Character of the opposition effect and negative polarization

Pieters, Carle M.; Shkuratov, Yu. G.; Stankevich, D. G.

Photometric and polarimetric properties at small phase angles were measured for silicates with controlled surface properties in order to distinguish properties that are associated with surface reflection from those that are associated with multiple scattering from internal grain boundaries. These data provide insight into the causes and conditions of photometric properties observed at small phase angles for dark bodies of the solar system. Obsidian was chosen to represent a silicate dielectric with no internal scattering boundaries. Because obsidian is free of internal scatterers, light reflected from both the rough and smooth obsidian samples is almost entirely single and multiple Fresnel reflections form surface facets with no body component. Surface structure alone cannot produce an opposition effect. Comparison of the obsidian and basalt results indicates that for an opposition effect to occur, surface texture must be both rough and contain internal scattering interfaces. Although the negative polarization observed for the obsidian samples indicates single and multiple reflections are part of negative polarization, the longer inversion angle of the multigrain inversion samples implies that internal reflections must also contribute a significant negative polarization component.

Document ID

19920001615

Acquisition Source

Legacy CDMS

Document Type

Other

Authors

Date Acquired

September 6, 2013

Publication Date

June 1, 1991

Publication Information

Publication: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990

Subject Category

Accession Number

92N10833

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Public

Work of the US Gov. Public Use Permitted.

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