Retroreflectance from a dense distribution of spherical particles

Kuga, Yasuo; Ishimaru, Akira

doi:10.1364/josaa.1.000831

Cited by 652 publications

(285 citation statements)

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“…29 A 3035 keV energy He-beam with square-section (1 mm in diagonal) was used thus taking advantage of the elastic resonance 16 O(a,a) 16 O occurring at this energy 30 and increasing the sensitivity to oxygen concentration by a factor of 23. The samples were kept in vacuum.…”

Section: Materials and Techniquesmentioning

confidence: 99%

“…13,14 This type of scattering has been observed in many different systems; 15,16 such materials are essentially composites consisting of organic dielectric materials and show intense colors and strong reflectance. The corresponding structures can be formally divided into ordered and disordered ones and can be treated as photonic crystals and photonic glass, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Composition, nanostructure, and optical properties of silver and silver-copper lusters

Pradell

Pavlov

Gutiérrez

et al. 2012

Journal of Applied Physics

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Influence of alloy inhomogeneities on the determination by Raman scattering of composition and strain in Si1-xGex/Si(001) layers J. Appl. Phys. 112, 023512 (2012) Plasmon coupling in circular-hole dimers: From separation-to touching-coupling regimes J. Appl. Phys. 112, 013113 (2012) Correlation between reflectivity and resistivity in multi-component metallic systems Appl. Phys. Lett. 101, 011902 (2012) Ultrathin metallic coatings can induce quantum levitation between nanosurfaces Appl. Phys. Lett. 100, 253104 (2012) Transmittance and optical constants of Sr films in the 6-1220eV spectral range J. Appl. Phys. 111, 113533 (2012) Additional information on J. Appl. Phys. Lusters are composite thin layers of coinage metal nanoparticles in glass displaying peculiar optical properties and obtained by a process involving ionic exchange, diffusion, and crystallization. In particular, the origin of the high reflectance (golden-shine) shown by those layers has been subject of some discussion. It has been attributed to either the presence of larger particles, thinner multiple layers or higher volume fraction of nanoparticles. The object of this paper is to clarify this for which a set of laboratory designed lusters are analysed by Rutherford backscattering spectroscopy, transmission electron microscopy, x-ray diffraction, and ultraviolet-visible spectroscopy. Model calculations and numerical simulations using the finite difference time domain method were also performed to evaluate the optical properties. Finally, the correlation between synthesis conditions, nanostructure, and optical properties is obtained for these materials. V C 2012 American Institute of Physics. [http://dx

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Section: Materials and Techniquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Composition, nanostructure, and optical properties of silver and silver-copper lusters

Pradell

Pavlov

Gutiérrez

et al. 2012

Journal of Applied Physics

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“…However, another effect that can cause a brightness surge near zero phase angle, coherent backscatter, was pointed out by Watson [1969] in connection with the scattering of radio waves by plasmas and later by Shkuratov [1988] for planetary regoliths. It was observed experimentally in colloidal suspensions of submicroscopic particles by Kuga and Ishimaru [1984], in planetary analog powders by Hapke and Blewett [1991], and in lunar soil samples by Hapke et al [1993]. In the coherent backscatter opposition effect (CBOE), two portions of a wave that travel the same, multiply scattered path through a regolith, but in opposite directions, combine randomly if the phase angle is large but interfere coherently and positively at near zero phase (see Hapke [1990] for a detailed explanation).…”

Section: Introductionmentioning

confidence: 99%

The wavelength dependence of the lunar phase curve as seen by the Lunar Reconnaissance Orbiter wide‐angle camera

et al. 2012

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[1] The Lunar Reconnaissance Orbiter wide-angle camera measured the bidirectional reflectances of two areas on the Moon at seven wavelengths between 321 and 689 nm and at phase angles between 0°and 120°. It is not possible to account for the phase curves unless both coherent backscatter and shadow hiding contribute to the opposition effect. For the analyzed highlands area, coherent backscatter contributes nearly 40% in the UV, increasing to over 60% in the red. This conclusion is supported by laboratory measurements of the circular polarization ratios of Apollo regolith samples, which also indicate that the Moon's opposition effect contains a large component of coherent backscatter. The angular width of the lunar opposition effect is almost independent of wavelength, contrary to theories of the coherent backscatter which, for the Moon, predict that the width should be proportional to the square of the wavelength. When added to the large body of other experimental evidence, this lack of wavelength dependence reinforces the argument that our current understanding of the coherent backscatter opposition effect is incomplete or perhaps incorrect. It is shown that phase reddening is caused by the increased contribution of interparticle multiple scattering as the wavelength and albedo increase. Hence, multiple scattering cannot be neglected in lunar photometric analyses. A simplified semiempirical bidirectional reflectance function is proposed for the Moon that contains four free parameters and that is mathematically simple and straightforward to invert. This function should be valid everywhere on the Moon for phase angles less than about 120°, except at large viewing and incidence angles close to the limb, terminator, and poles.Citation: Hapke, B., B. Denevi, H. Sato, S. Braden, and M. Robinson (2012), The wavelength dependence of the lunar phase curve as seen by the Lunar Reconnaissance Orbiter wide-angle camera,

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“…Those shadows are visible at large phase angles (the angle between the Sun and view directions), but at zero phase angle they are hidden by the particles that cast them. Coherent backscatter is another physical cause of enhancement of reflectance in the hot spot direction [Kuga and Ishimaru, 1984;Hapke et al, 1993]. It is based on the fact that portions of wave fronts that are multiply scattered within a nonuniform medium and follow the same path, but in opposite directions, combine constructively at zero phase angle.…”

Section: Introductionmentioning

confidence: 99%

Analysis of hot spot directional signatures measured from space

Bréon

2002

J. Geophys. Res.

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[1] Reflectance measurements from the spaceborne Polarization and Directionality of Earth Reflectances (POLDER) instrument are used to analyze the so-called hot spot directional signature in the backscattering direction. The hot spot is measured with an angular resolution better than half a degree using the directional capabilities of the radiometer, with some assumptions on the spatial homogeneity of the surface. The analysis yields the first quantitative observation of the hot spot signature of vegetated surfaces, with such angular resolution. The measurements show that the hot spot reflectance is a function of the phase angle x rather than a function of a parameter Á, often used in hot spot modeling, that quantifies the horizontal distance between Sun and view directions. The observed directional signature is very accurately fitted by a linear ratio of the phase angle, as predicted by a simple theory of radiative transfer within the canopy foliage. Most of the measured hot spot half widths are between 1°and 2°. Some dispersion occurs for the cases belonging to the forest and desert International Geosphere-Biosphere Program (IGBP) classes, in the range 1°to 5°. Theory predicts that the width is independent of wavelength. Our measurements indicate that the widths at 670 and 865 nm are very close, but with a significant scatter in regards to the rather small variability. The distribution of the width as a function of the IGBP surface classification shows a variability within the classes that is larger than between the classes, except for the ''evergreen broadleaf'' class. The hot spot reflectance amplitude is generally on the order of 0.10-0.20 at 865 nm and 0.03-0.18 at 670 nm, although the full range of values is wider. For thick canopies, it may be interpreted in terms of foliage element (leaf ) reflectance. Retrieved values are on the order of 0.4 in the near infrared and in the range 0.05-0.20 at 670 nm. At 440 nm, the amplitude of the signature is very small, as is expected from the small surface reflectance. This confirms that the atmospheric contribution to the reflectance increase at the backscattering direction is negligible.

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Retroreflectance from a dense distribution of spherical particles

Cited by 652 publications

References 10 publications

Composition, nanostructure, and optical properties of silver and silver-copper lusters

Composition, nanostructure, and optical properties of silver and silver-copper lusters

The wavelength dependence of the lunar phase curve as seen by the Lunar Reconnaissance Orbiter wide‐angle camera

Analysis of hot spot directional signatures measured from space

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