)

Kneipp, Katrin; Kneipp, Janina; Kneipp, Harald

2007-03-01

Spectroscopic effects can be strongly affected when they take place in the immediate vicinity of metal nanostructures due to coupling to surface plasmons. We introduce a new approach that suggests highly efficient two-photon labels as well as two-photon vibrational spectroscopy for non-destructive chemical probing. The underlying spectroscopic effect is the incoherent inelastic scattering of two photons on the vibrational quantum states performed in the enhanced local optical fields of gold nanoparticles, surface enhanced hyper Raman scattering (SEHRS). We infer effective two-photon cross sections for SEHRS on the order of 10^5 GM, similar or higher than the best known cross sections for two-photon fluorescence. SEHRS combines the advantages of two-photon spectroscopy with the structural information of vibrational spectroscopy, and the high sensitivity and nanometer-scale local confinement of plasmonics-based spectroscopy.

Fiber optics reflectance spectroscopy (45°x: 45°) for color analysis of dental composite.

Science.gov (United States)

Gargano, Marco; Ludwig, Nicola; Federighi, Veronica; Sykes, Ros; Lodi, Giovanni; Sardella, Andrea; Carrassi, Antonio; Varoni, Elena M

2016-08-01

To evaluate the application of a fiber optic reflectance spectroscopy (FORS) prototype probe for 45°x: 45° FORS for determining color of dental materials. A portable spectrophotometer with a highly manageable fiber optics co-axial probe was used to apply 45°x: 45° FORS for color matching in restorative dentistry. The color coordinates in CIELAB space of two dental shade guides and of the corresponding photopolymerized composites were collected and compared. The 45°x: 45° FORS with the co-axial probe (test system), the integrating sphere spectroscopy (reference system) and a commercial dental colorimeter (comparator system) were used to collect data and calculate color differences (ΔE and ΔE00). FORS system displayed high repeatability, reproducibility and accuracy. ΔE and ΔE00 values between the shade-guide, each other, and the corresponding composites resulted above the clinically acceptable limit. The 45°x: 45° FORS test system demonstrated suitable in vitro performance for dental composite color evaluation. 45°x: 45° fiber optic reflectance spectroscopy allows reliable color analysis of small surfaces of dental composites, favoring the color matching of material with the closely surrounding dental tissue, and confirming significant color differences between shade guide tabs and photo-polymerized composites.

Pedicle streaking: A novel and simple aid in pedicle positioning in free tissue transfer

Directory of Open Access Journals (Sweden)

Aditya Aggarwal

2015-01-01

Full Text Available Introduction: The pedicle positioning in free tissue transfer is critical to its success. Long thin pedicles are especially prone to this complication where even a slight twist in the perforator can result in flap loss. Pedicles passing through the long tunnels are similarly at risk. Streaking the pedicle with methylene blue is a simple and safe method which increases the safety of free tissue transfer. Materials and Methods: Once the flap is islanded on the pedicle and the vascularity of the flap is confirmed, the pedicle is streaked with methylene blue dye at a distance of 6-7 mm. The streaking starts from the origin of the vessels and continued distally on to the under surface of flap to mark the complete course of the pedicle in alignment. The presence of streaking in some parts and not in rest indicates twist in the pedicle. Observation and Results: Four hundred and sixty five free flaps have been done at our centre in the last 5 years. The overall success rate of free flaps is 95.3% (22 free flap failures. There has not been a single case of pedicle twist leading to flap congestion and failure. Conclusion: This simple and novel method is very reliable for pedicle positioning avoiding any twist necessary for successful free tissue transfer.

Label-free detection of HIV-1 infected cells via integration of optical tweezers and photoluminescence spectroscopy

Science.gov (United States)

Lugongolo, Masixole Yvonne; Ombinda-Lemboumba, Saturnin; Noto, Luyanda Lunga; Maaza, Malik; Mthunzi-Kufa, Patience

2018-02-01

The human immunodeficiency virus-1 (HIV-1) is currently detected using conventional qualitative and quantitative tests to determine the presence or absence of HIV in blood samples. However, the approach of these tests detects the presence of either viral antibodies or viral RNA that require labelling which may be costly, sophisticated and time consuming. A label-free approach of detecting the presence of HIV is therefore desirable. Of note optical tweezers can be coupled with other technologies including spectroscopy, which also investigates light-matter interactions. For example, coupling of optical tweezers with luminescence spectroscopy techniques has emerged as a powerful tool in biology for micro-manipulation, detection and analysis of individual cells. Integration of optical techniques has enabled studying biological particles in a label-free manner, whilst detecting functional groups and other essential molecules within mixed populations of cells. In the current study, an optical trapping system coupled to luminescence spectroscopy was utilised to detect the presence of HIV infection in TZM-bl cells in vitro. This was performed by infecting TZM-bl cells with the ZM53 HIV-1 pseudovirus, and incubating them for 48 hours prior analysis. The differences between infected and uninfected cells were thereafter displayed as shown by the spectrographs obtained. Combination of these two techniques has a potential in the field of infectious disease diagnostics.

Local optical spectroscopy of opaline photonic crystal films

Science.gov (United States)

Bakhia, T.; Baranchikov, A. E.; Gorelik, V. S.; Klimonsky, S. O.

2017-09-01

The homogeneity of opaline films obtained by vertical deposition of colloidal SiO2 microparticles has been studied by scanning electron microscopy (SEM) and local optical spectroscopy. It was found that the particle size distribution is narrowed during the deposition, the microstructure of the films improves, and the reflection peak in the first photonic stop band increases and narrows. These changes may be due to the fact that large microparticles, whose mass significantly exceeds the average mass, leave the solution in the course of time, falling on the bottom of the vessel under gravity. It is established that the microstructure of opaline films is improved with a decrease in thickness.

Development of micro-optics for high-resolution IL spectroscopy with a proton microbeam probe

International Nuclear Information System (INIS)

Kada, Wataru; Satoh, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro

2014-01-01

Confocal optics for ion luminescence (IL) was developed for the precise analysis of the chemical composition of microscopic targets with an external proton microbeam probe. Anti-reflection-coated confocal micro-lens optics with an effective focus area of approximately 800 × 800 μm was installed on the microbeam line of a single-ended accelerator. Chromatic aberrations of the confocal optics were examined at wavelengths of 300–900 nm. An electrically-cooled back-thinned charge coupled device spectrometer with a wavelength resolution of 0.5 nm was used for the microscopic spectroscopy and IL imaging of microscopic mineral targets. Simultaneous microscopic IL and micro-PIXE analysis were performed using an external 3 MeV H + microbeam with a current of less than 100 pA. A spectral resolution of 3 nm was achieved for a single IL peak which corresponded to Cr 3+ impurities in a single-crystal of aluminum oxide. The use of IL spectroscopy and imaging for aerosol targets revealed microscopic distributions of the chemical and elemental composition in the atmosphere

Optical spectroscopy, optical conductivity, dielectric properties and new methods for determining the gap states of CuSe thin films

International Nuclear Information System (INIS)

Sakr, G.B.; Yahia, I.S.; Fadel, M.; Fouad, S.S.; Romcevic, N.

2010-01-01

Research highlights: → The structural, optical dispersion parameters and the Raman spectroscopy have been studied for CuSe thin films. → X-ray diffraction results indicate the amorphous nature of the thermally evaporated CuSe thin films. → The refractive index shows an anomalous dispersion at the lower wavelength (absorption region) and a normal dispersion at the higher wavelengths (transparent region). → The refractive index dispersion obeys the single oscillator model proposed by Wemple and DiDomenico WDD model and the single oscillator parameters were determined. → The band gap of CuSe thin films was determined by three novel methods i.e. (relaxation time, real and imaginary dielectric constant and real and imaginary optical conductivity) which in a good agreement with the Tauc band gap value. - Abstract: The paper describes the structural and optical properties of CuSe thin films. X-ray diffraction pattern indicates that CuSe thin film has an amorphous structure. Transmittance T(λ) and reflectance R(λ) measurements in the wavelength range (300-1700 nm) were used to calculate the refractive index n(λ), the absorption index and the optical dispersion parameters according to Wemple and Didomenico WDD model. The dispersion curve of the refractive index shows an anomalous dispersion in the absorption region and a normal dispersion in the transparent region. The optical bandgap has been estimated and confirmed by four different methods. The value for the direct bandgap for the as-deposited CuSe thin film approximately equals 2.7 eV. The Raman spectroscopy was used to identify and quantify the individual phases presented in the CuSe films.

Semiclassical Path Integral Calculation of Nonlinear Optical Spectroscopy.

Science.gov (United States)

Provazza, Justin; Segatta, Francesco; Garavelli, Marco; Coker, David F

2018-02-13

Computation of nonlinear optical response functions allows for an in-depth connection between theory and experiment. Experimentally recorded spectra provide a high density of information, but to objectively disentangle overlapping signals and to reach a detailed and reliable understanding of the system dynamics, measurements must be integrated with theoretical approaches. Here, we present a new, highly accurate and efficient trajectory-based semiclassical path integral method for computing higher order nonlinear optical response functions for non-Markovian open quantum systems. The approach is, in principle, applicable to general Hamiltonians and does not require any restrictions on the form of the intrasystem or system-bath couplings. This method is systematically improvable and is shown to be valid in parameter regimes where perturbation theory-based methods qualitatively breakdown. As a test of the methodology presented here, we study a system-bath model for a coupled dimer for which we compare against numerically exact results and standard approximate perturbation theory-based calculations. Additionally, we study a monomer with discrete vibronic states that serves as the starting point for future investigation of vibronic signatures in nonlinear electronic spectroscopy.

FORS, Fiber Optics Reflectance Spectroscopy con gli spettrometri miniaturizzati per l’identificazione dei pigmenti

Directory of Open Access Journals (Sweden)

Antonino Cosentino

2014-01-01

Full Text Available AbstractQuesto articolo riporta i risultati del test di un sistema FORS (Fiber Optics Reflectance Spectroscopy assemblato con componenti Ocean Optics. Questa ditta ha sviluppato una linea di spettrometri miniaturizzati e dal costo estremamente contenuto. Le trascurabili dimensioni e peso di questo sistema FORS lo rendono uno strumento assolutamente adatto alle indagini dell’arte in cantiere. Sono stati testati 54 pigmenti storici in polvere e stesi con gomma arabica, tempera all’uovo, olio e affresco. Il sistema è stato provato su un quadro dell’800 e su opere murali del barocco siciliano.   This paper shows the results of the testing of a FORS (Fiber Optics Reflectance Spectroscopy system assembled with Ocean Optics components and featuring a USB4000 miniaturized and low cost spectrometer. The small dimensions and little weight of this FORS system make it adapt for the specific needs of art examination in the field. 54 historical pigments have been tested both in powder and laid with gum Arabic, egg tempera, linseed oil and fresco. The FORS system was also tested on a 1800s oil painting and on 1700s Sicilian baroque murals and the results compared with multispectral imaging analysis.   

The Properties of Post-Starburst Quasars Based on Optical Spectroscopy

OpenAIRE

Cales, Sabrina L.; Brotherton, Michael S.; Shang, Zhaohui; Runnoe, Jessie C.; DiPompeo, Michael A.; Bennert, Vardha Nicola; Canalizo, Gabriela; Hiner, Kyle D.; Stoll, R.; Ganguly, Rajib; Diamond-Stanic, Aleksandar

2012-01-01

We present optical spectroscopy of a sample of 38 post-starburst quasars (PSQs) at z ~ 0.3, 29 of which have morphological classifications based on Hubble Space Telescope imaging. These broad-lined active galactic nuclei (AGNs) possess the spectral signatures of massive intermediate-aged stellar populations making them potentially useful for studying connections between nuclear activity and host galaxy evolution. We model the spectra in order to determine the ages and masses of the host stell...

Shock wave propagation in soda lime glass using optical ...

Indian Academy of Sciences (India)

2016-06-16

Jun 16, 2016 ... probe beam in the transverse direction coupled with an optical streak .... (650 ps) was split using a beam splitter after the fifth amplifier stage in the ..... [17] A S Joshi et al, Fusion Engg. Design 44, 067 (1999). [18] A K Sharma ...

Remote Spectroscopy in the Visible Using Fibers on the Optical Internet Network

Science.gov (United States)

Ribeiro, Rafael A. S.; de Oliveira, Anderson R.; Zilio, Sergio C.

2010-01-01

The work presented here demonstrates the feasibility of using the single-mode fibers of an optical Internet network to deliver visible light between separate laboratories as a way to perform remote spectroscopy in the visible for teaching purposes. The coupling of a broadband light source into the single-mode fiber (SMF) and the characterization…

Diffuse Reflectance Spectroscopy of Human Skin Using a Commercial Fiber Optic Spectrometer

International Nuclear Information System (INIS)

Atencio, J. A. Delgado; Rodriguez, M. Cunill; Montiel, S. Vazquez y; Castro, Jorge; Rodriguez, A. Cornejo; Gutierrez, J. L.; Martinez, F.; Gutierrez, B.; Orozco, E.

2008-01-01

Diffuse reflectance spectroscopy is a reliable and easy to implement technique in human tissue characterization. In this work we evaluate the performance of the commercial USB4000 miniature fiber optic spectrometer in the in-vivo measurement of the diffuse reflectance spectra of different healthy skin sites and lesions in a population of 54 volunteers. Results show, that this spectrometer reproduces well the typical signatures of skin spectra over the 400-1000 nm region. Remarkable spectral differences exist between lesions and normal surrounding skin. A diffusion-based model was used to simulate reflectance spectra collected by the optical probe of the system

Quantitative trait loci for resistance to maize streak virus disease in ...

African Journals Online (AJOL)

STORAGESEVER

2008-07-18

Jul 18, 2008 ... African Journal of Biotechnology Vol. ... development ... Biotechnology Center, Kenya Agricultural Research Institute, P.O. Box 58711-00200, Nairobi, ... Maize streak virus disease is an important disease of maize in Kenya.

End point detection in ion milling processes by sputter-induced optical emission spectroscopy

International Nuclear Information System (INIS)

Lu, C.; Dorian, M.; Tabei, M.; Elsea, A.

1984-01-01

The characteristic optical emission from the sputtered material during ion milling processes can provide an unambiguous indication of the presence of the specific etched species. By monitoring the intensity of a representative emission line, the etching process can be precisely terminated at an interface. Enhancement of the etching end point is possible by using a dual-channel photodetection system operating in a ratio or difference mode. The installation of the optical detection system to an existing etching chamber has been greatly facilitated by the use of optical fibers. Using a commercial ion milling system, experimental data for a number of etching processes have been obtained. The result demonstrates that sputter-induced optical emission spectroscopy offers many advantages over other techniques in detecting the etching end point of ion milling processes

Non-linear optical studies of adsorbates: Spectroscopy and dynamics

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xiangdong.

1989-08-01

In the first part of this thesis, we have established a systematic procedure to apply the surface optical second-harmonic generation (SHG) technique to study surface dynamics of adsorbates. In particular, we have developed a novel technique for studies of molecular surface diffusions. In this technique, the laser-induced desorption with two interfering laser beams is used to produce a monolayer grating of adsorbates. The monolayer grating is detected with diffractions of optical SHG. By monitoring the first-order second-harmonic diffraction, we can follow the time evolution of the grating modulation from which we are able to deduce the diffusion constant of the adsorbates on the surface. We have successfully applied this technique to investigate the surface diffusion of CO on Ni(111). The unique advantages of this novel technique will enable us to readily study anisotropy of a surface diffusion with variable grating orientation, and to investigate diffusion processes of a large dynamic range with variable grating spacings. In the second part of this work, we demonstrate that optical infrared-visible sum-frequency generation (SFG) from surfaces can be used as a viable surface vibrational spectroscopic technique. We have successfully recorded the first vibrational spectrum of a monolayer of adsorbates using optical infrared-visible SFG. The qualitative and quantitative correlation of optical SFG with infrared absorption and Raman scattering spectroscopies are examined and experimentally demonstrated. We have further investigated the possibility to use transient infrared-visible SFG to probe vibrational transients and ultrafast relaxations on surfaces. 146 refs.

Non-linear optical studies of adsorbates: Spectroscopy and dynamics

International Nuclear Information System (INIS)

Zhu, Xiangdong.

1989-08-01

In the first part of this thesis, we have established a systematic procedure to apply the surface optical second-harmonic generation (SHG) technique to study surface dynamics of adsorbates. In particular, we have developed a novel technique for studies of molecular surface diffusions. In this technique, the laser-induced desorption with two interfering laser beams is used to produce a monolayer grating of adsorbates. The monolayer grating is detected with diffractions of optical SHG. By monitoring the first-order second-harmonic diffraction, we can follow the time evolution of the grating modulation from which we are able to deduce the diffusion constant of the adsorbates on the surface. We have successfully applied this technique to investigate the surface diffusion of CO on Ni(111). The unique advantages of this novel technique will enable us to readily study anisotropy of a surface diffusion with variable grating orientation, and to investigate diffusion processes of a large dynamic range with variable grating spacings. In the second part of this work, we demonstrate that optical infrared-visible sum-frequency generation (SFG) from surfaces can be used as a viable surface vibrational spectroscopic technique. We have successfully recorded the first vibrational spectrum of a monolayer of adsorbates using optical infrared-visible SFG. The qualitative and quantitative correlation of optical SFG with infrared absorption and Raman scattering spectroscopies are examined and experimentally demonstrated. We have further investigated the possibility to use transient infrared-visible SFG to probe vibrational transients and ultrafast relaxations on surfaces. 146 refs

A novel non-imaging optics based Raman spectroscopy device for transdermal blood analyte measurement

Directory of Open Access Journals (Sweden)

Chae-Ryon Kong

2011-09-01

Full Text Available Due to its high chemical specificity, Raman spectroscopy has been considered to be a promising technique for non-invasive disease diagnosis. However, during Raman excitation, less than one out of a million photons undergo spontaneous Raman scattering and such weakness in Raman scattered light often require highly efficient collection of Raman scattered light for the analysis of biological tissues. We present a novel non-imaging optics based portable Raman spectroscopy instrument designed for enhanced light collection. While the instrument was demonstrated on transdermal blood glucose measurement, it can also be used for detection of other clinically relevant blood analytes such as creatinine, urea and cholesterol, as well as other tissue diagnosis applications. For enhanced light collection, a non-imaging optical element called compound hyperbolic concentrator (CHC converts the wide angular range of scattered photons (numerical aperture (NA of 1.0 from the tissue into a limited range of angles accommodated by the acceptance angles of the collection system (e.g., an optical fiber with NA of 0.22. A CHC enables collimation of scattered light directions to within extremely narrow range of angles while also maintaining practical physical dimensions. Such a design allows for the development of a very efficient and compact spectroscopy system for analyzing highly scattering biological tissues. Using the CHC-based portable Raman instrument in a clinical research setting, we demonstrate successful transdermal blood glucose predictions in human subjects undergoing oral glucose tolerance tests.

Design of differential optical absorption spectroscopy long-path telescopes based on fiber optics.

Science.gov (United States)

Merten, André; Tschritter, Jens; Platt, Ulrich

2011-02-10

We present a new design principle of telescopes for use in the spectral investigation of the atmosphere and the detection of atmospheric trace gases with the long-path differential optical absorption spectroscopy (DOAS) technique. A combination of emitting and receiving fibers in a single bundle replaces the commonly used coaxial-Newton-type combination of receiving and transmitting telescope. This very simplified setup offers a higher light throughput and simpler adjustment and allows smaller instruments, which are easier to handle and more portable. The higher transmittance was verified by ray-tracing calculations, which result in a theoretical factor threefold improvement in signal intensity compared with the old setup. In practice, due to the easier alignment and higher stability, up to factor of 10 higher signal intensities were found. In addition, the use of a fiber optic light source provides a better spectral characterization of the light source, which results in a lower detection limit for trace gases studied with this instrument. This new design will greatly enhance the usability and the range of applications of active DOAS instruments.

Monitoring soft tissue coagulation by optical spectroscopy

Science.gov (United States)

Lihachev, A.; Lihacova, I.; Heinrichs, H.; Spigulis, J.; Trebst, T.; Wehner, M.

2017-12-01

Laser tissue welding (LTW) or laser tissue soldering (LTS) is investigated since many years for treatment of incisions, wound closure and anastomosis of vessels [1, 2]. Depending on the process, a certain temperature in the range between 65 °C to 85 °C must be reached and held for a few seconds. Care has to be taken not to overheat the tissue, otherwise necrosis or tissue carbonization may occur and will impair wound healing. Usually the temperature is monitored during the process to control the laser power [3]. This requires either bulky equipment or expensive and fragile infrared fibers to feed the temperature signal to an infrared detector. Alternatively, changes in tissue morphology can be directly observed by analysis of spectral reflectance. We investigate spectral changes in the range between 400 nm to 900 nm wavelength. Characteristic spectral changes occur when the temperature of tissue samples increase above 70 °C which is a typical setpoint value for temperature control of coagulation. We conclude that simple spectroscopy in the visible range can provide valuable information during LTS and LTW and probably replace the delicate measurement of temperature. A major advantage is that optical measurements can be performed using standard optical fibers and can be easily integrated into a surgical tool.

Optical Reflection Spectroscopy of GEO Objects

Science.gov (United States)

Seitzer, Patrick; Cardona, Tammaso; Lederer, Susan M.; Cowardin, Heather; Abercromby, Kira J.; Barker, Edwin S.; Bedard, Donald

2013-01-01

We report on optical reflection spectroscopy of geosynchronous (GEO) objects in the US Space Surveillance Network (SSN) catalog. These observations were obtained using imaging spectrographs on the 6.5-m Magellan telescopes at the Las Campanas Observatory in Chile. Our goal is to determine the composition of these objects by comparing these spectral observations with ground-based laboratory measurements of spacecraft materials. The observations are all low resolution (1 nm after smoothing) obtained through a 5 arcsecond wide slit and using a grism as the dispersing element. The spectral range covered was from 450 nm to 800 nm. All spectra were flux calibrated using observations of standard stars with the exact same instrumental setup. An effort was made to obtain all observations within a limited range of topocentric phase angle, although the solar incident angle is unknown due to the lack of any knowledge of the attitude of the observed surface at the time of observation.

Streaked, x-ray-transmission-grating spectrometer

International Nuclear Information System (INIS)

Ceglio, N.M.; Roth, M.; Hawryluk, A.M.

1981-08-01

A free standing x-ray transmission grating has been coupled with a soft x-ray streak camera to produce a time resolved x-ray spectrometer. The instrument has a temporal resolution of approx. 20 psec, is capable of covering a broad spectral range, 2 to 120 A, has high sensitivity, and is simple to use requiring no complex alignment procedure. In recent laser fusion experiments the spectrometer successfully recorded time resolved spectra over the range 10 to 120 A with a spectral resolving power, lambda/Δlambda of 4 to 50, limited primarily by source size and collimation effects

Automated computer analysis of plasma-streak traces from SCYLLAC

International Nuclear Information System (INIS)

Whitman, R.L.; Jahoda, F.C.; Kruger, R.P.

1977-01-01

An automated computer analysis technique that locates and references the approximate centroid of single- or dual-streak traces from the Los Alamos Scientific Laboratory SCYLLAC facility is described. The technique also determines the plasma-trace width over a limited self-adjusting region. The plasma traces are recorded with streak cameras on Polaroid film, then scanned and digitized for processing. The analysis technique uses scene segmentation to separate the plasma trace from a reference fiducial trace. The technique employs two methods of peak detection; one for the plasma trace and one for the fiducial trace. The width is obtained using an edge-detection, or slope, method. Timing data are derived from the intensity modulation of the fiducial trace. To smooth (despike) the output graphs showing the plasma-trace centroid and width, a technique of ''twicing'' developed by Tukey was employed. In addition, an interactive sorting algorithm allows retrieval of the centroid, width, and fiducial data from any test shot plasma for post analysis. As yet, only a limited set of sixteen plasma traces has been processed using this technique

Automated computer analysis of plasma-streak traces from SCYLLAC

International Nuclear Information System (INIS)

Whiteman, R.L.; Jahoda, F.C.; Kruger, R.P.

1977-11-01

An automated computer analysis technique that locates and references the approximate centroid of single- or dual-streak traces from the Los Alamos Scientific Laboratory SCYLLAC facility is described. The technique also determines the plasma-trace width over a limited self-adjusting region. The plasma traces are recorded with streak cameras on Polaroid film, then scanned and digitized for processing. The analysis technique uses scene segmentation to separate the plasma trace from a reference fiducial trace. The technique employs two methods of peak detection; one for the plasma trace and one for the fiducial trace. The width is obtained using an edge-detection, or slope, method. Timing data are derived from the intensity modulation of the fiducial trace. To smooth (despike) the output graphs showing the plasma-trace centroid and width, a technique of ''twicing'' developed by Tukey was employed. In addition, an interactive sorting algorithm allows retrieval of the centroid, width, and fiducial data from any test shot plasma for post analysis. As yet, only a limited set of the plasma traces has been processed with this technique

Diagnosis of breast cancer using diffuse optical spectroscopy from 500 to 1600 nm: comparison of classification methods

NARCIS (Netherlands)

Nachabé, Rami; Evers, Daniel; Evers, Daniel J.; Hendriks, Benno H.W.; Lucassen, Gerald W.; Lucassen, Gerald; van der Voort, Marjolein; Rutgers, Emiel J.; Vrancken Peeters, Marie-Jeanne; van der Hage, Jos A.; Oldenburg, Hester S.; Wesseling, Jelle; Ruers, Theo J.M.

2011-01-01

We report on the use of diffuse optical spectroscopy analysis of breast spectra acquired in the wavelength range from 500 to 1600 nm with a fiber optic probe. A total of 102 ex vivo samples of five different breast tissue types, namely adipose, glandular, fibroadenoma, invasive carcinoma, and ductal

A versatile optical microscope for time-dependent single-molecule and single-particle spectroscopy

Science.gov (United States)

Li, Hao; Yang, Haw

2018-03-01

This work reports the design and implementation of a multi-function optical microscope for time-dependent spectroscopy on single molecules and single nanoparticles. It integrates the now-routine single-object measurements into one standalone platform so that no reconfiguration is needed when switching between different types of sample or spectroscopy modes. The illumination modes include evanescent field through total internal reflection, dark-field illumination, and epi-excitation onto a diffraction-limited spot suitable for confocal detection. The detection modes include spectrally resolved line imaging, wide-field imaging with dual-color capability, and two-color single-element photon-counting detection. The switch between different spectroscopy and data acquisition modes is fully automated and executed through computer programming. The capability of this microscope is demonstrated through selected proof-of-principle experiments.

A versatile optical microscope for time-dependent single-molecule and single-particle spectroscopy.

Science.gov (United States)

Li, Hao; Yang, Haw

2018-03-28

This work reports the design and implementation of a multi-function optical microscope for time-dependent spectroscopy on single molecules and single nanoparticles. It integrates the now-routine single-object measurements into one standalone platform so that no reconfiguration is needed when switching between different types of sample or spectroscopy modes. The illumination modes include evanescent field through total internal reflection, dark-field illumination, and epi-excitation onto a diffraction-limited spot suitable for confocal detection. The detection modes include spectrally resolved line imaging, wide-field imaging with dual-color capability, and two-color single-element photon-counting detection. The switch between different spectroscopy and data acquisition modes is fully automated and executed through computer programming. The capability of this microscope is demonstrated through selected proof-of-principle experiments.

Optical spectroscopy of Eu3+ doped Th(MoO4)2

International Nuclear Information System (INIS)

Keskar, Meera; Phatak, Rohan; Gupta, Santhosh; Natarajan, V.

2014-01-01

Eu 3+ is often used as a structural probe, because of the relative simplicity of its energy-level structure and dependence on its site symmetry in the host material. The phonon energy of the host for rare-earth ions is a crucial factor to be considered for developing luminescent materials.Thorium molybdate can satisfy both low phonon energy environment for rare-earth ions and good chemical and mechanical stabilities for practical use. Thus Eu 3+ doped Th(MoO 4 ) 2 are expected to be a good promising optical materials. To the best of our knowledge, there is no report on optical spectroscopy of Eu 3+ doped thorium molybdate and thus work has been carried out and discussed in this paper

IDENTIFICATIONS OF FIVE INTEGRAL SOURCES VIA OPTICAL SPECTROSCOPY

International Nuclear Information System (INIS)

Butler, Suzanne C.; Tomsick, John A.; Chaty, Sylvain; Heras, Juan A. Zurita; Rodriguez, Jerome; Walter, Roland; Kaaret, Philip; Kalemci, Emrah; Oezbey, Mehtap

2009-01-01

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is discovering hundreds of new hard X-ray sources, many of which remain unidentified. We report on optical spectroscopy of five such sources for which X-ray observations at lower energies (∼0.5-10 keV) and higher angular resolutions than INTEGRAL have allowed for unique optical counterparts to be located. We find that INTEGRAL Gamma-Ray (IGR) J16426+6536 and IGR J22292+6647 are Type 1 Seyfert active galactic nuclei (with IGR J16426+6536 further classified as a Seyfert 1.5) which have redshifts of z = 0.323 and z = 0.113, respectively. IGR J18308-1232 is identified as a cataclysmic variable (CV), and we confirm a previous identification of IGR J19267+1325 as a magnetic CV. IGR J18214-1318 is identified as an obscured high-mass X-ray binary (HMXB), which are systems thought to have a compact object embedded in the stellar wind of a massive star. We combine Chandra fluxes with distances based on the optical observations to calculate X-ray luminosities of the HMXB and CVs, finding L 0.3-10keV = 5 x 10 36 erg s -1 for IGR J18214-1318, L 0.3-10keV = 1.3 x 10 32 erg s -1 for IGR J18308-1232, and L 0.3-10keV = 6.7 x 10 32 erg s -1 for IGR J19267+1325.

CW-THz vector spectroscopy and imaging system based on 1.55-µm fiber-optics.

Science.gov (United States)

Kim, Jae-Young; Song, Ho-Jin; Yaita, Makoto; Hirata, Akihiko; Ajito, Katsuhiro

2014-01-27

We present a continuous-wave terahertz (THz) vector spectroscopy and imaging system based on a 1.5-µm fiber optic uni-traveling-carrier photodiode and InGaAs photo-conductive receiver. Using electro-optic (EO) phase modulators for THz phase control with shortened optical paths, the system achieves fast vector measurement with effective phase stabilization. Dynamic ranges of 100 dB · Hz and 75 dB · Hz at 300 GHz and 1 THz, and phase stability of 1.5° per minute are obtained. With the simultaneous measurement of absorbance and relative permittivity, we demonstrate non-destructive analyses of pharmaceutical cocrystals inside tablets within a few minutes.

DETECTION OF REST-FRAME OPTICAL LINES FROM X-SHOOTER SPECTROSCOPY OF WEAK EMISSION-LINE QUASARS

International Nuclear Information System (INIS)

Plotkin, Richard M.; Gallo, Elena; Shemmer, Ohad; Trakhtenbrot, Benny; Anderson, Scott F.; Brandt, W. N.; Luo, Bin; Schneider, Donald P.; Fan, Xiaohui; Lira, Paulina; Richards, Gordon T.; Strauss, Michael A.; Wu, Jianfeng

2015-01-01

Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4–1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C iv) to low-ionization lines (e.g., Mg ii, Hβ, Hα) in individual objects. We detect broad Hβ and Hα emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., Hβ has rest-frame equivalent widths ranging from 15–40 Å). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe ii emission, Hβ FWHM ≲ 4000 km s −1 , and significant C iv blueshifts (≈1000–5500 km s −1 ) relative to the systemic redshift; two spectra also show elevated UV Fe ii emission, and an outflowing component to their (weak) Mg ii emission lines. These properties suggest that WLQs are exotic versions of “wind-dominated” quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum

Laser spectroscopy

CERN Document Server

Demtröder, Wolfgang

Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., ultrafast lasers (atto- and femto-second lasers) and parametric oscillators, coherent matter waves, Doppler-free Fourier spectroscopy with optical frequency combs, interference spectroscopy, quantum optics, the interferometric detection of gravitational waves and still more applications in chemical analysis, medical diagnostics, and engineering.

Optical diagnostics on the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Boguski, J. C.; Weber, T. E.; Intrator, T. P.; Smith, R. J.; Dunn, J. P.; Hutchinson, T. M.; Gao, K. W.

2013-10-01

The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory was built to investigate the physics of high Alfvén Mach number, supercritical, magnetized shocks through the acceleration and subsequent stagnation of a Field Reversed Configuration (FRC) plasmoid against a magnetic mirror and/or plasma target. A suite of optical diagnostics has recently been fielded on MSX to characterize plasma conditions during the formation, acceleration, and stagnation phases of the experiment. CCD-backed streak and framing cameras, and a fiber-based visible light array, provide information regarding FRC shape, velocity, and instability growth. Time-resolved narrow and broadband spectroscopy provides information on pre-shock plasma temperature, impurity levels, shock location, and non-thermal ion distributions within the shock region. Details of the diagnostic design, configuration, and characterization will be presented along with initial results. This work is supported by the Center for Magnetic Self Organization, DoE OFES and NNSA under LANS contract DE-AC52-06NA25369. Approved for public release: LA-UR- 13-25190.

Femtosecond optical parametric oscillators toward real-time dual-comb spectroscopy

Science.gov (United States)

Jin, Yuwei; Cristescu, Simona M.; Harren, Frans J. M.; Mandon, Julien

2015-04-01

We demonstrate mid-infrared dual-comb spectroscopy with an optical parametric oscillator (OPO) toward real-time field measurement. A singly resonant OPO based on a MgO-doped periodically poled lithium niobate (PPLN) crystal is demonstrated. Chirped mirrors are used to compensate the dispersion caused by the optical cavity and the crystal. A low threshold of 17 mW has been achieved. The OPO source generates a tunable idler frequency comb between 2.7 and 4.7 μm. Dual-comb spectroscopy is achieved by coupling two identical Yb-fiber mode-locked lasers to this OPO with slightly different repetition frequencies. A measured absorption spectrum of methane is presented with a spectral bandwidth of , giving an instrumental resolution of . In addition, a second OPO containing two MgO-doped PPLN crystals in a singly resonant ring cavity is demonstrated. As such, this OPO generates two idler combs (average power up to 220 mW), covering a wavelength range between 2.7 and 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyned signal between the two idler combs, broadband spectra of molecular gases can be observed over a spectral bandwidth of more than . This special cavity design allows the spectral resolution to be improved to without locking the OPO cavity, indicating that this OPO represents an ideal high-power broadband mid-infrared source for real-time gas sensing.

Inactivation of the Huntington's disease gene (Hdh impairs anterior streak formation and early patterning of the mouse embryo

Directory of Open Access Journals (Sweden)

Conlon Ronald A

2005-08-01

Full Text Available Abstract Background Huntingtin, the HD gene encoded protein mutated by polyglutamine expansion in Huntington's disease, is required in extraembryonic tissues for proper gastrulation, implicating its activities in nutrition or patterning of the developing embryo. To test these possibilities, we have used whole mount in situ hybridization to examine embryonic patterning and morphogenesis in homozygous Hdhex4/5 huntingtin deficient embryos. Results In the absence of huntingtin, expression of nutritive genes appears normal but E7.0–7.5 embryos exhibit a unique combination of patterning defects. Notable are a shortened primitive streak, absence of a proper node and diminished production of anterior streak derivatives. Reduced Wnt3a, Tbx6 and Dll1 expression signify decreased paraxial mesoderm and reduced Otx2 expression and lack of headfolds denote a failure of head development. In addition, genes initially broadly expressed are not properly restricted to the posterior, as evidenced by the ectopic expression of Nodal, Fgf8 and Gsc in the epiblast and T (Brachyury and Evx1 in proximal mesoderm derivatives. Despite impaired posterior restriction and anterior streak deficits, overall anterior/posterior polarity is established. A single primitive streak forms and marker expression shows that the anterior epiblast and anterior visceral endoderm (AVE are specified. Conclusion Huntingtin is essential in the early patterning of the embryo for formation of the anterior region of the primitive streak, and for down-regulation of a subset of dynamic growth and transcription factor genes. These findings provide fundamental starting points for identifying the novel cellular and molecular activities of huntingtin in the extraembryonic tissues that govern normal anterior streak development. This knowledge may prove to be important for understanding the mechanism by which the dominant polyglutamine expansion in huntingtin determines the loss of neurons in

Inactivation of the Huntington's disease gene (Hdh) impairs anterior streak formation and early patterning of the mouse embryo.

Science.gov (United States)

Woda, Juliana M; Calzonetti, Teresa; Hilditch-Maguire, Paige; Duyao, Mabel P; Conlon, Ronald A; MacDonald, Marcy E

2005-08-18

Huntingtin, the HD gene encoded protein mutated by polyglutamine expansion in Huntington's disease, is required in extraembryonic tissues for proper gastrulation, implicating its activities in nutrition or patterning of the developing embryo. To test these possibilities, we have used whole mount in situ hybridization to examine embryonic patterning and morphogenesis in homozygous Hdh(ex4/5) huntingtin deficient embryos. In the absence of huntingtin, expression of nutritive genes appears normal but E7.0-7.5 embryos exhibit a unique combination of patterning defects. Notable are a shortened primitive streak, absence of a proper node and diminished production of anterior streak derivatives. Reduced Wnt3a, Tbx6 and Dll1 expression signify decreased paraxial mesoderm and reduced Otx2 expression and lack of headfolds denote a failure of head development. In addition, genes initially broadly expressed are not properly restricted to the posterior, as evidenced by the ectopic expression of Nodal, Fgf8 and Gsc in the epiblast and T (Brachyury) and Evx1 in proximal mesoderm derivatives. Despite impaired posterior restriction and anterior streak deficits, overall anterior/posterior polarity is established. A single primitive streak forms and marker expression shows that the anterior epiblast and anterior visceral endoderm (AVE) are specified. Huntingtin is essential in the early patterning of the embryo for formation of the anterior region of the primitive streak, and for down-regulation of a subset of dynamic growth and transcription factor genes. These findings provide fundamental starting points for identifying the novel cellular and molecular activities of huntingtin in the extraembryonic tissues that govern normal anterior streak development. This knowledge may prove to be important for understanding the mechanism by which the dominant polyglutamine expansion in huntingtin determines the loss of neurons in Huntington's disease.

Visceral endoderm and the primitive streak interact to build the fetal-placental interface of the mouse gastrula.

Science.gov (United States)

Rodriguez, Adriana M; Downs, Karen M

2017-12-01

Hypoblast/visceral endoderm assists in amniote nutrition, axial positioning and formation of the gut. Here, we provide evidence, currently limited to humans and non-human primates, that hypoblast is a purveyor of extraembryonic mesoderm in the mouse gastrula. Fate mapping a unique segment of axial extraembryonic visceral endoderm associated with the allantoic component of the primitive streak, and referred to as the "AX", revealed that visceral endoderm supplies the placentae with extraembryonic mesoderm. Exfoliation of the AX was dependent upon contact with the primitive streak, which modulated Hedgehog signaling. Resolution of the AX's epithelial-to-mesenchymal transition (EMT) by Hedgehog shaped the allantois into its characteristic projectile and individualized placental arterial vessels. A unique border cell separated the delaminating AX from the yolk sac blood islands which, situated beyond the limit of the streak, were not formed by an EMT. Over time, the AX became the hindgut lip, which contributed extensively to the posterior interface, including both embryonic and extraembryonic tissues. The AX, in turn, imparted antero-posterior (A-P) polarity on the primitive streak and promoted its elongation and differentiation into definitive endoderm. Results of heterotopic grafting supported mutually interactive functions of the AX and primitive streak, showing that together, they self-organized into a complete version of the fetal-placental interface, forming an elongated structure that exhibited A-P polarity and was composed of the allantois, an AX-derived rod-like axial extension reminiscent of the embryonic notochord, the placental arterial vasculature and visceral endoderm/hindgut. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Diameter grouping in bulk samples of single-walled carbon nanotubes from optical absorption spectroscopy

NARCIS (Netherlands)

Golden, M.S.; Fink, J.; Dunsch, L.; Bauer, H.-D.; Reibold, M.; Knupfer, M.; Friedlein, R.; Pichler, T.; Jost, O.

1999-01-01

The influence of the synthesis parameters on the mean characteristics of single-wall carbon nanotubes in soot produced by the laser vaporization of graphite has been analyzed using optical absorption spectroscopy. The abundance and mean diameter of the nanotubes were found to be most influenced by

Spectroscopic properties of a self-assembled zinc porphyrin tetramer I. Steady state optical spectroscopy

NARCIS (Netherlands)

Yatskou, M.M.; Koehorst, R.B.M.; Donker, H.; Schaafsma, T.J.

2001-01-01

Aggregation of zinc mono-(4-pyridyl)-triphenylporphyrin (ZnPyP) in toluene and polystyrene/toluene mixtures has been investigated by steady-state optical spectroscopy. The Q-band absorption spectra, as well as the fluorescence spectra, show a temperature-dependent red shift as a result of ligation

Potential prospects in archaeological research by using optical spectroscopy through a black glass ocular

Science.gov (United States)

Cosyns, P.; Meulebroeck, W.; Thienpont, H.; Nys, K.

The aim of this paper is to draw attention to the potential usefulness of optical spectroscopy within the archaeological discourse. We therefore use the standardized color coordinates and the transmittance spectra in the region between 350- 1650 nm of nine fragmented Roman black glass artifacts from archaeological contexts in Avenches (Switzerland) and an intact piece from Tongeren (Belgium). Firstly, we demonstrate how the use of UV-Vis-NIR spectroscopy can help the archaeologist in understanding the various excavated features containing glass artifacts. The analysis of the optical spectra of Roman black glass artifacts demonstrates in the first place that an object has a very homogenous composition. The clustering of the different fragments with characteristic spectra permits to connect the pieces from various areas of an excavation to one single object or to several objects from the same batch. These results provide the archaeologist the possibility to merge recognized layers or to connect different features in the surrounding area. Secondly, we demonstrate how the use of UV-Vis-NIR spectroscopy can help improve the analysis process. This inexpensive method can facilitate a more convenient and purposive sampling by means of a preliminary inquiry, selecting the most interesting pieces out of a large group of artifacts suitable for chemical analysis.

Sky subtraction at the Poisson limit with fibre-optic multiobject spectroscopy

Science.gov (United States)

Sharp, R.; Parkinson, H.

2010-11-01

We report on the limitations of sky-subtraction accuracy for long-duration fibre-optic multiobject spectroscopy of faint astronomical sources during long-duration exposures. We show that while standard sky subtraction techniques yield accuracies consistent with the Poisson noise limit for exposures of 1h duration, there are large-scale systematic defects that inhibit the sensitivity gains expected on the summation of longer duration exposures. For the AAOmega system at the Anglo-Australian Telescope, we identify a limiting systematic sky-subtraction accuracy, which is reached after integration times of 4-10h. We show that these systematic defects can be avoided through the use of the fibre nod-and-shuffle (N+S) observing mode, but with a potential cost in observing efficiency. Finally, we demonstrate that these disadvantages can be overcome through the application of a Principal Components Analysis (PCA) sky-subtraction routine. Such an approach minimize systematic residuals across long-duration exposures, allowing deep integrations. We apply the PCA approach to over 200h of on-sky observations and conclude that for the AAOmega system, the residual error in long-duration observations falls at a rate proportional to τ-0.32 in contrast to the τ-0.5 rate expected from theoretical considerations. With this modest rate of decline, the PCA approach represents a more efficient mode of observation than the N+S technique for observations in the sky limited regime with durations of 10-100h (even before accounting for the additional signal-to-noise ratio and targeting efficiency losses often associated with the N+S technique). This conclusion has important implications for the observing strategies of the next generation of fibre-optics redshift surveys with existing facilities as well as design implications for fibre-optic systems destined for new facilities. It argues against the use of the inherently inefficient N+S technique for faint object fibre-optic survey

Optical Second Harmonic Spectroscopy of Boron-Reconstructed Si(001)

International Nuclear Information System (INIS)

Lim, D.; Downer, M. C.; Ekerdt, J. G.; Arzate, N.; Mendoza, Bernardo S.; Gavrilenko, V. I.; Wu, R. Q.

2000-01-01

Optical second harmonic generation (SHG) spectroscopy is used to probe Si(001) following thermal decomposition of diborane at the surface. Incorporation of boron (B) at second layer substitutional sites at H-free Si(001) intensifies and redshifts the E 1 SHG spectral peak, while subsequent H termination further intensifies and blueshifts E 1 , in sharp contrast to the effect of bulk B doping or nonsubstitutional B. Ab initio pseudopotential and semiempirical tight binding calculations independently reproduce these unique trends, and attribute them to the surface electric field associated with charge transfer to electrically active B acceptors, and rehybridization of atomic bonds. (c) 2000 The American Physical Society

Time-resolved measurements with streaked diffraction patterns from electrons generated in laser plasma wakefield

Science.gov (United States)

He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec; Beaurepaire, Benoît; Malka, Victor; Faure, Jérôme

2013-10-01

Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) applications due to the intrinsic short bunch duration and perfect synchronization with the optical pump. Recent results of electron diffraction from a single crystal gold foil, using LWFA electrons driven by 8-mJ, 35-fs laser pulses at 500 Hz, will be presented. The accelerated electrons were collimated with a solenoid magnetic lens. By applying a small-angle tilt to the magnetic lens, the diffraction pattern can be streaked such that the temporal evolution is separated spatially on the detector screen after propagation. The observable time window and achievable temporal resolution are studied in pump-probe measurements of photo-induced heating on the gold foil.

Probing focal cortical dysplasia in formalin fixed samples using tissue optical spectroscopy

Science.gov (United States)

Anand, Suresh; Cicchi, Riccardo; Giordano, Flavio; Buccoliero, Anna Maria; Conti, Valerio; Guerrini, Renzo; Pavone, Francesco Saverio

2016-03-01

Focal cortical dysplasia (FCD) is one of most common causes of intractable epilepsy in pediatric population and these are often insensitive to anti-epileptic drugs. FCD is characterized by a disarray in localized regions of the cerebral cortex and abnormal neurons which results them to misfire with incorrect signals. Resective neurosurgery to remove or disconnect the affected parts from the rest of the brain seems to be a viable option to treat FCD. Before neurosurgery the subject could undergo imaging studies including magnetic resonance imaging (MRI) or computed tomography (CT) scans. On the downside FCD could be elusive in MRI images and may be practically invisible in CT scans. Furthermore, unnecessary removal of normal tissues is to be taken into consideration as this could lead to neurological defects. In this context, optical spectroscopy have been widely investigated as an alternative technique for the detection of abnormal tissues in different organ sites. Disease progression is accompanied by a number of architectural, biochemical and morphological changes. These variations are reflected in the spectral intensity and line shape. Here, in this proof of concept study we propose to investigate the application of tissue optical spectroscopy based on fluorescence excitation at two wavelength 378 and 445 nm coupled along with Raman spectroscopy for the detection of FCD on formalin fixed tissue specimens from pediatric subjects. For fluorescence at both the excitation wavelengths FCD showed a decreased intensity at longer wavelength when compared to normal tissues. Also, differences exist in the Raman spectral profiles of normal and FCD.

Significance and transmission of maize streak virus disease in Africa ...

African Journals Online (AJOL)

STORAGESEVER

2008-12-29

Dec 29, 2008 ... soil nutrients, altitude and temperature on the biology of maize streak virus (MSV) / vector populations is discussed. ... status of maize host plants and its effects on population dynamics of Cicadulina mbila Naudé. (Homoptera: ..... time necessary for the leafhopper to reach the mesophyll of the leaf and ingest ...

Diagnosis of breast cancer using diffuse optical spectroscopy from 500 to 1600 nm: a comparison of classification methods

NARCIS (Netherlands)

Nachabe, R.; Evers, D.; Hendriks, B.H.W.; Lucassen, G.W.; Van der Voort, M.; Wesseling, J.; Rutgers, E. J.; Vrancken Peeters, M.J.; Hage, J.A.van der; Oldenbeng, H.S.; Ruers, T.

2011-01-01

We report on the use of diffuse optical spectroscopy analysis of breast spectra acquired in the wavelength range from 500 to 1600 nm with a fiber optic probe. A total of 102 ex vivo samples of five different breast tissue types, namely adipose, glandular, fibroadenoma, invasive carcinoma and ductal

Feasibility Study on Fiber-optic Radiation Sensor for Remote Gamma-ray Spectroscopy

International Nuclear Information System (INIS)

Jeon, Hyesu; Jang, Kyoung Won; Shin, Sang Hun and others

2014-01-01

In this study, we fabricated a fiber-optic radiation sensor using an optical fiber and various scintillators. To select an adequate inorganic scintillator for the sensing probe of fiber-optic radiation sensor, 5 types of scintillators were evaluated. The spectra of gamma-rays emitted from a Na-22 radiation source were measured by using the manufactured sensors. As a result, the BGO was suitable for the sensing probe of fiber-optic radiation sensor due to its high scintillation output and exact photoelectric peak for the gamma-ray energy. The basic principle of radiation detection is to detect the signals caused by interactions between radiations and materials. There are various types of radiation detectors depending on types of radiation to be detected and physical quantities to be measured. As one of the radiation detectors, a fiber-optic radiation sensor using a scintillator and an optical fiber has two advantages such as no space restraint and remote sensing. Moreover, in nuclear environments, this kind of sensor has immunities for electromagnetic field, temperature, and pressure. Thus, the fiber-optic radiation sensor can be used in various fields including nondestructive inspection, radioactive waste management, nuclear safety, radiodiagnosis and radiation therapy. As a fundamental study of the fiber-optic radiation sensor for remote gamma-ray spectroscopy, in this study, we fabricated a fiber-optic radiation sensor using an optical fiber and various scintillators. To select an adequate inorganic scintillator for the sensing probe of fiber-optic radiation sensor, 5 types of scintillators were evaluated. The spectra of gamma-rays emitted from a Na-22 radiation source were measured by using the manufactured sensors

Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

Directory of Open Access Journals (Sweden)

Christian G. Parigger

2010-01-01

Full Text Available Transient laser plasma is generated in laser-induced optical breakdown (LIOB. Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

Target 3-D reconstruction of streak tube imaging lidar based on Gaussian fitting

Science.gov (United States)

Yuan, Qingyu; Niu, Lihong; Hu, Cuichun; Wu, Lei; Yang, Hongru; Yu, Bing

2018-02-01

Streak images obtained by the streak tube imaging lidar (STIL) contain the distance-azimuth-intensity information of a scanned target, and a 3-D reconstruction of the target can be carried out through extracting the characteristic data of multiple streak images. Significant errors will be caused in the reconstruction result by the peak detection method due to noise and other factors. So as to get a more precise 3-D reconstruction, a peak detection method based on Gaussian fitting of trust region is proposed in this work. Gaussian modeling is performed on the returned wave of single time channel of each frame, then the modeling result which can effectively reduce the noise interference and possesses a unique peak could be taken as the new returned waveform, lastly extracting its feature data through peak detection. The experimental data of aerial target is for verifying this method. This work shows that the peak detection method based on Gaussian fitting reduces the extraction error of the feature data to less than 10%; utilizing this method to extract the feature data and reconstruct the target make it possible to realize the spatial resolution with a minimum 30 cm in the depth direction, and improve the 3-D imaging accuracy of the STIL concurrently.

Combined fluorescence-Raman spectroscopy measurements with an optical fiber probe for the diagnosis of melanocytic lesions

Science.gov (United States)

Cosci, Alessandro; Cicchi, Riccardo; Rossari, Susanna; De Giorgi, Vincenzo; Massi, Daniela; Pavone, Francesco S.

2012-02-01

We have designed and developed an optical fiber-probe for spectroscopic measurements on human tissues. The experimental setup combines fluorescence spectroscopy and Raman spectroscopy in a multidimensional approach. Concerning fluorescence spectroscopy, the excitation is provided by two laser diodes, one emitting in the UV (378 nm) and the other emitting in the visible (445 nm). These two lasers are used to selectively excite fluorescence from NADH and FAD, which are among the brightest endogenous fluorophores in human tissues. For Raman and NIR spectroscopy, the excitation is provided by a third laser diode with 785 nm excitation wavelength. Laser light is delivered to the tissue through the central optical fiber of a fiber bundle. The surrounding 48 fibers of the bundle are used for collecting fluorescence and Raman and for delivering light to the spectrograph. Fluorescence and Raman spectra are acquired on a cooled CCD camera. The instrument has been tested on fresh human skin biopsies clinically diagnosed as malignant melanoma, melanocytic nevus, or healthy skin, finding an optimal correlation with the subsequent histological exam. In some cases our examination was not in agreement with the clinical observation, but it was with the histological exam, demonstrating that the system can potentially contribute to improve clinical diagnostic capabilities and hence reduce the number of unnecessary biopsies.

Photoacoustic spectroscopy applied to the optical characterization of calcium phosphates for biomedical use

Energy Technology Data Exchange (ETDEWEB)

Mendez G, M. [ESFM-IPN, 07738 Mexico D.F. (Mexico); Cruz O, A. [CINVESTAV, Dept. of Physics, 07360 Mexico D.F. (Mexico)

2007-07-01

Full text: Photoacoustic Spectroscopy (PAS), based on the Rosencwaig and Gersho model, has been used for thermal and optical characterization of diverse materials. The use of PAS has become an important tool because is a nondestructive and no contact analytical technique. Furthermore its use to measure optical absorption spectra has advantages over the usual transmission measurements due to important features as the fact that scattered light does not disturb the measurements significantly and also the sample don't need to be prepared to have good quality surfaces. Then the optical properties of biological samples can be easily investigated with this technique. In the present study PAS is applied to obtain the optical absorption spectra of hydroxyapatite (HAp) [Ca{sub 10} (PO{sub 4} ){sub 6} (OH ){sub 2}] and bioactive calcium phosphates. The spectra of these samples ranged from 300 to 800 nm. All samples were prepared in a power form with particle size < 741m. Complementary studies X-ray diffraction and EDC were performed. (Author)

MR imaging of medullary streaks in osteosclerosis: a case report

International Nuclear Information System (INIS)

Lee, Hak Soo; Joo, Kyung Bin; Park, Tae Soo; Song, Ho Taek; Kim, Yong Soo; Park, Dong Woo; Park, Choong Ki

2000-01-01

We present a case of medullary sclerosis of the appendicular skeleton in a patient with chronic renal insufficiency for whom MR imaging findings were characteristic. T1- and T2-weighted MR images showed multiple vertical lines (medullary streaks) of low signal intensity in the metaphyses and diaphyses of the distal femur and proximal tibia

True resolution enhancement for optical spectroscopy

Science.gov (United States)

Cooper, Justin T.; Oleske, Jeffrey B.

2018-02-01

Resolving spectrally adjacent peaks is important for techniques, such as tracking small shifts in Raman or fluorescence spectra, quantifying pharmaceutical polymorph ratios, or molecular orientation studies. Thus, suitable spectral resolution is a vital consideration when designing most spectroscopic systems. Most parameters that influence spectral resolution are fixed for a given system (spectrometer length, grating groove density, excitation source, CCD pixel size, etc.). Inflexible systems are non-problematic if the spectrometer is dedicated for a single purpose; however, these specifications cannot be optimized for different applications with wider range resolution requirements. Data processing techniques, including peak fitting, partial least squares, or principal component analysis, are typically used to achieve sub-optical resolution information. These techniques can be plagued by spectral artifacts introduced by post-processing as well as the subjective implementation of statistical parameters. TruRes™, from Andor Technology, uses an innovative optical means to greatly improve and expand the range of spectral resolutions accessible on a single setup. True spectral resolution enhancement of >30% is achieved without mathematical spectral alteration, dataprocessing, or spectrometer component changes. Discreet characteristic spectral lines from Laser-Induced Breakdown Spectroscopy (LIBS) and atomic calibration sources are now fully resolved from spectrally-adjacent peaks under otherwise identical configuration. TruRes™ has added advantage of increasing the spectral resolution without sacrificing bandpass. Using TruRes™ the Kymera 328i resolution can approach that of a 500 mm focal spectrometer. Furthermore, the bandpass of a 500 mm spectrograph with would be 50% narrower than the Kymera 328i with all other spectrometer components constant. However, the Kymera 328i with TruRes™ is able to preserve a 50% wider bandpass.

Development of intelligent control system for X-ray streak camera in diagnostic instrument manipulator

International Nuclear Information System (INIS)

Pei, Chengquan; Wu, Shengli; Tian, Jinshou; Liu, Zhen; Fang, Yuman; Gao, Guilong; Liang, Lingliang; Wen, Wenlong

2015-01-01

An intelligent control system for an X ray streak camera in a diagnostic instrument manipulator (DIM) is proposed and implemented, which can control time delay, electric focusing, image gain adjustment, switch of sweep voltage, acquiring environment parameters etc. The system consists of 16 A/D converters and 16 D/A converters, a 32-channel general purpose input/output (GPIO) and two sensors. An isolated DC/DC converter with multi-outputs and a single mode fiber were adopted to reduce the interference generated by the common ground among the A/D, D/A and I/O. The software was designed using graphical programming language and can remotely access the corresponding instrument from a website. The entire intelligent control system can acquire the desirable data at a speed of 30 Mb/s and store it for later analysis. The intelligent system was implemented on a streak camera in a DIM and it shows a temporal resolution of 11.25 ps, spatial distortion of less than 10% and dynamic range of 279:1. The intelligent control system has been successfully used in a streak camera to verify the synchronization of multi-channel laser on the Inertial Confinement Fusion Facility

Development of intelligent control system for X-ray streak camera in diagnostic instrument manipulator

Energy Technology Data Exchange (ETDEWEB)

Pei, Chengquan [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); Wu, Shengli, E-mail: slwu@mail.xjtu.edu.cn [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); Tian, Jinshou [Xi' an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); Liu, Zhen [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); Fang, Yuman [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Gao, Guilong; Liang, Lingliang [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); Xi' an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Wen, Wenlong [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China)

2015-11-01

An intelligent control system for an X ray streak camera in a diagnostic instrument manipulator (DIM) is proposed and implemented, which can control time delay, electric focusing, image gain adjustment, switch of sweep voltage, acquiring environment parameters etc. The system consists of 16 A/D converters and 16 D/A converters, a 32-channel general purpose input/output (GPIO) and two sensors. An isolated DC/DC converter with multi-outputs and a single mode fiber were adopted to reduce the interference generated by the common ground among the A/D, D/A and I/O. The software was designed using graphical programming language and can remotely access the corresponding instrument from a website. The entire intelligent control system can acquire the desirable data at a speed of 30 Mb/s and store it for later analysis. The intelligent system was implemented on a streak camera in a DIM and it shows a temporal resolution of 11.25 ps, spatial distortion of less than 10% and dynamic range of 279:1. The intelligent control system has been successfully used in a streak camera to verify the synchronization of multi-channel laser on the Inertial Confinement Fusion Facility.

Time-resolved fluorescence spectroscopy

International Nuclear Information System (INIS)

Gustavsson, Thomas; Mialocq, Jean-Claude

2007-01-01

This article addresses the evolution in time of light emitted by a molecular system after a brief photo-excitation. The authors first describe fluorescence from a photo-physical point of view and discuss the characterization of the excited state. Then, they explain some basic notions related to fluorescence characterization (lifetime and decays, quantum efficiency, so on). They present the different experimental methods and techniques currently used to study time-resolved fluorescence. They discuss basic notions of time resolution and spectral reconstruction. They briefly present some conventional methods: intensified Ccd cameras, photo-multipliers and photodiodes associated with a fast oscilloscope, and phase modulation. Other methods and techniques are more precisely presented: time-correlated single photon counting (principle, examples, and fluorescence lifetime imagery), streak camera (principle, examples), and optical methods like the Kerr optical effect (principle and examples) and fluorescence up-conversion (principle and theoretical considerations, examples of application)

Dense electro-optic frequency comb generated by two-stage modulation for dual-comb spectroscopy.

Science.gov (United States)

Wang, Shuai; Fan, Xinyu; Xu, Bingxin; He, Zuyuan

2017-10-01

An electro-optic frequency comb enables frequency-agile comb-based spectroscopy without using sophisticated phase-locking electronics. Nevertheless, dense electro-optic frequency combs over broad spans have yet to be developed. In this Letter, we propose a straightforward and efficient method for electro-optic frequency comb generation with a small line spacing and a large span. This method is based on two-stage modulation: generating an 18 GHz line-spacing comb at the first stage and a 250 MHz line-spacing comb at the second stage. After generating an electro-optic frequency comb covering 1500 lines, we set up an easily established mutually coherent hybrid dual-comb interferometer, which combines the generated electro-optic frequency comb and a free-running mode-locked laser. As a proof of concept, this hybrid dual-comb interferometer is used to measure the absorption and dispersion profiles of the molecular transition of H 13 CN with a spectral resolution of 250 MHz.

Playing with Light: Adventures in Optics and Spectroscopy for Honors and Majors General Chemistry

Science.gov (United States)

van Staveren, Marie N.; Edwards, Kimberly D.; Apkarian, V. A.

2012-01-01

A lab was developed for use in an undergraduate honors and majors general chemistry laboratory to introduce students to optics, spectroscopy, and the underlying principles of quantum mechanics. This lab includes four mini-experiments exploring total internal reflection, the tunneling of light, spectra of sparklers and colored candles, and emission…

Depth-sensitive optical spectroscopy for noninvasive diagnosis of oral neoplasia

Science.gov (United States)

Schwarz, Richard Alan

Oral cancer is the 11th most common cancer in the world. Cancers of the oral cavity and oropharynx account for more than 7,500 deaths each year in the United States alone. Major advances have been made in the management of oral cancer through the combined use of surgery, radiotherapy and chemotherapy, improving the quality of life for many patients; however, these advances have not led to a significant increase in survival rates, primarily because diagnosis often occurs at a late stage when treatment is more difficult and less successful. Accurate, objective, noninvasive methods for early diagnosis of oral neoplasia are needed. Here a method is presented to noninvasively evaluate oral lesions using depth-sensitive optical spectroscopy (DSOS). A ball lens coupled fiber-optic probe was developed to enable preferential targeting of different depth regions in the oral mucosa. Clinical studies of the diagnostic performance of DSOS in 157 subjects were carried out in collaboration with the University of Texas M. D. Anderson Cancer Center. An overall sensitivity of 90% and specificity of 89% were obtained for nonkeratinized oral tissue relative to histopathology. Based on these results a compact, portable version of the clinical DSOS device with real-time automated diagnostic capability was developed. The portable device was tested in 47 subjects and a sensitivity of 82% and specificity of 83% were obtained for nonkeratinized oral tissue. The diagnostic potential of multimodal platforms incorporating DSOS was explored through two pilot studies. A pilot study of DSOS in combination with widefield imaging was carried out in 29 oral cancer patients, resulting in a combined sensitivity of 94% and specificity of 69%. Widefield imaging and spectroscopy performed slightly better in combination than each method performed independently. A pilot study of DSOS in combination with the optical contrast agents 2-NBDG, EGF-Alexa 647, and proflavine was carried out in resected tissue

Nonlinear optical spectroscopy and microscopy of model random and biological media

Science.gov (United States)

Guo, Yici

Nonlinear optical (NLO) spectroscopy and microscopy applied to biomedical science are emerging as new and rapidly growing areas which offer important insight into basic phenomena. Ultrafast NLO processes provide temporal, spectral and spatial sensitivities complementary or superior to those achieved through conventional linear optical approaches. The goal of this thesis is to explore the potential of two fundamental NLO processes to produce noninvasive histological maps of biological tissues. Within the goal of the thesis, steady state intensity, polarization and angular measurements of second- and third-harmonic generations (SHG, THG) have been performed on model random scattering and animal tissue samples. The nonlinear optical effects have been evaluated using models. Conversion efficiencies of SHG and THG from animal tissue interfaces have been determined, ranging from 10-7 to 10-10. The changes in the multiharmonic signals were found to depend on both local and overall histological structures of biological samples. The spectral signatures of two photon excitation induced fluorescence from intrinsic fluorophores have been acquired and used to characterize the physical state and types of tissues. Two dimensional scanning SHG and TPF tomographic images have been obtained from in vitro animal tissues, normal and diseased human breast tissues, and resolved subsurface layers and histo-chemical distributions. By combining consecutive 2D maps, a 3D image can be produced. The structure and morphology dependence of the SH signal has been utilized to image and evaluate subsurface tumor progression depth. Second harmonic microscopy in model random and biological cells has been studied using a CCD camera to obtain direct images from subcellular structures. Finally, near infrared (NIR) NLO spectroscopy and microscopy based on SHG and TPF have demonstrated high spatial resolution, deeper penetration depth, low level photo-damaging and enhanced morphological sensitivity for

Development of graphene process control by industrial optical spectroscopy setup

Science.gov (United States)

Fursenko, O.; Lukosius, M.; Lupina, G.; Bauer, J.; Villringer, C.; Mai, A.

2017-06-01

The successful integration of graphene into microelectronic devices depends strongly on the availability of fast and nondestructive characterization methods of graphene grown by CVD on large diameter production wafers [1-3] which are in the interest of the semiconductor industry. Here, a high-throughput optical metrology method for measuring the thickness and uniformity of large-area graphene sheets is demonstrated. The method is based on the combination of spectroscopic ellipsometry and normal incidence reflectometry in UV-Vis wavelength range (200-800 nm) with small light spots ( 30 μm2) realized in wafer optical metrology tool. In the first step graphene layers were transferred on a SiO2/Si substrate in order to determine the optical constants of graphene by the combination of multi-angle ellipsometry and reflectometry. Then these data were used for the development of a process control recipe of CVD graphene on 200 mm Ge(100)/Si(100) wafers. The graphene layer quality was additionally monitored by Raman spectroscopy. Atomic force microscopy measurements were performed for micro topography evaluation. In consequence, a robust recipe for unambiguous thickness monitoring of all components of a multilayer film stack, including graphene, surface residuals or interface layer underneath graphene and surface roughness is developed. Optical monitoring of graphene thickness uniformity over a wafer has shown an excellent long term stability (s=0.004 nm) regardless of the growth of interfacial GeO2 and surface roughness. The sensitivity of the optical identification of graphene during microelectronic processing was evaluated. This optical metrology technique with combined data collection exhibit a fast and highly precise method allowing one an unambiguous detection of graphene after transferring as well as after the CVD deposition process on a Ge(100)/Si(100) wafer. This approach is well suited for industrial applications due to its repeatability and flexibility.

Cavity-enhanced spectroscopies

CERN Document Server

van Zee, Roger

2003-01-01

""Cavity-Enhanced Spectroscopy"" discusses the use of optical resonators and lasers to make sensitive spectroscopic measurements. This volume is written by the researcchers who pioneered these methods. The book reviews both the theory and practice behind these spectroscopic tools and discusses the scientific discoveries uncovered by these techniques. It begins with a chapter on the use of optical resonators for frequency stabilization of lasers, which is followed by in-depth chapters discussing cavity ring-down spectroscopy, frequency-modulated, cavity-enhanced spectroscopy, intracavity spectr

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

Energy Technology Data Exchange (ETDEWEB)

Harilal, Sivanandan S.; Brumfield, Brian E.; LaHaye, Nicole L.; Hartig, Kyle C.; Phillips, Mark C.

2018-04-20

This review article covers the present status of isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Finally, concluding remarks will be made on the existing gaps between previous works in the literature and suggestions for future work.

Electronic structure of antiferromagnetic UN and UPtGe single crystals from optical and magneto-optical spectroscopy; Elektronische Struktur von antiferromagnetischen UN- und UPtGe-Einkristallen aus optischer und magnetooptischer Spektroskopie

Energy Technology Data Exchange (ETDEWEB)

Marutzky, M.

2006-10-12

In this thesis the study of the magneto-optical Kerr effect and the determination of the optical constants by means of ellipsometry and Fourier-transformation infrared spectroscopy of UN and UPtGe is described. In UPtGe an optical anisotropy was detected over a spectral range from 6 meV to 32 eV. (HSI)

Isotopic analysis using optical spectroscopy (1963); Analyse isotopique par spectroscopie optique (1963)

Energy Technology Data Exchange (ETDEWEB)

Gerstenkorn, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

The isotopic displacement in the atomic lines of certain elements (H, He, Li, Ne, Sr, Hg, Pb, U, Pu) is used for dosing these elements isotopically. The use of the Fabry-Perot photo-electric interference spectrometer is shown to be particularly adapted for this sort of problem: in each case we give on the one hand the essential results obtained with this apparatus, and on the other hand the results previously obtained with a conventional apparatus (grating, photographic plate). These results together give an idea of the possibilities of optical spectroscopy: in the best case, the precision which may be expected is of the order of 1 to 2 per cent for isotopes whose concentration is about 1 per cent. (author) [French] Le deplacement isotopique dans les raies atomiques de certains elements (H, He, Li, Ne, Sr, Hg, Pb, U, Pu) est utilise pour effectuer le dosage isotopique de ces elements. L'utilisation du spectrometre interferentiel Fabry-Perot photoelectrique se revele particulierement adapte a ce genre de probleme: dans chaque cas, nous donnons d'une part l'essentiel des resultats obtenus avec cet appareil, et d'autre part, les resultats obtenus anterieurement a l'aide de l'appareillage classique (reseau, plaque photographique). L'ensemble de ces informations donne une idee des possibilites offertes par la spectroscopie optique: dans le meilleur des cas, la precision que l'on peut esperer est de l'ordre de 1 a 2 pour cent pour des isotopes dont la concentration est de l'ordre de 1 pour cent. (auteur)

Time resolved optical emission spectroscopy of cross-beam pulsed laser ablation on graphite targets

International Nuclear Information System (INIS)

Sangines, R.; Sanchez Ake, C.; Sobral, H.; Villagran-Muniz, M.

2007-01-01

Cross-beam pulsed laser ablation with two delayed lasers is performed on two perpendicular graphite targets. The time delay between lasers is varied by up to 5 μs, and physical changes on the second plasma, due to the interaction with the first generated one, are determined by time resolved optical emission spectroscopy

Deep-level optical spectroscopy investigation of N-doped TiO2 films

International Nuclear Information System (INIS)

Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

2005-01-01

N-doped TiO 2 films were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined from x-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing by mixing with the O 2p valence band

Raman spectroscopy of individual monocytes reveals that single-beam optical trapping of mononuclear cells occurs by their nucleus

International Nuclear Information System (INIS)

Fore, Samantha; Chan, James; Taylor, Douglas; Huser, Thomas

2011-01-01

We show that laser tweezers Raman spectroscopy of eukaryotic cells with a significantly larger diameter than the tight focus of a single-beam laser trap leads to optical trapping of the cell by its optically densest part, i.e. typically the cell's nucleus. Raman spectra of individual optically trapped monocytes are compared with location-specific Raman spectra of monocytes adhered to a substrate. When the cell's nucleus is stained with a fluorescent live cell stain, the Raman spectrum of the DNA-specific stain is observed only in the nucleus of individual monocytes. Optically trapped monocytes display the same behavior. We also show that the Raman spectra of individual monocytes exhibit the characteristic Raman signature of cells that have not yet fully differentiated and that individual primary monocytes can be distinguished from transformed monocytes based on their Raman spectra. This work provides further evidence that laser tweezers Raman spectroscopy of individual cells provides meaningful biochemical information in an entirely non-destructive fashion that permits discerning differences between cell types and cellular activity

Optical trapping and Raman spectroscopy of single nanostructures using standing-wave Raman tweezers

Science.gov (United States)

Wu, Mu-ying; He, Lin; Chen, Gui-hua; Yang, Guang; Li, Yong-qing

2017-08-01

Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped micro-particle, but is generally less effective for individual nano-sized objects in the 10-100 nm range. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap (SWOT) with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus is more stable and sensitive in measuring nanoparticles in liquid with 4-8 fold increase in the Raman signals. It can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, polystyrene beads (100 nm), SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles with a low laser power of a few milliwatts. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints.

Ultrafast streak and framing technique for the observation of laser driven shock waves in transparent solid targets

International Nuclear Information System (INIS)

Van Kessel, C.G.M.; Sachsenmaier, P.; Sigel, R.

1975-01-01

Shock waves driven by laser ablation in plane transparent plexiglass and solid hydrogen targets have been observed with streak and framing techniques using a high speed image converter camera, and a dye laser as a light source. The framing pictures have been made by mode locking the dye laser and using a wide streak slit. In both materials a growing hemispherical shock wave is observed with the maximum velocity at the onset of laser radiation. (author)

Streak-Camera Measurements with High Currents in PEP-II and Variable Optics in SPEAR3

Energy Technology Data Exchange (ETDEWEB)

Cheng, Weixeng; Fisher, Alan, a Corbett, Jeff; /SLAC

2008-06-05

A dual-axis, synchroscan streak camera was used to measure longitudinal bunch profiles in three storage rings at SLAC: the PEP-II low- and high-energy rings, and SPEAR3. At high currents, both PEP rings exhibit a transient synchronous-phase shift along the bunch train due to RF-cavity beam loading. Bunch length and profile asymmetry were measured along the train for a range of beam currents. To avoid the noise inherent in a dual-axis sweep, we accumulated single-axis synchroscan images while applying a 50-ns gate to the microchannel plate. To improve the extinction ratio, an upstream mirror pivoting at 1 kHz was synchronized with the 2kHz MCP gate to deflect light from other bunches off the photocathode. Bunch length was also measured on the HER as a function of beam energy. For SPEAR3 we measured bunch length as a function of single-bunch current for several lattices: achromatic, low-emittance and low momentum compaction. In the first two cases, resistive and reactive impedance components can be extracted from the longitudinal bunch profiles. In the low-alpha configurations, we observed natural bunch lengths approaching the camera resolution, requiring special care to remove instrumental effects, and saw evidence of periodic bursting.

Attosecond photoelectron spectroscopy of electron transport in solids

International Nuclear Information System (INIS)

Magerl, Elisabeth

2011-01-01

Time-resolved photoelectron spectroscopy of condensed matter systems in the attosecond regime promises new insights into excitation mechanisms and transient dynamics of electrons in solids. This timescale became accessible directly only recently with the development of the attosecond streak camera and of laser systems providing few-cycle, phase-controlled laser pulses in the near-infrared, which are used to generate isolated, sub-femtosecond extreme-ultraviolet pulses with a well-defined timing with respect to the near-infrared pulse. Employing these pulses, the attosecond streak camera offers time resolutions as short as a few 10 attoseconds. In the framework of this thesis, a new, versatile experimental apparatus combining attosecond pulse generation in gases with state of the art surface science techniques is designed, constructed, and commissioned. Employing this novel infrastructure and the technique of the attosecond transient recorder, we investigate transport phenomena occurring after photoexcitation of electrons in tungsten and rhenium single crystals and show that attosecond streaking is a unique method for resolving extremely fast electronic phenomena in solids. It is demonstrated that electrons originating from different energy levels, i.e. from the conduction band and the 4f core level, are emitted from the crystal surface at different times. The origin of this time delay, which is below 150 attoseconds for all studied systems, is investigated by a systematic variation of several experimental parameters, in particular the photon energy of the employed attosecond pulses. These experimental studies are complemented by theoretical studies of the group velocity of highly-excited electrons based on ab initio calculations. While the streaking technique applied on single crystals can provide only information about the relative time delay between two types of photoelectrons, the absolute transport time remains inaccessible. We introduce a scheme of a reference

Attosecond photoelectron spectroscopy of electron transport in solids

Energy Technology Data Exchange (ETDEWEB)

Magerl, Elisabeth

2011-03-31

Time-resolved photoelectron spectroscopy of condensed matter systems in the attosecond regime promises new insights into excitation mechanisms and transient dynamics of electrons in solids. This timescale became accessible directly only recently with the development of the attosecond streak camera and of laser systems providing few-cycle, phase-controlled laser pulses in the near-infrared, which are used to generate isolated, sub-femtosecond extreme-ultraviolet pulses with a well-defined timing with respect to the near-infrared pulse. Employing these pulses, the attosecond streak camera offers time resolutions as short as a few 10 attoseconds. In the framework of this thesis, a new, versatile experimental apparatus combining attosecond pulse generation in gases with state of the art surface science techniques is designed, constructed, and commissioned. Employing this novel infrastructure and the technique of the attosecond transient recorder, we investigate transport phenomena occurring after photoexcitation of electrons in tungsten and rhenium single crystals and show that attosecond streaking is a unique method for resolving extremely fast electronic phenomena in solids. It is demonstrated that electrons originating from different energy levels, i.e. from the conduction band and the 4f core level, are emitted from the crystal surface at different times. The origin of this time delay, which is below 150 attoseconds for all studied systems, is investigated by a systematic variation of several experimental parameters, in particular the photon energy of the employed attosecond pulses. These experimental studies are complemented by theoretical studies of the group velocity of highly-excited electrons based on ab initio calculations. While the streaking technique applied on single crystals can provide only information about the relative time delay between two types of photoelectrons, the absolute transport time remains inaccessible. We introduce a scheme of a reference

Secondary-electron cascade in attosecond photoelectron spectroscopy from metals

DEFF Research Database (Denmark)

Baggesen, Jan Conrad; Madsen, Lars Bojer

2009-01-01

an analytical model based on an approximate solution to Boltzmann's transport equation to account for the amount and energy distribution of these secondary electrons. Our theory is in good agreement with the electron spectrum found in a recent attosecond streaking experiment. To suppress the background and gain......Attosecond spectroscopy is currently restricted to photon energies around 100 eV. We show that under these conditions, electron-electron scatterings, as the photoelectrons leave the metal, give rise to a tail of secondary electrons with lower energies and hence a significant background. We develop...

Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations

International Nuclear Information System (INIS)

Johansson, Malin B; Niklasson, Gunnar A; Österlund, Lars; Baldissera, Gustavo; Persson, Clas; Valyukh, Iryna; Arwin, Hans

2013-01-01

The optical and electronic properties of nanocrystalline WO 3 thin films prepared by reactive dc magnetron sputtering at different total pressures (P tot ) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low P tot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies E g ≈ 3.1 eV, which increase with increasing P tot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic δ-WO 3 , and monoclinic γ- and ε-WO 3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The δ-WO 3 and γ-WO 3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (>3 eV) and allowed transitions (>3.8 eV). The calculations show that E g in ε-WO 3 is higher than in the δ-WO 3 and γ-WO 3 phases, which provides an explanation for the P tot dependence of the optical data. (paper)

Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations

Science.gov (United States)

Johansson, Malin B.; Baldissera, Gustavo; Valyukh, Iryna; Persson, Clas; Arwin, Hans; Niklasson, Gunnar A.; Österlund, Lars

2013-05-01

The optical and electronic properties of nanocrystalline WO3 thin films prepared by reactive dc magnetron sputtering at different total pressures (Ptot) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low Ptot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies Eg ≈ 3.1 eV, which increase with increasing Ptot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic δ-WO3, and monoclinic γ- and ε-WO3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The δ-WO3 and γ-WO3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (>3 eV) and allowed transitions (>3.8 eV). The calculations show that Eg in ε-WO3 is higher than in the δ-WO3 and γ-WO3 phases, which provides an explanation for the Ptot dependence of the optical data.

Time-resolved brightness measurements by streaking

Science.gov (United States)

Torrance, Joshua S.; Speirs, Rory W.; McCulloch, Andrew J.; Scholten, Robert E.

2018-03-01

Brightness is a key figure of merit for charged particle beams, and time-resolved brightness measurements can elucidate the processes involved in beam creation and manipulation. Here we report on a simple, robust, and widely applicable method for the measurement of beam brightness with temporal resolution by streaking one-dimensional pepperpots, and demonstrate the technique to characterize electron bunches produced from a cold-atom electron source. We demonstrate brightness measurements with 145 ps temporal resolution and a minimum resolvable emittance of 40 nm rad. This technique provides an efficient method of exploring source parameters and will prove useful for examining the efficacy of techniques to counter space-charge expansion, a critical hurdle to achieving single-shot imaging of atomic scale targets.

Multivariate reference technique for quantitative analysis of fiber-optic tissue Raman spectroscopy.

Science.gov (United States)

Bergholt, Mads Sylvest; Duraipandian, Shiyamala; Zheng, Wei; Huang, Zhiwei

2013-12-03

We report a novel method making use of multivariate reference signals of fused silica and sapphire Raman signals generated from a ball-lens fiber-optic Raman probe for quantitative analysis of in vivo tissue Raman measurements in real time. Partial least-squares (PLS) regression modeling is applied to extract the characteristic internal reference Raman signals (e.g., shoulder of the prominent fused silica boson peak (~130 cm(-1)); distinct sapphire ball-lens peaks (380, 417, 646, and 751 cm(-1))) from the ball-lens fiber-optic Raman probe for quantitative analysis of fiber-optic Raman spectroscopy. To evaluate the analytical value of this novel multivariate reference technique, a rapid Raman spectroscopy system coupled with a ball-lens fiber-optic Raman probe is used for in vivo oral tissue Raman measurements (n = 25 subjects) under 785 nm laser excitation powers ranging from 5 to 65 mW. An accurate linear relationship (R(2) = 0.981) with a root-mean-square error of cross validation (RMSECV) of 2.5 mW can be obtained for predicting the laser excitation power changes based on a leave-one-subject-out cross-validation, which is superior to the normal univariate reference method (RMSE = 6.2 mW). A root-mean-square error of prediction (RMSEP) of 2.4 mW (R(2) = 0.985) can also be achieved for laser power prediction in real time when we applied the multivariate method independently on the five new subjects (n = 166 spectra). We further apply the multivariate reference technique for quantitative analysis of gelatin tissue phantoms that gives rise to an RMSEP of ~2.0% (R(2) = 0.998) independent of laser excitation power variations. This work demonstrates that multivariate reference technique can be advantageously used to monitor and correct the variations of laser excitation power and fiber coupling efficiency in situ for standardizing the tissue Raman intensity to realize quantitative analysis of tissue Raman measurements in vivo, which is particularly appealing in

Circularly polarized infrared and visible sum-frequency-generation spectroscopy: Vibrational optical activity measurement

International Nuclear Information System (INIS)

Cheon, Sangheon; Cho, Minhaeng

2005-01-01

Vibrational optical activity spectroscopies utilizing either circularly polarized ir or circularly polarized visible beams were theoretically investigated by considering the infrared and visible sum-frequency-generation (IV-SFG) schemes. In addition to the purely electric dipole-allowed chiral component of the IV-SFG susceptibility, the polarizability-electric quadrupole hyperpolarizability term also contributes to the vibrationally resonant IV-SFG susceptibility. The circular-intensity-difference signal is shown to be determined by the interferences between the all-electric dipole-allowed chiral component and the polarizability-electric-dipole or electric-dipole-electric-quadrupole Raman optical activity tensor components. The circularly polarized SFG methods are shown to be potentially useful coherent spectroscopic tools for determining absolute configurations of chiral molecules in condensed phases

Collinear laser spectroscopy of manganese isotopes using optical pumping in ISCOOL

CERN Multimedia

Marsh, B A; Neyens, G; Flanagan, K; Rajabali, M M; Reponen, M; Campbell, P; Procter, T J

Recently, optical pumping of ions has been achieved inside an ion beam cooler-buncher. By illuminating the central axis of the cooler with laser light, subsequent decay populates selected ionic metastable states. This population enhancement is retained as the ion beam is delivered to an experimental station. In the case of collinear laser spectroscopy, transitions can then be excited from a preferred metastable level, rather than the ground-state. This proposal seeks to establish and develop the technique for ISCOOL. As a test of efficiency, this will be applied to the study of $^{55-66}$Mn isotopes using collinear laser spectroscopy-expanding an earlier study where the benefit of the technique was demonstrated. This will provide nuclear spins, magnetic-dipole and electric-quadrupole moments and changes in mean-square charge radii across N = 40 shell closure candidate and into a region where an onset of deformation, and a new "island of inversion" is predicted.

Ultrafast wavelength multiplexed broad bandwidth digital diffuse optical spectroscopy for in vivo extraction of tissue optical properties

Science.gov (United States)

Torjesen, Alyssa; Istfan, Raeef; Roblyer, Darren

2017-03-01

Frequency-domain diffuse optical spectroscopy (FD-DOS) utilizes intensity-modulated light to characterize optical scattering and absorption in thick tissue. Previous FD-DOS systems have been limited by large device footprints, complex electronics, high costs, and limited acquisition speeds, all of which complicate access to patients in the clinical setting. We have developed a new digital DOS (dDOS) system, which is relatively compact and inexpensive, allowing for simplified clinical use, while providing unprecedented measurement speeds. The dDOS system utilizes hardware-integrated custom board-level direct digital synthesizers and an analog-to-digital converter to generate frequency sweeps and directly measure signals utilizing undersampling at six wavelengths modulated at discrete frequencies from 50 to 400 MHz. Wavelength multiplexing is utilized to achieve broadband frequency sweep measurements acquired at over 97 Hz. When compared to a gold-standard DOS system, the accuracy of optical properties recovered with the dDOS system was within 5.3% and 5.5% for absorption and reduced scattering coefficient extractions, respectively. When tested in vivo, the dDOS system was able to detect physiological changes throughout the cardiac cycle. The new FD-dDOS system is fast, inexpensive, and compact without compromising measurement quality.

Atomic and molecular data for optical stellar spectroscopy

International Nuclear Information System (INIS)

Heiter, U; Lind, K; Barklem, P S; Asplund, M; Bergemann, M; Magrini, L; Masseron, T; Mikolaitis, Š; Pickering, J C; Ruffoni, M P

2015-01-01

High-precision spectroscopy of large stellar samples plays a crucial role for several topical issues in astrophysics. Examples include studying the chemical structure and evolution of the Milky Way Galaxy, tracing the origin of chemical elements, and characterizing planetary host stars. Data are accumulating from instruments that obtain high-quality spectra of stars in the ultraviolet, optical and infrared wavelength regions on a routine basis. These instruments are located at ground-based 2–10 m class telescopes around the world, in addition to the spectrographs with unique capabilities available at the Hubble Space Telescope. The interpretation of these spectra requires high-quality transition data for numerous species, in particular neutral and singly ionized atoms, and di- or triatomic molecules. We rely heavily on the continuous efforts of laboratory astrophysics groups that produce and improve the relevant experimental and theoretical atomic and molecular data. The compilation of the best available data is facilitated by databases and electronic infrastructures such as the NIST Atomic Spectra Database, the VALD database, or the Virtual Atomic and Molecular Data Centre. We illustrate the current status of atomic data for optical stellar spectra with the example of the Gaia-ESO Public Spectroscopic Survey. Data sources for 35 chemical elements were reviewed in an effort to construct a line list for a homogeneous abundance analysis of up to 10 5 stars. (paper)

Atomic and molecular data for optical stellar spectroscopy

Science.gov (United States)

Heiter, U.; Lind, K.; Asplund, M.; Barklem, P. S.; Bergemann, M.; Magrini, L.; Masseron, T.; Mikolaitis, Š.; Pickering, J. C.; Ruffoni, M. P.

2015-05-01

High-precision spectroscopy of large stellar samples plays a crucial role for several topical issues in astrophysics. Examples include studying the chemical structure and evolution of the Milky Way Galaxy, tracing the origin of chemical elements, and characterizing planetary host stars. Data are accumulating from instruments that obtain high-quality spectra of stars in the ultraviolet, optical and infrared wavelength regions on a routine basis. These instruments are located at ground-based 2-10 m class telescopes around the world, in addition to the spectrographs with unique capabilities available at the Hubble Space Telescope. The interpretation of these spectra requires high-quality transition data for numerous species, in particular neutral and singly ionized atoms, and di- or triatomic molecules. We rely heavily on the continuous efforts of laboratory astrophysics groups that produce and improve the relevant experimental and theoretical atomic and molecular data. The compilation of the best available data is facilitated by databases and electronic infrastructures such as the NIST Atomic Spectra Database, the VALD database, or the Virtual Atomic and Molecular Data Centre. We illustrate the current status of atomic data for optical stellar spectra with the example of the Gaia-ESO Public Spectroscopic Survey. Data sources for 35 chemical elements were reviewed in an effort to construct a line list for a homogeneous abundance analysis of up to 105 stars.

Atomization efficiency and photon yield in laser-induced breakdown spectroscopy analysis of single nanoparticles in an optical trap

Science.gov (United States)

Purohit, Pablo; Fortes, Francisco J.; Laserna, J. Javier

2017-04-01

Laser-induced breakdown spectroscopy (LIBS) was employed for investigating the influence of particle size on the dissociation efficiency and the absolute production of photons per mass unit of airborne solid graphite spheres under single-particle regime. Particles of average diameter of 400 nm were probed and compared with 2 μm particles. Samples were first catapulted into aerosol form and then secluded in an optical trap set by a 532 nm laser. Trap stability was quantified before subjecting particles to LIBS analysis. Fine alignment of the different lines comprising the optical catapulting-optical trapping-laser-induced breakdown spectroscopy instrument and tuning of excitation parameters conditioning the LIBS signal such as fluence and acquisition delay are described in detail with the ultimate goal of acquiring clear spectroscopic data on masses as low as 75 fg. The atomization efficiency and the photon yield increase as the particle size becomes smaller. Time-resolved plasma imaging studies were conducted to elucidate the mechanisms leading to particle disintegration and excitation.

Study of optical emission spectroscopy with inductively coupled plasma torch

International Nuclear Information System (INIS)

Bauer, M.

1982-01-01

Inductively coupled plasma optical emission spectroscopy is an excellent tool for quantitative multielement trace analysis. This paper describes the performance of a computer-controlled sequential measurement system. Chemical and ionization interferences are shown to be negligible due to the characteristics of the inductively coupled plasma, spectral interferences are eliminated by using a high-resolution monochromator and computer data handling. Good accuracy is achieved for most of the interesting elements, as is shown from both an interlaboratory test and from comparison of the results of water samples from the rivers Elbe and Weser with those achieved with neutron activation and X-ray fluorescence analysis. (orig.) [de

Diagnosis of the local thermal equilibrium by optical emission spectroscopy in the evolution of electric discharge

International Nuclear Information System (INIS)

Valdivia B, R.; Pacheco S, J.; Pacheco P, M.; Ramos F, F.; Cruz A, A.; Velazquez P, S.

2008-01-01

In this work applies the technique of optical emission spectroscopy to diagnose the temperature of the species generated in plasma in the transition to glow discharge arc. Whit this diagnosis is possible to determine the local thermal equilibrium conditions of the discharge. (Author)

Optical fluorescence spectroscopy to detect hepatic necrosis after normothermic ischemia: animal model

Science.gov (United States)

Romano, Renan A.; Vollet-Filho, Jose D.; Pratavieira, Sebastião.; Fernandez, Jorge L.; Kurachi, Cristina; Bagnato, Vanderlei S.; Castro-e-Silva, Orlando; Sankarankutty, Ajith K.

2015-06-01

Liver transplantation is a well-established treatment for liver failure. However, the success of the transplantation procedure depends on liver graft conditions. The tissue function evaluation during the several transplantation stages is relevant, in particular during the organ harvesting, when a decision is made concerning the viability of the graft. Optical fluorescence spectroscopy is a good option because it is a noninvasive and fast technique. A partial normothermic hepatic ischemia was performed in rat livers, with a vascular occlusion of both median and left lateral lobes, allowing circulation only for the right lateral lobe and the caudate lobe. Fluorescence spectra under excitation at 532 nm (doubled frequency Nd:YAG laser) were collected using a portable spectrometer (USB2000, Ocean Optics, USA). The fluorescence emission was collected before vascular occlusion, after ischemia, and 24 hours after reperfusion. A morphometric histology analysis was performed as the gold standard evaluation - liver samples were analyzed, and the percentage of necrotic tissue was obtained. The results showed that changes in the fluorescence emission after ischemia can be correlated with the amount of necrosis evaluated by a morphometric analysis, the Pearson correlation coefficient of the generated model was 0.90 and the root mean square error was around 20%. In this context, the laser-induced fluorescence spectroscopy technique after normothermic ischemia showed to be a fast and efficient method to differentiate ischemic injury from viable tissues.

Reflective optical system for time-resolved electron bunch measurements at PITZ

Energy Technology Data Exchange (ETDEWEB)

Rosbach, K; Baehr, J [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Roensch-Schulenburg, J [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik

2011-01-15

The Photo-Injector Test facility at DESY, Zeuthen site (PITZ), produces pulsed electron beams with low transverse emittance and is equipped with diagnostic devices for measuring various electron bunch properties, including the longitudinal and transverse electron phase space distributions. The longitudinal bunch structure is recorded using a streak camera located outside the accelerator tunnel, connected to the diagnostics in the beam-line stations by an optical system of about 30 m length. This system mainly consists of telescopes of achromatic lenses, which transport the light pulses and image them onto the entrance slit of the streak camera. Due to dispersion in the lenses, the temporal resolution degrades during transport. This article presents general considerations for time-resolving optical systems as well as simulations and measurements of specific candidate systems. It then describes the development of an imaging system based on mirror telescopes which will improve the temporal resolution, with an emphasis on off-axis parabolic mirror systems working at unit magnification. A hybrid system of lenses and mirrors will serve as a proof of principle. (orig.)

Temporal resolution limit estimation of x-ray streak cameras using a CsI photocathode

Energy Technology Data Exchange (ETDEWEB)

Li, Xiang; Gu, Li; Zong, Fangke; Zhang, Jingjin; Yang, Qinlao, E-mail: qlyang@szu.edu.cn [Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Institute of Optoelectronics, Shenzhen University, Shenzhen 518060 (China)

2015-08-28

A Monte Carlo model is developed and implemented to calculate the characteristics of x-ray induced secondary electron (SE) emission from a CsI photocathode used in an x-ray streak camera. Time distributions of emitted SEs are investigated with an incident x-ray energy range from 1 to 30 keV and a CsI thickness range from 100 to 1000 nm. Simulation results indicate that SE time distribution curves have little dependence on the incident x-ray energy and CsI thickness. The calculated time dispersion within the CsI photocathode is about 70 fs, which should be the temporal resolution limit of x-ray streak cameras that use CsI as the photocathode material.

Oct4 is required ~E7.5 for proliferation in the primitive streak.

Directory of Open Access Journals (Sweden)

Brian DeVeale

2013-11-01

Full Text Available Oct4 is a widely recognized pluripotency factor as it maintains Embryonic Stem (ES cells in a pluripotent state, and, in vivo, prevents the inner cell mass (ICM in murine embryos from differentiating into trophectoderm. However, its function in somatic tissue after this developmental stage is not well characterized. Using a tamoxifen-inducible Cre recombinase and floxed alleles of Oct4, we investigated the effect of depleting Oct4 in mouse embryos between the pre-streak and headfold stages, ~E6.0-E8.0, when Oct4 is found in dynamic patterns throughout the embryonic compartment of the mouse egg cylinder. We found that depletion of Oct4 ~E7.5 resulted in a severe phenotype, comprised of craniorachischisis, random heart tube orientation, failed turning, defective somitogenesis and posterior truncation. Unlike in ES cells, depletion of the pluripotency factors Sox2 and Oct4 after E7.0 does not phenocopy, suggesting that ~E7.5 Oct4 is required within a network that is altered relative to the pluripotency network. Oct4 is not required in extraembryonic tissue for these processes, but is required to maintain cell viability in the embryo and normal proliferation within the primitive streak. Impaired expansion of the primitive streak occurs coincident with Oct4 depletion ∼E7.5 and precedes deficient convergent extension which contributes to several aspects of the phenotype.

Ultrafast gated imaging of laser produced plasmas using the optical Kerr effect

International Nuclear Information System (INIS)

Symes, D. R.; Wegner, U.; Ahlswede, H.-C.; Streeter, M. J. V.; Gallegos, P. L.; Divall, E. J.; Rajeev, P. P.; Neely, D.; Smith, R. A.

2010-01-01

Optical imaging is a versatile diagnostic for investigations of plasmas generated under intense laser irradiation. Electro-optic gating techniques operating on the >100 ps timescale are commonly used to reduce the amount of light detected from self-emission of hot plasma or improve the temporal resolution of the detector. The use of an optical Kerr gate enables a superior dynamic range and temporal resolution compared to electronically gated devices. The application of this method for enhanced imaging of laser produced plasmas with gate time ∼100 fs is demonstrated, and the possibility to produce a sub-10 fs, high dynamic range 'all optical' streak camera is discussed.

Below band-gap optical absorption and photoluminescence excitation spectroscopy at room temperature in low-defect-density bulk GaN:Fe

Czech Academy of Sciences Publication Activity Database

Gladkov, Petar; Hulicius, Eduard; Paskova, T.; Preble, E.; Evans, K.R.

2012-01-01

Roč. 100, č. 3 (2012), "031908-1"-"031908-3" ISSN 0003-6951 Grant - others:US Missile Defense Agency(US) HQ 0147-09-C-0005 Institutional support: RVO:68378271 ; RVO:67985882 Keywords : GaN * spectroscopy * optical absorption Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.794, year: 2012

Optical analysis of trapped Gas—Gas in Scattering Media Absorption Spectroscopy

Science.gov (United States)

Svanberg, S.

2010-01-01

An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. The technique investigates sharp gas spectral signatures, typically 10000 times sharper than those of the host material, in which the gas is trapped in pores or cavities. The presence of pores causes strong multiple scattering. GASMAS combines narrow-band diode-laser spectroscopy, developed for atmospheric gas monitoring, with diffuse media optical propagation, well-known from biomedical optics. Several applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, and this is also true for haemoglobin, making propagation possible in many natural materials. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities (frontal, maxillary and mastoideal) have been studied, demonstrating new possibilities for characterization and diagnostics. Transport of gas in porous media (diffusion) can be studied by first subjecting the material to, e.g., pure nitrogen, and then observing the rate at which normal, oxygen-containing air, reinvades the material. The conductance of the passages connecting a sinus with the nasal cavity can be objectively assessed by observing the oxygen gas dynamics when flushing the nose with nitrogen. Drying of materials, when liquid water is replaced by air and water vapour, is another example of dynamic processes which can be studied. The technique has also been extended to remote-sensing applications (LIDAR-GASMAS or Multiple-Scattering LIDAR).

ACADEMIC TRAINING: Probing nature with high precision; particle traps, laser spectroscopy and optical combs

CERN Multimedia

Françoise Benz

2002-01-01

17, 18, 19 June LECTURE SERIES from 11.00 to 12.00 hrs - Auditorium, bldg. 500 Probing nature with high precision; particle traps, laser spectroscopy and optical combs by G. GABRIELSE / Harvard University, USA Experiments with atomic energy scales probe nature and its symmetries with exquisite precision. Particle traps allow the manipulation of single charged particles for months at a time, allow the most accurate comparison of theory and experiment, and promise to allow better measurement of fundamental quantities like the fine structure constant. Ions and atoms can be probed with lasers that are phase locked to microwave frequency standards via optical combs, thus calibrating optical sources in terms of the official cesium second. A series of three lectures will illustrate what can be measured and discuss key techniques.  ACADEMIC TRAINING Françoise Benz Tel. 73127 francoise.benz@cern.ch

Towards optical fibre based Raman spectroscopy for the detection of surgical site infection

Science.gov (United States)

Thompson, Alex J.; Koziej, Lukasz; Williams, Huw D.; Elson, Daniel S.; Yang, Guang-Zhong

2016-03-01

Surgical site infections (SSIs) are common post-surgical complications that remain significant clinical problems, as they are associated with substantial mortality and morbidity. As such, there is significant interest in the development of minimally invasive techniques that permit early detection of SSIs. To this end, we are applying a compact, clinically deployable Raman spectrometer coupled to an optical fibre probe to the study of bacteria, with the long term goal of using Raman spectroscopy to detect infection in vivo. Our system comprises a 785 nm laser diode for excitation and a commercial (Ocean Optics, Inc.) Raman spectrometer for detection. Here we discuss the design, optimisation and validation of this system, and describe our first experiences interrogating bacterial cells (Escherichia coli) in vitro.

Electron streaking in the autoionization region of H2

International Nuclear Information System (INIS)

Palacios, Alicia; González-Castrillo, Alberto; Martín, Fernando

2015-01-01

We use a UV-pump/IR-probe scheme, combining a single attosecond UV pulse and a 750 nm IR pulse, to explore laser-assisted photoionization of the hydrogen molecule in the autoionization region. The electron energy distributions exhibit unusual streaking patterns that are explored for different angles of the electron ejection with respect to the polarization vector and the molecular axis. Moreover, by controlling the time delay between the pulses, we observe that one can suppress the autoionization channel. (paper)

Self-absorption influence on the optical spectroscopy of zinc oxide laser produced plasma

Energy Technology Data Exchange (ETDEWEB)

De Posada, E; Arronte, M A; Ponce, L; Rodriguez, E; Flores, T [Centro de Investigacion en Ciencia Aplicada y TecnologIa Avanzada-Unidad Altamira, Tamaulipas (Mexico); Lunney, J G, E-mail: edeposada@ipn.mx [School of Physics, Trinity College Dublin (Ireland)

2011-01-01

Optical spectroscopy is used to study the laser ablation process of ZnO targets. It is demonstrated that even if Partial Local Thermal Equilibrium is present, self absorption process leads to a decrease of recorded lines emission intensities and have to be taken into account to obtain correct values of such parameters. It is presented a method that combines results of both Langmuir probe technique and Anisimov model to obtain correct values of plasma parameters.

Real time assessment of RF cardiac tissue ablation with optical spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Demos, S G; Sharareh, S

2008-03-20

An optical spectroscopy approach is demonstrated allowing for critical parameters during RF ablation of cardiac tissue to be evaluated in real time. The method is based on incorporating in a typical ablation catheter transmitting and receiving fibers that terminate at the tip of the catheter. By analyzing the spectral characteristics of the NIR diffusely reflected light, information is obtained on such parameters as, catheter-tissue proximity, lesion formation, depth of penetration of the lesion, formation of char during the ablation, formation of coagulum around the ablation site, differentiation of ablated from healthy tissue, and recognition of micro-bubble formation in the tissue.

Extracting Optical Fiber Background from Surface-Enhanced Raman Spectroscopy Spectra Based on Bi-Objective Optimization Modeling.

Science.gov (United States)

Huang, Jie; Shi, Tielin; Tang, Zirong; Zhu, Wei; Liao, Guanglan; Li, Xiaoping; Gong, Bo; Zhou, Tengyuan

2017-08-01

We propose a bi-objective optimization model for extracting optical fiber background from the measured surface-enhanced Raman spectroscopy (SERS) spectrum of the target sample in the application of fiber optic SERS. The model is built using curve fitting to resolve the SERS spectrum into several individual bands, and simultaneously matching some resolved bands with the measured background spectrum. The Pearson correlation coefficient is selected as the similarity index and its maximum value is pursued during the spectral matching process. An algorithm is proposed, programmed, and demonstrated successfully in extracting optical fiber background or fluorescence background from the measured SERS spectra of rhodamine 6G (R6G) and crystal violet (CV). The proposed model not only can be applied to remove optical fiber background or fluorescence background for SERS spectra, but also can be transferred to conventional Raman spectra recorded using fiber optic instrumentation.

Authenticity screening of stained glass windows using optical spectroscopy

Science.gov (United States)

Meulebroeck, Wendy; Wouters, Hilde; Nys, Karin; Thienpont, Hugo

2016-11-01

Civilized societies should safeguard their heritage as it plays an important role in community building. Moreover, past technologies often inspire new technology. Authenticity is besides conservation and restoration a key aspect in preserving our past, for example in museums when exposing showpieces. The classification of being authentic relies on an interdisciplinary approach integrating art historical and archaeological research complemented with applied research. In recent decades analytical dating tools are based on determining the raw materials used. However, the traditional applied non-portable, chemical techniques are destructive and time-consuming. Since museums oftentimes only consent to research actions which are completely non-destructive, optical spectroscopy might offer a solution. As a case-study we apply this technique on two stained glass panels for which the 14th century dating is nowadays questioned. With this research we were able to identify how simultaneous mapping of spectral signatures measured with a low cost optical spectrum analyser unveils information regarding the production period. The significance of this research extends beyond the re-dating of these panels to the 19th century as it provides an instant tool enabling immediate answering authenticity questions during the conservation process of stained glass, thereby providing the necessary data for solving deontological questions about heritage preservation.

Online quantitative monitoring of live cell engineered cartilage growth using diffuse fiber-optic Raman spectroscopy.

Science.gov (United States)

Bergholt, Mads S; Albro, Michael B; Stevens, Molly M

2017-09-01

Tissue engineering (TE) has the potential to improve the outcome for patients with osteoarthritis (OA). The successful clinical translation of this technique as part of a therapy requires the ability to measure extracellular matrix (ECM) production of engineered tissues in vitro, in order to ensure quality control and improve the likelihood of tissue survival upon implantation. Conventional techniques for assessing the ECM content of engineered cartilage, such as biochemical assays and histological staining are inherently destructive. Raman spectroscopy, on the other hand, represents a non-invasive technique for in situ biochemical characterization. Here, we outline current roadblocks in translational Raman spectroscopy in TE and introduce a comprehensive workflow designed to non-destructively monitor and quantify ECM biomolecules in large (>3 mm), live cell TE constructs online. Diffuse near-infrared fiber-optic Raman spectra were measured from live cell cartilaginous TE constructs over a 56-day culturing period. We developed a multivariate curve resolution model that enabled quantitative biochemical analysis of the TE constructs. Raman spectroscopy was able to non-invasively quantify the ECM components and showed an excellent correlation with biochemical assays for measurement of collagen (R 2  = 0.84) and glycosaminoglycans (GAGs) (R 2  = 0.86). We further demonstrated the robustness of this technique for online prospective analysis of live cell TE constructs. The fiber-optic Raman spectroscopy strategy developed in this work offers the ability to non-destructively monitor construct growth online and can be adapted to a broad range of TE applications in regenerative medicine toward controlled clinical translation. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Rho kinase activity controls directional cell movements during primitive streak formation in the rabbit embryo.

Science.gov (United States)

Stankova, Viktoria; Tsikolia, Nikoloz; Viebahn, Christoph

2015-01-01

During animal gastrulation, the specification of the embryonic axes is accompanied by epithelio-mesenchymal transition (EMT), the first major change in cell shape after fertilization. EMT takes place in disparate topographical arrangements, such as the circular blastopore of amphibians, the straight primitive streak of birds and mammals or in intermediate gastrulation forms of other amniotes such as reptiles. Planar cell movements are prime candidates to arrange specific modes of gastrulation but there is no consensus view on their role in different vertebrate classes. Here, we test the impact of interfering with Rho kinase-mediated cell movements on gastrulation topography in blastocysts of the rabbit, which has a flat embryonic disc typical for most mammals. Time-lapse video microscopy, electron microscopy, gene expression and morphometric analyses of the effect of inhibiting ROCK activity showed - besides normal specification of the organizer region - a dose-dependent disruption of primitive streak formation; this disruption resulted in circular, arc-shaped or intermediate forms, reminiscent of those found in amphibians, fishes and reptiles. Our results reveal a crucial role of ROCK-controlled directional cell movements during rabbit primitive streak formation and highlight the possibility that temporal and spatial modulation of cell movements were instrumental for the evolution of gastrulation forms. © 2015. Published by The Company of Biologists Ltd.

Microwave-optical double resonance spectroscopy. Progress report, February 1, 1975--January 31, 1976

International Nuclear Information System (INIS)

Pratt, D.W.

1975-01-01

Zero-field and high-field optical detection of magnetic resonance (ODMR), electron paramagnetic resonance (EPR), and optical spectroscopy experiments were performed on several systems in order to further basic knowledge of the structure, reactions, and response to radiation of atoms, molecules, and ions. Results on the following studies are reported: the direct observation of level anticrossing and mixing effects in excited molecular triplet states; anomalous zero-field splittings in the lowest triplet state of 1-iodonaphthalene; evidence for second-order spin-orbit coupling and spin delocalization effects in the lowest triplet state of benzophenone; direct observation of the optical absorption spectra of reactive free radicals at room temperature; measurements of the activation and thermodynamic parameters of several cyclohexenyl and cyclohexanonyl radicals; complete analyses of the level anticrossing and cross relaxation spectra of oriented molecular triplet states; solutions to the spin Hamiltonian for S = 1, I = 5/2 systems in both zero-field and high-field, an improvement by a factor of ten in the resolution of ODMR experiments in high field; and measurements of the optical and magnetic resonance properties of a series of halogenated naphthalenes in their lowest triplet states

Ultrafast optical pump terahertz-probe spectroscopy of strongly correlated electron materials

International Nuclear Information System (INIS)

Averitt, R.D.; Taylor, Antoinette J.; Thorsmolle, V.K.; Jia, Quanxi; Lobad, A.I.; Trugman, S.A.

2001-01-01

We have used optical-pump far-infrared probe spectroscopy to probe the low energy electron dynamics of high temperature superconductors and colossal magnetoresistance manganites. For the superconductor YBa2Cu3O7, picosecond conductivity measurements probe the interplay between Cooper-pairs and quasiparticles. In optimally doped films, the recovery time for long-range phase-coherent pairing increases from ∼1.5 ps at 4K to ∼3.5 ps near Tc, consistent with the closing of the superconducting gap. For underdoped films, the measured recovery time is temperature independent (3.5 ps) in accordance with the presence of a pseudogap. Ultrafast picosecond measurements of optically induced changes in the absolute conductivity of La0:7M0:3MnO3 thin films (M = Ca, Sr) from 10K to ∼0.9Tc reveal a two-component relaxation. A fast, ∼2 ps, conductivity decrease arises from optically induced modification of the effective phonon temperature. The slower component, related to spin-lattice relaxation, has a lifetime that increases upon approaching Tc from below in accordance with an increasing spin specific heat. Our results indicate that for T<< Tc, the conductivity is determined by incoherent phonons while spin fluctuations dominate near Tc.

Combination of the optical waveguide lightmode spectroscopy method with electrochemical measurements

Energy Technology Data Exchange (ETDEWEB)

Szendro, I.; Erdelyi, K.; Fabian, M. [MicroVacuum Ltd., Kerekgyarto u.: 10, H-1147 Budapest (Hungary); Puskas, Zs. [Minvasive Ltd., Goldmann Gy. ter 3., H-1111 Budapest (Hungary); Adanyi, N. [Central Food Research Institute, H-1537 Budapest, P.O.B. 393 (Hungary); Somogyi, K. [MicroVacuum Ltd., Kerekgyarto u.: 10, H-1147 Budapest (Hungary)], E-mail: karoly.somogyi@microvacuum.com

2008-09-30

Optical waveguides are normally sensitive to the surrounding media and also to the surface contaminations. The effective refractive index changes at the surface. Various sensor systems were developed based on this effect. One of the most sensitive and effective methods is the optical waveguide lightmode spectroscopy (OWLS). At the same time, electrochemical methods are widely used both in inorganic and organic chemistry, and also advantages in microbiology were demonstrated. In this work, efforts are made and results are presented for the combination of these two methods for simultaneous measurement of refractive index and electrical current changes caused by the presence of cells/molecules/ions to be investigated. An electrically conductive indium tin oxide (ITO) nanolayer is deposited and activated on the top of the OWLS planar waveguide oxide layer. ITO layers serve as working electrodes in the electrochemical measurements. The basic setup and an integrated system are demonstrated here. Measurements using H{sub 2}O{sub 2}, toluidine blue solutions, and KCl and TRIS solutions as buffer and transport media are represented. Measurements show both the changes detected by the sensor layer and the effect of the applied potential in cyclic and chrono voltammetric measurements. Results demonstrate an effective combination of optical and electrochemical methods.

Simultaneous streak and frame interferometry for electron density measurements of laser produced plasmas

Energy Technology Data Exchange (ETDEWEB)

Quevedo, H. J., E-mail: hjquevedo@utexas.edu; McCormick, M.; Wisher, M.; Bengtson, Roger D.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

2016-01-15

A system of two collinear probe beams with different wavelengths and pulse durations was used to capture simultaneously snapshot interferograms and streaked interferograms of laser produced plasmas. The snapshots measured the two dimensional, path-integrated, electron density on a charge-coupled device while the radial temporal evolution of a one dimensional plasma slice was recorded by a streak camera. This dual-probe combination allowed us to select plasmas that were uniform and axisymmetric along the laser direction suitable for retrieving the continuous evolution of the radial electron density of homogeneous plasmas. Demonstration of this double probe system was done by measuring rapidly evolving plasmas on time scales less than 1 ns produced by the interaction of femtosecond, high intensity, laser pulses with argon gas clusters. Experiments aimed at studying homogeneous plasmas from high intensity laser-gas or laser-cluster interaction could benefit from the use of this probing scheme.

A Linear Ion Trap with an Expanded Inscribed Diameter to Improve Optical Access for Fluorescence Spectroscopy

Science.gov (United States)

Rajagopal, Vaishnavi; Stokes, Chris; Ferzoco, Alessandra

2018-02-01

We report a custom-geometry linear ion trap designed for fluorescence spectroscopy of gas-phase ions at ambient to cryogenic temperatures. Laser-induced fluorescence from trapped ions is collected from between the trapping rods, orthogonal to the excitation laser that runs along the axis of the linear ion trap. To increase optical access to the ion cloud, the diameter of the round trapping rods is 80% of the inscribed diameter, rather than the roughly 110% used to approximate purely quadrupolar electric fields. To encompass as much of the ion cloud as possible, the first collection optic has a 25.4 mm diameter and a numerical aperture of 0.6. The choice of geometry and collection optics yields 107 detected photons/s from trapped rhodamine 6G ions. The trap is coupled to a closed-cycle helium refrigerator, which in combination with two 50 Ohm heaters enables temperature control to below 25 K on the rod electrodes. The purpose of the instrument is to broaden the applicability of fluorescence spectroscopy of gas-phase ions to cases where photon emission is a minority relaxation pathway. Such studies are important to understand how the microenvironment of a chromophore influences excited state charge transfer processes.

A diode-laser optical frequency standard based on laser-cooled Ca atoms: sub-kilohertz spectroscopy by optical shelving detection

International Nuclear Information System (INIS)

Oates, C.W.; Bondu, F.; Fox, R.W.; Hollberg, L.

1999-01-01

We report an optical frequency standard at 657 nm based on laser-cooled/trapped Ca atoms. The system consists of a novel, compact magneto-optic trap which uses 50 mW of frequency-doubled diode laser light at 423 nm and can trap >10 7 Ca atoms in 20 ms. High resolution spectroscopy on this atomic sample using the narrow 657 nm intercombination line resolves linewidths (FWHM) as narrow as 400 Hz, the natural linewidth of the transition. The spectroscopic signal-to-noise ratio is enhanced by an order of magnitude with the implementation of a ''shelving'' detection scheme on the 423 nm transition. Our present apparatus achieves a fractional frequency instability of 5 x 10 -14 in 1 s with a potential atom shot-noise-limited performance of 10 -16 τ -1/2 and excellent prospects for high accuracy. (orig.)

X-ray streak-camera study of the dynamics of laser-imploded microballoons

International Nuclear Information System (INIS)

Key, M.H.; Lamb, M.J.; Lewis, C.L.S.; Moore, A.; Evans, R.G.

1979-01-01

The time and space development of the x-ray emission from the irradiated target surface and the implosion core in laser-compressed glass microballoons is recorded by x-ray streak photography. The experimental variation of implosion time with target mass and laser energy is considered and compared with computer modeling of the implosion

Synthesis and Study of Optical Properties of Graphene/TiO2 Composites Using UV-VIS Spectroscopy

Science.gov (United States)

Rathod, P. B.; Waghuley, S. A.

2016-09-01

Graphene and TiO2 were synthesized using electrochemical exfoliation and co-precipitation methods, respectively. An ex situ approach was adopted for the graphene/TiO2 composites. The conformation of graphene in the TiO2 samples was examined through X-ray diffraction. Optical properties of the as-synthesised composites such as optical absorption, extinction coefficient, refractive index, real dielectric constant, imaginary dielectric constant, dissipation factor, and optical conductivity were measured using UV-Vis spectroscopy. The varying concentration of graphene in TiO2 affects the optical properties which appear different for 10 wt.% as compared to 5 wt.% graphene/ TiO2 composite. The composites exhibit an absorption peak at 300 nm with a decrease in band gap for 10 wt.% as compared to 5 wt.% graphene/TiO2 composite. The maximum optical conductivity for the graphene/TiO2 composite of 10 wt.% was found to be 1.86·10-2 Ω-1·m-1 at 300 nm.

Rapid and sensitive trace gas detection with continuous wave Optical Parametric Oscillator-based Wavelength Modulation Spectroscopy

NARCIS (Netherlands)

Arslanov, D.D.; Spunei, M.; Ngai, A.K.Y.; Cristescu, S.M.; Lindsay, I.D.; Lindsay, I.D.; Boller, Klaus J.; Persijn, S.T.; Harren, F.J.M.

2011-01-01

A fiber-amplified Distributed Bragg Reflector diode laser is used to pump a continuous wave, singly resonant Optical Parametric Oscillator (OPO). The output radiation covers the 3–4 μm with ability of rapid (100 THz/s) and broad mode-hop-free tuning (5 cm−1). Wavelength Modulation Spectroscopy is

Spectroscopy of optically selected BL Lac objects and their γ-ray emission

Energy Technology Data Exchange (ETDEWEB)

Sandrinelli, A.; Treves, A.; Farina, E. P.; Landoni, M. [Università degli Studi dell' Insubria, Via Valleggio 11, I-22100 Como (Italy); Falomo, R. [INAF-Osservatorio Astronomico di Padova, Vicolo dell Osservatorio 5, I-35122 Padova (Italy); Foschini, L.; Sbarufatti, B., E-mail: angela.sandrinelli@brera.inaf.it [INAF-Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, I-23807 Merate (Italy)

2013-12-01

We present Very Large Telescope optical spectroscopy of nine BL Lac objects of unknown redshift belonging to the list of optically selected radio-loud BL Lac candidates. We explore their spectroscopic properties and possible link with gamma-ray emission. From the new observations we determine the redshifts of four objects from faint emission lines or from absorption features of their host galaxies. In three cases we find narrow intervening absorptions from which a lower limit to the redshift is inferred. For the remaining two featureless sources, lower limits to the redshift are deduced from the absence of spectral lines. A search for γ counterpart emission shows that six out of the nine candidates are Fermi γ-ray emitters and we find two new detections. Our analysis suggests that most of the BL Lac objects still lacking redshift information are most likely located at high redshifts.

Challenges and opportunities in clinical translation of biomedical optical spectroscopy and imaging

Science.gov (United States)

Wilson, Brian C.; Jermyn, Michael; Leblond, Frederic

2018-03-01

Medical devices face many hurdles before they enter routine clinical practice to address unmet clinical needs. This is also the case for biomedical optical spectroscopy and imaging systems that are used here to illustrate the opportunities and challenges involved. Following initial concept, stages in clinical translation include instrument development, preclinical testing, clinical prototyping, clinical trials, prototype-to-product conversion, regulatory approval, commercialization, and finally clinical adoption and dissemination, all in the face of potentially competing technologies. Optical technologies face additional challenges from their being extremely diverse, often targeting entirely different diseases and having orders-of-magnitude differences in resolution and tissue penetration. However, these technologies can potentially address a wide variety of unmet clinical needs since they provide rich intrinsic biochemical and structural information, have high sensitivity and specificity for disease detection and localization, and are practical, safe (minimally invasive, nonionizing), and relatively affordable.

Characterization of tunable light source by optical parametric oscillator for high resolution spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Wu, J. W. [Ewha Womens Univ., Seoul (Korea); Rhee, B. G. [Sejong Univ., Seoul (Korea); Park, S. W. [Yonsei Univ., Seoul (Korea); Noh, J. W. [Inha Univ., Incheon (Korea)

1998-04-01

A tunable light source is developed by the optical parametric oscillator, which is very useful for a high resolution spectroscopy. The electronic structure of molecules and atoms can be examined by a proper coherent light source. Optical parametric oscillator provides light sources stable and widely tunable. In this work, the characteristics of the parametric optical generation are examined in the LiNbO{sub 3}. The theoretical analysis as well as the experimental measurement is performed. The pump laser is a second harmonic of Nd:YAG laser, and the parametric gain is measured. The characteristics of singly resonant oscillator and doubly resonant oscillator is studied as a function of temperature. It is found that 1mole% MgO:LiNbO{sub 3} crystal provides the tunability from 0.6{mu}m to 3.0{mu}m wavelength. Both the critical and noncritical phase matching are studied. The optical damage occurring in a congruent LiNbO{sub 3} crystal was not observed in 1mole% MgO:LiNbO{sub 3} crystal, opening a possibility for a high power optical parametric oscillation generation. The current work can be extended to an experiment employing the fundamental Nd:YAG as pump to provide a coherent light source for the study of molecular vibrations. 28 refs., 14 figs., 3 tabs. (Author)

Effect of patterns and inhomogeneities on the surface of waveguides used for optical waveguide lightmode spectroscopy applications

DEFF Research Database (Denmark)

Horvath, R.; Voros, J.; Graf, R.

2001-01-01

It has been found that patterns acid inhomogeneities on the surface of the waveguide used fur optical waveguide lightmode spectroscopy applications can produce broadening and fine structure in the incoupled light peak spectra. During cell spreading on the waveguide, a broadening of the incoupling...

Nuclear import of Maize fine streak virus proteins in Drosophila S2 cells

Science.gov (United States)

Maize fine streak virus (MFSV) is a member of the genus Nucleorhabdovirus, family Rhabdoviridae and is transmitted by the leafhopper Graminella nigrifons. The virus replicates in both its plant host and in its insect vector. Nucleorhabdoviruses replicate in the nucleus and assemble at the inner nu...

Investigation of optical pump on dielectric tunability in PZT/PT thin film by THz spectroscopy.

Science.gov (United States)

Ji, Jie; Luo, Chunya; Rao, Yunkun; Ling, Furi; Yao, Jianquan

2016-07-11

The dielectric spectra of single-layer PbTiO3 (PT), single-layer PbZrxTi1-xO3 (PZT) and multilayer PZT/PT thin films under an external optical field were investigated at room temperature by time-domain terahertz (THz) spectroscopy. Results showed that the real part of permittivity increased upon application of an external optical field, which could be interpreted as hardening of the soft mode and increasing of the damping coefficient and oscillator strength. Furthermore, the central mode was observed in the three films. Among the dielectric property of the three thin films studied, the tunability of the PZT/PT superlattice was the largest.

Application of optical emission spectroscopy to high current proton sources

International Nuclear Information System (INIS)

Castro, G; Mazzaglia, M; Nicolosi, D; Mascali, D; Reitano, R; Celona, L; Leonardi, O; Leone, F; Naselli, E; Neri, L; Torrisi, G; Gammino, S; Zaniol, B

2017-01-01

Optical Emission Spectroscopy (OES) represents a very reliable technique to carry out non-invasive measurements of plasma density and plasma temperature in the range of tens of eV. With respect to other diagnostics, it also can characterize the different populations of neutrals and ionized particles constituting the plasma. At INFN-LNS, OES techniques have been developed and applied to characterize the plasma generated by the Flexible Plasma Trap, an ion source used as 'testbench' of the proton source built for European Spallation Source. This work presents the characterization of the parameters of a hydrogen plasma in different conditions of neutral pressure, microwave power and magnetic field profile, along with perspectives for further upgrades of the OES diagnostics system. (paper)

A method for measurements of neutral fragments kinetic energies released to a specific dissociation threshold: optical translational spectroscopy

International Nuclear Information System (INIS)

Roney, A.; Frigon, C.; Larzilliere, M.

1999-01-01

The optical translational spectroscopy technique, based on the principles of fast ion beam laser spectroscopy (FIBLAS) and translational spectroscopy, allows the kinetic energies study of neutral fragments released through free dissociation of a neutral molecule. This method presents interesting features such as near-threshold energy measurements and selection of a specific dissociation limit. The fragments resulting from free dissociation (not induced) of neutral molecules, produced by charge exchange processes with a fast ion beam, are probed by laser radiation. Monitoring of the laser-induced fluorescence allows high-resolution spectra due to the kinematic compression of the velocity spread. Measurements of kinetic energies released to the second limit of dissociation H(1s) + H(2l) of H 2 are put forth and compared with those obtained by means of off-axis translational spectroscopy

Acousto-Optic Q-Switched Fiber Laser-Based Intra-Cavity Photoacoustic Spectroscopy for Trace Gas Detection.

Science.gov (United States)

Zhang, Qinduan; Chang, Jun; Wang, Qiang; Wang, Zongliang; Wang, Fupeng; Qin, Zengguang

2017-12-25

We proposed a new method for gas detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser by merging a transmission PAS cell (resonant frequency f ₀ = 5.3 kHz) inside the fiber laser cavity. The Q-switching was achieved by an acousto-optic modulator, achieving a peak pulse power of ~679 mW in the case of the acousto-optic modulation signal with an optimized duty ratio of 10%. We used a custom-made fiber Bragg grating with a central wavelength of 1530.37 nm (the absorption peak of C₂H₂) to select the laser wavelength. The system achieved a linear response (R² = 0.9941) in a concentration range from 400 to 7000 ppmv, and the minimum detection limit compared to that of a conventional intensity modulation system was enhanced by 94.2 times.

In vivo proton magnetic resonance spectroscopy (1H-MRS) evaluation of the metabolite concentration of optic radiation in primary open angle glaucoma

Energy Technology Data Exchange (ETDEWEB)

Sidek, Sabrilhakim [University of Malaya, Department of Biomedical Imaging, University Malaya Research Imaging Centre (UMRIC), Kuala Lumpur (Malaysia); Universiti Teknologi MARA, Medical Imaging Unit, Faculty of Medicine, Sg Buloh, Selangor (Malaysia); Ramli, Norlisah; Rahmat, Kartini; Kuo, Tan Li [University of Malaya, Department of Biomedical Imaging, University Malaya Research Imaging Centre (UMRIC), Kuala Lumpur (Malaysia); Ramli, Norlina Mohd; Abdulrahman, Fadzlina [University of Malaya, Department of Ophthalmology, Faculty of Medicine, Kuala Lumpur (Malaysia)

2016-12-15

To compare the metabolite concentration of optic radiation in glaucoma patients with that of healthy subjects using Proton Magnetic Resonance Spectroscopy (1H-MRS). 1H-MRS utilising the Single-Voxel Spectroscopy (SVS) technique was performed using a 3.0Tesla MRI on 45 optic radiations (15 from healthy subjects, 15 from mild glaucoma patients, and 15 from severe glaucoma patients). A standardised Volume of Interest (VOI) of 20 x 20 x 20 mm was placed in the region of optic radiation. Mild and severe glaucoma patients were categorised based on the Hodapp-Parrish-Anderson (HPA) classification. Mean and multiple group comparisons for metabolite concentration and metabolite concentration ratio between glaucoma grades and healthy subjects were obtained using one-way ANOVA. The metabolite concentration and metabolite concentration ratio between the optic radiations of glaucoma patients and healthy subjects did not demonstrate any significant difference (p > 0.05). Our findings show no significant alteration of metabolite concentration associated with neurodegeneration that could be measured by single-voxel 1H-MRS in optic radiation among glaucoma patients. (orig.)

Refractive index gradient diagnostics: analysis of different optical systems and application to COBRA ion diode

Energy Technology Data Exchange (ETDEWEB)

Knyazev, B A; Greenly, J B; Hammer, D A; Krastelev, E G [Cornell Univ., Ithaca, NY (United States). Laboratory of Plasma Studies; Cuneo, M E [Sandia National Laboratories, Albuquerque, NM (United States)

1997-12-31

Different optical system variations for refractive index gradient diagnostics with a laser beam probe have been analyzed. A `three-telescope` optical system which permits simultaneous measurement of both the laser beam centroid deflection by a bi-cell photodiode and the spatial Fourier spectrum of the deflected beam by a streak camera has been implemented on the COBRA ion diode. The dynamics of the anode plasma layer was studied with these techniques. (author). 3 figs., 8 refs.

In-situ optical spectroscopy and electronic properties of pyrrole sub-monolayers on Ga-rich GaAs(001)

International Nuclear Information System (INIS)

Bruhn, Thomas; Ewald, Marcel; Fimland, Bjørn-Ove; Kneissl, Michael; Esser, Norbert; Vogt, Patrick

2011-01-01

We report on the characterization of sub-monolayers of pyrrole adsorbed on Ga-rich GaAs(001) surfaces. The interfaces were characterized by scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS) and reflectance anisotropy spectroscopy (RAS) in a spectral range between 1.5 and 8 eV. The adsorption of pyrrole on Ga-rich GaAs(001) modifies the RAS spectrum of the clean GaAs surface significantly at the surface transitions at 2.2 and 3.5 eV indicating a chemisorption of the molecules. By the help of transients at these surface transitions during the adsorption process, we were able to prepare different molecular coverages from a sub-monolayer up to a complete molecular layer. The different coverages of pyrrole were imaged by STM and electronically characterized by STS. The measurements reveal that the adsorbed molecules electronically insulate the surface and indicate the formation of new interface states around −3.5 and +4.2 eV. The RAS measurements in the UV region show new anisotropies in the spectral range of the optical transitions of the adsorbed pyrrole molecules. Our measurements demonstrate the potential of optical and electronic spectroscopy methods for the characterization of atomically thin molecular layers on semiconductor surfaces allowing a direct access to the properties of single adsorbed molecules.

Plasmonic optical antenna design for performing tip-enhanced Raman spectroscopy and microscopy

International Nuclear Information System (INIS)

Kharintsev, S S; Fishman, A I; Salakhov, M Kh; Hoffmann, G G

2013-01-01

This paper highlights optical plasmonic antennas designed with dc-pulsed low-voltage electrochemical etching of a gold wire for implementing tip-enhanced Raman scattering (TERS) measurements. We demonstrate a versatile electrochemical system that allows one to engineer TERS-active metallic gold tips with diverse shapes and sizes in a highly reproducible fashion. The underlying etching mechanism at a voltage-driven meniscus around a gold wire immersed into an electrolyte is discussed in detail. We show that the developed method is suitable to produce not only the simplest geometries such as cones and spheroids, but more complex designs. Attempts have been made to design plasmonic tapered antennas with quasi-uniformly spaced nano-sized bumps on the mesoscopic zone for the extra surface plasmon-light coupling. The capability of the patterned antenna to enhance and localize optical fields is demonstrated with near-field Raman microscopy and spectroscopy of single-walled carbon nanotubes bundles. (paper)

Atoms, molecules and optical physics 2. Molecules and photons - Spectroscopy and collisions

Energy Technology Data Exchange (ETDEWEB)

Hertel, Ingolf V.; Schulz, Claus-Peter [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie im Forschungsverbund Berlin e.V. (Germany)

2015-09-01

This is the second volume of textbooks on atomic, molecular and optical physics, aiming at a comprehensive presentation of this highly productive branch of modern physics as an indispensable basis for many areas in physics and chemistry as well as in state of the art bio- and material-sciences. It primarily addresses advanced students (including PhD students), but in a number of selected subject areas the reader is lead up to the frontiers of present research. Thus even the active scientist is addressed. This volume 2 introduces lasers and quantum optics, while the main focus is on the structure of molecules and their spectroscopy, as well as on collision physics as the continuum counterpart to bound molecular states. The emphasis is always on the experiment and its interpretation, while the necessary theory is introduced from this perspective in a compact and occasionally somewhat heuristic manner, easy to follow even for beginners.

Study of atmospheric air AC glow discharge using optical emission spectroscopy and near infrared diode laser cavity ringdown spectroscopy

Science.gov (United States)

Srivastava, Nimisha; Wang, Chuji; Dibble, Theodore S.

2008-11-01

AC glow discharges were generated in atmospheric pressure by applying high voltage AC in the range of 3500-15000 V to a pair of stainless steel electrodes separated by an air gap. The discharges were characterized by optical emission spectroscopy (OES) and continuous wave cavity ringdown spectroscopy (cw-CRDS). The electronic (Tex), vibrational (Tv), and rotational (Tr) temperatures were measured. Spectral stimulations of the emission spectra of several vibronic bands of the 2^nd positive system of N2, the 1^st negative system of N2^+, the (0,1,2,3-0) bands of NO (A-X), and the (0-0) band of OH (A-X), which were obtained under various plasma operating conditions, show that Tr, Tv, and Tex are in the ranges of 2000 - 3800, 3500 - 5000, and 6000 - 10500^ K, respectively. Emission spectra show that OH concentration increases while NO concentration decreases with an increase of electrode spacing. The absorption spectra of H2O and OH overtone in the near infrared (NIR) were measured by the cw-CRDS with a telecommunications diode laser at wavelength near 1515 nm.

Study of the interaction of Tb (III) with dextran through fluorescence spectroscopy and optical rotatory dispersion

International Nuclear Information System (INIS)

Vasconcelos, Sandra S.; Rodrigues, J.F.

1984-01-01

A study of the interaction of Tb(III) with dextran in aqueous solution was perform using fluorescence spectroscopy and optical rotatory dispersion. The results indicate the formation of a complex with the displacent of water from the cation coordinated sphere by hydroxyl groups at the second and third carbon atoms of the monomer unit. (Author) [pt

SO2 EMISSION MEASUREMENT BY DOAS (DIFFERENTIAL OPTICAL ABSORPTION SPECTROSCOPY AND COSPEC (CORRELATION SPECTROSCOPY AT MERAPI VOLCANO (INDONESIA

Directory of Open Access Journals (Sweden)

Hanik Humaida

2010-06-01

Full Text Available The SO2 is one of the volcanic gases that can use as indicator of volcano activity. Commonly, SO2 emission is measured by COSPEC (Correlation Spectroscopy. This equipment has several disadvantages; such as heavy, big in size, difficulty in finding spare part, and expensive. DOAS (Differential Optical Absorption Spectroscopy is a new method for SO2 emission measurement that has advantages compares to the COSPEC. Recently, this method has been developed. The SO2 gas emission measurement of Gunung Merapi by DOAS has been carried out at Kaliadem, and also by COSPEC method as comparation. The differences of the measurement result of both methods are not significant. However, the differences of minimum and maximum result of DOAS method are smaller than that of the COSPEC. It has range between 51 ton/day and 87 ton/day for DOAS and 87 ton/day and 201 ton/day for COSPEC. The measurement of SO2 gas emission evaluated with the seismicity data especially the rockfall showed the presence of the positive correlation. It may cause the gas pressure in the subsurface influencing instability of 2006 eruption lava.   Keywords: SO2 gas, Merapi, DOAS, COSPEC

In-vivo optical detection of cancer using chlorin e6 – polyvinylpyrrolidone induced fluorescence imaging and spectroscopy

International Nuclear Information System (INIS)

Chin, William WL; Thong, Patricia SP; Bhuvaneswari, Ramaswamy; Soo, Khee Chee; Heng, Paul WS; Olivo, Malini

2009-01-01

Photosensitizer based fluorescence imaging and spectroscopy is fast becoming a promising approach for cancer detection. The purpose of this study was to examine the use of the photosensitizer chlorin e6 (Ce6) formulated in polyvinylpyrrolidone (PVP) as a potential exogenous fluorophore for fluorescence imaging and spectroscopic detection of human cancer tissue xenografted in preclinical models as well as in a patient. Fluorescence imaging was performed on MGH human bladder tumor xenografted on both the chick chorioallantoic membrane (CAM) and the murine model using a fluorescence endoscopy imaging system. In addition, fiber optic based fluorescence spectroscopy was performed on tumors and various normal organs in the same mice to validate the macroscopic images. In one patient, fluorescence imaging was performed on angiosarcoma lesions and normal skin in conjunction with fluorescence spectroscopy to validate Ce6-PVP induced fluorescence visual assessment of the lesions. Margins of tumor xenografts in the CAM model were clearly outlined under fluorescence imaging. Ce6-PVP-induced fluorescence imaging yielded a specificity of 83% on the CAM model. In mice, fluorescence intensity of Ce6-PVP was higher in bladder tumor compared to adjacent muscle and normal bladder. Clinical results confirmed that fluorescence imaging clearly captured the fluorescence of Ce6-PVP in angiosarcoma lesions and good correlation was found between fluorescence imaging and spectral measurement in the patient. Combination of Ce6-PVP induced fluorescence imaging and spectroscopy could allow for optical detection and discrimination between cancer and the surrounding normal tissues. Ce6-PVP seems to be a promising fluorophore for fluorescence diagnosis of cancer

Multiphoton Absorption Order of CsPbBr3 As Determined by Wavelength-Dependent Nonlinear Optical Spectroscopy.

Science.gov (United States)

Saouma, Felix O; Stoumpos, Constantinos C; Kanatzidis, Mercouri G; Kim, Yong Soo; Jang, Joon I

2017-10-05

CsPbBr 3 is a direct-gap semiconductor where optical absorption takes place across the fundamental bandgap, but this all-inorganic halide perovskite typically exhibits above-bandgap emission when excited over an energy level, lying above the conduction-band minimum. We probe this bandgap anomaly using wavelength-dependent multiphoton absorption spectroscopy and find that the fundamental gap is strictly two-photon forbidden, rendering it three-photon absorption (3PA) active. Instead, two-photon absorption (2PA) commences when the two-photon energy is resonant with the optical gap, associated with the level causing the anomaly. We determine absolute nonlinear optical dispersion over this 3PA-2PA region, which can be explained by two-band models in terms of the optical gap. The polarization dependence of 3PA and 2PA is also measured and explained by the relevant selection rules. CsPbBr 3 is highly luminescent under multiphoton absorption at room temperature with marked polarization and wavelength dependence at the 3PA-2PA crossover and therefore has potential for nonlinear optical applications.

Beam profile measurements on the advanced test accelerator using optical techniques

International Nuclear Information System (INIS)

Chong, Y.P.; Kalibjian, R.; Cornish, J.P.; Kallman, J.S.; Donnelly, D.

1986-01-01

Beam current density profiles of ATA have been measured both spatially and temporally using a number of diagnostics. An extremely important technique involves measuring optical emissions from either a target foil inserted into the beam path or gas atoms and molecules excited by beam electrons. This paper describes the detection of the optical emission. A 2-D gated television camera with a single or dual micro-channel-plate (MCP) detector for high gain provides excellent spatial and temporal resolution. Measurements are routinely made with resolutions of 1 mm and 5 ns respectively. The optical line of sight allows splitting part of the signal to a streak camera or photometer for even higher time resolution

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy.

Science.gov (United States)

Hippler, Michael; Mohr, Christian; Keen, Katherine A; McNaghten, Edward D

2010-07-28

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.

Optical spectroscopy and imaging of the higher energy excitons and bandgap of monolayer MoS2

Science.gov (United States)

Borys, Nicholas; Bao, Wei; Barnard, Edward; Ko, Changhyun; Tongay, Sefaatin; Wu, Junqiao; Yang, Li; Schuck, P. James

Monolayer MoS2 (ML-MoS2) exhibits a rich manifold of excitons that dictate optoelectronic performance and functionality. Disentangling these states, which include the quasi-particle bandgap, is critical for developing 2D optoelectronic devices that operate beyond the optical bandgap. Whereas photoluminescence (PL) spectroscopy only probes the lowest-energy radiative state and absorption spectroscopy fails to discriminate energetically degenerate states, photoluminescence excitation (PLE) spectroscopy selectively probes only the excited states that thermalize to the emissive ground state exciton. Using PLE spectroscopy of ML-MoS2, we identify the Rydberg series of the exciton A and exciton B states as well as signatures of the quasi-particle bandgap and coupling between the indirect C exciton and the lowest-energy A exciton, which have eluded previous PLE studies. The assignment of these states is confirmed with density functional theory. Mapping the PLE spectrum reveals spatial variations of the higher-energy exciton manifold and quasi-particle bandgap which mirror the heterogeneity in the PL but also indicate variations in local exciton thermalization processes and chemical potentials.

Autobalanced Ramsey Spectroscopy

Science.gov (United States)

Sanner, Christian; Huntemann, Nils; Lange, Richard; Tamm, Christian; Peik, Ekkehard

2018-01-01

We devise a perturbation-immune version of Ramsey's method of separated oscillatory fields. Spectroscopy of an atomic clock transition without compromising the clock's accuracy is accomplished by actively balancing the spectroscopic responses from phase-congruent Ramsey probe cycles of unequal durations. Our simple and universal approach eliminates a wide variety of interrogation-induced line shifts often encountered in high precision spectroscopy, among them, in particular, light shifts, phase chirps, and transient Zeeman shifts. We experimentally demonstrate autobalanced Ramsey spectroscopy on the light shift prone Yb+ 171 electric octupole optical clock transition and show that interrogation defects are not turned into clock errors. This opens up frequency accuracy perspectives below the 10-18 level for the Yb+ system and for other types of optical clocks.

Tip-enhanced near-field Raman spectroscopy with a scanning tunneling microscope and side-illumination optics.

Science.gov (United States)

Yi, K J; He, X N; Zhou, Y S; Xiong, W; Lu, Y F

2008-07-01

Conventional Raman spectroscopy (RS) suffers from low spatial resolution and low detection sensitivity due to the optical diffraction limit and small interaction cross sections. It has been reported that a highly localized and significantly enhanced electromagnetic field could be generated in the proximity of a metallic tip illuminated by a laser beam. In this study, a tip-enhanced RS system was developed to both improve the resolution and enhance the detection sensitivity using the tip-enhanced near-field effects. This instrument, by combining RS with a scanning tunneling microscope and side-illumination optics, demonstrated significant enhancement on both optical sensitivity and spatial resolution using either silver (Ag)-coated tungsten (W) tips or gold (Au) tips. The sensitivity improvement was verified by observing the enhancement effects on silicon (Si) substrates. Lateral resolution was verified to be below 100 nm by mapping Ag nanostructures. By deploying the depolarization technique, an apparent enhancement of 175% on Si substrates was achieved. Furthermore, the developed instrument features fast and reliable optical alignment, versatile sample adaptability, and effective suppression of far-field signals.

Multi-distance diffuse optical spectroscopy with a single optode via hypotrochoidal scanning.

Science.gov (United States)

Applegate, Matthew B; Roblyer, Darren

2018-02-15

Frequency-domain diffuse optical spectroscopy (FD-DOS) is an established technique capable of determining optical properties and chromophore concentrations in biological tissue. Most FD-DOS systems use either manually positioned, handheld probes or complex arrays of source and detector fibers to acquire data from many tissue locations, allowing for the generation of 2D or 3D maps of tissue. Here, we present a new method to rapidly acquire a wide range of source-detector (SD) separations by mechanically scanning a single SD pair. The source and detector fibers are mounted on a scan head that traces a hypotrochoidal pattern over the sample that, when coupled with a high-speed FD-DOS system, enables the rapid collection of dozens of SD separations for depth-resolved imaging. We demonstrate that this system has an average error of 4±2.6% in absorption and 2±1.8% in scattering across all SD separations. Additionally, by linearly translating the device, the size and location of an absorbing inhomogeneity can be determined through the generation of B-scan images in a manner conceptually analogous to ultrasound imaging. This work demonstrates the potential of single optode diffuse optical scanning for depth resolved visualization of heterogeneous biological tissues at near real-time rates.

Identification and Removal of High Frequency Temporal Noise in a Nd:YAG Macro-Pulse Laser Assisted with a Diagnostic Streak Camera

International Nuclear Information System (INIS)

Kent Marlett; Ke-Xun Sun

2004-01-01

This paper discusses the use of a reference streak camera (SC) to diagnose laser performance and guide modifications to remove high frequency noise from Bechtel Nevada's long-pulse laser. The upgraded laser exhibits less than 0.1% high frequency noise in cumulative spectra, exceeding National Ignition Facility (NIF) calibration specifications. Inertial Confinement Fusion (ICF) experiments require full characterization of streak cameras over a wide range of sweep speeds (10 ns to 480 ns). This paradigm of metrology poses stringent spectral requirements on the laser source for streak camera calibration. Recently, Bechtel Nevada worked with a laser vendor to develop a high performance, multi-wavelength Nd:YAG laser to meet NIF calibration requirements. For a typical NIF streak camera with a 4096 x 4096 pixel CCD, the flat field calibration at 30 ns requires a smooth laser spectrum over 33 MHz to 68 GHz. Streak cameras are the appropriate instrumentation for measuring laser amplitude noise at these very high frequencies since the upper end spectral content is beyond the frequency response of typical optoelectronic detectors for a single shot pulse. The SC was used to measure a similar laser at its second harmonic wavelength (532 nm), to establish baseline spectra for testing signal analysis algorithms. The SC was then used to measure the new custom calibration laser. In both spatial-temporal measurements and cumulative spectra, 6-8 GHz oscillations were identified. The oscillations were found to be caused by inter-surface reflections between amplifiers. Additional variations in the SC spectral data were found to result from temperature instabilities in the seeding laser. Based on these findings, laser upgrades were made to remove the high frequency noise from the laser output

Acousto-Optic Q-Switched Fiber Laser-Based Intra-Cavity Photoacoustic Spectroscopy for Trace Gas Detection

Directory of Open Access Journals (Sweden)

Qinduan Zhang

2017-12-01

Full Text Available We proposed a new method for gas detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser by merging a transmission PAS cell (resonant frequency f0 = 5.3 kHz inside the fiber laser cavity. The Q-switching was achieved by an acousto-optic modulator, achieving a peak pulse power of ~679 mW in the case of the acousto-optic modulation signal with an optimized duty ratio of 10%. We used a custom-made fiber Bragg grating with a central wavelength of 1530.37 nm (the absorption peak of C2H2 to select the laser wavelength. The system achieved a linear response (R2 = 0.9941 in a concentration range from 400 to 7000 ppmv, and the minimum detection limit compared to that of a conventional intensity modulation system was enhanced by 94.2 times.

Blood glucose measurement with multiple quantum cascade lasers using hollow-optical fiber-based ATR spectroscopy

Science.gov (United States)

Yoshioka, K.; Kino, S.; Matsuura, Y.

2018-02-01

For non-invasive blood glucose measurement, a measurement system based on mid-infrared ATR spectroscopy equipped with a combination of a QCL as a light source and a hollow-optical fiber as a beam delivery medium is developed. Firstly the measurement sensitivity of the system is evaluated by using glucose solutions and the result shows a significant correlation between optical absorbance and solution concentration. It is also confirmed that the system has a sensitivity that is enough for blood glucose measurement. Then optical absorption of human lips in the mid-infrared wavelength region is measured using a QCL with a wavenumber of 1080 cm-1 where human tissue exhibits strong absorption of glucose and its metabolites. As a result, the measured absorption follows the change of blood glucose well with a time delay of around 10 minutes and correlation factor between the absorbance and the blood glucose level is 0.42.

Consistency-dependent optical properties of lubricating grease studied by terahertz spectroscopy

International Nuclear Information System (INIS)

Tian Lu; Zhao Kun; Zhou Qing-Li; Shi Yu-Lei; Zhao Dong-Mei; Zhang Cun-Lin; Zhao Song-Qing; Zhao Hui; Bao Ri-Ma; Zhu Shou-Ming; Miao Qing

2011-01-01

The optical properties of four kinds of lubricating greases (urea, lithium, extreme pressure lithium, molybdenum disulfide lithium greases) with different NLGL (National Lubricant Grease Institute of America) numbers were investigated using terahertz time-domain spectroscopy. Greases with different NLGL grades have unique spectral features in the terahertz range. Comparison of the experimental data with predictions based on Lorentz—Lorenz theory exhibited that the refractive indices of each kind of lubricating grease were dependent on the their consistency. In addition, molybdenum disulfide (MoS 2 ) as a libricant additive shows strong absorption from 0.2 to 1.4 THz, leading to higher absorption of MoS 2 -lithium grease than that of lithium grease. (general)

High resolution optical spectroscopy of air-induced electrical instabilities in n-type polymer semiconductors.

Science.gov (United States)

Di Pietro, Riccardo; Sirringhaus, Henning

2012-07-03

We use high-resolution charge-accumulation optical spectroscopy to measure charge accumulation in the channel of an n-type organic field-effect transistor. We monitor the degradation of device performance in air, correlate the onset voltage shift with the reduction of charge accumulated in the polymer semiconductor, and explain the results in view of the redox reaction between the polymer, water and oxygen in the accumulation layer. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diode-Laser Induced Fluorescence Spectroscopy of an Optically Thick Plasma in Combination with Laser Absorption Spectroscopy

Directory of Open Access Journals (Sweden)

S. Nomura

2013-01-01

Full Text Available Distortion of laser-induced fluorescence profiles attributable to optical absorption and saturation broadening was corrected in combination with laser absorption spectroscopy in argon plasma flow. At high probe-laser intensity, saturated absorption profiles were measured to correct probe-laser absorption. At low laser intensity, nonsaturated absorption profiles were measured to correct fluorescence reabsorption. Saturation broadening at the measurement point was corrected using a ratio of saturated to non-saturated broadening. Observed LIF broadening and corresponding translational temperature without correction were, respectively, 2.20±0.05 GHz and 2510±100 K and corrected broadening and temperature were, respectively, 1.96±0.07 GHz and 1990±150 K. Although this correction is applicable only at the center of symmetry, the deduced temperature agreed well with that obtained by LAS with Abel inversion.

Simultaneous fingerprint and high-wavenumber fiber-optic Raman spectroscopy improves in vivo diagnosis of esophageal squamous cell carcinoma at endoscopy

Science.gov (United States)

Wang, Jianfeng; Lin, Kan; Zheng, Wei; Yu Ho, Khek; Teh, Ming; Guan Yeoh, Khay; Huang, Zhiwei

2015-08-01

This work aims to evaluate clinical value of a fiber-optic Raman spectroscopy technique developed for in vivo diagnosis of esophageal squamous cell carcinoma (ESCC) during clinical endoscopy. We have developed a rapid fiber-optic Raman endoscopic system capable of simultaneously acquiring both fingerprint (FP)(800-1800 cm-1) and high-wavenumber (HW)(2800-3600 cm-1) Raman spectra from esophageal tissue in vivo. A total of 1172 in vivo FP/HW Raman spectra were acquired from 48 esophageal patients undergoing endoscopic examination. The total Raman dataset was split into two parts: 80% for training; while 20% for testing. Partial least squares-discriminant analysis (PLS-DA) and leave-one patient-out, cross validation (LOPCV) were implemented on training dataset to develop diagnostic algorithms for tissue classification. PLS-DA-LOPCV shows that simultaneous FP/HW Raman spectroscopy on training dataset provides a diagnostic sensitivity of 97.0% and specificity of 97.4% for ESCC classification. Further, the diagnostic algorithm applied to the independent testing dataset based on simultaneous FP/HW Raman technique gives a predictive diagnostic sensitivity of 92.7% and specificity of 93.6% for ESCC identification, which is superior to either FP or HW Raman technique alone. This work demonstrates that the simultaneous FP/HW fiber-optic Raman spectroscopy technique improves real-time in vivo diagnosis of esophageal neoplasia at endoscopy.

Structural, optical spectroscopy, optical conductivity, dielectric ...

Indian Academy of Sciences (India)

13

different methods of preparation [36-41]. The electrical insulator materials with low refractive index and low absorption are needed for various optical devices, such as low loss waveguides, resonators, photonic crystals, distributed Bragg reflectors, light-emitting diodes, passive splitters, biosensors, attenuators and filters ...

Mechanism for propagation of the step leader of streak lightning

International Nuclear Information System (INIS)

Golubev, A.I.; Zolotovskil, V.I.; Ivanovskil, A.V.

1992-01-01

A hypothetical scheme for the development of the step leader of streak lightning is discussed. The mathematical problem of modeling the propagation of the leader in this scheme is stated. The main parameters of the leader are estimated: the length and propagation velocity of the step, the average propagation velocity, etc. This is compared with data from observations in nature. The propagation of the leader is simulated numerically. Results of the calculation are presented for two 'flashes' of the step leader. 25 refs., 6 figs

Extending differential optical absorption spectroscopy for limb measurements in the UV

Directory of Open Access Journals (Sweden)

J. Puķīte

2010-05-01

Full Text Available Methods of UV/VIS absorption spectroscopy to determine the constituents in the Earth's atmosphere from measurements of scattered light are often based on the Beer-Lambert law, like e.g. Differential Optical Absorption Spectroscopy (DOAS. While the Beer-Lambert law is strictly valid for a single light path only, the relation between the optical depth and the concentration of any absorber can be approximated as linear also for scattered light observations at a single wavelength if the absorption is weak. If the light path distribution is approximated not to vary with wavelength, also linearity between the optical depth and the product of the cross-section and the concentration of an absorber can be assumed. These assumptions are widely made for DOAS applications for scattered light observations.

For medium and strong absorption of scattered light (e.g. along very long light-paths like in limb geometry the relation between the optical depth and the concentration of an absorber is no longer linear. In addition, for broad wavelength intervals the differences in the travelled light-paths at different wavelengths become important, especially in the UV, where the probability for scattering increases strongly with decreasing wavelength.

However, the DOAS method can be extended to cases with medium to strong absorptions and for broader wavelength intervals by the so called air mass factor modified (or extended DOAS and the weighting function modified DOAS. These approaches take into account the wavelength dependency of the slant column densities (SCDs, but also require a priori knowledge for the air mass factor or the weighting function from radiative transfer modelling.

We describe an approach that considers the fitting results obtained from DOAS, the SCDs, as a function of wavelength and vertical optical depth and expands this function into a Taylor series of both quantities. The Taylor coefficients are then applied as

Coherent Femtosecond Spectroscopy and Nonlinear Optical Imaging on the Nanoscale

Science.gov (United States)

Kravtsov, Vasily

Optical properties of many materials and macroscopic systems are defined by ultrafast dynamics of electronic, vibrational, and spin excitations localized on the nanoscale. Harnessing these excitations for material engineering, optical computing, and control of chemical reactions has been a long-standing goal in science and technology. However, it is challenging due to the lack of spectroscopic techniques that can resolve processes simultaneously on the nanometer spatial and femtosecond temporal scales. This thesis describes the fundamental principles, implementation, and experimental demonstration of a novel type of ultrafast microscopy based on the concept of adiabatic plasmonic nanofocusing. Simultaneous spatio-temporal resolution on a nanometer-femtosecond scale is achieved by using a near-field nonlinear optical response induced by ultrafast surface plasmon polaritons nanofocused on a metal tip. First, we study the surface plasmon response in metallic structures and evaluate its prospects and limitations for ultrafast near-field microscopy. Through plasmon emission-based spectroscopy, we investigate dephasing times and interplay between radiative and non-radiative decay rates of localized plasmons and their modification due to coupling. We identify a new regime of quantum plasmonic coupling, which limits the achievable spatial resolution to several angstroms but at the same time provides a potential channel for generating ultrafast electron currents at optical frequencies. Next, we study propagation of femtosecond wavepackets of surface plasmon polaritons on a metal tip. In time-domain interferometric measurements we detect group delays that correspond to slowing of the plasmon polaritons down to 20% of the speed of light at the tip apex. This provides direct experimental verification of the plasmonic nanofocusing mechanism and suggests enhanced nonlinear optical interactions at the tip apex. We then measure a plasmon-generated third-order nonlinear optical

Optical emission spectroscopy of carbon laser plasma ion source

Science.gov (United States)

Balki, Oguzhan; Rahman, Md. Mahmudur; Elsayed-Ali, Hani E.

2018-04-01

Carbon laser plasma generated by an Nd:YAG laser (wavelength 1064 nm, pulse width 7 ns, fluence 4-52 J cm-2) is studied by optical emission spectroscopy and ion time-of-flight. Up to C4+ ions are detected with the ion flux strongly dependent on the laser fluence. The increase in ion charge with the laser fluence is accompanied by observation of multicharged ion lines in the optical spectra. The time-integrated electron temperature Te is calculated from the Boltzmann plot using the C II lines at 392.0, 426.7, and 588.9 nm. Te is found to increase from ∼0.83 eV for a laser fluence of 22 J cm-2 to ∼0.90 eV for 40 J cm-2. The electron density ne is obtained from the Stark broadened profiles of the C II line at 392 nm and is found to increase from ∼ 2 . 1 × 1017cm-3 for 4 J cm-2 to ∼ 3 . 5 × 1017cm-3 for 40 J cm-2. Applying an external electric field parallel to the expanding plume shows no effect on the line emission intensities. Deconvolution of ion time-of-flight signal with a shifted Maxwell-Boltzmann distribution for each charge state results in an ion temperature Ti ∼4.7 and ∼6.0 eV for 20 and 36 J cm-2, respectively.

OPTICAL SPECTROSCOPY AND NEBULAR OXYGEN ABUNDANCES OF THE SPITZER/SINGS GALAXIES

International Nuclear Information System (INIS)

Moustakas, John; Kennicutt, Robert C. Jr.; Tremonti, Christy A.; Dale, Daniel A.; Smith, John-David T.; Calzetti, Daniela

2010-01-01

We present intermediate-resolution optical spectrophotometry of 65 galaxies obtained in support of the Spitzer Infrared Nearby Galaxies Survey (SINGS). For each galaxy we obtain a nuclear, circumnuclear, and semi-integrated optical spectrum designed to coincide spatially with mid- and far-infrared spectroscopy from the Spitzer Space Telescope. We make the reduced, spectrophotometrically calibrated one-dimensional spectra, as well as measurements of the fluxes and equivalent widths of the strong nebular emission lines, publicly available. We use optical emission-line ratios measured on all three spatial scales to classify the sample into star-forming, active galactic nuclei (AGNs), and galaxies with a mixture of star formation and nuclear activity. We find that the relative fraction of the sample classified as star forming versus AGN is a strong function of the integrated light enclosed by the spectroscopic aperture. We supplement our observations with a large database of nebular emission-line measurements of individual H II regions in the SINGS galaxies culled from the literature. We use these ancillary data to conduct a detailed analysis of the radial abundance gradients and average H II-region abundances of a large fraction of the sample. We combine these results with our new integrated spectra to estimate the central and characteristic (globally averaged) gas-phase oxygen abundances of all 75 SINGS galaxies. We conclude with an in-depth discussion of the absolute uncertainty in the nebular oxygen abundance scale.

State-Resolved Metal Nanoparticle Dynamics Viewed through the Combined Lenses of Ultrafast and Magneto-optical Spectroscopies.

Science.gov (United States)

Zhao, Tian; Herbert, Patrick J; Zheng, Hongjun; Knappenberger, Kenneth L

2018-05-08

Electronic carrier dynamics play pivotal roles in the functional properties of nanomaterials. For colloidal metals, the mechanisms and influences of these dynamics are structure dependent. The coherent carrier dynamics of collective plasmon modes for nanoparticles (approximately 2 nm and larger) determine optical amplification factors that are important to applied spectroscopy techniques. In the nanocluster domain (sub-2 nm), carrier coupling to vibrational modes affects photoluminescence yields. The performance of photocatalytic materials featuring both nanoparticles and nanoclusters also depends on the relaxation dynamics of nonequilibrium charge carriers. The challenges for developing comprehensive descriptions of carrier dynamics spanning both domains are multifold. Plasmon coherences are short-lived, persisting for only tens of femtoseconds. Nanoclusters exhibit discrete carrier dynamics that can persist for microseconds in some cases. On this time scale, many state-dependent processes, including vibrational relaxation, charge transfer, and spin conversion, affect carrier dynamics in ways that are nonscalable but, rather, structure specific. Hence, state-resolved spectroscopy methods are needed for understanding carrier dynamics in the nanocluster domain. Based on these considerations, a detailed understanding of structure-dependent carrier dynamics across length scales requires an appropriate combination of spectroscopic methods. Plasmon mode-specific dynamics can be obtained through ultrafast correlated light and electron microscopy (UCLEM), which pairs interferometric nonlinear optical (INLO) with electron imaging methods. INLO yields nanostructure spectral resonance responses, which capture the system's homogeneous line width and coherence dynamics. State-resolved nanocluster dynamics can be obtained by pairing ultrafast with magnetic-optical spectroscopy methods. In particular, variable-temperature variable-field (VTVH) spectroscopies allow quantification

A Robust In-Situ Warp-Correction Algorithm For VISAR Streak Camera Data at the National Ignition Facility

International Nuclear Information System (INIS)

Labaria, George R.; Warrick, Abbie L.; Celliers, Peter M.; Kalantar, Daniel H.

2015-01-01

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a 192-beam pulsed laser system for high-energy-density physics experiments. Sophisticated diagnostics have been designed around key performance metrics to achieve ignition. The Velocity Interferometer System for Any Reflector (VISAR) is the primary diagnostic for measuring the timing of shocks induced into an ignition capsule. The VISAR system utilizes three streak cameras; these streak cameras are inherently nonlinear and require warp corrections to remove these nonlinear effects. A detailed calibration procedure has been developed with National Security Technologies (NSTec) and applied to the camera correction analysis in production. However, the camera nonlinearities drift over time, affecting the performance of this method. An in-situ fiber array is used to inject a comb of pulses to generate a calibration correction in order to meet the timing accuracy requirements of VISAR. We develop a robust algorithm for the analysis of the comb calibration images to generate the warp correction that is then applied to the data images. Our algorithm utilizes the method of thin-plate splines (TPS) to model the complex nonlinear distortions in the streak camera data. In this paper, we focus on the theory and implementation of the TPS warp-correction algorithm for the use in a production environment.

A Robust In-Situ Warp-Correction Algorithm For VISAR Streak Camera Data at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Labaria, George R. [Univ. of California, Santa Cruz, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Warrick, Abbie L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Celliers, Peter M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kalantar, Daniel H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-01-12

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a 192-beam pulsed laser system for high-energy-density physics experiments. Sophisticated diagnostics have been designed around key performance metrics to achieve ignition. The Velocity Interferometer System for Any Reflector (VISAR) is the primary diagnostic for measuring the timing of shocks induced into an ignition capsule. The VISAR system utilizes three streak cameras; these streak cameras are inherently nonlinear and require warp corrections to remove these nonlinear effects. A detailed calibration procedure has been developed with National Security Technologies (NSTec) and applied to the camera correction analysis in production. However, the camera nonlinearities drift over time, affecting the performance of this method. An in-situ fiber array is used to inject a comb of pulses to generate a calibration correction in order to meet the timing accuracy requirements of VISAR. We develop a robust algorithm for the analysis of the comb calibration images to generate the warp correction that is then applied to the data images. Our algorithm utilizes the method of thin-plate splines (TPS) to model the complex nonlinear distortions in the streak camera data. In this paper, we focus on the theory and implementation of the TPS warp-correction algorithm for the use in a production environment.

Atoms, molecules and optical physics 1. Atoms and spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Hertel, Ingolf V.; Schulz, Claus-Peter

2015-09-01

This is the first volume of textbooks on atomic, molecular and optical physics, aiming at a comprehensive presentation of this highly productive branch of modern physics as an indispensable basis for many areas in physics and chemistry as well as in state of the art bio- and material-sciences. It primarily addresses advanced students (including PhD students), but in a number of selected subject areas the reader is lead up to the frontiers of present research. Thus even the active scientist is addressed. This volume 1 provides the canonical knowledge in atomic physics together with basics of modern spectroscopy. Starting from the fundamentals of quantum physics, the reader is familiarized in well structured chapters step by step with the most important phenomena, models and measuring techniques. The emphasis is always on the experiment and its interpretation, while the necessary theory is introduced from this perspective in a compact and occasionally somewhat heuristic manner, easy to follow even for beginners.

Sub-Doppler spectroscopy

International Nuclear Information System (INIS)

Hansch, T.W.

1983-01-01

This chapter examines Doppler-free saturation spectroscopy, tunable cw sources, and Doppler-free two-photon spectroscopy. Discusses saturation spectroscopy; continuous wave saturation spectroscopy in the ultraviolet; and two-photon spectroscopy of atomic hydrogen 1S-2S. Focuses on Doppler-free laser spectroscopy of gaseous samples. Explains that in saturation spectroscopy, a monochromatic laser beam ''labels'' a group of atoms within a narrow range of axial velocities through excitation or optical pumping, and a Doppler-free spectrum of these selected atoms is observed with a second, counterpropagating beam. Notes that in two-photon spectroscopy it is possible to record Doppler-free spectra without any need for velocity selection by excitation with two counterpropagating laser beams whose first order Doppler shifts cancel

Optical trapping and Feshbach spectroscopy of an ultracold Rb-Cs mixture

International Nuclear Information System (INIS)

Pilch, K.

2009-01-01

We investigate quantum-mechanical interactions between ultracold rubidium and cesium in an optical trap at temperatures of a few micro kelvin. Our results provide, on the one hand, an experimental key to understand the collisional properties and, on the other hand, a tool to control the interspecies interactions. By performing loss measurements we locate several Feshbach resonances, which provide insight into the energy structure of weakly bound RbCs molecules near the dissociation threshold and allow for the production of such heteronuclear Feshbach molecules. In the future we will transfer these loosely-bound molecules into the absolute internal ground state. The availability of ultracold heteronuclear ground state molecules will open the door to investigate phenomena associated with ultracold polar quantum gases. In our new experimental set-up we are able to trap and cool rubidium and cesium atoms in their lowest internal states. First we load both species into a two-color magneto-optical trap, having full control over the single-species atom number. We extend the technique of degenerate Raman-sideband cooling to a two-color version, which is able to simultaneously cool and polarize both rubidium and cesium. Thereafter we load the atoms into a levitated crossed optical dipole trap. Because of the presence of the gradient magnetic field the trap is highly state selective and consequently provides perfect spin-polarization of the sample. Furthermore, a coincidence of the magnetic-moment-to-mass ratios of the two species allows for simultaneous levitation of both, which assures an almost perfect spatial overlap between the species. We perform Feshbach spectroscopy in two dierent spin channels of the mixture within a magnetic field ranging from 20 to 300 Gauss. In the lowest spin combination of the species we locate 23 interspecies Feshbach resonances, while in a higher spin mixture we find 2 resonances. The high number of resonances found within this range of

Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries

Science.gov (United States)

Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

2015-06-01

A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

Nonlinear optics in germanium mid-infrared fiber material: Detuning oscillations in femtosecond mid-infrared spectroscopy

Directory of Open Access Journals (Sweden)

M. Ordu

2017-09-01

Full Text Available Germanium optical fibers hold great promise in extending semiconductor photonics into the fundamentally important mid-infrared region of the electromagnetic spectrum. The demonstration of nonlinear response in fabricated Ge fiber samples is a key step in the development of mid-infrared fiber materials. Here we report the observation of detuning oscillations in a germanium fiber in the mid-infrared region using femtosecond dispersed pump-probe spectroscopy. Detuning oscillations are observed in the frequency-resolved response when mid-infrared pump and probe pulses are overlapped in a fiber segment. The oscillations arise from the nonlinear frequency resolved nonlinear (χ(3 response in the germanium semiconductor. Our work represents the first observation of coherent oscillations in the emerging field of germanium mid-infrared fiber optics.

Intellectual streaking: The value of teachers exposing minds (and hearts).

Science.gov (United States)

Bearman, Margaret; Molloy, Elizabeth

2017-12-01

As teachers we often ask learners to be vulnerable and yet present ourselves as high status, knowledgeable experts, often with pre-prepared scripts. This paper investigates the metaphoric notion of "intellectual streaking" - the nimble exposure of a teacher's thought processes, dilemmas, or failures - as a way of modeling both reflection-in-action and resilience. While there is a tension between credibility and vulnerability, both of which are necessary for trust, we argue that taking a few risks and revealing deficits in knowledge or performance can be illuminating and valuable for all parties.

Commissioning of the advanced light source dual-axis streak camera

International Nuclear Information System (INIS)

Hinkson, J.; Keller, R.; Byrd, J.

1997-05-01

A dual-axis camera, Hamamatsu model C5680, has been installed on the Advanced Light Source photon-diagnostics beam-line to investigate electron-beam parameters. During its commissioning process, the camera has been used to measure single-bunch length vs. current, relative bunch charge in adjacent RF buckets, and bunchphase stability. In this paper the authors describe the visible-light branch of the diagnostics beam-line, the streak-camera installation, and the timing electronics. They will show graphical results of beam measurements taken during a variety of accelerator conditions

Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

Energy Technology Data Exchange (ETDEWEB)

Kamaraju, N., E-mail: nkamaraju@lanl.gov; Taylor, A. J.; Prasankumar, R. P., E-mail: rpprasan@lanl.gov [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Pan, W.; Reno, J. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Ekenberg, U. [Semiconsultants, Brunnsgrnd 12, SE-18773 Täby (Sweden); Gvozdić, D. M. [School of Electrical Engineering, University of Belgrade, Belgrade 11120 (Serbia); Boubanga-Tombet, S. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai (Japan); Upadhya, P. C. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Laboratory for Electro-Optics Systems, Indian Space Research Organization, Bangalore 560058 (India)

2015-01-19

Two-dimensional hole gases (2DHGs) have attracted recent attention for their unique quantum physics and potential applications in areas including spintronics and quantum computing. However, their properties remain relatively unexplored, motivating the use of different techniques to study them. We used terahertz magneto-optical spectroscopy to investigate the cyclotron resonance frequency in a high mobility 2DHG, revealing a nonlinear dependence on the applied magnetic field. This is shown to be due to the complex non-parabolic valence band structure of the 2DHG, as verified by multiband Landau level calculations. We also find that impurity scattering dominates cyclotron resonance decay in the 2DHG, in contrast with the dominance of superradiant damping in two-dimensional electron gases. Our results shed light on the properties of 2DHGs, motivating further studies of these unique 2D nanosystems.

The application of UV LEDs for differential optical absorption spectroscopy

Science.gov (United States)

Geiko, Pavel P.; Smirnov, Sergey S.; Samokhvalov, Ignatii V.

2018-04-01

Modern UV LEDs represent a potentially very advantageous alternative to thermal light sources, in particular xenon arc lamps, which are the most common light sources in trace gas-analyzers. So, the light-emitting diodes are very attractive for use of as light sources for Long Path Differential Optical Absorption Spectroscopy (DOAS) measurements of trace gases in the open atmosphere. Recent developments in fibre-coupling telescope technology and the availability of ultraviolet light emitting diodes have now allowed us to construct a portable, long path DOAS instrument for use at remote locations and specifically for measuring degassing from active volcanic systems. First of all, we are talking about the measurement of sulphur dioxide, carbon disulphide and, oxides of chlorine and bromine. The parallel measurements of sulfur dioxide using a certified gas analyzer, were conducted and showed good correlation.

Diffuse reflectance spectroscopy and optical polarization imaging of in-vivo biological tissue

Science.gov (United States)

Mora-Núñez, A.; Castillejos, Y.; García-Torales, G.; Martínez-Ponce, G.

2013-11-01

A number of optical techniques have been reported in the scientific literature as accomplishable methodologies to diagnose diseases in biological tissue, for instance, diffuse reflectance spectroscopy (DRS) and optical polarization imaging (OPI). The skin is the largest organ in the body and consists of three primary layers, namely, the epidermis (the outermost layer exposed to the world), the dermis, and the hypodermis. The epidermis changes from to site to site, mainly because of difference in hydration. A lower water content increase light scattering and reduce the penetration depth of radiation. In this work, two hairless mice have been selected to evaluate their skin features by using DRS and OPI. Four areas of the specimen body were chosen to realize the comparison: back, abdomen, tail, and head. From DRS, it was possible to distinguish the skin nature because of different blood irrigation at dermis. In the other hand, OPI shows pseudo-depolarizing regions in the measured Mueller images related to a spatially varying propagation of the scattered light. This provides information about the cell size in the irradiated skin.

Cavity-Enhanced Raman Spectroscopy of Natural Gas with Optical Feedback cw-Diode Lasers.

Science.gov (United States)

Hippler, Michael

2015-08-04

We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 mW of 636.2 nm diode laser excitation and 30 s integration time, cavity enhancement achieves noise-equivalent detection limits below 1 mbar at 1 bar total pressure, depending on Raman cross sections. Detection limits can be easily improved using higher power diodes. We further demonstrate a relevant analytical application of CERS, the multicomponent analysis of natural gas samples. Several spectroscopic features have been identified and characterized. CERS with low power diode lasers is suitable for online monitoring of natural gas mixtures with sensitivity and spectroscopic selectivity, including monitoring H2, H2S, N2, CO2, and alkanes.

Physician attitudes toward dissemination of optical spectroscopy devices for cervical cancer control: an industrial-academic collaborative study.

Science.gov (United States)

Shinn, Eileen; Qazi, Usman; Gera, Shalini; Brodovsky, Joan; Simpson, Jessica; Follen, Michele; Basen-Engquist, Karen; Macaulay, Calum

2012-02-01

Optical spectroscopy has been studied for biologic plausibility, technical efficacy, clinical effectiveness, patient satisfaction, and cost-effectiveness. We sought to identify health care provider attitudes or practices that might act as barriers or to the dissemination of this new technology. Through an academic-industrial partnership, we conducted a series of focus groups to examine physician barriers to optical diagnosis. The study was conducted in 2 stages. First, a pilot group of 10 physicians (8 obstetrician gynecologists and 2 family practitioners) was randomly selected from 8 regions of the United States and each physician was interviewed individually. Physicians were presented with the results of a large trial (N = 980) testing the accuracy of a spectroscopy-based device in the detection of cervical neoplasia. They were also shown a prototype of the device and were given a period of time to ask questions and receive answers regarding the device. They were also asked to provide feedback on a questionnaire that was then revised and presented to 3 larger focus groups (n = 13, 15, and 17 for a total N = 45). The larger focus groups were conducted during national scientific meetings with 20 obstetrician gynecologists and 25 primary care physicians (family practitioners and internists). When asked about the dissemination potential of the new cervical screening technology, all study groups tended to rely on established clinical guidelines from their respective professional societies with regard to the screening and diagnosis of cervical cancer. In addition, study participants consistently agreed that real-time spectroscopy would be viewed positively by their patients. Participants were positive about the new technology's potential as an adjunct to colposcopy and agreed that the improved accuracy would result in reduced health care costs (due to decreased biopsies and decreased visits). Although all participants saw the potential of real-time diagnosis, there

Proceedings of the Third Symposium Optical Spectroscopy SOS-84

International Nuclear Information System (INIS)

Fassler, D.; Feller, K.H.; Wilhelmi, B.

1985-01-01

The main topics of the symposium were: 1) new developments and applications of laser spectroscopy including time resolved UV/VIS spectroscopy, time resolved fluorescence spectroscopy, and laser Raman spectroscopy, 2) dynamics and photokinetics of molecular systems, and 3) spectroscopy and photoprocesses in organized biological systems

Retrieving the optical parameters of biological tissues using diffuse reflectance spectroscopy and Fourier series expansions. I. theory and application.

Science.gov (United States)

Muñoz Morales, Aarón A; Vázquez Y Montiel, Sergio

2012-10-01

The determination of optical parameters of biological tissues is essential for the application of optical techniques in the diagnosis and treatment of diseases. Diffuse Reflection Spectroscopy is a widely used technique to analyze the optical characteristics of biological tissues. In this paper we show that by using diffuse reflectance spectra and a new mathematical model we can retrieve the optical parameters by applying an adjustment of the data with nonlinear least squares. In our model we represent the spectra using a Fourier series expansion finding mathematical relations between the polynomial coefficients and the optical parameters. In this first paper we use spectra generated by the Monte Carlo Multilayered Technique to simulate the propagation of photons in turbid media. Using these spectra we determine the behavior of Fourier series coefficients when varying the optical parameters of the medium under study. With this procedure we find mathematical relations between Fourier series coefficients and optical parameters. Finally, the results show that our method can retrieve the optical parameters of biological tissues with accuracy that is adequate for medical applications.

Clinical research device for ovarian cancer detection by optical spectroscopy in the ultraviolet C-visible

Science.gov (United States)

George, Ronie; Chandrasekaran, Archana; Brewer, Molly A.; Hatch, Kenneth D.; Utzinger, Urs

2010-09-01

Early detection of ovarian cancer could greatly increase the likelihood of successful treatment. However, present detection techniques are not very effective, and symptoms are more commonly seen in later stage disease. Amino acids, structural proteins, and enzymatic cofactors have endogenous optical properties influenced by precancerous changes and tumor growth. We present the technical details of an optical spectroscopy system used to quantify these properties. A fiber optic probe excites the surface epithelium (origin of 90% of cases) over 270 to 580 nm and collects fluorescence and reflectance at 300 to 800 nm with four or greater orders of magnitude instrument to background suppression. Up to four sites per ovary are investigated on patients giving consent to oophorectomy and the system's in vivo optical evaluation. Data acquisition is completed within 20 s per site. We illustrate design, selection, and development of the components used in the system. Concerns relating to clinical use, performance, calibration, and quality control are addressed. In the future, spectroscopic data will be compared with histological biopsies from the corresponding tissue sites. If proven effective, this technique can be useful in screening women at high risk of developing ovarian cancer to determine whether oophorectomy is necessary.

Correction of fluorescence for depth-specific optical and vascular properties using reflectance and differential path-length spectroscopy during PDT

Science.gov (United States)

van Zaane, F.; Middelburg, T. A.; de Bruijn, H. S.; van der Ploeg-van den Heuvel, A.; de Haas, E. R. M.; Sterenborg, H. J. C. M.; Neumann, H. A. M.; Robinson, D. J.

2009-06-01

Introduction: The rate of PpIX fluorescence photobleaching is routinely used as a dose metric for ALA-PDT. Diffuse reflection spectroscopy is often used to account for variations in tissue optical properties at the photosensitizer excitation and emission bands. It can be used to quantify changes in vascular parameters, such as blood volume fraction and saturation, and can aid understanding of tissue response to PDT. The volume and(/or) depth over which these signals are acquired are critical. The aim of this study is to use quantitative reflectance spectroscopy (DPS) to correct fluorescence for changes in tissue optical properties and monitor PDT. Materials & Methods: ALA was topically applied to hairless mice skin and the incubated spot was treated with PDT according to fractionated illumination schemes. DPS measurements of vascular parameters and optical properties were performed directly before and after illumination. Both the differential signal, delivery-and-collection-fiber signal and the collection fiber signal, which all probe different measurement volumes, are analyzed. Results & Conclusions: Analysis of DPS measurements shows that at the depth where most fluorescence originates, there is almost no blood present. During PDT vascular parameters at this depth stay constant. In more oxygenated layers of the tissue, the optical properties do change during PDT, suggesting that only a small part of PpIX fluorescence originates from the interesting depths where vascular response occurs. Correcting fluorescence emission spectra for optical changes at specific depths and not for the total of changes in a larger volume, as is usually done now, can improve PpIX photobleaching based treatment monitoring.

Effect of Heat-treatment on Accuracy of Infrared Spectroscopy and Digital and Optical Brix Refractometers for Measuring Immunoglobulin G Concentration in Bovine Colostrum.

Science.gov (United States)

Elsohaby, I; McClure, J T; Dow, N; Keefe, G P

2018-01-01

Heat-treatment of colostrum is a method developed to reduce calf exposure to pathogens. Infrared (IR) spectroscopy and Brix refractometers can be used for measuring colostral IgG concentration and assessing colostrum quality. To determine the impact of heat-treatment on accuracy of IR spectroscopy and Brix refractometers for measuring colostral IgG concentration and assessing colostrum quality before and after heat-treatment. A total of 60 Holstein dairy cows on 8 commercial dairy farms. A cross-sectional study was designed to determine the effect of heat-treatment at 60°C and 63°C each for 30 and 60 minutes duration on colostral IgG concentration measured by the reference radial immunodiffusion (RID) assay, IR spectroscopy, and digital and optical refractometers. Colostrum IgG concentration significantly decreased after heat-treatment at 63°C for 30 or 60 minutes as measured by RID, but the IgG values remained unchanged when measured by IR spectroscopy and refractometers. The lowest correlation coefficient found between IR spectroscopy (r = 0.70) and RID results was in colostrum heat-treated at 63°C for 60 minutes. For digital (r = 0.48) and optical (r = 0.50) refractometers, the lowest correlation coefficient was at 63°C for 30 minutes when compared to RID. The accuracy of the IR spectroscopy, digital and optical Brix refractometers was decreased from 91.7 to 80%, 81.7 to 45%, and 80 to 45%, respectively, when colostrum heat-treated at 63°C for 60 minutes. Radial immunodiffusion, IR spectroscopy, and Brix refractometers exhibit utility for measuring IgG concentration when colostrum heat-treated at 60°C but does not detect decrease IgG concentrations when heat-treated at 63°C. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Observation of Lorentzian lineshapes in the room temperature optical spectra of strongly coupled Jaggregate/metal hybrid nanostructures by linear two-dimensional optical spectroscopy

International Nuclear Information System (INIS)

Wang, Wei; Sommer, Ephraim; De Sio, Antonietta; Gross, Petra; Vogelgesang, Ralf; Lienau, Christoph; Vasa, Parinda

2014-01-01

We analyze the linear optical reflectivity spectra of a prototypical, strongly coupled metal/molecular hybrid nanostructure by means of a new experimental approach, linear two-dimensional optical spectroscopy. White-light, broadband spectral interferometry is used to measure amplitude and spectral phase of the sample reflectivity or transmission with high precision and to reconstruct the time structure of the electric field emitted by the sample upon impulsive excitation. A numerical analysis of this time-domain signal provides a two-dimensional representation of the coherent optical response of the sample as a function of excitation and detection frequency. The approach is used to study a nanostructure formed by depositing a thin J-aggregated dye layer on a gold grating. In this structure, strong coupling between excitons and surface plasmon polaritons results in the formation of hybrid polariton modes. In the strong coupling regime, Lorentzian lineshape profiles of different polariton modes are observed at room temperature. This is taken as an indication that the investigated strongly coupled polariton excitations are predominantly homogeneously broadened at room temperature. This new approach presents a versatile, simple and highly precise addition to nonlinear optical spectroscopic techniques for the analysis of line broadening phenomena. (paper)

Multidimensional high harmonic spectroscopy

International Nuclear Information System (INIS)

Bruner, Barry D; Soifer, Hadas; Shafir, Dror; Dudovich, Nirit; Serbinenko, Valeria; Smirnova, Olga

2015-01-01

High harmonic generation (HHG) has opened up a new frontier in ultrafast science where attosecond time resolution and Angstrom spatial resolution are accessible in a single measurement. However, reconstructing the dynamics under study is limited by the multiple degrees of freedom involved in strong field interactions. In this paper we describe a new class of measurement schemes for resolving attosecond dynamics, integrating perturbative nonlinear optics with strong-field physics. These approaches serve as a basis for multidimensional high harmonic spectroscopy. Specifically, we show that multidimensional high harmonic spectroscopy can measure tunnel ionization dynamics with high precision, and resolves the interference between multiple ionization channels. In addition, we show how multidimensional HHG can function as a type of lock-in amplifier measurement. Similar to multi-dimensional approaches in nonlinear optical spectroscopy that have resolved correlated femtosecond dynamics, multi-dimensional high harmonic spectroscopy reveals the underlying complex dynamics behind attosecond scale phenomena. (paper)

Optical Waveguide Lightmode Spectroscopy (OWLS) as a Sensor for Thin Film and Quantum Dot Corrosion

OpenAIRE

Yu, Hao; Eggleston, Carrick M.; Chen, Jiajun; Wang, Wenyong; Dai, Qilin; Tang, Jinke

2012-01-01

Optical waveguide lightmode spectroscopy (OWLS) is usually applied as a biosensor system to the sorption-desorption of proteins to waveguide surfaces. Here, we show that OWLS can be used to monitor the quality of oxide thin film materials and of coatings of pulsed laser deposition synthesized CdSe quantum dots (QDs) intended for solar energy applications. In addition to changes in data treatment and experimental procedure, oxide- or QD-coated waveguide sensors must be synthesized. We synthesi...

Optical alignment techniques for line-imaging velocity interferometry and line-imaging self-emulsion of targets at the National Ignition Facility (NIF)

International Nuclear Information System (INIS)

Malone, Robert M.; Frogget, Brent C.; Kaufman, Morris I.; Tunnell, Thomas W.; Guyton, Robert L.; Reinbachs, Imants P.; Watts, Phillip W.

2007-01-01

The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The Velocity Interferometer System for Any Reflector (VISAR) measures shock velocities, shock breakout times, and emission of 1- to 5-mm targets at a location remote to the NIF target chamber. Three optical systems using the same vacuum chamber port each have a total track of 69 feet. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accuracy of the optical axis to be checked. Counter-propagating laser beams (orange and red) align these diagnostics to a listing of tolerances. The orange alignment laser is introduced at the entrance to the two-level interferometer table and passes forward through the optical systems to the recording streak cameras. The red alignment laser is introduced in front of the recording streak cameras and passes in the reverse direction through all optical elements, out of the interferometer table, eventually reaching the target chamber center. Red laser wavelength is selected to be at the 50 percent reflection point of a special beamsplitter used to separate emission light from the Doppler-shifted interferometer light. Movable aperture cards, placed before and after lens groups, show the spread of alignments spots created by the orange and red alignment lasers. Optical elements include 1- to 15-inch-diameter mirrors, lenses with up to 10.5-inch diameters, beamsplitters, etalons, dove prisms, filters, and pellicles. Alignment of more than 75 optical elements must be verified before each target shot. Archived images from eight alignment cameras prove proper alignment before each shot

Initial Results of Optical Vortex Laser Absorption Spectroscopy in the HYPER-I Device

Science.gov (United States)

Yoshimura, Shinji; Asai, Shoma; Aramaki, Mitsutoshi; Terasaka, Kenichiro; Ozawa, Naoya; Tanaka, Masayoshi; Morisaki, Tomohiro

2015-11-01

Optical vortex beams have a potential to make a new Doppler measurement, because not only parallel but perpendicular movement of atoms against the beam axis causes the Doppler shift of their resonant absorption frequency. As the first step of a proof-of-principle experiment, we have performed the optical vortex laser absorption spectroscopy for metastable argon neutrals in an ECR plasma produced in the HYPER-I device at the National Institute for Fusion Science, Japan. An external cavity diode laser (TOPTICA, DL100) of which center wavelength was 696.735 nm in vacuum was used for the light source. The Hermite-Gaussian (HG) beam was converted into the Laguerre-Gaussian (LG) beam (optical vortex) by a computer-generated hologram displayed on the spatial light modulator (Hamamatsu, LCOS-SLM X10468-07). In order to make fast neutral flow across the LG beam, a high speed solenoid valve system was installed on the HYPER-I device. Initial results including the comparison of absorption spectra for HG and LG beams will be presented. This study was supported by NINS young scientists collaboration program for cross-disciplinary study, NIFS collaboration research program (NIFS13KOAP026), and JSPS KAKENHI grant number 15K05365.

Wheat streak mosaic virus coat protein is a host-specific long-distance transport determinant in oat

Science.gov (United States)

Viral determinants involved in systemic infection of hosts by monocot-infecting plant viruses are poorly understood. Wheat streak mosaic virus (WSMV, genus Tritimovirus, family Potyviridae) exclusively infects monocotyledonous crops such as wheat, oat, barley, maize, triticale, and rye. Previously, ...

Optical Fiber Spectroscopy

Science.gov (United States)

Buoncristiani, A. M.

1999-01-01

This is the final report of work done on NASA Grant NAG-1-443. The work covers the period from July 1, 1992 to December 1, 1998. During this period several distinct but related research studies and work tasks were undertaken. These different subjects are enumerated below with a description of the work done on each of them. The focus of the research was the development of optical fibers for use as distributed temperature and stress sensors. The initial concept was to utilize the utilize the temperature and stress dependence of emission from rare earth and transition metal ions substitutionally doped into crystalline or glass fibers. During the course of investigating this it became clear that fiber Bragg gratings provided a alternative for making the desired measurements and there was a shift of research focus on to include the photo-refractive properties of germano-silicate glasses used for most gratings and to the possibility of developing fiber laser sources for an integrated optical sensor in the research effort. During the course of this work several students from Christopher Newport University and other universities participated in this effort. Their names are listed below. Their participation was an important part of their education.

Epistatic determinism of durum wheat resistance to the wheat spindle streak mosaic virus.

Science.gov (United States)

Holtz, Yan; Bonnefoy, Michel; Viader, Véronique; Ardisson, Morgane; Rode, Nicolas O; Poux, Gérard; Roumet, Pierre; Marie-Jeanne, Véronique; Ranwez, Vincent; Santoni, Sylvain; Gouache, David; David, Jacques L

2017-07-01

The resistance of durum wheat to the Wheat spindle streak mosaic virus (WSSMV) is controlled by two main QTLs on chromosomes 7A and 7B, with a huge epistatic effect. Wheat spindle streak mosaic virus (WSSMV) is a major disease of durum wheat in Europe and North America. Breeding WSSMV-resistant cultivars is currently the only way to control the virus since no treatment is available. This paper reports studies of the inheritance of WSSMV resistance using two related durum wheat populations obtained by crossing two elite cultivars with a WSSMV-resistant emmer cultivar. In 2012 and 2015, 354 recombinant inbred lines (RIL) were phenotyped using visual notations, ELISA and qPCR and genotyped using locus targeted capture and sequencing. This allowed us to build a consensus genetic map of 8568 markers and identify three chromosomal regions involved in WSSMV resistance. Two major regions (located on chromosomes 7A and 7B) jointly explain, on the basis of epistatic interactions, up to 43% of the phenotypic variation. Flanking sequences of our genetic markers are provided to facilitate future marker-assisted selection of WSSMV-resistant cultivars.

Two-colour dip spectroscopy of jet-cooled molecules

Science.gov (United States)

Ito, Mitsuo

In optical-optical double resonance spectroscopy, the resonance transition from an intermediate state to a final state can be detected by a dip of the signal (fluorescence or ion) associated with the intermediate state. This method probing the signal of the intermediate state may be called `two-colour dip spectroscopy'. Various kinds of two-colour dip spectroscopy such as two-colour fluorescence/ion dip spectroscopy, two-colour ionization dip spectroscopy employing stimulated emission, population labelling spectroscopy and mass-selected ion dip spectroscopy with dissociation were briefly described, paying special attention to their characteristics in excitation, detection and application. They were extensively and successfully applied to jet-cooled large molecules and provided us with new useful information on the energy and dynamics of excited molecules.

Optical feedback in dfb quantum cascade laser for mid-infrared cavity ring-down spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Terabayashi, Ryohei, E-mail: terabayashi.ryouhei@h.mbox.nagoya-u.ac.jp; Sonnenschein, Volker, E-mail: volker@nagoya-u.jp; Tomita, Hideki, E-mail: tomita@nagoya-u.jp; Hayashi, Noriyoshi, E-mail: hayashi.noriyoshi@h.mbox.nagoya-u.ac.jp; Kato, Shusuke, E-mail: katou.shuusuke@f.mbox.nagoya-u.ac.jp; Jin, Lei, E-mail: kin@nuee.nagoya-u.ac.jp; Yamanaka, Masahito, E-mail: yamanaka@nuee.nagoya-u.ac.jp; Nishizawa, Norihiko, E-mail: nishizawa@nuee.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan); Sato, Atsushi, E-mail: atsushi.sato@sekisui.com; Nozawa, Kohei, E-mail: kohei.nozawa@sekisui.com; Hashizume, Kenta, E-mail: kenta.hashizume@sekisui.com; Oh-hara, Toshinari, E-mail: toshinari.ohara@sekisui.com [Sekisui Medical Co., Ltd., Drug Development Solutions Center (Japan); Iguchi, Tetsuo, E-mail: t-iguchi@nucl.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan)

2017-11-15

A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

Precise optical observation of 0.5-GPa shock waves in condensed materials

Science.gov (United States)

Nagayama, Kunihito; Mori, Yasuhito

1999-06-01

Precision optical observation method was developed to study impact-generated high-pressure shock waves in condensed materials. The present method makes it possible to sensitively detect the shock waves of the relatively low shock stress around 0.5 GPa. The principle of the present method is based on the use of total internal reflection by triangular prisms placed on the free surface of a target assembly. When a plane shock wave arrives at the free surface, the light reflected from the prisms extinguishes instantaneously. The reason is that the total internal reflection changes to the reflection depending on micron roughness of the free surface after the shock arrival. The shock arrival at the bottom face of the prisms can be detected here by two kinds of methods, i.e., a photographic method and a gauge method. The photographic method is an inclined prism method of using a high-speed streak camera. The shock velocity and the shock tilt angle can be estimated accurately from an obtained streak photograph. While in the gauge method, an in-material PVDF stress gauge is combined with an optical prism-pin. The PVDF gauge records electrically the stress profile behind the shockwave front, and the Hugoniot data can be precisely measured by combining the prism pin with the PVDF gauge.

Combining optical trapping in a microfluidic channel with simultaneous micro-Raman spectroscopy and motion detection

Science.gov (United States)

Lawton, Penelope F.; Saunter, Christopher D.; Girkin, John M.

2014-03-01

Since their invention by Ashkin optical tweezers have demonstrated their ability and versatility as a non-invasive tool for micromanipulation. One of the most useful additions to the basic optical tweezers system is micro-Raman spectroscopy, which permits highly sensitive analysis of single cells or particles. We report on the development of a dual laser system combining two spatial light modulators to holographically manipulate multiple traps (at 1064nm) whilst undertaking Raman spectroscopy using a 532nm laser. We can thus simultaneously trap multiple particles and record their Raman spectra, without perturbing the trapping system. The dual beam system is built around micro-fluidic channels where crystallisation of calcium carbonate occurs on polymethylmethacrylate (PMMA) beads. The setup is designed to simulate at a microscopic level the reactions that occur on items in a dishwasher, where permanent filming of calcium carbonate on drinking glasses is a problem. Our system allows us to monitor crystal growth on trapped particles in which the Raman spectrum and changes in movement of the bead are recorded. Due to the expected low level of crystallisation on the bead surfaces this allows us to obtain results quickly and with high sensitivity. The long term goal is to study the development of filming on samples in-situ with the microfl.uidic system acting as a model dishwasher.

Optical absorption, {sup 31}P NMR, and photoluminescence spectroscopy study of copper and tin co-doped barium–phosphate glasses

Energy Technology Data Exchange (ETDEWEB)

Jiménez, J.A., E-mail: jose.jimenez@unf.edu; Zhao, C.

2014-10-15

The optical and structural properties of 50P{sub 2}O{sub 5}:50BaO glasses prepared by melting have been investigated for additive concentrations of 10 and 1 mol% of CuO and SnO dopants. Absorption and photoluminescence spectroscopies were employed in the optical characterization, whereas structural properties were assessed by {sup 31}P nuclear magnetic resonance (NMR) spectroscopy. Residual Cu{sup 2+} was detectable by absorption spectroscopy for the highest concentration of CuO and SnO. More prominently, the optical data suggests contributions from both twofold-coordinated Sn centers and Cu{sup +} ions to light absorption and emission in the glasses. The luminescence depends strongly on excitation wavelength for the highest concentration of dopants where a blue–white emission is observed under short-wavelength excitation (e.g., 260 nm) largely due to tin, while an orange luminescence is exhibited for longer excitation wavelengths (e.g., 360 nm) essentially due to Cu{sup +} ions. On the other hand, dissimilar luminescent properties were observed in connection to Cu{sup +} ions for the lowest concentration studied, as the copper ions were preferentially excited in a narrower range at shorter wavelengths near tin centers absorption. The structural analyses revealed the glass matrix to be composed essentially of Q{sup 2} (two bridging oxygens) and Q{sup 1} (one bridging oxygen) phosphate tetrahedra. A slight increase in the Q{sup 1}/Q{sup 2} ratio reflected upon SnO doping alone suggests a major incorporation of tin into the glass network via P–O–Sn bonds, compatible with the 2-coordinated state attributed to the luminescent Sn centers. However, a significant increase in the Q{sup 1}/Q{sup 2} ratio was indicated with the incorporation of copper at the highest concentration, consistent with a key role of the metal ions as network modifiers. Thus, the change in Cu{sup +} optical properties concurs with different distributions of local environments around the

The Optical Absorption Coefficient of Maize Grains Investigated by Photoacoustic Spectroscopy

Science.gov (United States)

Rodríguez-Páez, C. L.; Carballo-Carballo, A.; Rico-Molina, R.; Hernández-Aguilar, C.; Domínguez-Pacheco, A.; Cruz-Orea, A.; Moreno-Martínez, E.

2017-01-01

In the maize and tortilla industry, it is important to characterize the color of maize ( Zea mays L.) grain, as it is one of the attributes that directly affect the quality of the tortillas consumed by the population. For this reason, the availability of alternative techniques for assessing and improving the quality of grain is valued. Photoacoustic spectroscopy has proven to be a useful tool for characterizing maize grain. So, the objective of the present study was to determine the optical absorption coefficient β of the maize grain used to make tortillas from two regions of Mexico: (a) Valles Altos, 2012-2013 production cycle and (b) Guasave, Sinaloa, 2013-2014 production cycle. Traditional reflectance measurements, physical characteristics of the grain and nutrient content were also calculated. The experimental results show different characteristics for maize grains.

Evaluation of banana hybrids for tolerance to black leaf streak (Mycosphaerella fijiensis Morelet) in Puerto Rico

Science.gov (United States)

In Puerto Rico, bananas (including plantains) are important agricultural commodities; their combined production totaled 133,500 tons in 2008. Black leaf streak (BLS) and Sigatoka leaf spot diseases, caused by Mycosphaerella fijiensis and M. musicola, respectively, are responsible for significant los...

Resonant acoustic spectroscopy of soft tissues using embedded magnetomotive nanotransducers and optical coherence tomography

International Nuclear Information System (INIS)

Oldenburg, Amy L; Boppart, Stephen A

2010-01-01

We present a new method for performing dynamic elastography of soft tissue samples. By sensing nanoscale displacements with optical coherence tomography, a chirped, modulated force is applied to acquire the mechanical spectrum of a tissue sample within a few seconds. This modulated force is applied via magnetic nanoparticles, named 'nanotransducers', which are diffused into the tissue, and which contribute negligible inertia to the soft tissue mechanical system. Using this novel system, we observed that excised tissues exhibit mechanical resonance modes which are well described by a linear damped harmonic oscillator. Results are validated by using cylindrical tissue phantoms of agarose in which resonant frequencies (30-400 Hz) are consistent with longitudinal modes and the sample boundary conditions. We furthermore show that the Young's modulus can be computed from their measured resonance frequencies, analogous to resonant ultrasound spectroscopy for stiff material analysis. Using this new technique, named magnetomotive resonant acoustic spectroscopy (MRAS), we monitored the relative stiffening of an excised rat liver during a chemical fixation process.

Optical properties and extinction spectroscopy to characterize the synthesis of amine capped silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Roldan, Maria Virginia [Laboratorio de Materiales Ceramicos, FCEIyA, IFIR, UNR, Rosario (Argentina)], E-mail: vroldan@fceia.unr.edu.ar; Scaffardi, Lucia B. [CIOp - CONICET, CIC, c.c. 124, 1900 La Plata (Argentina) and Area Departamental de Ciencias Basicas, Facultad de Ingenieria, Universidad Nacional de La Plata, La Plata (Argentina); Sanctis, Oscar de [Laboratorio de Materiales Ceramicos, FCEIyA, IFIR, UNR, Rosario (Argentina); Pellegri, Nora [Laboratorio de Materiales Ceramicos, FCEIyA, IFIR, UNR, Rosario (Argentina)], E-mail: pellegri@fceia.unr.edu.ar

2008-12-20

The present work describes a method for preparation of Ag nanoparticles from chemical reduction of AgNO{sub 3} in ethanol with ATS [N-[3-(trimethoxysilyl)propyl] diethylenetriamine] as surface modifier. We study the influence of different parameters such as concentration, time, temperature and reductor agents on the size and shape of the nanoparticles. We present the morphologic and structural characterization of samples by UV-vis extinction spectroscopy, Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Particularly, using optical extinction spectroscopy, the present work shows the analysis of size evolution in the fabrication process of spherical silver nanoparticles. This evolution is studied as a function of the time elapsed between the beginning of the reaction and the extraction of the sample (temporal delayed synthesis), and as a function of the temperature during the chemical reaction. In both the cases, we propose the study of the plasmon width as a useful, simple and inexpensive method for analysis of the mean radius, specially, for values below 6 nm.

Optical properties and extinction spectroscopy to characterize the synthesis of amine capped silver nanoparticles

International Nuclear Information System (INIS)

Roldan, Maria Virginia; Scaffardi, Lucia B.; Sanctis, Oscar de; Pellegri, Nora

2008-01-01

The present work describes a method for preparation of Ag nanoparticles from chemical reduction of AgNO 3 in ethanol with ATS [N-[3-(trimethoxysilyl)propyl] diethylenetriamine] as surface modifier. We study the influence of different parameters such as concentration, time, temperature and reductor agents on the size and shape of the nanoparticles. We present the morphologic and structural characterization of samples by UV-vis extinction spectroscopy, Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Particularly, using optical extinction spectroscopy, the present work shows the analysis of size evolution in the fabrication process of spherical silver nanoparticles. This evolution is studied as a function of the time elapsed between the beginning of the reaction and the extraction of the sample (temporal delayed synthesis), and as a function of the temperature during the chemical reaction. In both the cases, we propose the study of the plasmon width as a useful, simple and inexpensive method for analysis of the mean radius, specially, for values below 6 nm

Optical tool for salinity detection by remote sensing spectroscopy: application on Oran watershed, Algeria

Science.gov (United States)

Abdellatif, Dehni; Mourad, Lounis

2017-07-01

Soil salinity is a complex problem that affects groundwater aquifers and agricultural lands in the semiarid regions. Remote sensing and spectroscopy database systems provide accuracy for salinity autodetection and dynamical delineation. Salinity detection techniques using polychromatic wavebands by field geocomputation and experimental data are time consuming and expensive. This paper presents an automated spectral detection and identification of salt minerals using a monochromatic waveband concept from multispectral bands-Landsat 8 Operational Land Imager (OLI) and Thermal InfraRed Sensor (TIRS) and spectroscopy United States Geological Survey database. For detecting mineral salts related to electrolytes, such as electronical and vibrational transitions, an integrated approach of salinity detection related to the optical monochromatic concept has been addressed. The purpose of this paper is to discriminate waveband intrinsic spectral similarity using the Beer-Lambert and Van 't Hoff laws for spectral curve extraction such as transmittance, reflectance, absorbance, land surface temperature, molar concentration, and osmotic pressure. These parameters are primordial for hydrodynamic salinity modeling and continuity identification using chemical and physical approaches. The established regression fitted models have been addressed for salt spectroscopy validation for suitable calibration and validation. Furthermore, our analytical tool is conducted for better decision interface using spectral salinity detection and identification in the Oran watershed, Algeria.

Colloquium on Atomic, Molecular and Optical Physics of the French Physics Society. Days of Molecular Spectroscopy, Lille, 7-10 July 2008

International Nuclear Information System (INIS)

Balcou, Philippe; Aspect, Alain; Merkt, Frederic; Haroche, Serge; Hendecourt, Louis d'; Dereux, Alain; Bloch, Daniel; Courty, Jean-Michel; Demaison, Jean; Hynes, James T.; Lievin, Jacky; Billy, J.; Josse, V.; Zuo, Z.; Bernard, A.; Hambrecht, B.; Lugan, P.; Clement, D.; Sanchez-Palencia, L.; Bouyer, P.; Aspect, A.; Garreau, Jean-Claude; Chabe, Julien; Szriftgiser, Pascal; Lemarie, Gabriel; Gremaud, Benoit; Delande, Dominique; Simoni, Andrea; Browaeys, Antoine; Kasparian, Jerome; Boutou, Veronique; Guyon, Laurent; Courvoisier, Francois; Roth, Matthias; Roslund, Jon; Rabitz, Herschel; Bonacina, Luigi; Rondi, Ariana; Extermann, Jerome; Wolf, Jean-Pierre; Maitre, Philippe; Zehnacker, Anne; Le Barbu-Debus, Katia; Sidis, Victor; Aguillon, Francois; Sizun, Muriel; Rougeau, Nathalie; Teillet-Billy, Dominique; Bachellerie, Damien; Jeloaica, Leonard; Morisset, Sabine; Picaud, Sylvain; Cacciani, Patrice; Grosliere, Marie-Christine; Joly, Gilles; Joly, Nicolas; Kudlinsky, Alexandre; Martinelli, Gilbert; Buchard, Virginie; Tudorie, Marcela; Khelkhal, Mohamed; Cosleou, Jean; Hennequin, Daniel; Beaugeois, Maxime; Lebrun, Nathalie; Droz, Daniel; El Aydam, Mohamed; Gama, Marie-Jose; Ferri, Sandrine; Schyns, Bernadette; Courty, Jean Michel

2008-07-01

This colloquium of the French Physics Society on atomic, molecular and optical physics (and more particularly on molecular spectroscopy) comprised several mini-colloquia: methane and its applications in planetology, moving mirrors and Casimir, atoms and molecules in interaction with surfaces, electronic properties of small molecules, molecular spectroscopy for atmospheric applications, quantum memories in atomic sets, methods and applications of reaction dynamics, dynamics of super-excited molecular statuses, mass spectrometry, quantum spectroscopy and chemistry, spectroscopy and reactivity of of confined molecules, electronic and molecular dynamics, dipolar quantum gases. It also comprised plenary sessions: atto-second optics, the atomic Hanbury-Brown-Twiss effect with fermions and bosons, atom and molecule slowing down by Zeeman effect and by Stark effect on Rydberg levels, non destructive counting of photons trapped in a cavity, interstellar chemistry, atom-surface van der Waals interaction noticed in the exotic regime of short distances, communication, vulgarisation and education (the multiple lives of a scientific result), the actual precision of molecular parameters, towards the formation of an amine acid precursor in the interstellar medium via proton transfer, prediction of the ionized and excited molecular electronic structure by Quantum Chemistry (from bi-atomic to bio-molecules), direct observation of Anderson location of matter waves in a controlled disordered potential, experimental observation of the Anderson transition of cold atoms, ultra-cold collisions as a key towards the quantum world, Quantum physics with a single atom, Teramobile or plasma filaments to study the atmosphere, optimal control or how to discriminate two almost identical bio-molecules, infrared spectroscopy as a new dimension for mass spectrometry, chiral recognition in gaseous phase, interactions and reactions between H atoms and graphite surfaces, modelling of gas

Design of high-efficiency diffractive optical elements towards ultrafast mid-infrared time-stretched imaging and spectroscopy

Science.gov (United States)

Xie, Hongbo; Ren, Delun; Wang, Chao; Mao, Chensheng; Yang, Lei

2018-02-01

Ultrafast time stretch imaging offers unprecedented imaging speed and enables new discoveries in scientific research and engineering. One challenge in exploiting time stretch imaging in mid-infrared is the lack of high-quality diffractive optical elements (DOEs), which encode the image information into mid-infrared optical spectrum. This work reports the design and optimization of mid-infrared DOE with high diffraction-efficiency, broad bandwidth and large field of view. Using various typical materials with their refractive indices ranging from 1.32 to 4.06 in ? mid-infrared band, diffraction efficiencies of single-layer and double-layer DOEs have been studied in different wavelength bands with different field of views. More importantly, by replacing the air gap of double-layer DOE with carefully selected optical materials, one optimized ? triple-layer DOE, with efficiency higher than 95% in the whole ? mid-infrared window and field of view greater than ?, is designed and analyzed. This new DOE device holds great potential in ultrafast mid-infrared time stretch imaging and spectroscopy.

Plasma control using neural network and optical emission spectroscopy

International Nuclear Information System (INIS)

Kim, Byungwhan; Bae, Jung Ki; Hong, Wan-Shick

2005-01-01

Due to high sensitivity to process parameters, plasma processes should be tightly controlled. For plasma control, a predictive model was constructed using a neural network and optical emission spectroscopy (OES). Principal component analysis (PCA) was used to reduce OES dimensionality. This approach was applied to an oxide plasma etching conducted in a CHF 3 /CF 4 magnetically enhanced reactive ion plasma. The etch process was systematically characterized by means of a statistical experimental design. Three etch outputs (etch rate, profile angle, and etch rate nonuniformity) were modeled using three different approaches, including conventional, OES, and PCA-OES models. For all etch outputs, OES models demonstrated improved predictions over the conventional or PCA-OES models. Compared to conventional models, OES models yielded an improvement of more than 25% in modeling profile angle and etch rate nonuniformtiy. More than 40% improvement over PCA-OES model was achieved in modeling etch rate and profile angle. These results demonstrate that nonreduced in situ data are more beneficial than reduced one in constructing plasma control model

Optical near-fields & nearfield optics

OpenAIRE

Meixner, Alfred J; Leiderer, Paul

2014-01-01

Optical methods provide exceedingly powerful tools in science and technology for measuring, analyzing and manipulating, from optical microscopy and spectroscopy to the characterization of ultrafast processes by femtosecond pulses and the modification of materials by intense laser radiation. However, when it comes to applications in the nanometer-regime, the conventional optical techniques suffer from the resolution limit – formulated by Ernst Abbe one and a half centuries ago – that light can...

Dye lasers in atomic spectroscopy

International Nuclear Information System (INIS)

Lange, W.; Luther, J.; Steudel, A.

1974-01-01

The properties of dye lasers which are relevant to atomic spectroscopy are discussed. Several experiments made possible by tunable dye lasers are discussed. Applications of high spectral density dye lasers are covered in areas such as absorption spectroscopy, fluorescence spectroscopy, photoionization and photodetachment, and two- and multi-photon processes. Applications which take advantage of the narrow bandwidth of tunable dye lasers are discussed, including saturation spectroscopy, fluorescence line narrowing, classic absorption and fluorescence spectroscopy, nonoptical detection of optical resonances, heterodyne spectroscopy, and nonlinear coherent resonant phenomena. (26 figures, 180 references) (U.S.)

Study of the effective inverse photon efficiency using optical emission spectroscopy combined with cavity ring-down spectroscopy approach

Science.gov (United States)

Wu, Xingwei; Li, Cong; Wang, Yong; Wang, Zhiwei; Feng, Chunlei; Ding, Hongbin

2015-09-01

The hydrocarbon impurities formation is inevitable due to wall erosion in a long pulse high performance scenario with carbon-based plasma facing materials in fusion devices. The standard procedure to determine the chemical erosion yield in situ is by means of inverse photon efficiency D/XB. In this work, the conversion factor between CH4 flux and photon flux of CH A → X transition (effective inverse photon efficiency PE-1) was measured directly using a cascaded arc plasma simulator with argon/methane. This study shows that the measured PE-1 is different from the calculated D/XB. We compared the photon flux measured by optical emission spectroscopy (OES) and calculated by electron impact excitation of CH(X) which was diagnosed by cavity ring-down spectroscopy (CRDS). It seems that charge exchange and dissociative recombination processes are the main channels of CH(A) production and removal which lead to the inconsistency of PE -1 and D/XB at lower temperature. Meanwhile, the fraction of excited CH(A) produced by dissociative recombination processes was investigated, and we found it increased with Te in the range from 4% to 13% at Te definition instead of D/XB since the electron impact excitation is not the only channel of CH(A) production. These results have an effect on evaluating the yield of chemical erosion in divertor of fusion device.

Temporal measures and controls in ultrafast laser domain; Mesures et controles temporels dans le domaine des lasers ultrabrefs

Energy Technology Data Exchange (ETDEWEB)

Oksenhendler, Th

2004-12-15

This work presents the development of a streak camera 'jitter free' sweep unit synchronized on a femtosecond laser. This application of high voltage photoconductive switches ('High voltage Auston switch') yields subpicosecond resolution for accumulated images on streak camera on a few hundreds micro joule femtosecond laser. Two others applications of these photoconductive switches are studied: - ultrafast optical commutation by a Pockels cell directly driven by a photoconductive switch (rising edge < 100 ps and jitter < 2 ps), - laser pulse energy self-stabilization experimentally proving that driving a Pockels cell by a photoconductive switch can increase the stability of the laser pulse energy from 7 % to 0.7 % rms. Additionally, the application of the acoustic-optical programmable dispersive filter (Dazzler) to the self referenced spectral phase measurement is presented. As these measurements require a linear filter combined with a non linear filter, it is possible to replace the complete linear part (generally a complex optical set-up) by the Dazzler leading to new kind of linear filters and new measurements. Thus base band autocorrelation and time-domain SPIDER (SPIDER by Fourier transform spectroscopy) have been demonstrated experimentally for the first time. (author)

Diagnostics of helium plasma by collisional-radiative modeling and optical emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Lee, Wonwook; Kwon, Duck-Hee [KAERI, Daejeon (Korea, Republic of)

2015-05-15

Optical diagnostics for the electron temperature (T{sub e}) and the electron density (n{sub e}) of fusion plasma is important for understanding and controlling the edge and the divertor plasmas in tokamak. Since the line intensity ratio method using the collisional-radiative modeling and OES (optical emission spectroscopy) is simple and does not disturb the plasma, many fusion devices with TEXTOR, JET, JT-60U, LHD, and so on, have employed the line intensity ratio method as a basic diagnostic tool for neutral helium (He I). The accuracy of the line intensity ratio method depends on the reliability of the cross sections and rate coefficients. We performed state-of-the-art R-matrix calculations including couplings up to n=7 states and the distorted wave (DW) calculations for the electron-impact excitation (EIE) cross sections of He I using the flexible atomic code (FAC). The collisional-radiative model for He I was constructed using the calculated the cross sections. The helium collisional-radiative model for He I was constructed to diagnose the electron temperature and the electron density of the plasma. The electron temperature and density were determined by using the line intensity ratio method.

Optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy

International Nuclear Information System (INIS)

Saleem, M; Bilal, M; Anwar, S; Rehman, A; Ahmed, M

2013-01-01

We present the optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy. Raman spectra were acquired from 18 blood serum samples using a laser at 532 nm as the excitation source. A multivariate regression model based on partial least-squares regression is developed that uses Raman spectra to predict dengue infection with leave-one-sample-out cross validation. The prediction of dengue infection by our model yields correlation coefficient r 2 values of 0.9998 between the predicted and reference clinical results. The model was tested for six unknown human blood sera and found to be 100% accurate in accordance with the clinical results. (letter)

Evanescent spectroscopy - theory and experiment

OpenAIRE

Karabchevsky, Alina

2014-01-01

Outline1 Introduction2 Literature Overview3 Photonic-Plasmonic WaveguideStructureModellingTheory4 ResultsOptical TransmittanceLoss of Fundamental Mode in a Gold RegionOptical Surface Intensity5 NIR Spectroscopy - Experiment6 Conclusions7 Acknowledgements

Spectral staining of tumor tissue by fiber optic FTIR spectroscopy

Science.gov (United States)

Salzer, Reiner; Steiner, Gerald; Kano, Angelique; Richter, Tom; Bergmann, Ralf; Rodig, Heike; Johannsen, Bernd; Kobelke, Jens

2003-07-01

Infrared (IR) optical fiber have aroused great interest in recent years because of their potential in in-vivo spectroscopy. This potential includes the ability to be flexible, small and to guide IR light in a very large range of wavelengths. Two types - silver halide and chalcogenide - infrared transmitting fibers are investigated in the detection of a malignant tumor. As a test sample for all types of fibers we used a thin section of an entire rat brain with glioblastoma. The fibers were connected with a common infrared microscope. Maps across the whole tissue section with more than 200 spectra were recorded by moving the sample with an XY stage. Data evaluation was performed using fuzzy c-means cluster analysis (FCM). The silver halide fibers provided excellent results. The tumor was clearly discernible from healthy tissue. Chalcogenide fibers are not suitable to distinguish tumor from normal tissue because the fiber has a very low transmittance in the important fingerprint region.

Time-resolved photoluminescence spectroscopy of semiconductors for optical applications beyond the visible spectral range

Energy Technology Data Exchange (ETDEWEB)

Chernikov, Alexey A.

2011-07-01

The work discussed in this thesis is focused on the experimental studies regarding these three steps: (1) investigation of the fundamental effects, (2) characterization of new material systems, and (3) optimization of the semiconductor devices. In all three cases, the experimental technique of choice is photoluminescence (PL) spectroscopy. The thesis is organized as follows. Chapter 2 gives a summary of the PL properties of semiconductors relevant for this work. The first section deals with the intrinsic processes in an ideal direct band gap material, starting with a brief summary of the theoretical background followed by the overview of a typical PL scenario. In the second part of the chapter, the role of the lattice-vibrations, the internal electric fields as well as the influence of the band-structure and the dielectric environment are discussed. Finally, extrinsic PL properties are presented in the third section, focusing on defects and disorder in real materials. In chapter 3, the experimental realization of the spectroscopic studies is discussed. The time-resolved photoluminescence (TRPL) setup is presented, focusing on the applied excitation source, non-linear frequency mixing, and the operation of the streak camera used for the detection. In addition, linear spectroscopy setup for continous-wave (CW) PL and absorption measurements is illustrated. Chapter 4 aims at the study of the interactions between electrons and lattice-vibrations in semiconductor crystals relevant for the proper description of carrier dynamics as well as the heat-transfer processes. The presented discussion covers the experimental studies of many-body effects in phonon-assisted emission of semiconductors due to the carriercarrier Coulomb-interaction. The corresponding theoretical background is discussed in detail in chapter 2. The investigations are focused on the two main questions regarding electron-hole plasma contributions to the phonon-assisted light-matter interaction as well as

Accuracy of optical spectroscopy for the detection of cervical intraepithelial neoplasia without colposcopic tissue information; a step toward automation for low resource settings.

Science.gov (United States)

Yamal, Jose-Miguel; Zewdie, Getie A; Cox, Dennis D; Atkinson, E Neely; Cantor, Scott B; MacAulay, Calum; Davies, Kalatu; Adewole, Isaac; Buys, Timon P H; Follen, Michele

2012-04-01

Optical spectroscopy has been proposed as an accurate and low-cost alternative for detection of cervical intraepithelial neoplasia. We previously published an algorithm using optical spectroscopy as an adjunct to colposcopy and found good accuracy (sensitivity=1.00 [95% confidence interval (CI)=0.92 to 1.00], specificity=0.71 [95% CI=0.62 to 0.79]). Those results used measurements taken by expert colposcopists as well as the colposcopy diagnosis. In this study, we trained and tested an algorithm for the detection of cervical intraepithelial neoplasia (i.e., identifying those patients who had histology reading CIN 2 or worse) that did not include the colposcopic diagnosis. Furthermore, we explored the interaction between spectroscopy and colposcopy, examining the importance of probe placement expertise. The colposcopic diagnosis-independent spectroscopy algorithm had a sensitivity of 0.98 (95% CI=0.89 to 1.00) and a specificity of 0.62 (95% CI=0.52 to 0.71). The difference in the partial area under the ROC curves between spectroscopy with and without the colposcopic diagnosis was statistically significant at the patient level (p=0.05) but not the site level (p=0.13). The results suggest that the device has high accuracy over a wide range of provider accuracy and hence could plausibly be implemented by providers with limited training.

Construction of Double Right-Border Binary Vector Carrying Non-Host Gene Rxol Resistant to Bacterial Leaf Streak of Rice

Institute of Scientific and Technical Information of China (English)

Xu Mei-rong; XIA Zhi-hui; ZHAI Wen-xue; XU Jian-long; ZHOU Yong-li; LI Zhi-kang

2008-01-01

Rxol cloned from maize is a non-host gene resistant to bacterial leaf streak of rice. pCAMBIA1305-1 with Rxol was digested with Sca Ⅰ and NgoM Ⅳ and the double right-border binary vector pMNDRBBin6 was digested with Hpa Ⅰ and Xma Ⅰ.pMNDRBBin6 carrying the gene Rxol was acquired by ligation of blunt-end and cohesive end. The results of PCR, restriction enzyme analysis and sequencing indicated that the Rxol gene had been cloned into pMNDRBBin6. This double right-border binary vector,named as pMNDRBBin6-Rxol, will play a role in breeding marker-free plants resistant to bacterial leaf streak of rice by genetic transformation.

Statistical iterative reconstruction for streak artefact reduction when using multidetector CT to image the dento-alveolar structures.

Science.gov (United States)

Dong, J; Hayakawa, Y; Kober, C

2014-01-01

When metallic prosthetic appliances and dental fillings exist in the oral cavity, the appearance of metal-induced streak artefacts is not avoidable in CT images. The aim of this study was to develop a method for artefact reduction using the statistical reconstruction on multidetector row CT images. Adjacent CT images often depict similar anatomical structures. Therefore, reconstructed images with weak artefacts were attempted using projection data of an artefact-free image in a neighbouring thin slice. Images with moderate and strong artefacts were continuously processed in sequence by successive iterative restoration where the projection data was generated from the adjacent reconstructed slice. First, the basic maximum likelihood-expectation maximization algorithm was applied. Next, the ordered subset-expectation maximization algorithm was examined. Alternatively, a small region of interest setting was designated. Finally, the general purpose graphic processing unit machine was applied in both situations. The algorithms reduced the metal-induced streak artefacts on multidetector row CT images when the sequential processing method was applied. The ordered subset-expectation maximization and small region of interest reduced the processing duration without apparent detriments. A general-purpose graphic processing unit realized the high performance. A statistical reconstruction method was applied for the streak artefact reduction. The alternative algorithms applied were effective. Both software and hardware tools, such as ordered subset-expectation maximization, small region of interest and general-purpose graphic processing unit achieved fast artefact correction.

Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems

International Nuclear Information System (INIS)

Johnston, Mark D.; Oliver, Bryan V.; Droemer, Darryl W.; Frogget, Brent; Crain, Marlon D.; Maron, Yitzhak

2012-01-01

This paper describes a convenient and accurate method to calibrate fast ( 2 /steradian/nm). Error analysis shows this method to be accurate to within +/– 20%, which represents a high level of accuracy for this type of measurement.

Cavity-enhanced spectroscopy and sensing

Energy Technology Data Exchange (ETDEWEB)

Gagliardi, Gianluca [CNR-Istituto Nazionale di Ottica (INO), Pozzuoli (Italy); Loock, Hans-Peter (ed.) [Queen' s Univ., Kingston, ON (Canada). Dept. of Chemistry

2014-07-01

The book reviews the dramatic recent advances in the use of optical resonators for high sensitivity and high resolution molecular spectroscopy as well as for chemical, mechanical and physical sensing. It encompasses a variety of cavities including those made of two or more mirrors, optical fiber loops, fiber gratings and spherical cavities. The book focuses on novel techniques and their applications. Each chapter is written by an expert and/or pioneer in the field. These experts also provide the theoretical background in optics and molecular physics where needed. Examples of recent breakthroughs include the use of frequency combs (Nobel prize 2005) for cavity enhanced sensing and spectroscopy, the use of novel cavity materials and geometries, the development of optical heterodyne detection techniques combined to active frequency-locking schemes. These methods allow the use and interrogation of optical resonators with a variety of coherent light sources for trace gas detection and sensing of strain, temperature and pressure.

Cavity-enhanced spectroscopy and sensing

CERN Document Server

Loock, Hans-Peter

2014-01-01

The book reviews the dramatic recent advances in the use of optical resonators for high sensitivity and high resolution molecular spectroscopy as well as for chemical, mechanical and physical sensing.  It encompasses a variety of cavities including those made of two or more mirrors, optical fiber loops, fiber gratings and spherical cavities. The book focuses on novel techniques and their applications. Each chapter is written by an expert and/or pioneer in the field. These experts also provide the theoretical background in optics and molecular physics where needed. Examples of recent breakthroughs include the use of frequency combs (Nobel prize 2005) for cavity enhanced sensing and spectroscopy, the use of novel cavity materials and geometries, the development of optical heterodyne detection techniques combined to active frequency-locking schemes. These methods allow the use and interrogation of optical resonators with a variety of coherent light sources for trace gas detection and sensing of strain, temperat...

Optical spectroscopy of an atomic nucleus: Progress toward direct observation of the {sup 229}Th isomer transition

Energy Technology Data Exchange (ETDEWEB)

Hehlen, Markus P., E-mail: hehlen@lanl.gov [Los Alamos National Laboratory, Mailstop E549, Los Alamos, NM 87545 (United States); Greco, Richard R. [Los Alamos National Laboratory, Mailstop E549, Los Alamos, NM 87545 (United States); Rellergert, Wade G.; Sullivan, Scott T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); DeMille, David [Department of Physics, Yale University, New Haven, CT 06511 (United States); Jackson, Robert A. [School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Hudson, Eric R. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Torgerson, Justin R. [Los Alamos National Laboratory, Mailstop E549, Los Alamos, NM 87545 (United States)

2013-01-15

The nucleus of the thorium-229 isotope possesses a first excited nuclear state ({sup 229m}Th) at an exceptionally low energy of 7.8{+-}0.5 eV above the nuclear ground state ({sup 229g}Th), as determined by earlier indirect measurements. This is the only nuclear excited state known that is within the range of optical spectroscopy. This paper reports progress toward detecting the {sup 229m}Th state directly by luminescence spectroscopy in the vacuum ultraviolet spectral region. The estimated natural linewidth of the {sup 229g}Th{r_reversible}{sup 229m}Th isomer transition of 2{pi} Multiplication-Sign 0.1 to 2{pi} Multiplication-Sign 10 mHz is expected to broaden to {approx}10 kHz for {sup 229}Th{sup 4+} doped into a suitable crystal. The factors governing the choice of crystal system and the substantial challenges in acquiring a sufficiently large quantity of {sup 229}Th are discussed. We show that the {sup 229g}Th{r_reversible}{sup 229m}Th transition energy can be identified to within 0.1 nm by luminescence excitation and luminescence spectroscopy using the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. This would open the door for subsequent laser-based measurements of the isomer transition and future applications of {sup 229}Th in nuclear clocks. We also show that {sup 233}U-doped materials should produce an intrinsic, continuous, and sufficiently high rate of {sup 229m}Th{yields}{sup 229g}Th luminescence and could be a useful aid in the initial direct search of the isomer transition. - Highlights: Black-Right-Pointing-Pointer Thorium-229 has a long-lived nuclear excited state. Black-Right-Pointing-Pointer It is the only known nuclear isomer within the reach of optical spectroscopy. Black-Right-Pointing-Pointer Thorium-229 doped fluoride crystals may offer sufficiently high luminescence rates. Black-Right-Pointing-Pointer Luminescence excitation spectroscopy in the vacuum ultraviolet spectral region may enable the first direct observation of

Microresonator soliton dual-comb spectroscopy

Science.gov (United States)

Suh, Myoung-Gyun; Yang, Qi-Fan; Yang, Ki Youl; Yi, Xu; Vahala, Kerry J.

2016-11-01

Measurement of optical and vibrational spectra with high resolution provides a way to identify chemical species in cluttered environments and is of general importance in many fields. Dual-comb spectroscopy has emerged as a powerful approach for acquiring nearly instantaneous Raman and optical spectra with unprecedented resolution. Spectra are generated directly in the electrical domain, without the need for bulky mechanical spectrometers. We demonstrate a miniature soliton-based dual-comb system that can potentially transfer the approach to a chip platform. These devices achieve high-coherence pulsed mode locking. They also feature broad, reproducible spectral envelopes, an essential feature for dual-comb spectroscopy. Our work shows the potential for integrated spectroscopy with high signal-to-noise ratios and fast acquisition rates.

Time-resolved spectroscopy of nonequilibrium ionization in laser-produced plasmas

International Nuclear Information System (INIS)

Marjoribanks, R.S.

1988-01-01

The highly transient ionization characteristic of laser-produced plasmas at high energy densities has been investigated experimentally, using x-ray spectroscopy with time resolution of less than 20 ps. Spectroscopic diagnostics of plasma density and temperature were used, including line ratios, line profile broadening and continuum emission, to characterize the plasma conditions without relying immediately on ionization modeling. The experimentally measured plasma parameters were used as independent variables, driving an ionization code, as a test of ionization modeling, divorced from hydrodynamic calculations. Several state-of-the-art streak spectrographs, each recording a fiducial of the laser peak along with the time-resolved spectrum, characterized the laser heating of thin signature layers of different atomic numbers imbedded in plastic targets. A novel design of crystal spectrograph, with a conically curved crystal, was developed. Coupled with a streak camera, it provided high resolution (λ/ΔΛ > 1000) and a collection efficiency roughly 20-50 times that of planar crystal spectrographs, affording improved spectra for quantitative reduction and greater sensitivity for the diagnosis of weak emitters. Experimental results were compared to hydrocode and ionization code simulations, with poor agreement. The conclusions question the appropriateness of describing electron velocity distributions by a temperature parameter during the time of laser illumination and emphasis the importance of characterizing the distribution more generally

A multipurpose TIM-based optical telescope for Omega and the Trident laser facilities

International Nuclear Information System (INIS)

Oertel, J.A.; Murphy, T.J.; Berggren, R.R.

1998-01-01

The authors have recently designed and are building a telescope which acts as an imaging light collector relaying the image to an optical table for experiment dependent analysis and recording. The expected primary use of this instrument is a streaked optical pyrometer for witness plate measurements of Hohlraum drive temperature. The telescope is based on University of Rochester's Ten-Inch Manipulator (TIM) which allows compatibility between Omega, Trident, and the NIF lasers. The optics capture a f/7 cone of light, have a field of view of 6-mm, have a spatial resolution of 5 to 7-microm per line pair at the object plane, and are optimized for operation at 280-nm. The image is at a magnification of 11.7x, which is convenient for many experiments, but can be changed using additional optics that reside outside the TIM

Evaluation of Optical Depths and Self-Absorption of Strontium and Aluminum Emission Lines in Laser-Induced Breakdown Spectroscopy (LIBS).

Science.gov (United States)

Alfarraj, Bader A; Bhatt, Chet R; Yueh, Fang Yu; Singh, Jagdish P

2017-04-01

Laser-induced breakdown spectroscopy (LIBS) is a widely used laser spectroscopic technique in various fields, such as material science, forensic science, biological science, and the chemical and pharmaceutical industries. In most LIBS work, the analysis is performed using radiative transitions from atomic emissions. In this study, the plasma temperature and the product [Formula: see text] (the number density N and the absorption path length [Formula: see text]) were determined to evaluate the optical depths and the self-absorption of Sr and Al lines. A binary mixture of strontium nitrate and aluminum oxide was used as a sample, consisting of variety of different concentrations in powder form. Laser-induced breakdown spectroscopy spectra were collected by varying various parameters, such as laser energy, gate delay time, and gate width time to optimize the LIBS signals. Atomic emission from Sr and Al lines, as observed in the LIBS spectra of different sample compositions, was used to characterize the laser induced plasma and evaluate the optical depths and self-absorption of LIBS.

Characterization of Chromatic Dispersion and Refractive Index of Polymer Optical Fibers

Directory of Open Access Journals (Sweden)

Igor Ayesta

2017-12-01

Full Text Available The chromatic dispersion and the refractive index of poly(methyl methacrylate polymer optical fibers (POFs have been characterized in this work by using a tunable femtosecond laser and a Streak Camera. The characterization technique is based on the measurement of the time delays of light pulses propagating along POFs at different wavelengths. Polymer fibers of three different lengths made by two manufacturers have been employed for that purpose, and discrepancies lower than 3% have been obtained in all cases.

Practical in-situ determination of ortho-para hydrogen ratios via fiber-optic based Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sutherland, Liese-Marie; Knudson, James N.; Mocko, Michal; Renneke, Richard M.

2016-02-21

An experiment was designed and developed to prototype a fiber-optic-based laser system, which measures the ratio of ortho-hydrogen to para-hydrogen in an operating neutron moderator system at the Los Alamos Neutron Science Center (LANSCE) spallation neutron source. Preliminary measurements resulted in an ortho to para ratio of 3.06:1, which is within acceptable agreement with the previously published ratio. The successful demonstration of Raman Spectroscopy for this measurement is expected to lead to a practical method that can be applied for similar in-situ measurements at operating neutron spallation sources.

Molecular confirmation of Maize rayado fino virus as the Brazilian corn streak virus

OpenAIRE

Hammond,Rosemarie Wahnbaeck; Bedendo,Ivan Paulo

2005-01-01

Maize rayado fino virus (MRFV), present in various countries in Latin America, has shown similarities to corn streak virus that occurs in Brazil, regarding pathogenic, serological and histological characteristics. In the current report both virus were molecularly compared to confirm the similarities between them. MRFV was identified by nucleic acid hybridization in samples of maize tissues exhibiting symptoms of "corn stunt" disease, collected from two Brazilian States - São Paulo and Minas G...

Optical Frequency Comb Fourier Transform Spectroscopy with Resolution Exceeding the Limit Set by the Optical Path Difference

Science.gov (United States)

Foltynowicz, Aleksandra; Rutkowski, Lucile; Johanssson, Alexandra C.; Khodabakhsh, Amir; Maslowski, Piotr; Kowzan, Grzegorz; Lee, Kevin; Fermann, Martin

2015-06-01

Fourier transform spectrometers (FTS) based on optical frequency combs (OFC) allow detection of broadband molecular spectra with high signal-to-noise ratios within acquisition times orders of magnitude shorter than traditional FTIRs based on thermal sources. Due to the pulsed nature of OFCs the interferogram consists of a series of bursts rather than a single burst at zero optical path difference (OPD). The comb mode structure can be resolved by acquiring multiple bursts, in both mechanical FTS systems and dual-comb spectroscopy. However, in all existing demonstrations the resolution was ultimately limited either by the maximum available OPD between the interferometer arms or by the total acquisition time enabled by the storage memory. We present a method that provides spectral resolution exceeding the limit set by the maximum OPD using an interferogram containing only a single burst. The method allows measurements of absorption lines narrower than the OPD-limited resolution without any influence of the instrumental lineshape function. We demonstrate this by measuring undistorted CO2 and CO absorption lines with linewidth narrower than the OPD-limited resolution using OFC-based mechanical FTS in the near- and mid-infrared wavelength ranges. The near-infrared system is based on an Er:fiber femtosecond laser locked to a high finesse cavity, while the mid-infrared system is based on a Tm:fiber-laser-pumped optical parametric oscillator coupled to a multi-pass cell. We show that the method allows acquisition of high-resolution molecular spectra with interferometer length orders of magnitude shorter than traditional FTIR. Mandon, J., G. Guelachvili, and N. Picque, Nat. Phot., 2009. 3(2): p. 99-102. Zeitouny, M., et al., Ann. Phys., 2013. 525(6): p. 437-442. Zolot, A.M., et al., Opt. Lett., 2012. 37(4): p. 638-640.

XX International Youth Scientific School “Coherent Optics and Optical Spectroscopy”

International Nuclear Information System (INIS)

2017-01-01

The XX International Youth School on Coherent Optics and Optical Spectroscopy (COOS2016) was held in Kazan, Russia, from October 18 to October 20 on the Nikolai Lobachevsky Scientific Library of Kazan Federal University. The School follows the global tendency to comprehensive studies of matter properties and its interaction with electromagnetic fields. Since 1997 more than 100 famous scientists from USA, Germany, Ukraine, Belarus and Russia had plenary lectures presentations. This is the right place, where over 1000 young scientists had an opportunity to participate in hot discussions of the latest scientific news. Many young people have submitted interesting reports on photonics, quantum electronics, laser physics, quantum optics, traditional optical and laser spectroscopy, non-linear optics, material science and nanotechnology. Here we are publishing the full-size papers prepared from the most interesting lectures and reports selected by the Program Committee of the School. Plenary sessions were offered by the following invited speakers: Ildar Gabitov, University of Arizona, USA. • Error statistics in coherent communication lines Andrei Naumov, Institute for Spectroscopy RAS, Troitsk, Moscow, Russia. • Revisiting the question of the experimental realization of a nonclassical light source on the basis of single organic molecules of dyes Gerd Hermann, University of Giessien, Germany. • Applications of Coherent Spectroscopy Askhat Basharov, National Research Center ‘Kurchatov Institute’, Moscow, Russia. • Low-frequency emission in resonant processes • Evolution of a two-level quantum particle in the noise classical e.-m. field within and beyond the resonant approximation Anastas Bukharaev, Kazan E. K. Zavoisky Physical-Technical Institute, Kazan, Russia. • Straintronics Maxim Gladush, Institute for Spectroscopy RAS, Troitsk, Moscow, Russia. • Fluorescent properties of single quantum emitters and their ensembles in dielectric media Sergey Sazonov

Optical excitation spectroscopy of the Luna 24 sample 24125

International Nuclear Information System (INIS)

Telfer, D.J.; Fielder, G.

1980-01-01

Luminescence optical excitation spectroscopy carried out at room temperature on sample L24125 with light made monochromatic from a 450 W xenon source has shown that Fe 3+ ions are present in the plagioclase component at concentrations such that the ligand field bands of this species are observed. The spectrum closely resembles that of Fe 3+ in plagioclase-rich Apollo samples and in terrestrial calcic plagioclases, including synthetic material activated with this ion. Although the amount of sample was small (5 mg) compared with those for which comparison spectra were obtained (30 mg) and the albedo was lower, resolution of spectral bands was achieved with the aid of a digital signal averager, giving an eight-fold enhancement of signal:noise ratio. It would be very instructive and of great value to compare these results with those obtained for samples from the same core but at several different depths and also with an 'interior' rock (as opposed to breccia) sample suite, for which the Fe 3+ luminescence centres would be relatively well shielded from environmental influences, particularly those implicated in the formation of Fe 0 (metal) and Fe 2+ in the lunar regolith. (author)

Diffuse-light absorption spectroscopy by fiber optics for detecting and quantifying the adulteration of extra virgin olive oil

Science.gov (United States)

Mignani, A. G.; Ciaccheri, L.; Ottevaere, H.; Thienpont, H.; Conte, L.; Marega, M.; Cichelli, A.; Attilio, C.; Cimato, A.

2010-09-01

A fiber optic setup for diffuse-light absorption spectroscopy in the wide 400-1700 nm spectral range is experimented for detecting and quantifying the adulteration of extra virgin olive oil caused by lower-grade olive oils. Absorption measurements provide spectral fingerprints of authentic and adulterated oils. A multivariate processing of spectroscopic data is applied for discriminating the type of adulterant and for predicting its fraction.

Electronic structure of ferromagnetic semiconductor Ga1-xMnxAs probed by sub-gap magneto-optical spectroscopy

OpenAIRE

Acbas, G.; Kim, M. -H.; Cukr, M.; Novak, V.; Scarpulla, M. A.; Dubon, O. D.; Jungwirth, T.; Sinova, Jairo; Cerne, J.

2009-01-01

We employ Faraday and Kerr effect spectroscopy in the infrared range to investigate the electronic structure of Ga1-xMnxAs near the Fermi energy. The band structure of this archetypical dilute-moment ferromagnetic semiconductor has been a matter of controversy, fueled partly by previous measurements of the unpolarized infrared absorption and their phenomenological impurity-band interpretation. The infrared magneto-optical effects we study arise directly from the spin-splitting of the carrier ...

Optical spectroscopy and luminescence quenching of LuI3:Ce3+

International Nuclear Information System (INIS)

Birowosuto, M.D.; Dorenbos, P.; Haas, J.T.M. de; Eijk, C.W.E. van; Kraemer, K.W.; Guedel, H.U.

2006-01-01

Optical spectroscopy of LuI 3 doped with Ce 3+ using ultraviolet and visible light excitation is reported. LuI 3 host excitation and emission and 4f-5d excitation and emission of Ce 3+ are observed. An empirical model based on crystal field splitting was used to estimate the energy of the highest 4f-5d excitation band. The crystal field splitting and centroid shift were compared to those of LuCl 3 :Ce 3+ and LuBr 3 :Ce 3+ . Temperature dependence of X-ray excited luminescence spectra shows thermal quenching, whereas that of the decay curve of Ce 3+ emission excited at the lowest 5d band of Ce 3+ does not indicate the presence of quenching of Ce 3+ emission for temperature below 625K. The quenching in LuI 3 :Ce 3+ therefore occurs before the 5d Ce 3+ emission takes place

Electrical and optical deep level spectroscopy on Os doped p-InP

International Nuclear Information System (INIS)

Parveen, S.; Zafar, N.; Khan, A.; Qureshi, U.S.; Iqbal, M.Z.

1997-01-01

Transition metal (TM) impurities are introduced for obtaining semi insulating (III-V) compound semiconductors used as base material for electronic and optoelectronic devices. TM doping introduces near mid gap levels which are used to compensate shallow level donors and acceptors in (III-V) compound semiconductors. The study of electrical properties of heavier transition metals in InP has been turned to an active field of research owing to their potential to produce thermally stable semi insulating substrate materials. Osmium has been tried for this purpose in our work. InP: Os samples have been grown by low pressure metalorganic chemical vapour deposition (LP-MOCVD). Optical and electrical Deep Level Transient Spectroscopy Techniques have been used to characterise osmium related deep level defects in the p-type samples. Three majority carrier (Hole) emitting levels OsA, OsB, OsC and one minority carrier (electron) emitting level Osl are observed in the DLTS and ODLTS measurements on p-type InP:Os. ON optical injection, only Osl appears and all other majority carrier emitting levels disappear dramatically. Special emphasis is given to the detailed comparison by ODLTS and EDLTS, which yields important information on the relative capture cross-sections of Osmium induced levels in p-InP. (author)

Determination of the size distribution of metallic nanoparticles by optical extinction spectroscopy

International Nuclear Information System (INIS)

Pena, Ovidio; Rodriguez-Fernandez, Luis; Rodriguez-Iglesias, Vladimir; Kellermann, Guinther; Crespo-Sosa, Alejandro; Cheang-Wong, Juan Carlos; Silva-Pereyra, Hector Gabriel; Arenas-Alatorre, Jesus; Oliver, Alicia

2009-01-01

A method is proposed to estimate the size distribution of nearly spherical metallic nanoparticles (NPs) from optical extinction spectroscopy (OES) measurements based on Mie's theory and an optimization algorithm. The described method is compared against two of the most widely used techniques for the task: transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS). The size distribution of Au and Cu NPs, obtained by ion implantation in silica and a subsequent thermal annealing in air, was determined by TEM, grazing-incidence SAXS (GISAXS) geometry, and our method, and the average radius obtained by all the three techniques was almost the same for the two studied metals. Concerning the radius dispersion (RD), OES and GISAXS give very similar results, while TEM considerably underestimates the RD of the distribution

Optical coherence techniques for plasma doppler spectroscopy

International Nuclear Information System (INIS)

Howard, J.; Michael, C.; Glass, F.; Cheetham, A.D.

2000-01-01

A new electro-optically Modulated Optical Solid-State (MOSS) interferometer has been constructed for measurement of the low order spectral moments of line emission from optically thin radiant media. The instrument, which is based on the principle of the Fourier transform spectrometer, has high etendue and is rugged, compact and inexpensive. By employing electro-optical path-length modulation techniques, the spectral information is transferred to the temporal frequency domain and can be obtained using a single photodetector. Specifically, the zeroth moment (brightness) is given by the average signal level, the first moment (shift) by the modulation phase and the second moment (line width) by the modulation amplitude. (author)

Elimination of residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy using an optical fiber delay line.

Science.gov (United States)

Chakraborty, Arup Lal; Ruxton, Keith; Johnstone, Walter; Lengden, Michael; Duffin, Kevin

2009-06-08

A new fiber-optic technique to eliminate residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy is presented. The modulated laser output is split to pass in parallel through the gas measurement cell and an optical fiber delay line, with the modulation frequency / delay chosen to introduce a relative phase shift of pi between them. The two signals are balanced using a variable attenuator and recombined through a fiber coupler. In the absence of gas, the direct laser intensity modulation cancels, thereby eliminating the high background. The presence of gas induces a concentration-dependent imbalance at the coupler's output from which the absolute absorption profile is directly recovered with high accuracy using 1f detection.

Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Lee, Geon Joon, E-mail: gjlee@kw.ac.kr; Sim, Geon Bo; Choi, Eun Ha [Plasma Bioscience Research Center/Department of Electrical and Biological Physics, Kwangwoon University, Seoul 139-701 (Korea, Republic of); Kwon, Young-Wan [KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Jun Young; Jang, Siun; Kim, Seong Hwan, E-mail: piceae@naver.com [Department of Microbiology and Institute of Basic Sciences, Dankook University, Cheonan 330-714 (Korea, Republic of)

2015-01-14

To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

A comparative study of the enhancement of molecular emission in a spatially confined plume through optical emission spectroscopy and probe beam deflection measurements

Energy Technology Data Exchange (ETDEWEB)

Ding, Dayu; Liang, Peipei; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian, E-mail: jsun@fudan.edu.cn

2013-01-01

The spatial confinement effects of shock wave on the expansion of a carbon plume induced by pulsed laser ablation of graphite in air and the enhancement of the plume emission were studied by optical emission spectroscopy and probe beam deflection measurements. A metal disk was set in the way of the ablation-generated shock wave to block and reflect the supersonically propagating shock wave. The reflected shock wave propagated backwards and confined the expanding plume. The optical emission of CN molecules was enhanced in contrast to the case without the block disk and the emission enhancement was dependent on the position of the disk. Based on the results of time-integrated and -resolved optical emission spectroscopy, and the time- and space-resolved probe beam deflection measurements, the processes occurring in the plume were discussed and the mechanisms responsible for the enhancement of molecular emission in the spatially confined plume were investigated. - Highlights: ► Spatial confinement and optical emission enhancement of carbon plume were studied. ► Ablation-generated shockwave propagating in air was reflected by a block disk. ► The effects of reflected shockwave on the emission enhancement were confirmed. ► The reflect shockwave confined the carbon plume and enhanced the plume emission.

A comparative study of the enhancement of molecular emission in a spatially confined plume through optical emission spectroscopy and probe beam deflection measurements

International Nuclear Information System (INIS)

Ding, Dayu; Liang, Peipei; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian

2013-01-01

The spatial confinement effects of shock wave on the expansion of a carbon plume induced by pulsed laser ablation of graphite in air and the enhancement of the plume emission were studied by optical emission spectroscopy and probe beam deflection measurements. A metal disk was set in the way of the ablation-generated shock wave to block and reflect the supersonically propagating shock wave. The reflected shock wave propagated backwards and confined the expanding plume. The optical emission of CN molecules was enhanced in contrast to the case without the block disk and the emission enhancement was dependent on the position of the disk. Based on the results of time-integrated and -resolved optical emission spectroscopy, and the time- and space-resolved probe beam deflection measurements, the processes occurring in the plume were discussed and the mechanisms responsible for the enhancement of molecular emission in the spatially confined plume were investigated. - Highlights: ► Spatial confinement and optical emission enhancement of carbon plume were studied. ► Ablation-generated shockwave propagating in air was reflected by a block disk. ► The effects of reflected shockwave on the emission enhancement were confirmed. ► The reflect shockwave confined the carbon plume and enhanced the plume emission

Optical spectroscopy and high pressure on emeralds: synthetic and natural

Science.gov (United States)

Sánchez-Alejo, M. A.; Hernández-Alcántara, J. M.; Flores Jiménez, C.; Calderón, T.; Murrieta S., H.; Camarillo García, E.

2011-09-01

Emerald, natural and synthetic, are the subject of study by means of optical spectroscopy techniques. Particularly, natural emeralds have been considered as a gemstone in jewelry not being so the synthetic ones. But, in general, the properties of these are very good for applications, for instance as a laser system, due to the impurities control. In this work a comparison between natural and synthetic emeralds is done. Chromium ions are the main responsible of the characteristic fascinating green color of these gemstones, entering in the crystals in octahedral sites. Absorption at room temperature show up two broad bands in the visible region and two narrow bands called the R-lines. That spectrum corresponds to trivalent chromium ions in an octahedral site, as it happens in ruby and alexandrite. On other hand, photoemission arises in the range 640-850 nm. at room temperature . It is shown that the luminescence spectra changes as the temperature is lowered. The effect on the main peak of luminescence when high pressure is applied on small samples of emerald shows as a linear function.

Spectrally selective molecular doped solids: spectroscopy, photophysics and their application to ultrafast optical pulse processing

International Nuclear Information System (INIS)

Galaup, Jean-Pierre

2005-01-01

The persistent spectral hole-burning (PSHB) phenomenon observed in molecular doped polymers cooled down to liquid helium temperatures allows the engraving of spectral structures in the inhomogeneous absorption profile of the material. This phenomenon known since 1974 has became a fruitful field for the study of the intimacy of complex molecular systems in the solid state, revealing high-resolution spectroscopy, photophysics, photochemistry and dynamics of molecular doped amorphous media, organic as well as inorganic. A PSHB molecular doped solid can be programmed in spectral domain and therefore, it can be converted in an optical processor capable to achieve user-defined optical functions. Some aspects of this field are illustrated in the present paper. An application is presented where a naphthalocyanine doped polymer film is used in a demonstrative experiment to prove that temporal aberration free re-compression of ultra-short light pulses is feasible. Perspectives for the coherent control of light fields or photochemical processes are also evoked

Spectroscopy, Understanding the Atom Series.

Science.gov (United States)

Hellman, Hal

This booklet is one of the "Understanding the Atom" Series. The science of spectroscopy is presented by a number of topics dealing with (1) the uses of spectroscopy, (2) its origin and background, (3) the basic optical systems of spectroscopes, spectrometers, and spectrophotometers, (4) the characteristics of wave motion, (5) the…

Wheat streak mosaic virus coat protein is a determinant for vector transmission by the wheat curl mite

Science.gov (United States)

Wheat streak mosaic virus (WSMV; genus Tritimovirus; family Potyviridae), is transmitted by the wheat curl mite (Aceria tosichella Keifer). The requirement of coat protein (CP) for WSMV transmission by the wheat curl mite was examined using a series of viable deletion and point mutations. Mite trans...

Growth and optical spectroscopy of synthetic diamonds

International Nuclear Information System (INIS)

Mudryj, A.V.; Larionova, T.P.; Shakin, I.A.; Gysakov, G.A.; Dubrov, G.A.; Tikhonov, V.V.

2003-01-01

It is studied the growth and optical properties of synthetic diamonds, which may be used for detection of ionizing radiation, optical windows, heat removal, ultraviolet and thermo sensors, optoelectronic devices. Optical properties of diamonds (grown in different technological conditions) were studied in temperature range 78 - 300 K by means of measuring transmission in spectral band 0.2 - 25 μm, photoluminescence and registration of luminescence excitation spectra in spectral band 0.2 - 2 μm

Spectroscopy Division: progress report for January 1989-December 1989

International Nuclear Information System (INIS)

Sharma, A.; Marathe, S.M.

1990-01-01

Research and development activities of the Spectroscopy Division during the calendar year 1989 are reported in the form of individual summaries which are grouped under the headings entitled: (i)analysis by optical emission spectroscopy, inductively coupled plasma atomic emission spectrometry and x-ray fluroescence techniques, (ii)atomic, molecular, solid state and laser-spectroscopy, (iii)optics and thin films, (iv)electronics, (v)fabrication, (vi)publications, and (vii)other academic activities. A divisional staff chart is given at the end. (author). figs., tabs

Microwave-optical double resonance spectroscopy. Progress report, February 1, 1976--January 31, 1977

Energy Technology Data Exchange (ETDEWEB)

Pratt, D.W.

1976-11-01

Zero-field and high-field optical detection of magnetic resonance (ODMR), electron paramagnetic resonance (EPR), and optical spectroscopy experiments have been performed on several systems in order to further basic knowledge of the structure, reactions, and response to radiation of atoms, molecules, and ions in their ground and/or excited electronic states. Particularly noteworthy results for the present contract year include the determination of the complete magnetic and optical properties of the lowest triplet states of 1-chloro, 1-bromo, and 1-iodonaphthalene, the development of a microscopic model for the intramolecular heavy-atom effect in the /sup 3/(..pi..,..pi..*) states of aromatic molecules, a detailed analysis of the angular dependence of the hyperfine and quadrupole structure in triplet 1-bromonaphthalene, observation of proton hyperfine structure in the hf ODMR spectra of short-lived triplet states, a definitive paper on the relative importance of spin delocalization and second-order spin-orbit coupling effects in /sup 3/(n,..pi..*) benzophenone (a phototype photochemical system), a detailed analysis of the level-anticrossing spectra of several triplet state benzophenones which exhibit hyperfine structure in the cross-relaxation region (thus permitting the determination of key magnetic parameters in the complete absence of perturbing microwave or radiofrequency fields), optical detection of ground-state NQR transitions in host crystal molecules, the observation of strong radiofrequency transitions near avoided crossing points in Zeeman energy level diagrams of photoexcited triplet states, the construction of zero-field ODMR, ODENDOR, and hf ODENDOR spectrometers, measurements of the activation parameters for ring interconversions of several free radicals containing five- and six-membered rings, and experimental proof that the triplet state of trimethylenemethane (a key reactive intermediate in organic chemistry) is the ground state.

Signatures of Förster and Dexter transfer processes in coupled nanostructures for linear and two-dimensional coherent optical spectroscopy

Science.gov (United States)

Specht, Judith F.; Richter, Marten

2015-03-01

In this manuscript, we study the impact of the two Coulomb induced resonance energy transfer processes, Förster and Dexter coupling, on the spectral signatures obtained by double quantum coherence spectroscopy. We show that the specific coupling characteristics allow us to identify the underlying excitation transfer mechanism by means of specific signatures in coherent spectroscopy. Therefore, we control the microscopic calculated coupling strength of spin preserving and spin flipping Förster transfer processes by varying the mutual orientation of the two quantum emitters. The calculated spectra reveal the optical selection rules altered by Förster and Dexter coupling between two semiconductor quantum dots. We show that Dexter coupling between bright and dark two-exciton states occurs.

Effects of Hot Streak and Phantom Cooling on Heat Transfer in a Cooled Turbine Stage Including Particulate Deposition

Energy Technology Data Exchange (ETDEWEB)

Bons, Jeffrey [The Ohio State Univ., Columbus, OH (United States); Ameri, Ali [The Ohio State Univ., Columbus, OH (United States)

2016-01-08

The objective of this research effort was to develop a validated computational modeling capability for the characterization of the effects of hot streaks and particulate deposition on the heat load of modern gas turbines. This was accomplished with a multi-faceted approach including analytical, experimental, and computational components. A 1-year no cost extension request was approved for this effort, so the total duration was 4 years. The research effort succeeded in its ultimate objective by leveraging extensive experimental deposition studies complemented by computational modeling. Experiments were conducted with hot streaks, vane cooling, and combinations of hot streaks with vane cooling. These studies contributed to a significant body of corporate knowledge of deposition, in combination with particle rebound and deposition studies funded by other agencies, to provide suitable conditions for the development of a new model. The model includes the following physical phenomena: elastic deformation, plastic deformation, adhesion, and shear removal. It also incorporates material property sensitivity to temperature and tangential-normal velocity rebound cross-dependencies observed in experiments. The model is well-suited for incorporation in CFD simulations of complex gas turbine flows due to its algebraic (explicit) formulation. This report contains model predictions compared to coefficient of restitution data available in the open literature as well as deposition results from two different high temperature turbine deposition facilities. While the model comparisons with experiments are in many cases promising, several key aspects of particle deposition remain elusive. The simple phenomenological nature of the model allows for parametric dependencies to be evaluated in a straightforward manner. This effort also included the first-ever full turbine stage deposition model published in the open literature. The simulations included hot streaks and simulated vane cooling

Optical spectroscopy of two-dimensional layered (C(6)H(5)C(2)H(4)-NH(3))(2)-PbI(4) perovskite.

Science.gov (United States)

Gauthron, K; Lauret, J-S; Doyennette, L; Lanty, G; Al Choueiry, A; Zhang, S J; Brehier, A; Largeau, L; Mauguin, O; Bloch, J; Deleporte, E

2010-03-15

We report on optical spectroscopy (photoluminescence and photoluminescence excitation) on two-dimensional self-organized layers of (C(6)H(5)C(2)H(4)-NH(3))(2)-PbI(4) perovskite. Temperature and excitation power dependance of the optical spectra gives a new insight into the excitonic and the phononic properties of this hybrid organic/inorganic semiconductor. In particular, exciton-phonon interaction is found to be more than one order of magnitude higher than in GaAs QWs. As a result, photoluminescence emission lines have to be interpreted in the framework of a polaron model.

Genomic and phylogenetic evidence that Maize rough dwarf and Rice black-streaked dwarf fijiviruses should be classified as different geographic strains of a single species.

Science.gov (United States)

Xie, L; Lv, M-F; Yang, J; Chen, J-P; Zhang, H-M

Maize rough dwarf disease (MRDD) has long been known as one of the most devastating viral diseases of maize worldwide and is caused by single or complex infection by four fijiviruses: Maize rough dwarf virus (MRDV) in Europe and the Middle East, Mal de Rio Cuarto virus (MRCV) in South America, rice black-streaked dwarf virus (RBSDV), and Southern rice black-streaked dwarf virus (SRBSDV or Rice black-streaked dwarf virus 2, RBSDV-2) in East Asia. These are currently classified as four distinct species in the genus Fijivirus, family Reoviridae, but their taxonomic status has been questioned. To help resolve this, the nucleotide sequences of the ten genomic segments of an Italian isolate of MRDV have been determined, providing the first complete genomic sequence of this virus. Its genome has 29144 nucleotides and is similar in organization to those of RBSDV, SRBSDV, and MRCV. The 13 ORFs always share highest identities (81.3-97.2%) with the corresponding ORFs of RBSDV and phylogenetic analyses of the different genome segments and ORFs all confirm that MRDV clusters most closely with RBSDV and that MRCV and SRBSDV are slightly more distantly related. The results suggest that MRDV and RBSDV should be classified as different geographic strains of the same virus species and we suggest the name cereal black-streaked dwarf fijivirus (CBSDV) for consideration.

Investigating Low-Cost Optical Spectroscopy for Sensing Pressure Ulcers

Science.gov (United States)

Mirchandani, Smruti Suresh

Diffuse Reflectance Spectroscopy has been used widely to characterize tissue properties for diagnostic and therapeutic applications. This thesis focuses on the use of spectroscopy for early pressure ulcer detection. The most common early diagnosis technique for pressure ulcers is a blanch test. A major issue with a blanch test is that it is purely visual and cannot be visibly observed on dark skinned individuals. Studies have already proven that spectroscopy can be used to detect blanch response in skin across light and dark skinned individuals. The portable reflectance spectroscopy setup showed that pressure changes to the skin can be detected spectroscopically. Some work on an iPhone based spectrometer was also done to have a low-cost spectroscopy alternative to the usual DRS equipment. This study failed to develop an iPhone based spectrometer but various factors that can be changed to better this research have been mentioned in this thesis.

Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

International Nuclear Information System (INIS)

Ribic, B.; DebRoy, T.; Burgardt, P.

2011-01-01

During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

Interference-free optical detection for Raman spectroscopy

Science.gov (United States)

Fischer, David G (Inventor); Kojima, Jun (Inventor); Nguyen, Quang-Viet (Inventor)

2012-01-01

An architecture for spontaneous Raman scattering (SRS) that utilizes a frame-transfer charge-coupled device (CCD) sensor operating in a subframe burst gating mode to realize time-resolved combustion diagnostics is disclosed. The technique permits all-electronic optical gating with microsecond shutter speeds (<5 .mu.s), without compromising optical throughput or image fidelity. When used in conjunction with a pair of orthogonally-polarized excitation lasers, the technique measures time-resolved vibrational Raman scattering that is minimally contaminated by problematic optical background noise.

The influence of optical parameters on impurity determinations by IR spectroscopy

International Nuclear Information System (INIS)

Lombard, O.J.

1985-01-01

The important role of impurities in semiconductor materials is the subject of continuous research. The concentration of interstitial oxygen impurities in silicon are determined with the aid of infrared spectroscopy. The maximum absorption coefficient of the oxygen absorption peak, centered at 9,06 μm, is determined and the impurity concentration is then calculated using a calibration factor. This procedure was evaluated, paying particular attention to those optical parameters which may influence these impurity determinations. A thorough discussion of the theoretical and experimental aspects of infrared spectroscopy in general is followed by an overview of previous experimental work. This lead to some theoretical analysis regarding the influence of the index of refraction, the index of absorption and multiple reflections in the silicon wafer on impurity determinations. This lead to specific experimental investigations. The influence of the surface morphology of samples on impurity determinations was studied by determining the reflectance of silicon surfaces. It was established that the surface reflectance plays a role and that it must be taken into consideration for accurate impurity concentration determinations. The most accurate values for the absorption coefficient due to oxygen in silicon are calculated. This requires that the surface of the silicon wafers must be highly polished for the formula to be valid. Acceptable values for the absorption coefficient of damaged surfaces are obtained if the uncorrected formula is used. Experimental results may deviate as much as 32% from the real impurity concentration if the wrong formula is used to calculate the absorption coefficient of oxygen in silicon at 9,06 μm

Introgression of chromosome segments from multiple alien species in wheat breeding lines with wheat streak mosaic virus resistance

Science.gov (United States)

Pyramiding of alien-derived Wheat streak mosaic virus (WSMV) resistance and resistance enhancing genes in wheat is a costeffective and environmentally safe strategy for disease control. PCR-based markers and cytogenetic analysis with genomic in situ hybridisation were applied to identify alien chrom...

Near-Field Spectroscopy with Nanoparticles Deposited by AFM

Science.gov (United States)

Anderson, Mark S.

2008-01-01

An alternative approach to apertureless near-field optical spectroscopy involving an atomic-force microscope (AFM) entails less complexity of equipment than does a prior approach. The alternative approach has been demonstrated to be applicable to apertureless near-field optical spectroscopy of the type using an AFM and surface enhanced Raman scattering (SERS), and is expected to be equally applicable in cases in which infrared or fluorescence spectroscopy is used. Apertureless near-field optical spectroscopy is a means of performing spatially resolved analyses of chemical compositions of surface regions of nanostructured materials. In apertureless near-field spectroscopy, it is common practice to utilize nanostructured probe tips or nanoparticles (usually of gold) having shapes and dimensions chosen to exploit plasmon resonances so as to increase spectroscopic-signal strengths. To implement the particular prior approach to which the present approach is an alternative, it is necessary to integrate a Raman spectrometer with an AFM and to utilize a special SERS-active probe tip. The resulting instrumentation system is complex, and the tasks of designing and constructing the system and using the system to acquire spectro-chemical information from nanometer-scale regions on a surface are correspondingly demanding.

Potential Fluctuations and Localization Effects in CZTS Single Crystals, as Revealed by Optical Spectroscopy

Science.gov (United States)

Bleuse, Joël; Ducroquet, Frédérique; Mariette, Henri

2018-03-01

Reports on Cu_2 ZnSn(S_x Se_{1-x} )_4 (CZTSSe) solar cell devices all show an open-circuit voltage lower than expected, especially when compared to CuIn_x Ga_{1-x} (S,Se)_2 devices, which reduces their power efficiency and delays their development. A high concentration of intrinsic defects in CZTSSe, and their stabilization through neutral complex formation, which induces some local fluctuations, are at the origin of local energy shifts in the conduction and valence band edges. The implied band tail in Cu_2 ZnSnS_4 is studied in this work by combining three types of optical spectroscopy data: emission spectra compared to photoluminescence excitation spectroscopy, emission spectra as a function of excitation power, and time-resolved photoluminescence spectra. All these data converge to show that both the bandgap and the band tail of localized states just below are dependent on the degree of order/disorder in the Cu/Zn cation sublattice of the quaternary structure: in the more ordered structures, the bandgap increases by about 50 meV, and the energy range of the band tail is decreased from about 110 to 70 meV.

Spectral studies of ocean water with space-borne sensor SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS

Directory of Open Access Journals (Sweden)

M. Vountas

2007-09-01

Full Text Available Methods enabling the retrieval of oceanic parameter from the space borne instrumentation Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY (SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS are presented. SCIAMACHY onboard ENVISAT measures back scattered solar radiation at a spectral resolution (0.2 to 1.5 nm. The DOAS method was used for the first time to fit modelled Vibrational Raman Scattering (VRS in liquid water and in situ measured phytoplankton absorption reference spectra to optical depths measured by SCIAMACHY. Spectral structures of VRS and phytoplankton absorption were clearly found in these optical depths. Both fitting approaches lead to consistent results. DOAS fits correlate with estimates of chlorophyll concentrations: low fit factors for VRS retrievals correspond to large chlorophyll concentrations and vice versa; large fit factors for phytoplankton absorption correspond with high chlorophyll concentrations and vice versa. From these results a simple retrieval technique taking advantage of both measurements is shown. First maps of global chlorophyll concentrations were compared to the corresponding MODIS measurements with very promising results. In addition, results from this study will be used to improve atmospheric trace gas DOAS-retrievals from visible wavelengths by including these oceanographic signatures.

Time-Resolved Diffuse Optical Spectroscopy and Imaging Using Solid-State Detectors: Characteristics, Present Status, and Research Challenges.

Science.gov (United States)

Alayed, Mrwan; Deen, M Jamal

2017-09-14

Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are emerging non-invasive imaging modalities that have wide spread potential applications in many fields, particularly for structural and functional imaging in medicine. In this article, we review time-resolved diffuse optical imaging (TR-DOI) systems using solid-state detectors with a special focus on Single-Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). These TR-DOI systems can be categorized into two types based on the operation mode of the detector (free-running or time-gated). For the TR-DOI prototypes, the physical concepts, main components, figures-of-merit of detectors, and evaluation parameters are described. The performance of TR-DOI prototypes is evaluated according to the parameters used in common protocols to test DOI systems particularly basic instrumental performance (BIP). In addition, the potential features of SPADs and SiPMs to improve TR-DOI systems and expand their applications in the foreseeable future are discussed. Lastly, research challenges and future developments for TR-DOI are discussed for each component in the prototype separately and also for the entire system.

Optical spectroscopy and microscopy of radiation-induced light-emitting point defects in lithium fluoride crystals and films

Science.gov (United States)

Montereali, R. M.; Bonfigli, F.; Menchini, F.; Vincenti, M. A.

2012-08-01

Broad-band light-emitting radiation-induced F2 and F3+ electronic point defects, which are stable and laser-active at room temperature in lithium fluoride crystals and films, are used in dosimeters, tuneable color-center lasers, broad-band miniaturized light sources and novel radiation imaging detectors. A brief review of their photoemission properties is presented, and their behavior at liquid nitrogen temperatures is discussed. Some experimental data from optical spectroscopy and fluorescence microscopy of these radiation-induced point defects in LiF crystals and thin films are used to obtain information about the coloration curves, the efficiency of point defect formation, the effects of photo-bleaching processes, etc. Control of the local formation, stabilization, and transformation of radiation-induced light-emitting defect centers is crucial for the development of optically active micro-components and nanostructures. Some of the advantages of low temperature measurements for novel confocal laser scanning fluorescence microscopy techniques, widely used for spatial mapping of these point defects through the optical reading of their visible photoluminescence, are highlighted.

Determination of the optical properties of melanin-pigmented human skin equivalents using terahertz time-domain spectroscopy

Science.gov (United States)

Lipscomb, Dawn; Echchgadda, Ibtissam; Peralta, Xomalin G.; Wilmink, Gerald J.

2013-02-01

Terahertz time-domain spectroscopy (THz-TDS) methods have been utilized in previous studies in order to characterize the optical properties of skin and its primary constituents (i.e., water, collagen, and keratin). However, similar experiments have not yet been performed to investigate whether melanocytes and the melanin pigment that they synthesize contribute to skin's optical properties. In this study, we used THz-TDS methods operating in transmission geometry to measure the optical properties of in vitro human skin equivalents with or without normal human melanocytes. Skin equivalents were cultured for three weeks to promote gradual melanogenesis, and THz time domain data were collected at various time intervals. Frequency-domain analysis techniques were performed to determine the index of refraction (n) and absorption coefficient (μa) for each skin sample over the frequency range of 0.1-2.0 THz. We found that for all samples as frequency increased, n decreased exponentially and the μa increased linearly. Additionally, we observed that skin samples with higher levels of melanin exhibited greater n and μa values than the non-pigmented samples. Our results indicate that melanocytes and the degree of melanin pigmentation contribute in an appreciable manner to the skin's optical properties. Future studies will be performed to examine whether these contributions are observed in human skin in vivo.

Major QTL Conferring Resistance to Rice Bacterial Leaf Streak

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

Bacterial leaf streak (BLS) is one of the important limiting factors to rice production in southern China and other tropical and sub-tropical areas in Asia. Resistance to BLS was found to be a quantitative trait and no major resistant gene was located in rice until date. In the present study, a new major quantitative trait locus (QTL) conferring resistance to BLS was identified from a highly resistant variety Dular by the employment of Dular/Balilla (DB) and Dular/IR24 (DI) segregation populations and was designated qBLSR-11-1. This QTL was located between the simple sequence repeat (SSR) markers RM120 and RM441 on chromosome 11 and could account for 18.1-21.7% and 36.3% of the variance in DB and DI populations, respectively. The genetic pattern of rice resistance to BLS was discussed.

Multipurpose 10 in. manipulator-based optical telescope for Omega and the Trident laser facilities