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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Scattered-light uniformity imager for diagnosing laser absorption asymmetries on OMEGA

Light scattered from a target is the most-direct measurement for diagnosing laser absorption in a direct-drive implosion. Observations from OMEGA implosions show much larger scattered-light asymmetries than predictions. A new instrument has been developed to absolutely measure the scattered-light intensity and nonuniformity for the purpose of diagnosing the asymmetry. The scattered-light uniformity imager (SLUI) diagnostic records the variation in scattered-light intensity over a transmission diffuser using a charge-coupled device (CCD)/lens assembly. At the standard operating position, an 11.3° (f/2.5) cone of light is collected. A stray light baffle, debris shield, and antireflection absorbing filter are also incorporated into the diagnostic payload inserted into the target chamber. The imaging parts of the diagnostic (light baffle, vacuum window, filters, lens, and CCD camera) are located outside the target chamber. Five SLUIs have been built and deployed in OMEGA’s ten-inch manipulator diagnostic ports, covering almost 5% of the emission surface, enabling an absolute scattered-light measurement should be within a few percent of the global average. Each SLUI system is calibrated offline, providing absolute scattered-light intensity measurements. Based on the measured point spread function, each diffuser plate image contains over 20 000 independent scattered-light absolute-intensity measurements of the variation over the collection cone. SLUI provides a platform to study scattered light and absorption asymmetries, and their possible sources.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

A novel full-angle scanning light scattering profiler to quantitatively evaluate forward and backward light scattering from intraocular lenses

Glare, glistenings, optical defects, dysphotopsia, and poor image quality are a few of the known deficiencies of intraocular lenses (IOLs). All of these optical phenomena are related to light scatter. However, the specific direction that light scatters makes a critical difference between debilitating glare and a slightly noticeable decrease in image quality. Consequently, quantifying the magnitude and direction of scattered light is essential to appropriately evaluate the safety and efficacy of IOLs. In this study, we introduce a full-angle scanning light scattering profiler (SLSP) as a novel approach capable of quantitatively evaluating the light scattering from IOLs with a nearly 360° view. The SLSP method can simulate in situ conditions by controlling the parameters of the light source including angle of incidence. This testing strategy will provide a more effective nonclinical approach for the evaluation of IOL light scatter.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

LIGHT SCATTERING BY FRACTAL DUST AGGREGATES. I. ANGULAR DEPENDENCE OF SCATTERING

In protoplanetary disks, micron-sized dust grains coagulate to form highly porous dust aggregates. Because the optical properties of these aggregates are not completely understood, it is important to investigate how porous dust aggregates scatter light. In this study, the light scattering properties of porous dust aggregates were calculated using a rigorous method, the T -matrix method, and the results were then compared with those obtained using the Rayleigh–Gans–Debye (RGD) theory and Mie theory with the effective medium approximation (EMT). The RGD theory is applicable to moderately large aggregates made of nearly transparent monomers. This study considered two types of porous dust aggregates—ballistic cluster–cluster agglomerates (BCCAs) and ballistic particle–cluster agglomerates. First, the angular dependence of the scattered intensity was shown to reflect the hierarchical structure of dust aggregates; the large-scale structure of the aggregates is responsible for the intensity at small scattering angles, and their small-scale structure determines the intensity at large scattering angles. Second, it was determined that the EMT underestimates the backward scattering intensity by multiple orders of magnitude, especially in BCCAs, because the EMT averages the structure within the size of the aggregates. It was concluded that the RGD theory is a very useful method for calculating the optical properties of BCCAs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Light scattering study of highly absorptive, non-fractal, hematite aggregates

In this paper, we present measurements of the scattered light intensity by aerosolized hematite aggregate particles. The measurements were made at a wavelength of 532 nm in the scattering angle range from 0.32° to 157°. Hematite has high values of the real and imaginary parts of the refractive index m = n + iκ = 3 + i0.5 at the studied wavelength. Scanning electron micrographs (SEM) indicated that the particles were aggregates whereas the optical microscope pictures showed that the aerosol had a bimodal distribution with effective mean diameters of roughly 1 and 10 µm. This is consistent with the light scattering results which displayed two Guinier regimes. The aggregates were composed of smaller grains with an approximate size of 200 nm. Ultra Small-Angle X-ray Scattering (USAXS) indicate that the aggregates were uniform and non-fractal. Mie calculations for a sphere equivalent to the aggregate size were compared to the experimentally observed results. The observed results showed an enhanced backscattering, whereas the Mie calculations did not due to the large imaginary part of the refractive index. Hematite aggregates were simulated by assuming they were composed of spherical monomers inside a spherical volume. Then the light scattering was calculated using the T-matrix method for these simulated aggregates. The calculated results show an enhanced backscattering. We present a dimensional analysis to estimate the extent of multiple scattering within the aggregate and find a correlation between the average number of scattering events within the aggregate and the enhancement in the backscattering.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Galactic Latitude Dependence of Near-infrared Diffuse Galactic Light: Thermal Emission or Scattered Light?

Near-infrared (IR) diffuse Galactic light (DGL) consists of scattered light and thermal emission from interstellar dust grains illuminated by the interstellar radiation field (ISRF). At 1.25 and 2.2 μm, a recent observational study shows that intensity ratios of the DGL to interstellar 100 μm dust emission steeply decrease toward high Galactic latitudes (b). In this paper, we investigate the origin(s) of the b-dependence on the basis of models of thermal emission and scattered light. Combining a thermal emission model with the regional variation of the polycyclic aromatic hydrocarbon abundance observed with Planck, we show that the contribution of the near-IR thermal emission component to the observed DGL is lower than ∼20%. We also examine the b-dependence of the scattered light, assuming a plane–parallel Galaxy with smooth distributions of the ISRF and dust density along the vertical direction, and assuming a scattering phase function according to a recently developed model of interstellar dust. We normalize the scattered light intensity to the 100 μm intensity corrected for deviation from the cosecant-b law according to the Planck observation. As the result, the present model that considers the b-dependence of dust and the ISRF properties can account for the observed b-dependence of the near-IR DGL. However, the uncertainty in the correction for the 100 μm emission is large, and other normalizing quantities may be appropriate for a more robust analysis of the DGL.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

FIRST SCATTERED-LIGHT IMAGE OF THE DEBRIS DISK AROUND HD 131835 WITH THE GEMINI PLANET IMAGER

We present the first scattered-light image of the debris disk around HD 131835 in the H band using the Gemini Planet Imager. HD 131835 is a ∼15 Myr old A2IV star at a distance of ∼120 pc in the Sco-Cen OB association. We detect the disk only in polarized light and place an upper limit on the peak total intensity. No point sources resembling exoplanets were identified. Compared to its mid-infrared thermal emission, in scattered light the disk shows similar orientation but different morphology. The scattered-light disk extends from ∼75 to ∼210 AU in the disk plane with roughly flat surface density. Our Monte Carlo radiative transfer model can describe the observations with a model disk composed of a mixture of silicates and amorphous carbon. In addition to the obvious brightness asymmetry due to stronger forward scattering, we discover a weak brightness asymmetry along the major axis, with the northeast side being 1.3 times brighter than the southwest side at a 3σ level.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Particle-modified polymeric cladding on glass optical fibers enhances radial light scattering

Radially light-emitting optical fibers are of increasing interest for applications in medicine, visible aesthetics, and environmental remediation. Optical fibers contain a light guiding core coated by protective polymer layers (cladding and coating), which assure both the strength and flexibility of the optical fiber. This paper examines the feasibility of scattering light radially from fibers by loading the fiber cladding with particle scattering centers during the optical fiber fabrication process. This work uses an in-line full-scale scalable facility to coat the fibers and control the polymer cladding and silica sphere. Loadings up to 2.0 wt. % of 500 nm silica particles on the cladding of the optical fiber led to an average of 80 times higher scattering for visible light and up to 30 times higher in the UVA wavelength range compared against cladding without particle modifications. We report this study illustrated the feasibility of fabricating broadband light scattering optical fibers for use with modified polymeric cladding.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

Angle-resolved spin wave band diagrams of square antidot lattices studied by Brillouin light scattering

The Brillouin light scattering technique has been exploited to study the angle-resolved spin wave band diagrams of squared Permalloy antidot lattice. Frequency dispersion of spin waves has been measured for a set of fixed wave vector magnitudes, while varying the wave vector in-plane orientation with respect to the applied magnetic field. The magnonic band gap between the two most dispersive modes exhibits a minimum value at an angular position, which exclusively depends on the product between the selected wave vector magnitude and the lattice constant of the array. The experimental data are in very good agreement with predictions obtained by dynamical matrix method calculations. The presented results are relevant for magnonic devices where the antidot lattice, acting as a diffraction grating, is exploited to achieve multidirectional spin wave emission.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Probing the light scattering properties of insulin secretory granules in single live cells

Light scattering was recently demonstrated to serve as an intrinsic indicator for pancreatic islet cell mass and secretion. The insulin secretory granule (ISG), in particular, was proposed to be a reasonable candidate as the main intracellular source of scattered light due to the densely-packed insulin semi-crystal in the granule lumen. This scenario, if confirmed, would in principle open new perspectives for label-free single-granule imaging, tracking, and analysis. Contrary to such expectations, here we demonstrate that ISGs are not a primary source of scattering in primary human β-cells, as well as in immortalized β-like cells, quantitatively not superior to other intracellular organelles/structures, such as lysosomes and internal membranes. This result is achieved through multi-channel imaging of scattered light along with fluorescence arising from selectively-labelled ISGs. Co-localization and spatiotemporal cross-correlation analysis is performed on these signals, and compared among different cell lines. Obtained results suggest a careful re-thinking of the possibility to exploit intrinsic optical properties originating from ISGs for single-granule imaging purposes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Stimulated concentration (diffusion) light scattering on nanoparticles in a liquid suspension

A nonlinear growth of the light scattering intensity has been observed and the frequency shift of the spectral line of scattered light has been measured in light backscattered in suspensions of diamond and latex nanoparticles in water. The shift corresponds to the HWHM of the line of spontaneous scattering on particles. We may conclude that there exists stimulated concentration (diffusion) light scattering on variations of the particle concentration, which is also called the stimulated Mie scattering. In a fibre probe scheme, the growth of the shift of the scattered spectral line is observed with an increase in the exciting beam power. The variation of the frequency shift with an increase in the exciting power is explained by convection in liquid. (light scattering)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Probing the Quantum State of a 1D Bose Gas Using Off-Resonant Light Scattering

We present a theoretical treatment of coherent light scattering from an interacting 1D Bose gas at finite temperatures. We show how this can provide a nondestructive measurement of the atomic system states. The equilibrium states are determined by the temperature and interaction strength, and are characterized by the spatial density-density correlation function. We show how this correlation function is encoded in the angular distribution of the fluctuations of the scattered light intensity, thus providing a sensitive, quantitative probe of the density-density correlation function and therefore the quantum state of the gas.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Ultrafast image-based dynamic light scattering for nanoparticle sizing

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

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Influence of low concentrations of scatterers and signal detection time on the results of their measurements using dynamic light scattering

The influence of limited detection time on the form of the autocorrelation function (ACF) has been analysed for measurements in low-concentration suspensions by dynamic light scattering with allowance for the spatial distribution of the laser beam intensity. The general view of the ACF of the scattered light intensity is obtained for a Gaussian beam and a finite measurement time. The results of the theoretical analysis are compared with the experimental data and the results obtained by computer simulation of the scattering from an ensemble of particles involved in Brownian motion in a Gaussian beam. It is shown that, in the case of low suspension concentrations, the ACF distortions related to finite detection time lead to underestimation of the particle sizes and occurrence of an artefact peak in the distribution of the scattered light intensity over scatterer sizes. An empirical dependence of the measured size of particles on their number in the scattering volume is found. (light scattering)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Enhanced efficiency of large-area dye-sensitized solar cells by light-scattering effect using multilayer TiO2 photoanodes

Highlights: • DSSCs with an active area of 100.6 cm{sup 2} and light-scattering layers are fabricated. • The light-scattering effect is shown to enhance the light absorption in the red part of the solar spectrum. • The light-scattering effect is more important than the dye adsorption capacity for TiO{sub 2} photoanodes with same thickness. • The highest power conversion efficiency of 7.52% has been obtained by the DSSC with optimized conditions. - Abstract: In order to reduce the usage of photoactive dye and improve light harvesting by the photoanode of dye-sensitized solar cells (DSSCs), TiO{sub 2} scatting layers were introduced. We have investigated the light-scattering effect in large-area DSSCs with an active area of 100.6 cm{sup 2} that contain diffusing or reflective layers. The result shows that the light-scattering effect is more important than the dye adsorption capacity for the light harvesting property of TiO{sub 2} photoanodes with same thickness, and the light-scattering effect is shown to enhance the light absorption in the red part of the solar spectrum. The highest power conversion efficiency of 7.52% has been obtained by the cell with optimized high dye adsorption layer and high light-scattering layer, which is 9.5% higher than that of the cell without the light-scattering layer (6.87%).

14 SOLAR ENERGY↗
DOE OSTI2017

Growth and characterization of ZnO nanostructure on TiO{sub 2}-ZnO films as a light scattering layer for dye sensitized solar cells

Graphical abstract: Pictorial representation of (a,b) electron transport path in nanoparticles and nanorods (red arrow marks), and (c,d) light scattering effect on TiO2-ZnO film without and with light scattering layer (blue, red and green arrow marks are incident, transmit and scattering light, respectively). - Abstract: In the present work, we studied the effect of light scattering layer on the performance of DSSCs. TiO{sub 2}-ZnO thin films were coated onto FTO glass substrate by spin coating technique as a photoanode for DSSCs. ZnO nanorods with flower structures were potentiostatically grown on TiO{sub 2}-ZnO films at various potentials from −1.1 to 1–1.3 V as a light scattering layer. XRD patterns reveal that as the deposition potentials increase the growth of ZnO nanorods increases along with (101) plane orientation. FE-SEM images display agglomerated grains and nanorods with flower structures for TiO{sub 2}-ZnO film, and ZnO has grown on TiO{sub 2}-ZnO film at a deposition potential of −1.3 V. UV–vis spectra confirm the TiO{sub 2}-ZnO with ZnO nanorods having a higher light scattering effect, absorbance and dye loading than that of another film. The efficiency of the DSSCs consisting of without and with scattering layer is estimated to be 0.79 and 1.81%, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The Scattered Light Time-history Diagnostic suite at the National Ignition Facility

The Scattered Light Time-history Diagnostic (SLTD) is being implemented at the National Ignition Facility (NIF) to greatly expand the angular coverage of absolute scattered-light measurements for direct- and indirect-drive inertial confinement fusion (ICF) experiments. The SLTD array will ultimately consist of 15 units mounted at a variety of polar and azimuthal angles on the NIF target chamber, complementing the existing NIF backscatter suite. Each SLTD unit collects and diffuses scattered light onto a set of three optical fibers, which transport the light to filtered photodiodes to measure scattered light in different wavelength bands: stimulated Brillouin scattering (350 nm–352 nm), stimulated Raman scattering (430 nm–760 nm), and ω/2 (695 nm–745 nm). SLTD measures scattered light with a time resolution of ~1 ns and a signal-to-noise ratio of up to 500. Currently, six units are operational and recording data. Measurements of the angular dependence of scattered light will strongly constrain models of laser energy coupling in ICF experiments and allow for a more robust inference of the total laser energy coupled to implosions.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

A mobile system for a comprehensive online-characterization of nanoparticle aggregates based on wide-angle light scattering and laser-induced incandescence

A mobile demonstrator for the comprehensive online-characterization of gas-borne nanoparticle aggregates is presented. Two optical measurement techniques are combined, both utilizing a pulsed Nd:YAG laser as light source. Aggregate size and fractal dimension are measured by Wide-Angle Light Scattering (WALS). An ellipsoidal mirror images elastically scattered light from scattering angles between 10° and 165° onto a CCD-camera chip resulting in an almost complete scattering diagram with high angular resolution. Primary particle size and volume fraction are measured by time-resolved Laser-Induced Incandescence (TiRe-LII). Here, particles are heated up to about 3000 K by the short laser pulse, the enhanced thermal radiation signal is detected with gated photomultiplier tubes. Analysis of the signal decay time and maximum LII-signal allows for the determination of primary particle diameter and volume fraction. The performance of the system is demonstrated by combined measurements on soot nanoparticle aggregates from a soot aerosol generator. Particle and aggregate sizes are varied by using different equivalence ratios of the combustion in the generator. Soot volume fraction can be adjusted by different levels of dilution with air. Online-measurements were carried out demonstrating the favorable performance of the system and the potential for industrial applications such as process control and product development. The particle properties obtained are confirmed through transmission electron microscopy analysis on representative samples.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗