Anisotropic reflectance from turbid media I Theory

Neuman, Magnus; Edström, Per

doi:10.1364/josaa.27.001032

Cited by 21 publications

(13 citation statements)

References 18 publications

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“…Paper is a highly randomized dielectric turbid medium with a rough surface and significant anisotropic bulk reflectance [28,29]. The purpose of this work is to deduce if the proposed method, realized by using ordinary printing techniques, can be applied to matte paper.…”

Section: Introductionmentioning

confidence: 99%

Separation of surface and bulk reflectance by absorption of bulk scattered light

et al. 2013

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A method is proposed for separating light reflected from turbid media with a rough surface into a bulk and a surface component. Dye is added to the sample, thereby increasing absorption and canceling bulk scattering. The remaining reflected light is surface reflectance, which can be subtracted from the total reflectance of an undyed sample to obtain the bulk component. The method is applied to paper where the addition of dye is accomplished by inkjet printing. The results show that the bulk scattered light is efficiently canceled, and that both the spectrally neutral surface reflectance and the surface topography of the undyed paper is maintained. The proposed method is particularly suitable for characterization of dielectric, highly randomized materials with significant bulk reflectance and rough surfaces, which are difficult to analyze with existing methods. A reliable separation method opens up for new ways of analyzing, e.g., biological tissues and optical coatings, and is also a valuable tool in the development of more comprehensive reflectance models.

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Section: Introductionmentioning

confidence: 99%

Separation of surface and bulk reflectance by absorption of bulk scattered light

et al. 2013

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“…The determination of the scattering and absorption coefficients in regions of strong absorption is a difficult task because the reflectance of one single sheet does not significantly differ from the reflectance of an opaque pad. New methods based on angle-resolved reflectance measurements might lead to better estimation of the scattering and absorption coefficients (Neuman, Edström 2010a;2010b).…”

Section: Discussionmentioning

confidence: 99%

Limitations in the efficiency of fluorescent whitening agents in uncoated paper

Coppel¹,

Andersson

Edström

et al. 2011

Nordic Pulp &Amp; Paper Research Journal

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SUMMARY:The fluorescence efficiency of one fluorescent whitening agent (FWA) in uncoated and unfilled paper is characterised at different FWA concentrations. An extended Kubelka-Munk model proposed earlier by several authors is applied to quantify the effect on CIE whiteness of light absorption by the FWA in the visible spectrum. At high FWA concentration, chemical interactions slightly modify the quantum efficiency, which then depends on the FWA concentration. This effect has however a negligible effect on the CIE whiteness for FWA concentrations used in practice. Light absorption by the FWA in the visible spectrum is shown to be the main cause of greening (a shift of the chromaticity towards green) and saturation of the fluorescence effect. With increasing FWA concentration, the positive effect of fluorescence is neutralised by the reduction of the reflected radiance factor in the violet-blue region of the spectrum induced by a significant absorption by the FWA in that region. The effect is well predicted with a simple extension of the Kubelka-Munk model for light scattering in paper.

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“…This is not correct if light can be multiply scattered, which is the case for paper media. When multiple scattering is considered the framework of general RT theory is necessary since the KM approach to the radiative transfer problem has been shown insufficient [19,20].…”

Section: δV δUmentioning

confidence: 99%

Point spreading in turbid media with anisotropic single scattering

Neuman¹,

Coppel²,

Edström³

2011

Opt. Express

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This is the published version of a paper published in Optics Express.Citation for the original published paper (version of record): Abstract: Point spreading is investigated using general radiative transfer theory. We find that the single scattering anisotropy plays a significant role for point spreading together with the medium mean free path, single scattering albedo and thickness. When forward scattering dominates, the light will on average undergo more scattering events to give a specific optical response in reflectance measurements. This will significantly increase point spreading if the medium is low absorbing with large mean free path.Any fundamental and generic model of point spreading must capture the dependence on all of these medium characteristics.

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Anisotropic reflectance from turbid media I Theory

Cited by 21 publications

References 18 publications

Separation of surface and bulk reflectance by absorption of bulk scattered light

Separation of surface and bulk reflectance by absorption of bulk scattered light

Limitations in the efficiency of fluorescent whitening agents in uncoated paper

Point spreading in turbid media with anisotropic single scattering

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