Topics in Particle and Dispersion Science

Attenuation of light: Effect of single scattering

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Fig. 2. Schematic illustration of the effect of elastic single scattering (see Single and multiple scattering) on transmission of light through a medium. The white arrows symbolically represent the photon paths. A path should not be interpreted as a localized photon trajectory because photons of a plane wave have infinite extent in a direction orthogonal to the propagation direction. Fly the mouse over a path link in the text below to show the relevant path alone. The source (S) is unidirectional and the detector (D) is sensitive only to radiation incident along a direction indicated by white arrows emerging from S.

It is assumed here that the probability for the photon to be scattered more than once is negligible in this a medium. Photons may pass through the medium unscattered (path 1). A photon experiencing a scattering event (for example, path 3) terminates its path at the event's location. However, another photon is essentially immediately re-emitted by the center, at the same wavelength as that of the incident photon (elastic scattering), but in an unpredictable direction. Such a photon may (path 2) or may not (path 3) reach the detector depending on the source-medium-detector system geometry. However, if the photon reaches the detector while arriving from a direction outside the range of directions accepted by the detector, it does not contribute to the detector output (path 2), hence the last leg of this path is differentiated from the others by making it dashed. The probability distribution of path lengths, L, between the light source and an absorption event is p(L) = exp(-bL), where b is the scattering coefficient (Mobley CD 1994, Ch. 6). The probability of scattering into a certain range of directions, relative to the direction of the incident photon, depends on the single-scattering phase function. See also effects of absorption and multiple scattering on transmission of light by a medium.

CITATION: Swanson N. L., Jonasz M. 2007. Attenuation of light: Contributing processes - effect of single scattering (www.tpdsci.com/Tpc/AtnCtbFigSSca.php). In: Top. Part. Disp. Sci. (www.tpdsci.com).

HISTORY: Published: 21-Nov-2007 Modified: 04-Jun-2010 Peer-reviewed: 22-Dec-2007

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